Boats hate breaking surf. If you’ve ever watched somebody try to punch a small skiff out through the waves, you know the routine: wait for a gap between sets, gun the throttle, and hope the bow lands pointing the right way. That churned-up strip between the beach and the calm water is where small boats get spun sideways, swamped and rolled, so most of them stay well clear of it.<\/p>\n
The US Army can’t stay clear of it. When the Corps of Engineers dredges an inlet, or the military needs to land supplies across a beach with no port around, somebody’s got to know how deