Saturday, May 20, 2023

Project Neptune 100 : the Science, with Aquanaut, Dr. Dituri

This video covers some of the science behind Dr. Dituri's ground breaking and historic research mission beginning on March 1st, 2023.
He will spend 100 consecutive days under the sea in the Jules Undersea Habitat conducting unique scientific experiments on the effects on the Human body after exposure to elevated partial pressures of Oxygen while at depth over extended periods of time (100 Days).
From BBC by Madeline Halpert

A US researcher has broken the record for the longest time spent living underwater without depressurisation.

Joseph Dituri has spent more than 74 days at the bottom of a 30ft-deep lagoon in Key Largo, Florida.

And he does not have plans to stop yet. 
On Sunday, he said he would stay in Jules' Undersea Lodge for at least 100 days.
"The curiosity for discovery has led me here," he said.
"My goal from day one has been to inspire generations to come, interview scientists who study life undersea and learn how the human body functions in extreme environments," he added.

The previous record for most days spent living underwater at ambient pressure - 73 - was established by two professors in 2014 in the same Key Largo lodge.

Unlike a submarine, the lodge does not use technology to adjust for the increased underwater pressure.

Prof Dituri - who goes by the nickname Dr Deep Sea - began his journey on 1 March at Jules' Undersea Lodge, a small room that sits at the bottom of a lagoon in the Florida Keys.

It is named after Jules Verne, who wrote the well-known sci-fi book 20,000 Leagues Under the Sea.

For the project, called Project Neptune 100, the University of South Florida professor is studying how the human body reacts to long-term exposure to extreme pressure.

Researchers are studying the 55-year-old's health, as well as the psychological effects of being isolated and confined for so long, by running a series of medical tests.

But his time underwater has not kept him from his professorial duties. Prof Dituri - who also served in the Navy for 28 years - is teaching his biomedical engineering classes online while he lives in the lagoon, according to the University of South Florida.

To keep busy, the professor wakes up at 05:00 each day to exercise.
He stays full by reportedly eating protein-heavy meals such as eggs and salmon that he can keep warm with his microwave.

And while his underwater stay has proven ground-breaking, he is excited to get back to some above-ground activities.
"The thing that I miss the most about being on the surface is literally the sun," he told the Associated Press.

Links :

Friday, May 19, 2023

The mystery of fish deaths in a Foul Chartreuse Sea

With the right combination of nutrients, light, and temperature, cyanobacteria can reproduce quickly or “bloom.” 
Photo by NASA

Hakai by Saima Sidik

Researchers in Kotzebue, Alaska, are investigating why their town is increasingly playing host to harmful cyanobacteria.

Dead fish were everywhere, speckling the beach near town and extending onto the surrounding coastline.
The sheer magnitude of the October 2021 die-off, when hundreds, possibly thousands, of herring washed up, is what sticks in the minds of the residents of Kotzebue, Alaska.
Fish were “literally all over the beaches,” says Bob Schaeffer, a fisherman and elder from the Qikiqtaġruŋmiut tribe.

Despite the dramatic deaths, there was no apparent culprit.
“We have no idea what caused it,” says Alex Whiting, the environmental program director for the Native Village of Kotzebue.
He wonders if the die-off was a symptom of a problem he’s had his eye on for the past 15 years: blooms of toxic cyanobacteria, sometimes called blue-green algae, that have become increasingly noticeable in the waters around this remote Alaska town.

Kotzebue sits about 40 kilometers north of the Arctic Circle, on Alaska’s western coastline.
Before the Russian explorer Otto von Kotzebue had his name attached to the place in the 1800s, the region was called Qikiqtaġruk, meaning “place that is almost an island.” One side of the 2-kilometer-long settlement is bordered by Kotzebue Sound, an offshoot of the Chukchi Sea, and the other by a lagoon.
Planes, boats, and four-wheelers are the main modes of transportation.
The only road out of town simply loops around the lagoon before heading back in.

Kotzebue, Alaska, about 40 kilometers north of the Arctic Circle, is in the Qikiqtaġruk region and home to the Qikiqtaġruŋmiut tribe.
Photo by Peace Portal Photo/Alamy Stock Photo

In the middle of town, the Alaska Commercial Company sells food that’s popular in the lower 48—from cereal to apples to two-bite brownies—but the ocean is the real grocery store for many people in town.
Alaska Natives, who make up about three-quarters of Kotzebue’s population, pull hundreds of kilograms of food out of the sea every year.
Kotzebue Harbor with the GeoGarage platform (NOAA raster chart)

“We’re ocean people,” Schaeffer tells me.
The two of us are crammed into the tiny cabin of Schaeffer’s fishing boat in the just-light hours of a drizzly September 2022 morning.
We’re motoring toward a water-monitoring device that’s been moored in Kotzebue Sound all summer.
On the bow, Ajit Subramaniam, a microbial oceanographer from Columbia University, New York, Whiting, and Schaeffer’s son Vince have their noses tucked into upturned collars to shield against the cold rain.
We’re all there to collect a summer’s worth of information about cyanobacteria that might be poisoning the fish Schaeffer and many others depend on.

Huge colonies of algae are nothing new, and they’re often beneficial.
In the spring, for example, increased light and nutrient levels cause phytoplankton to bloom, creating a microbial soup that feeds fish and invertebrates.
But unlike many forms of algae, cyanobacteria can be dangerous.
Some species can produce cyanotoxins that cause liver or neurological damage, and perhaps even cancer, in humans and other animals.

Many communities have fallen foul of cyanobacteria.
Although many cyanobacteria can survive in the marine environment, freshwater blooms tend to garner more attention, and their effects can spread to brackish environments when streams and rivers carry them into the sea.
In East Africa, for example, blooms in Lake Victoria are blamed for massive fish kills.
People can also suffer: in an extreme case in 1996, 26 patients died after receiving treatment at a Brazilian hemodialysis center, and an investigation found cyanotoxins in the clinic’s water supply.
More often, people who are exposed experience fevers, headaches, or vomiting.

When phytoplankton blooms decompose, whole ecosystems can take a hit.
Rotting cyanobacteria rob the waters of oxygen, suffocating fish and other marine life.
In the brackish waters of the Baltic Sea, cyanobacterial blooms contribute to deoxygenation of the deep water and harm the cod industry.
In the 45,000 square mile Chesapeake Bay, the country’s largest estuary, nitrogen and phosphorus from wastewater treatment plants, and urban and agricultural run-off is continuously suffocating marine life. “What happens in the Chesapeake Bay is not only important to our residents, but it also impacts seafood industries, recreation and commercial anglers all along the Atlantic Coast,” says Allison Colden, a senior fisheries scientist at the Chesapeake Bay Foundation, an independent conservation organization.
Despite decades of clean up efforts, and evolving regulations from the Environmental Protection Agency, the bay remains in a critical state.
To make matters worse, climate change is compounding the region’s problems.
Increased rainfall, which flushes more nutrients into the bay, and warming water temperatures is making it harder to reverse the damage already done to the bay.

As climate change reshapes the Arctic, nobody knows how—or if—cyanotoxins will affect Alaskan people and wildlife.
“I try not to be alarmist,” says Thomas Farrugia, coordinator of the Alaska Harmful Algal Bloom Network, which researches, monitors, and raises awareness of harmful algal blooms around the state.
“But it is something that we, I think, are just not quite prepared for right now.” Whiting and Subramaniam want to change that by figuring out why Kotzebue is playing host to cyanobacterial blooms and by creating a rapid response system that could eventually warn locals if their health is at risk.

Whiting’s cyanobacteria story started in 2008.
One day while riding his bike home from work, he came across an arresting site: Kotzebue Sound had turned chartreuse, a color unlike anything he thought existed in nature.
His first thought was: Where’s this paint coming from?

The story of cyanobacteria on this planet goes back about 1.9 billion years, however.
As the first organisms to evolve photosynthesis, they’re often credited with bringing oxygen to Earth’s atmosphere, clearing the path for complex life forms such as ourselves.

Over their long history, cyanobacteria have evolved tricks that let them proliferate wildly when shifts in conditions such as nutrient levels or salinity kill off other microbes.
“You can think of them as sort of the weedy species,” says Raphael Kudela, a phytoplankton ecologist at the University of California, Santa Cruz.
Most microbes, for example, need a complex form of nitrogen that is sometimes only available in limited quantities to grow and reproduce, but the predominant cyanobacteria in Kotzebue Sound can use a simple form of nitrogen that’s found in virtually limitless quantities in the air.

Cyanotoxins are likely another tool that help cyanobacteria thrive, but researchers aren’t sure exactly how toxins benefit these microbes.
Some scientists think they deter organisms that eat cyanobacteria, such as bigger plankton and fish.
Hans Paerl, an aquatic ecologist from the University of North Carolina at Chapel Hill, favors another hypothesis: that toxins shield cyanobacteria from the potentially damaging astringent byproducts of photosynthesis.

Around the time when Kotzebue saw its first bloom, scientists were realizing that climate change would likely increase the frequency of cyanobacterial blooms, and what’s more, that blooms could spread from fresh water—long the focus of research—into adjacent brackish water.
Kotzebue Sound’s blooms probably form in a nearby lake before flowing into the sea.

The latest science on cyanobacteria, however, had not reached Kotzebue in 2008.
Instead, officers from the Alaska Department of Fish and Game tested the chartreuse water for petroleum and its byproducts.
The tests came back negative, leaving Whiting stumped.
“I had zero idea,” he says.
It was biologist Lisa Clough, then from East Carolina University and now with the National Science Foundation, with whom Whiting had previously collaborated, who suggested he consider cyanobacteria.
The following year, water sample analysis confirmed she was correct.

In 2017, Subramaniam visited Kotzebue as part of a research team studying sea ice dynamics.
When Whiting learned that Subramaniam had a long-standing interest in cyanobacteria, “we just immediately clicked,” Subramaniam says.
Alex Whiting, the environmental program director for the Native Village of Kotzebue, left, and Ajit Subramaniam, a microbial oceanographer from Columbia University, New York, right, prepare water-monitoring equipment for deployment. 
Photo by Saima Sidik

The 2021 fish kill redoubled Whiting and Subramaniam’s enthusiasm for understanding how Kotzebue Sound’s microbial ecosystem could affect the town.
A pathologist found damage to the dead fish’s gills, which may have been caused by the hard, spiky shells of diatoms (a type of algae), but the cause of the fish kill is still unclear.
With so many of the town’s residents depending on fish as one of their food sources, that makes Subramaniam nervous.
“If we don’t know what killed the fish, then it’s very difficult to address the question of, Is it safe to consume?” he says.

I watch the latest chapter of their collaboration from a crouched position on the deck of Schaeffer’s precipitously swaying fishing boat.
Whiting reassures me that the one-piece flotation suit I’m wearing will save my life if I end up in the water, but I’m not keen to test that theory.
Instead, I hold onto the boat with one hand and the phone I’m using to record video with the other while Whiting, Subramaniam, and Vince Schaeffer haul up a white and yellow contraption they moored in the ocean, rocking the boat in the process.
Finally, a metal sphere about the diameter of a hula hoop emerges.
From it projects a meter-long tube that contains a cyanobacteria sensor.

The sensor allows Whiting and Subramaniam to overcome a limitation that many researchers face: a cyanobacterial bloom is intense but fleeting, so “if you’re not here at the right time,” Subramaniam explains, “you’re not going to see it.” In contrast to the isolated measurements that researchers often rely on, the sensor had taken a reading every 10 minutes from the time it was deployed in June to this chilly September morning.
By measuring levels of a fluorescent compound called phycocyanin, which is found only in cyanobacteria, they hope to correlate these species’ abundance with changes in water qualities such as salinity, temperature, and the presence of other forms of plankton.

Whiting, Subramaniam, and Vince Schaeffer, son of the boat’s captain, Bob Schaeffer, deploy the water-monitoring equipment. Information gathered from the device will help determine the conditions in which cyanobacteria tend to bloom.
Photo by Saima Sidik
Researchers are enthusiastic about the work because of its potential to protect the health of Alaskans, and because it could help them understand why blooms occur around the world.
“That kind of high resolution is really valuable,” says Malin Olofsson, an aquatic biologist from the Swedish University of Agricultural Sciences, who studies cyanobacteria in the Baltic Sea.
By combining phycocyanin measurements with toxin measurements, the scientists hope to provide a more complete picture of the hazards facing Kotzebue, but right now Subramaniam’s priority is to understand which species of cyanobacteria are most common and what’s causing them to bloom.

Farrugia, from the Alaska Harmful Algal Bloom Network, is excited about the possibility of using similar methods in other parts of Alaska to gain an overall view of where and when cyanobacteria are proliferating.
Showing that the sensor works in one location “is definitely the first step,” he says.

Understanding the location and potential source of cyanobacterial blooms is only half the battle; the other question is what to do about them.
In the Baltic Sea, where fertilizer runoff from industrial agriculture has exacerbated blooms, neighboring countries have put a lot of effort into curtailing that runoff—and with success, Olofsson says.
Kotzebue is not in an agricultural area, however, and instead some scientists have hypothesized that thawing permafrost may release nutrients that promote blooms.
There’s not much anyone can do to prevent this, short of reversing the climate crisis.
Some chemicals, including hydrogen peroxide, show promise as ways to kill cyanobacteria and bring temporary relief from blooms without affecting ecosystems broadly, but so far chemical treatments haven’t provided permanent solutions.

Instead, Whiting is hoping to create a rapid response system so he can notify the town if a bloom is turning water and food toxic.
But this will require building up Kotzebue’s research infrastructure.
At the moment, Subramaniam prepares samples in the kitchen at the Selawik National Wildlife Refuge’s office, then sends them across the country to researchers, who can take days, sometimes even months, to analyze them.
To make the work safer and faster, Whiting and Subramaniam are applying for funding to set up a lab in Kotzebue and possibly hire a technician who can process samples in-house.
Getting a lab is “probably the best thing that could happen up here,” says Schaeffer.
Subramaniam is hopeful that their efforts will pay off within the next year.

In the meantime, interest in cyanobacterial blooms is also popping up in other regions of Alaska.
Emma Pate, the training coordinator and environmental planner for the Norton Sound Health Corporation, started a monitoring program after members of local tribes noticed increased numbers of algae in rivers and streams.
In Utqiaġvik, on Alaska’s northern coast, locals have also started sampling for cyanobacteria, Farrugia says.

Whiting sees this work as filling a critical hole in Alaskans’ understanding of water quality.
Regulatory agencies have yet to devise systems to protect Alaskans from the potential threat posed by cyanobacteria, so “somebody needs to do something,” he says.
“We can’t all just be bumbling around in the dark waiting for a bunch of people to die.”
Perhaps this sense of self-sufficiency, which has let Arctic people thrive on the frozen tundra for millennia, will once again get the job done.

Links :

Thursday, May 18, 2023

Tonga volcano eruption triggered ‘mega-tsunami’

Tsunami simulations for the repetitive blasts of HTHH. 
Credit: Steven N. Ward - Institute of Geophysics and Planetary Physics, University of California Santa Cruz, U.S.A.

From Nature by Gemma Conroy 

Detailed analysis of the January 2022 event shows how underwater blasts generated huge waves that battered coastlines throughout the island nation.

The events following last year’s massive eruption of an underwater volcano in the island nation of Tonga have been reconstructed in a simulation that captures how the resulting tsunami spread throughout the region.

The study, published on 14 April in Science Advances, shows that the blast generated waves that towered more than 40 metres high along some of Tonga’s coastlines, and could offer insights that might help to improve future hazard assessments and disaster preparation.

“The event last year provided the best opportunity for researchers to understand volcanic tsunami behaviours,” says Annie Lau, a coastal geomorphologist at the University of Queensland in Brisbane, Australia.

Hunga Tonga–Hunga Haʻapai erupted on 15 January 2022.Credit: Dana Stephenson/Getty Images
Underwater explosion

The Hunga Tonga–Hunga Haʻapai volcano in the South Pacific ocean erupted on 15 January 2022, generating shockwaves that resulted in unusually high waves that reached as far away as the Caribbean.
Tsunamis triggered in this way are difficult to monitor, because they move faster than those caused by earthquakes or landslides, says Linlin Li, a tsunami scientist at Sun Yat-sen University in Guangzhou, China. 
“Underwater volcanic explosions are one of the least understood mechanisms for triggering tsunamis.”

To investigate how the tsunami unfolded, researchers built a digital simulation of the event using satellite imagery taken before and after the eruption, together with data collected by drones and other field observations. 
They mapped 118 sites across 10 islands in Tonga to track the movement of the waves generated by three key blasts from the volcano.

The last of the three blasts generated as much energy as 15 megatonnes of TNT, making it hundreds of times more powerful than the atomic bomb dropped on Hiroshima during World War II.

On the northern side of Hunga Tonga–Hunga Haʻapai, waves surged 85 metres high within one minute of the eruption, while waves on the southern end reached a height of 65 metres.

Some 20 minutes after the explosion, 45-metre-high waves inundated the coastline of Tofua Island, located 90 kilometres north of the volcano.
To the south, Tongapatu — the most populated island in Tonga — experienced waves 17 metres high. “This was very much in the league of a ‘megatsunami’,” says study co-author Sam Purkis, a marine geoscientist at the University of Miami in Florida. 
Other locations managed to escape the brute force of the tsunami.
Waves hitting the east coast of ‘Eua island — roughly 25 kilometres away from Tongatapu — were a relatively modest five metres high on average.

Trapped waves

The vast, shallow reef platforms in the Tonga Archipelago probably shaped the height and flow of the tsunami waves throughout the region. 
“That’s a blessing and a curse,” says Purkis.
These shallow reefs acted as a barrier that dampened some of the larger waves as they charged in from the open ocean.
But the reefs also became a trap for waves generated by weaker eruptions that had occurred earlier in the day. 
As a result, small waves became larger, more unpredictable ones that bounced around Tonga’s islands for more than an hour. 
“By then, the open ocean was calm, but the waves were trapped,” says Purkis.

The study is “arguably the most comprehensive analysis to date” of a megatsunami, says Matthew Hornbach, a marine geophysicist at Southern Methodist University in Dallas, Texas.
He adds that the findings offer surprising insights about how tsunami waves can affect areas that are thought to be better protected.
“We believed that the largest waves would be relatively limited in scope [along] coastlines nearest to the eruption,” says Hornbach.
“This study demonstrates that these waves have the ability to impact areas we previously believed were lower risk.”
Links :

Wednesday, May 17, 2023

How ships are protected from lightning – ships earthing system

From Marine Insight by Ranek
A ship always has hazards around her while she sails across the sea.
Most of these dangers belong to the troubling waters and the weather conditions outside.
Heavy weather overhead and lightning are a big part of these elements too.
Hence, it is critical to understand how ships are protected from Lightning incidents.

Many risks originate from such incidents of the loose electrical outbreak of any nature.
However, lightning is not the only electrical hazard present for ships to deal with.
Many short circuit incidents prove to be life-taking for seagoing vessels every year.

More than 1,200 electrical accidents and incidents of major and minor nature occur every year.
Under such conditions, the ships earthing systems installations become essential for every size of the vessel.
Such systems protect the internal electrical hazards and also any external electrical risks too.

The article explains how modern-day ships exhibit their ability to deal with Lightning incidents.
It also includes their earthing design and how the neutral system works onboard.
We also identify the probable risks if such incidents or the current breaks happen too often.
Lightning strikes down from the sky.
(AP Photo/Robert Bukaty)

Ships Earthing System Working

The purpose of an Earthing connection on the electrical systems is to handle the flow of leaking current.
Any waste charge flows through these connections, saving the equipment and the lines.
It resolves the possible hazards that come from such an outbreak.

A current break or leak can occur from different sources, a few of which include:
  • A glitch or cut in the wire or transmission lines leading to the electrical leaks
  • A piece of faulty equipment such as broken motor winding
  • A fault in the circuit breakers or the electrical panel leading to a major current surge

Nature of Ship Earthing Design

Cargo and Passenger ships earthing systems are insulated neutral, in contrast to the land designs of earthing neutral.
It means that the neutral does not have direct tapping to the earth and has an insulating nature.

Hence, there is no direct pathway for the leaking current to flow to the earth.
Despite this, ships adopt the insulated neutral design because of their critical operations.

On the land, a single earth fault of severe kind can cause the equipment to trip.
It happens because the earthing connection allows a simple route for the current to flow, leading to a surge.

However, ships do not want their essential machinery to stop working under critical situations.
Such lapses will lead to loss of propulsion, electrical power supply, or other incidents.
These faults lead to navigation accidents and loss of cargo operations under serious situations.

Steering gear, navigation radar, fire pumps, and engine controls are highly critical equipment.
Hence, the insulated neutral allows the machinery to work with one fault across the line.
Earth Fault Monitoring

A trip will happen when there is another earth fault across the other line, leading to interference.
The two separate faults across phases cause the current flow to interfere in a hazardous manner.

Moreover, the higher number of machinery within a ship gives rise to more possibilities of earth faults.
However, a short circuit is critical and does not usually occur because of the monitoring systems.

The monitoring system indicates the magnitude of the earth-fault for an initial idea.
It helps the engineers on board to detect and isolate the faulty line and the equipment.

While the zones or equipment are not detectable, the step-wise fault-finding allows corrections.
The indicating needle moves between 0 to infinity, depending on the occurrence of the fault.
Hence, the earth fault correction and repairs take place to prevent any accidental trip.
Possible Risks

In the event of breakages within ships earthing systems, many risks loom large.
The most severe situations coming from the possible earth fault and trips will be:
Fire Hazards

These can be from the possible sparks that result from the wires or the loose connections.
Moreover, the overheating of systems before the equipment trip can result in fires too.

Fires are the scariest of shipboard risks due to their engulfing nature.
The critical elements onboard do not have any other means of substitution.
Once these systems catch fire, the total loss of ship control and accident becomes inevitable.
Short Circuit

The short circuit originating from these faults is a risk to the equipment.
Under changing conditions, the short-circuit can lead to complete breakdown and failure too.

While there is protecting equipment in the line, a saving action does not guarantee from them.
The rapid surges can also lead to overload trips or blackouts which becomes a threat to stability.

Life Threat

A fault in the earthing system creates a live nature of the current passage.
It means any contact with the naked limb will give an easy way for current.

The current creates a shock leading to cardiac arrest or permanent damage to the body part.
Almost 1400 incidents of varying nature of electrical shocks occur on ships every year.
Lightning Protection of Ships

To understand how ships are protected from lightning, the probable effects are equally important.
It includes the understanding of the nature of lightning bolts and how they disturb the vessels.
Moreover, the possible outcome of these lightning strikes and their hazards are equally important.
Lightning at Sea

The lightning and thunder at sea need a path of movement like on land.
During storms, the clouds have a changing polarization within themselves.
It leads to the separation of charges, with the electrons at the bottom half.

These negative charges are ready to combine with the positive polarity of the land surface.
Hence, a lightning bolt comes out as a way of dissipation of this energy into the Earth.

These thunderbolts look for an easy way out at sea for the flow of this charge too.
It means any conducting surface present above the water will provide lighting with an easy way out.
Ships as Conductors

Since current seeks the best and shortest route to ground, the conductors come into play.
The nature of the charges to find the best way amplifies in the presence of such bodies.
Hence, the floating ships with an all-metal design become the perfect conductor.

Moreover, the height of the ship along with the mast is several meters over the water surface.
Hence, this path presents a better trajectory for the lightning instead of the air passage.
In such conditions, the absence of preventing equipment positions vessels as an ideal conductor of lightning.
Damages From Lightning

If ships do not have a protective system for lightning, there will be severe results.
The damages do not happen to machinery or equipment but to the people on board too.

Sensitive Systems

Navigation equipment and communication systems onboard ships operate at relatively low voltages.
It means any surge in the power supply can severely damage them or make them useless.
Moreover, errors in the signal can originate from such interference too.

Lightning strikes of any magnitude will result in voltage surges at these terminals.
It will spoil the equipment or create short circuits, causing risk to navigation safety.

The radar mast, radio antenna, and GPS positioner also fall in the line of action.
These instruments have maximum exposure to lightning and are at most risk.
Human Life

The systems leading to how ships are protected from lightning have a high focus on human lives.
Any electrical shocks act as a life-ending impact on the human body.
Hence, lightning needs to dissipate into the surroundings before it contacts the people onboard.

It includes any small residual current from the lightning in the hull.
Moreover, it can also cause damage to the vulnerable property available on the ship.

The sheer impact of a lightning strike causes enough charge movement in a definite time.
It creates a volatile environment, leading to fires on board in the region of the impact.
Such fires are uncontrollable out at sea when the equipment is out of service after the strike.

Lightning Protection Equipment Requirements

The lightning protection system onboard a vessel contains multiple layers of protection equipment.
These elements play different roles in the overall safety protection of a ship against lightning.
Direct Strike Protection

The damages and impact of a direct lightning strike are the sources of lightning hazards.
Hence, the protection system needs to mitigate the bolts while contacting the ship’s surface.
Moreover, the system needs to move the lightning at one point instead to protect the other areas too.
Surge Protection

A surge in the voltage causes critical components of the vessel operation system to go ineffective.
Hence, the lightning protection setup needs to account for surge protection with the bonding arrangement.
It also includes the diversion of the lightning strikes to a safe zone onboard for further handling.

Flashing Safety

The side risk of a lightning incident onboard is the arc flashes on the systems.
These will instantly lead to fires or blasts in the nearby area, causing fatalities and losses.
Hence, direct bonding arrangements for all the equipment to a common point becomes essential.
Life Protection

The dissipation of lightning into the hull will impact the people on board with immediate shock.
These shocks will range up to several thousand volts, immediately killing everything in sight.
Hence, proper grounding arrangement for all the accommodation and other spaces takes care of this hazard.
Lighting Protection Installation

The lightning protection installation systems are the best explanation of how ships are protected from lightning.
The installation starts at the top of the monkey island from the radar mast, progressing towards the hull.
The critical elements handle lightning from the time of contact up to its final mitigation.

Air Terminal Installation

The air terminal at the mast will be a single rising element with additional electrodes as a cluster.
The element gathers the lightning and directs it towards a safe zone for grounding into the electrodes.
The voltage rating of these terminals goes up to 500-750 kV for modern systems.

While the main body is of steel, the inside consists of a series of resistors to lower the intensity.
The outer shielding consists of a fibreglass rod that shields the inner elements.
These are secured onto the mast base with the help of U-bolts and a rubber clamp for security.

The air terminal further connects to the bonding cable that carries the lightning safely into the water.
The crucial components of this unit summarize into:
  • Upper termination Unit
  • U-clamps
  • Fiberglass rod
  • Lower Termination Unit
  • Bonding Conductor
  • Bonding Cable
The bonding or the shielding cable connects the air terminal to immersing clamp that acts as ground screws.
The high voltage cable contains multiple layers of sheathing and a rating of 1.25 times the air terminal.
It ensures the safe handling of any transient surges for safely dissipating them in the water.
Surge Suppression Unit

The Surge suppression unit contains individual breakers and fuses, and the interconnection to a surging box.
These contain single-phase and 3-phase power supply protection kits of different ratings.
A common example is that of the trademark 3DR100KA-385-NE100 surge protection setup.

The surge protection box also has connections from several critical elements.
These wires are of the equivalent rating for the shielding cable.
The cables further connect the box to the single bonding point for the grounding of the lightning into the water.

Bonding and Earth Discharge Connection

The bonding and earthing arrangements vary as per the size and nature of the vessel.
An oil tanker bonding screw at the hull is different from that of a bulk carrier.
A simple silicon or bronze screw electrode has a higher rate of reduction in comparison to other designs.

These bonding connections are the final point of contact where the lightning safely dissipates into the water.
Hence, the safe passage of lightning finally ends with grounding into the sea.

Ship Earthing and Lightning Protection

Ships earthing systems design and the lightning protection system play critical roles in safety.
Catastrophic incidents of marine pollution, ship sinking, and loss of life are avoidable with these installations.

Each vessel has a particular choice of installations, with variations in the makers too.
However, the basics of lightning handling through a safe passage and finally into the water remains constant.

With the increasing sensitivity of equipment and the importance of human life, lightning protection is always critical.
All these arrangements in place lead to a safer and more efficient shipping operation future.
Links :

Tuesday, May 16, 2023

Scientists discover colossal underwater mountain off Vancouver Island

An underwater seamount 645 kilometres off B.C.'s coast has been found to climb 3,105 metres off the ocean floor — a third higher than previously thought.NOAA

From TimesColonist by Stefan Labbé

Measured by scientists aboard the U.S. research ship Okeanos Explorer, the seamount rivals Mount Baker and re-writes old nautical charts.

A team of scientists mapping the ocean floor off British Columbia have discovered a colossal seamount rivalling Mount Baker.

Scientists aboard the U.S. research vessel Okeanos Explorer discovered the underwater mountain as they sailed 645 kilometres off Vancouver Island.
When they beamed sonar into the deep, the topographic image that came back showed a seamount climbing at least 3,105 metres from the bottom of the ocean.

The find, a third higher than previous estimates, re-writes previous nautical charts.
The underwater mountain rises from a base sitting at 4,000 metres below the surface to its peak 895 metres below sea level.
Measured top to bottom, it's roughly a thousand metres higher than the peak of Whistler Mountain.

 Nautical charts (CHS top) and NGA (above)with the GeoGarage platform
"High-resolution mapping is immensely valuable to scientists," Sam Cuellar, the expedition's coordinator, said in an email.
"It allows us to see the 'big picture' of what underlies 70 per cent of our planet."

The Okeanos Explorer is at sea as part of the U.S. National Oceanic and Atmospheric Administration's (NOAA) Aleutians Deepwater Mapping project, a mission to map unexplored regions of seabed off Alaska.
The expedition is exploring over a million square miles of sea floor using sonar.

Cuellar said they mapped the seamount in transit from Seattle, Wash., to the Gulf of Alaska where they plan to carry out their survey.
Previous collected bathymetric scans of the deep had only captured the slopes of the underwater mountain, he said.

It's not clear what kind of life exists on the seamount, but others are known to act as a "hot spot" of biodiversity.
Home to everything from corals and fish to sponges and other creatures, the raised features feed the surrounding water with nutrients, attracting a vast array of larger creatures such as sharks, whales, squid and octopus.

Cuellar said the mapping project is part of a wider push to trace the deep ocean and provide a “critical baseline” to understand the region’s little explored deep-ocean environment.
Humans have so far only mapped 23.4 per cent of the ocean floor at high resolution, according to the Seabed 2030 initiative.
Adding to that total will help scientists better understand marine habitats so they can be protected.

Data from the mission — which can be tracked on multiple livestreams — is meant to provide a deeper understanding of deep-sea geology and how such features are formed.
Detailed imagery of the deep sea also allows scientists to identify potential hazards like volcanic activity or earthquake-prone fault lines, added Cuellar.

The NOAA expedition also plans to use underwater robotic submarines to locate a Second World War-era B-25 bomber, which disappeared with its nine crew members in 1944.

A seamount 645 kilometres off B.C.'s coast ascends to 3,105 metres from the ocean floor, a third higher than previously thought.
Visualization with the GeoGarage platform (STRM source) 
 Links :

Monday, May 15, 2023

Uncrewed surface systems facilitating a new era of global ocean exploration

From IHO by Larry Mayer

There is growing recognition that key to addressing critical issues like climate change, global sea level rise and the long-term sustainability of humankind is a more complete understanding of our oceans and processes within them that account for the distribution of global heat, CO and provide sustenance to so many.
Yet, despite years of effort, less than 25% of the global ocean seafloor has been mapped and less than 5% of the ocean volume explored, likely due to the cost and inefficiency of traditional ocean mapping and exploration techniques using large, very expensive, crewed research vessels.
Recent advances in the development of uncrewed surface vessels offer the possibility to reduce costs and increase efficiency of ocean mapping and exploration.
Such efficiencies can be gained by using small mother ship-deployed uncrewed vessels acting as relatively inexpensive mapping and sampling force multipliers or the use of small uncrewed vessels launched to from a mother ship to monitor and control autonomous underwater vehicles, allowing multiple operations simultaneously and “verified, directed sampling”, all while freeing the mother ship for independent operations.
We are also seeing the development of larger uncrewed vessels launched from shore with long-endurance and range, capable of carrying a full suite of deep ocean mapping and exploration tools.
All of these systems and approaches offer great hope but it is very early in our understanding of their full capabilities, costs and limitations and we must be careful not to overpromise, leading to disappointments and early abandonment of a potentially innovative approach, while at the same time maintaining the patience required to continue the research, investment and innovation that will hopefully bring us to a new world of efficient and effective ocean mapping and exploration that will allow us to meet our goal of complete coverage of the ocean.

1 Introduction

As we celebrate the 100th anniversary of The International Hydrographic Review (IHR) one might ask why we would devote a paper to the topic of the future of ocean exploration.
The answer is simple.
The mapping tools and techniques that have been pioneered, developed, and implemented by the hydrographic community are, without question, the primary tools of ocean exploration.
Almost all great explorations were built around the creation of maps that offered an initial geospatial context for “terra incognita”, and many of the great explorers were either mapmakers themselves or had mapmakers as key members of their team.
As early explorers looked outward to the seas, it was innovation in the development of navigation and positioning tools that allowed them to head far offshore and begin to map the extent of new landmasses and the resources they may possess.
Even in these earliest days of exploration there was the need to probe and chart seafloor depths to assure safe passage of the vessel as it approached unexplored regions.
Over the centuries that have passed since these early days of exploration we have, for the most part, completed mapping the distribution of terrestrial components of our planet and with modern satellite imaging technology, it is hard to imagine that there are new landmasses yet to be discovered.
Indeed, given the general availability of high-resolution satellite imagery and tools like Google Earth, almost anyone can produce a high-resolution image (and with overlapping imagery, a digital terrain model) or map of almost any landmass on earth, all precisely positioned through a Global Navigation Satellite System (GNSS).

As our knowledge and understanding of the distribution of the landmasses and peoples of our planet grew, the oceans became highways of trade.
The vessels that traveled these highways increased in size and capability, and the need for hydrographic mapping became, and still is, critical to assure the safe navigation of vessels in and out of ports (Jonas, 2023).
This evolution of mapping, exploration, discovery, technical innovation, and exploitation (of resources and sadly peoples), led to the remarkable growth of the global economy over the past few hundred years and the recognition that the ocean is vital in sustaining the lives and livelihoods of those who inhabit Earth.
As we have come into the 21st century, however, we have also recognized that this rapid growth has put tremendous strains on the health of the earth and that such growth cannot be sustained without a better understanding of its environmental impacts.
We have also learned that the earth is a complex system of interconnected systems (land, atmosphere, and ocean) and that understanding the ocean system, which represents more than approximately 71% of the earth’s surface and is central in regulating temperature, climate, CO , and other critical parameters, is key to developing approaches for the long-term sustainability of Earth.
It is this recognition of the key role that the ocean plays in feeding our planet as well as moderating and sustaining Earth’s climate and other environmental systems that has led to renewed emphasis on a better understanding the oceans as exemplified by the United Nations’ Decade of Ocean Science in Support of Sustainable Development1.
In developing the goals of the Decade of Ocean Science in Support of Sustainable Development, the complete mapping of the seafloor was recognized as a critical need yet, as we begin the U.N. Decade of Ocean Science, we do so with the sad recognition that at this point in time, less than 25% of the global ocean’s seafloor has been mapped and likely only about 5% of the global ocean volume has been explored.
How can we hope to understand the oceans we so depend on, when we do not yet know what is there?

In this paper we will explore the efforts being made to correct this situation and look at new technologies that might help us achieve the dream of a fully explored ocean.
Much of our focus will be on approaches to increasing the efficiency of mapping the seafloor, particularly the deep ocean seafloor beyond the realm of hydrographic organizations – because as was stated earlier, all exploration must start with the establishment of a geospatial context.
For this we will focus on the need to cover large, often totally unmapped regions rather than meeting critical hydrographic standards and thus much of the focus of this paper will be on new, more efficient ways to deploy critical ocean mapping and exploration sensors.
We will also look at new approaches for looking at the ocean volume and explore, in general terms, what the future might hold for the development and deployment of new tools that will support and enhance ocean exploration.

2 Mapping the global ocean seafloor

We begin our focus on ocean exploration by examining the state of our understanding of global seafloor bathymetry – a critical boundary condition for many ocean processes including controlling the pathways of deep-sea currents and the frictional loss of heat through generation of turbulence as currents pass over seafloor of various roughness.
Knowledge of both these parameters (the flow-path of deep ocean currents and seafloor roughness) is essential for the accurate modeling of global climate (Gille et al., 2004 and references therein).
In the polar regions, knowledge of where relatively warm subsurface currents can access margins of glaciers through bathymetric passages is essential to the modeling of glacial melting rates and the associated rise in global sea level (Jakobsson & Mayer, 2022).
Bathymetry is also essential for understanding deep sea hazards (slumping and other mass wasting events; Avdievitch & Coe, 2022) and for the prediction of storm surge and tsunami hazards (Parker, 2013).
Seafloor mapping is needed for establishing the routes of deep-sea cables and pipelines and has offered key insights into the nature of earth processes including the development of the theory of plate tectonics which was greatly aided by maps of seafloor morphology.
With the addition of backscatter, mapping has played a key role in delineating critical benthic habitats (Roberts et al., 2005).
Yet, as stated above, at the present time less than 25% of the seafloor has been directly mapped.
We say “directly mapped” because nearly complete global seafloor maps have been produced through the remarkable technique of deriving bathymetry from satellite altimetry (Smith & Sandwell, 1997).
Satellite-altimetry derived bathymetric maps are based on the principle that the sea surface is, to a first approximation, an equipotential surface of the earth’s gravity field that is affected by the gravitational attraction of large masses on the seafloor (e.g., seamounts) or the absence of mass (e.g., trenches) causing the sea surface to change elevation relative to the ellipsoid.
These changes in elevation can be measured by accurate satellite altimeters and thus the measured height of the sea surface reflects large-scale changes in bathymetry.
Through the comparison of satellite altimetry-derived measurements (for which there is continuous cover over most of the oceans) to actual soundings, Smith and Sandwell were able to predict the bathymetric values for places where there are no soundings.
This was a tremendous step forward in providing a global estimate of seafloor depths, however, the lateral resolution is on the order of 10–15 kms and the vertical accuracy is limited (Smith & Sandwell, 1997), meaning that to address many of the critical applications discussed above, the satellite altimetry-derived bathymetry does not have the needed resolution nor accuracy, and instead we must use direct measurements of depth.

Over the past 40 to 50 years, we have seen the technology used to make direct measurements of depth change radically.
For literally thousands of years depth measurements were made by measuring the length of a weighted line deployed from a vessel (lead line).
With the rapid evolution of sonar systems during the second world war, the single beam echo sounder became the tool of choice for most hydrographic and deep-sea ocean mapping missions.
Towards the end of the 20th century, multibeam sonars came out of classified military development and became commercially available.
Multibeam sonars (along with concomitant developments in satellite positioning and computer processing) revolutionized deep ocean mapping.
A single beam sonar (with a beam width of typically 15–30 degrees ensonifies an area on the seafloor with a diameter of approximately one half the water depth and produces only one depth (the shoalest depth) in the ensonified area with no knowledge of where that depth was within the area.
The position of the shoal can only be assumed to be directly below the vessel.
The result is a laterally averaged (over the beam footprint, i.e., half the water depth) portrayal of bathymetry.
Multibeam sonars, however, produce many narrow (depending on the model but typically 0.5 to 2 degree) beams in a broad (athwartship), but thin (alongship) swath across the seafloor perpendicular to the direction of travel of the vessel.
The result is many (tens to hundreds) of individual, highly accurate depth measurements across a swath that is typically three to five times the water depth wide.
With multibeam sonars thus came the ability to produce many individual high-resolution depth measurements from a single ping across a wide swath of the seafloor, revolutionizing our ability to map and visualize the deep ocean floor.

Because of vessel motion and the wide swath achievable, multibeam sonars require complex integration with other ships’ sensors (e.g., sound speed profiler, inertial motion sensor) but both sensor integration and post-processing software for these systems has improved greatly over the years and these systems have now been adopted by most institutions that map the seafloor.
High-frequency (200–400 kHz) shallow water systems (200 m or less) are small and compact (sonar array dimensions are on the order of 50 cm to 1 m), however, to maintain spatial resolution (narrow beam footprints), array sizes must scale up with the lower frequencies needed for deep-water mapping (12–30 kHz).
To achieve a 1-degree beamwidth at 12 kHz (the frequency used for full-ocean depth mapping) the sonar array must be on the order of 9 meters long.
Inasmuch as multibeam sonars use separate transmit and receive arrays (orthogonally oriented to create what is known as a Mills Cross or Mills T), if one wants to both transmit and receive 1degree beams, the receive array (which is mounted in the athwartship direction) must also be 9 m long, meaning that the vessel must be able to support a 9m long array along across its keel i.e., it must be a large vessel.
Thus, the state-of-the-art for deep-sea ocean exploration requires multibeam sonars mounted on large (typically 60 m or longer) survey vessels.

Recognizing the critical need for more complete maps of the ocean floor, the Nippon Foundation and GEBCO joined forces to create the Seabed 2030 Project, an ambitious effort aimed at establishing an infrastructure to facilitate the complete mapping of the global ocean floor by 2030.
The project was organized around four regional data centers (located in New Zealand, Germany, the U.S., and Sweden) and a global data center located at the British Oceanographic Data Center in the U.K.
The project began in earnest in 2017 with the data centers inventorying how much data was publicly available in global databases and addressing the difficult question of how much of the seafloor was mapped and at what resolution.
This analysis revealed that if the seafloor were divided into approximately 1 km square grid cells, 18% of them had at least one sounding in them and 9% of them had some multibeam data (Mayer et al., 2018).
Acknowledging that the beam footprint of a mapping sonar varies as function of depth, Seabed 2030 defined a series of depth-dependent grid resolutions for defining mapping coverage (see Mayer et al., 2018 for details).
When these depth dependent resolutions were considered, direct mapping data were available for only 6.9% of the seafloor.
Starting with this estimate of coverage in 2018, we have seen, through the concerted efforts of the Nippon Foundation-GEBCO Seabed 2030 teams and collaborating partners, the coverage increase to 24.4% at the beginning of 2023 (Fig. 1).
While this represents a tremendous increase in data availability, much of this increase was the result of discovery and provision of existing data sets and, as the amount of undiscovered data decreases, new data acquisition will be required to cover the more than 75% of the ocean floor unmapped by direct means.

Fig. 1 Global bathymetric coverage in the GEBCO 2022 digital grid, representing most of the publicly available bathymetric data – viewer available at
Areas that are black indicate no available direct bathymetric data.

It has been estimated that it will take between 70,000 and 127,000 ship days to map, with state-of-the art multibeam sonar, the yet unmapped regions of the seafloor deeper than 200 m to the Seabed 2030 defined resolutions.
Given the high costs of operating the relatively large vessels needed to carry deep water multibeam sonars, the overall cost of this undertaking has been estimated to be on the order of three to five billion dollars (Mayer et al., 2018).
This is a seemingly large number, but it should be noted that there have been many mapping missions to other planets that cost on the same order, raising the question of why we would not be willing to invest this amount in the mapping of our own planet.
While efforts continue to seek the funding to complete the mapping and exploration of the global ocean, here we will address whether new technologies can increase the efficiency of ocean mapping (and ocean exploration in general) and thus facilitate the complete mapping and extended exploration of our oceans.

3 Expanding the efficiency of ocean exploration with “autonomous” systems

Exploration of the surface of the earth (both land and oceans) was revolutionized with the advent of satellite imagery and remote sensing.
With respect to the oceans, these tools have offered tremendous insights into sea surface temperature, productivity, current and wave patterns.
Unfortunately, these insights are limited to the upper few meters of the ocean surface as the electromagnetic waves used for ocean imagery and remote sensing do not propagate far in water.
And thus, as outlined above, the fundamental tools for exploring the seafloor and volume of the ocean are acoustic systems, typically carried by large, slow, and expensive to operate, research vessels.
If we look at costs for typical sea-going research vessels we see that a significant percentage of the operating costs (in many cases over 50%) are associated with crew-related expenses (salary, travel, food, etc.).
Recognizing the significant crew-related costs involved in operating a research vessel, the concept of using uncrewed systems becomes an appealing option for increasing the efficiency of ocean mapping and exploration.
Note that we are calling these operations “uncrewed” rather than autonomous.
Despite the tremendous advances we have seen in the past few years in the development of uncrewed vessels, none of the current systems can be called truly autonomous; they all require some level of human interaction (pilots, operators, etc.) and thus do not remove all personnel expenses from the equation.
However, even at this early stage of development, the potential is there to demonstrate increased efficiencies.

We have already seen the private sector step up and demonstrate remote operation of small autonomous systems for near-shore surveys.
These are early days for these types of operations, but initial indications are that such approaches to survey work are enjoying success, demonstrating improved safety (i.e., no one offshore), 24 hour per day operation, and a reduced carbon footprint both with respect to the vessel and much-reduced travel requirements.
With respect to offshore ocean mapping and exploration, the use of uncrewed systems is in its infancy and much remains to be learned about concepts of operations and the ultimate viability and cost-effectiveness of operating uncrewed vessels in support of ocean exploration (Schmidt, 2020).
In addressing these questions, we will report on our own recent experiences working with funding from the U.S.
National Oceanic and Atmospheric Agency (NOAA) to explore the potential use of uncrewed systems in support of mapping and ocean exploration.
In relating these experiences, many will be based on the uncrewed vehicles that we are currently working with (DriX built by Exail and Saildrone) but will hopefully be generic enough to draw broader conclusions about the future role of uncrewed systems for deep ocean mapping and exploration.

4 Uncrewed systems as force multipliers for offshore mapping

One of the most obvious applications of uncrewed systems for offshore survey work is as a ‘force-multiplier’.
Large offshore research vessels typically have capitalization costs of over $100 million USD and day-rates often over $50,000 USD per day.
The diesel-powered uncrewed systems we have been using have capitalization costs of a few million dollars and operating dayrates (still being determined) on the order $10K per day (including operator costs).
Thus, the deployment of one or more uncrewed systems from a mother vessel offers the opportunity to multiply the efficiency of surveying for a fraction of the cost.
NOAA-funded work with DriX (Fig. 2) has demonstrated that this is indeed possible with the uncrewed vessel launched from the mother ship and surveying in tandem with the mother ship at speeds up to 10 knots and continuous operation over several days.
Full data transmission to the mother ship (typically at the end of each line) was possible when operating within the limits of the marine broadband radio system used to communicate between the mother ship and the uncrewed vessel (maximum about 20 km depending on atmospheric conditions).
In this mode, data processing can be done on board the mother ship as data is being collected, and data products produced not long after the survey is completed.
NOAA has estimated that such operations will increase survey efficiency by at least 40% (using a single uncrewed vessel).
Carrying more vessels should further increase efficiency but this has yet to be demonstrated.

To date the uncrewed systems that we have deployed from larger ships have been relatively small (7–8 m long) and capable of carrying high-resolution, shallow water multibeam sonars (200–400 kHz) along with broadband water-column mapping sonars (EK-80s), however, we have recently installed a new compact, 70–110 kHz multibeam sonar (EM-712) providing mapping capabilities to depths beyond 2000 meters and offering the option for using even our smaller uncrewed systems as force multipliers for deeper water mapping.
Depending on mission requirements, the uncrewed systems can be equipped with a range of sensors, including winch-deployed sensors (e.g., CTD) offering the opportunity to act as force multipliers for a range of oceanographic measurements.
At described above, at present, operation of uncrewed vessels can be carried out from a mother ship with full situational awareness and data transmission to ranges supported by marine broadband radio (~20 km).
Operations can be carried out beyond the range of the marine broadband radio (and even from shore-based facilities anywhere in the world) using satellite-based systems like Iridium’s Certus, however the bandwidth provided by these systems can currently can only support the transmission of situational awareness information and limited data rather than full data transmission.
The recent introduction of low-earth orbiting satellites supporting the maritime domain (e.g., Starlink) now offers the possibility of high-bandwidth communications with uncrewed systems and opens the possibility of full data transmission to and from uncrewed vehicles, world-wide.
These systems have just been introduced and their full capabilities and limitations have yet to be demonstrated but many efforts are currently underway to assess these systems including the recent installation of a Starlink system on our own uncrewed vehicles.
Testing of this system will begin over the next few months.

Fig. 2 The 7.7 m long DriX uncrewed vessel used by UNH as a platform to explore the applicability of uncrewed vessels to support ocean mapping and exploration missions.

5 Shore-deployed uncrewed systems for deep-water mapping and exploration

As we seek to extend the efficiency of deep-water mapping and other open-ocean exploration measurements, the size of the uncrewed vessel becomes an issue as the sonar arrays, winches, and wires, all need to be larger or longer to work in deeper water.
How large of an uncrewed vessel (or vessels) can be carried by a mother ship (and how large must the mother ship be)? At some point it becomes impossible to efficiently carry, deploy and recover uncrewed systems that are fully capable of undertaking deep water mapping and exploration activities and we must look to the concept of large, shore-deployed uncrewed vessels, capable of long-range deployments and carrying a full suite of ocean exploration tools.
A commercial entity, Ocean Infinity has been pioneering this approach through the development of a fleet of very large (78 m), fuel-efficient, offshore controlled vessels that will initially be crewed but are designed to eventually operate in an uncrewed mode.
Other manufacturers are also building larger platforms with extended range and the ability to carry deeper water exploration tools.
As these capabilities evolve and are implemented, the community will learn if these approaches prove to be a cost-effective and energy efficient approach to addressing our need to map and explore the global ocean, but the potential is clearly great.

As these purpose-built large uncrewed vessels are being built and approaches to autonomous operations being further developed, a concept to be explored is that of a mapping and exploration barge (Fig. 3) whose form-factor could accommodate a very large mapping sonar array (e.g., ~ 30m × 15m which would result in beamwidths of ~ 0.25 deg × 0.5 deg or a lateral resolution on the seafloor of on the order of 17.5 m × 35 m at nadir in 4000 m of water).
Such a platform would be relatively inexpensive to build (or acquire) and initially could be transported by a sea-going tug with a small crew at a fraction of the cost of a fully crewed research vessel.
The deck space available on a barge could accommodate a range of other ocean and atmospheric sensors providing a relatively inexpensive means of collecting a suite of ocean measurements (including sensors that need to be deployed by wire to probe the depths).
Sonar systems and other sensors could be operated remotely (the technology for this exists now) and with improved bandwidth from low earth orbiting satellites, these remote capabilities will increase.
As uncrewed ship operations evolve, we could envision a time when the entire barge could be a self-contained autonomous platform and a platform from which to launch other autonomous systems.

Fig. 3 The concept of an ocean exploration barge capable of carrying a very large MBES system and many other sensors.
Such a barge can be deployed with an ocean going tug at a fraction of the cost of a crewed research vessel and eventually could be designed to be a fully autonomous platform.
Image drawn by Ines Jakobsson.

6 Reducing fuel costs and extending range

The uncrewed vessels discussed above are all dependent on engines for their propulsion and while we are seeing exciting and important innovations in low-carbon footprint propulsion systems (i.e., hydrogen and ammonia-based), the dependence on any source of combustible fuel places limits on endurance of the vehicle.
The introduction of sail powered uncrewed systems has offered the intriguing possibility of mapping and exploration vessels with long endurance and a very low carbon footprint.
Several years ago Saildrone introduced a 7 m long, wind and solar powered uncrewed vehicle (Explorer) that has now demonstrated the ability to undertake long endurance ( >6 months), long-distance (>20,000 kms) missions surviving hurricanes and tropical storms.
These vehicles are equipped with an array of oceanographic and atmospheric sensors and have been equipped with single beam echo sounders, but they currently do not have the energy budget to support multibeam sonars.
Two larger vehicles are being introduced, however, the 10 m long Voyager and the 20 m long Surveyor (Fig. 4), each of which is equipped with an auxiliary diesel/electric power system that allows them to support multibeam sonars and winch-deployed sensors.
While the Voyager will be equipped with shallow water multibeam sonar systems, the 20 m Surveyor has already been deployed with a 30 kHz, EM-304 multibeam sonar, along with a shallow water EM-2040 and a full suite of EK-80 water column sonars creating a platform that is well-suited for deep-water ocean mapping and exploration.
Saildrones are operated from a shore-based control center with a sophisticated mission portal offering full situational awareness but not full data transmission.
With the advent of low earth orbiting satellites, full data transmission may be a possibility.

Fig. 4 The 20 m long Saildrone Surveyor arriving in Hawaii after a 28-day transit from San Francisco.
This prototype Saildrone Surveyor is equipped with a 30 kHz EM-304 and 200–400 kHz EM2040, a full suite of EK-80 broadband sonars and environmental sensors as well an ESP-3 eDNA sampling system from the Monterey Bay Aquarium Research Institute.

The Saildrone Surveyor underwent sea trials, funded by NOAA’s Ocean Exploration Program, in June of 2021 and then undertook its maiden voyage, an uncrewed mapping transit from San Francisco to Hawaii, funded by the Nippon Foundation/GEBCO Seabed 2030 Program, in July of 2021.
The Surveyor collected high-quality mapping data during this 3650km long transit, especially while under sail where the swath widened due to reduced noise (Fig. 5).
In the course of the transit, many lessons were learned about transit speed capabilities and how often the engine needed to be run in order to keep the batteries appropriately charged.
In 2022 the Saildrone Surveyor conducted work on behalf of NOAA’s Office of Ocean Exploration in remote areas of the Aleutian Islands (Fig. 6) and it is currently undertaking surveys of the U.S. EEZ off the coast of California.
As these surveys are completed, we continue to learn more about the capabilities and limitations of this innovative system particularly respect to endurance, speed, trade-offs between motoring and sailing, data quality, and overall cost-effectiveness of this approach to addressing our long-term mapping and exploration needs.
Saildrone is also using lessons learned to upgrade the design and produce a new generation of Surveyors with faster hull speed and extended capabilities.

Along with its acoustic systems, Saildrone Surveyor also carried a suite of environmental sensors including an exciting Environmental DNA (eDNA) sampling system from the Monterey Bay Aquarium Institute (MBARI).
eDNA is a relatively new approach of analyzing the nuclear or mitochondrial DNA that is released by organisms into water (Pillioid et al., 2013).
Analysis of eDNA allows the detection and identification of species that were present in the water mass and is a powerful new tool for understanding biodiversity.
MBARI has created an eDNA sampling system (ESP-3) that can be deployed on autonomous systems, filter water on command and preserves the samples for later analysis (Truelove et al., 2022).
On each of the completed Saildrone Surveyor missions, a complete suite of eDNA samples were taken with the ESP-3, demonstrating the viability of making these important environmental measurements from platforms much less expensive to operate than large, crewed research vessels as well as the potential of collecting these important measurements in remote and unexplored regions.

Fig. 5 The maiden voyage of the Saildrone Surveyor as it transited from San Francisco to Honolulu covering 3650 km over 28 days.
Insert shows increase in achievable swath width coverage going from using diesel motor to pure sailing mode.

Fig.6 Saildrone Surveyor surveys of remote regions of the Aleutians conducted during two missions over 51 days.
For this mission Saildrone departed from San Francisco, had a port call in Dutch Harbor and returned to San Francisco.

7 Every measurement counts

While our aspiration is to see the ocean completely mapped and explored with the greatest resolution possible, the unmapped and unexplored regions of the oceans are so vast that we must recognize that any additional measurement adds to our knowledge base.
ARGO floats are freely drifting floats that are deployed through an international program and designed to collect temperature, salinity, and pressure measurements over the upper 2000 m of the ocean.
The floats use a buoyancy engine to profile down to depth, drift (typically at 1000 m) for about 10 days, profile down to 2000 m, and then return to the surface to transmit their data via satellite.
They repeat this cycle until their batteries are depleted (typically about 3–5 years).
A new suite of floats can also collect biogeochemical measurements and some floats are being designed for deeper depths (to 6000 m).
There are currently about 4000 floats drifting around the oceans providing measurements of ocean temperature and salinity distribution that have revolutionized our understanding of ocean warming and other ocean processes.
With 4000 floats drifting around the ocean basins, it has been estimated that approximately 8% of these floats will ground in regions where bathymetry is poorly constrained and van Wijk et al.
(2022) have cleverly proposed that in these situations, information on grounding depth can supplement our bathymetric data base and provide additional bathymetric information in remote regions.

Taking the concept of using a profiling float for bathymetric data acquisition one step further, Seatrec Inc.
is developing, though funding from Schmidt Marine Technology Partners, the infiniTE™ (infinite Thermal Energy) float, a profiling float powered by an energy harvesting system that derives power from the thermal differences in the upper ocean (Fig. 7; Jones et al., 2011).
The energy harvesting system provides enough power for the profiling float to make as many as three profiles per day and to use an active echo-sounder to collect bathymetric information along with the standard oceanographic data collected with a CTD.
Like Argo floats, the infiniTE floats are navigated by GPS and transmit their data via satellite link when they surface (Coley, 2023).
The first two prototypes of these new echo-sounding floats will be deployed for the first time in the spring of 2023.
Should these floats prove successful, they offer a relatively inexpensive approach for long-term bathymetric data collection in remote regions of the oceans where ships rarely venture and where existing data coverage is very sparse.

Beyond their ability to provide single beam sounding measurements in remote regions, it may be possible to use a group of profiling and echo-sounding floats to form a large baseline sparse array that can make very high-resolution bathymetric measurements over a wide area (Ryu et al., submitted).
Envision an array of echo-sounding infiniTE floats deployed over an area of say 20–40 km.
If the floats are commanded to profile at the same time, they can capture the three-dimensional sound speed field of the ocean volume.
When the floats return to the surface, several of the floats could be used as acoustic sources and the rest used as a disaggregated sparse array of receivers, all precisely positioned with GNSS.
The combination of the precise location of sources and receivers along with knowledge of the three-dimensional sound speed field offer the opportunity to solve the more difficult aspects of providing a coherent 3-D solution for the ray paths leading to the possibility of very high-resolution bathymetric solutions over a wide area.
Certainly speculative, but research efforts are currently underway at MIT Lincoln Labs to explore the use of sparse arrays for bathymetric measurements.

Fig.7 Seatrec infiniTE profiling float uses a solid to liquid phase change caused by the thermal difference in upper water column to provide enough energy to drive a deep-water echo-sounder along with other profiler instrumentation.
The profiler will dive to depth and make a sounding then drift and make another sounding before returning to surface getting another GPS fix and transmitting data via satellite.
Image courtesy of of Yi Chao, Seatrec Inc.

8 Expanding the ocean exploration footprint

While we have emphasized the role of uncrewed systems as a force multiplier that has the potential to greatly increase the efficiency with which we can map and explore the oceans by providing more cost-effective and fuel-efficient means to cover large areas of the oceans, there is another important role that uncrewed vehicles can play in enhancing our ocean exploration capabilities.
Ocean exploration missions often begin with regional mapping to set the geospatial context before more detailed exploration and prosecution of targets takes place.
Regional mapping is indeed a role where we have argued that uncrewed systems can provide increased efficiency by covering large areas at reduced cost with respect to ship time, personnel, and fuel.
But once targets are selected for detailed mapping and exploration (e.g., a hydrothermal vent field), a large mother ship typically deploys high-resolution mapping and imagery systems (e.g., ROVs and AUVs) to provide detailed analyses and sampling.
Typically such operations involve the deployment of a single system at a time and require the dedicated support of the large mother vessel.
We have recently, however, demonstrated how, through the use of relatively small uncrewed systems, multiple underwater uncrewed vehicle operations can be supported and the mother ship freed to pursue independent activities.

On a recent expedition of the E/V NAUTILUS (NA-139; May 2022), sponsored by NOAA’s Office of Ocean Exploration, teams from the University of New Hampshire, the Woods Hole Oceanographic Institution and the Ocean Exploration Trust, worked together to demonstrate collaborative behaviors among multiple vehicles and the mother ship (NAUTILUS) to demonstrate the potential for simultaneous, multiple vehicle deployments, and thus increased efficiency in the use of these expensive assets.
On board NAUTILUS was the 7 m long DriX uncrewed system described earlier, the Mesobot, a slow moving autonomous underwater vehicle designed to track particles in the mesopelagic (midwater) and collect eDNA samples (Yoerger et al., 2018), and NUI, a hybrid ROV/AUV designed to travel 10s of kms laterally underwater connected to the mother ship by a thin fiber but then act as an AUV when the fiber is cut (Barker et al., 2020; Fig.8).
NUI carries a full suite of cameras and acoustic systems as well as a manipulator arm for sampling.

The initial step in developing collaborative behaviors was to establish a common acoustics communication system among the vehicles.
This was achieved through the use of a Sonardyne HPT 3000 tracking and communications transceiver mounted on the DriX and acoustic transponders mounted on the AUVs.
The team also developed a series of standard Robot Operating System (ROS) messages to allow the transfer of data and commands among the vehicles.
Once deployed, the DriX was able to track, communicate and follow the AUVs using the HPT 3000.
Inasmuch as the AUVs move very slowly (1–2 knots) and DriX tends to travel much faster, a special behavior was created to allow DriX to circle above the vehicles and thus always stay centered above the vehicles (Fig.9).

Fig.8 The vehicles associated with the multi-vehicle collaboration mission and E/V NAUTILUS.
Fig.9 Behavior developed to allow fast-moving uncrewed vessel DriX (represented by red arrow) to follow and stay on top of slow-moving mid-water AUV Mesobot (yellow dot).

Full situational awareness of the position and status of all vehicles was provided by CAMP – CCOM Autonomous Mission Planner (Arsenault & Schmidt, 2020), an application that serves as a backseat driver for autonomous vehicles and allows for monitoring the progress of multiple vehicles and the mother ship as well as the ability to quickly and easy make and revise mission plans, all on top of raster images (e.g. charts or bathymetry; Fig.10).
Most importantly, the sonars on the DriX were able to provide real-time (while within range of the marine broadband radio – ~20 km) information on potential targets for investigation by the AUVs.
For example, while Mesobot was deployed, the EK80 on the DriX which was following, tracking, and communicating with Mesobot, located a strong midwater scattering layer that was seen in real-time through data transmitted from DriX to the mother ship (Fig.11).
Commands were sent to Mesobot to move to the layer and when Mesobot was in the layer (visually confirmed by the ability to see Mesobot in the EK-80 display), Mesobot was sent commands to begin sampling for eDNA (Fig.12).
This ability to see, in real-time, the location of the AUV and its sampling systems with respect to the target layer opens a new world of “verified directed sampling”.
This ability will remove many ambiguities and uncertainties associated with the sampling or measurement of oceanographic phenomena as well as help address questions of sample bias and avoidance.
Through the combination of surface and subsurface autonomous vehicles we will be able to see exactly where samples or measurements are being taken and how the targets being sampled behave during sampling.

With respect to gained efficiencies, we were able to operate with Mesobot, NUI and DriX simultaneously, with DriX on the surface, Mesobot exploring the midwater, and NUI mapping and exploring the seafloor.
Throughout this exercise, the DriX served as the communications link between the vehicles and the mother ship, tracking their location and transmitting data and commands to and from the ship.
When NUI went into full AUV mode (i.e., off the fiber tether), the NAUTILUS was free to leave the direct vicinity of the AUVs and carry on its own activities.
During this mission we were limited by the range of the marine broadband radio and thus the NAUTILUS could not go beyond about 20 km from the AUVs’ operating area but with the implementation of low earth orbiting satellite communications from the uncrewed surface vehicle, there should be no limit to the range at which the uncrewed surface vessel could operate from the mother ship while following the AUVs, and thus the AUVs could easily be monitored and controlled from a shore-based facility anywhere in the world.

Carrying this one step further, as demonstrated in the Shell Ocean Discovery XPrize competition, we are already seeing the introduction of large-format shore-based uncrewed surface vessels that can carry and deploy their own ROV (Zwolak et al., 2020).
With such systems we can envision the uncrewed surface vessel using its suite of sensors for broad exploration and initial mapping and when targets of interest are found (perhaps by automated processing and detection algorithms on board the vessel), the ROV can then be deployed for detailed study and mapping of the targets without human intervention.
With the advent of high-bandwidth communications through low-earth orbiting satellites in combination with growing capacity for telepresence (Raineault et al., 2018) shore-based scientists can remain in the decision and control loop offering tremendous opportunities for truly expanding the footprint of ocean exploration while bringing the wonders of deep-sea exploration to school children and the public at large, world-wide.

Fig. 10 The UNH CAMP applications providing full situational awareness of the location of multiple vehicles in the context of underlying raster mapping data.

Fig. 11 Display of 200 kHz EK80 data from EK-80 on DriX, transmitted in real-time via marine broadband radio to mother ship (NAUTILUS).
The blue horizontal line at about 70 m depth is the scattering layer that scientists wanted to sample.
The red diagonal line is the reflection of Mesobot traveling underneath DriX as it is being directed by commands from the mother ship to move to the scattering layer.

Fig. 12 The Mesobot (red horizontal target) confirmed to be directly in the scattering layer.
At this point sampling is triggered assuring that eDNA samples were taken directly in the targeted layer.

9 Conclusions

The global community is recognizing that the long-term sustainability of humankind is inextricably linked to our understanding of the oceans and the processes within them that control the distribution of heat, CO, nutrients, and other critical parameters.
Yet our oceans are vast and despite more than 100 years of effort, our traditional approaches to studying the oceans using large, crewed research vessels, have resulted in less than 25% of the seafloor mapped and on the order of only 5% of the ocean volume explored.
If we are to address the pressing problems associated with climate change, sea level rise, and many other ocean-related issues in a timely fashion, we will need to accelerate our efforts to map and explore the deep global ocean as we cannot understand what we do not know.
Uncrewed surface vessels are being developed that may offer the chance to greatly reduce the cost and increase the efficiency of global mapping and exploration.
Multiple approaches are being taken.
The deployment of relatively small uncrewed vessels that can be carried from larger mother ships has already been demonstrated as a force multiplier offshore, but there are limits to the size of the uncrewed vessels that can be carried aboard a mother ship and this limits the size of the sensor systems that can be carried (and thus the water depths that can be mapped and explored.) Additionally, the range over which full data sets can be transmitted from the uncrewed vessel to (and from) the mother ship has been limited by the capabilities of marine broadband radios (typically on the order of 20 km depending on atmospheric conditions), but with advent of high bandwidth transmission through low-earth orbiting satellites, we may be able to operate uncrewed vessels (and transmit full data sets) much further from the mother ship or from shore-based stations anywhere in the world.
Uncrewed vessels can also play an important role as command-and-control stations, monitoring and controlling the location and behavior of underwater autonomous systems and relaying data and commands from the mother ship or shore stations to underwater vehicles, while freeing up the mother ship to pursue independent tasks.
The ability for operators to see, in real-time through the uncrewed surface vessel link, the location of underwater vehicles with respect to seafloor or midwater targets combined with the ability to direct the underwater vehicle to those targets, opens a new world of verified directed sampling where there is no ambiguity about what has been sampled or imaged.

Larger uncrewed vessels are being developed that can be launched from shore, with ranges of many 1000s of kms, that can carry deep-water sonars and exploration tools, and can spend extended time offshore.
These systems are exploring the use of energy efficient fuel systems and some can deploy their own remotely operated vehicles.
Large uncrewed sail-powered vessels are also being developed that offer a very low carbon footprint, the ability to carry large mapping systems and other sensors and the potential for long deployments to remote regions.

It is clear that much is going on with respect to the use of uncrewed surface vessels for ocean exploration and mapping, however, the critical words in the paragraphs and pages above are “being developed”, “may be able to”, “have the potential to”, and “exploring the use of”.
We are at the very early stages of understanding just what role uncrewed and eventually truly autonomous systems will play in our quest to map and explore the oceans.
We need to fully understand the capabilities, limitations, and tradeoffs associated with these systems with respect to gained efficiencies and overall costs.
The great challenges we face with respect to mapping and exploring the oceans impel us to seek new technologies and there is great potential that uncrewed systems will revolutionize our efforts, but the change will not be instantaneous and will not come without continued research, investment, innovation, and the steep learning curves associated with technological revolutions.
We must find the balance between too quickly jumping into approaches that are really not mature enough to appropriately serve our needs and thus lead to disappointment and abandonment of what might eventually be a very effective tool, and the frustration associated with long-term research and development projects.
The broad recognition of the great potential of uncrewed vessels across the private sector, government agencies, academia and NGOs, and the collaborations being established among these organizations is helping us find this balance and will hopefully expeditiously bring us to our collective objective of much more efficient mapping and exploration of the world’s oceans.
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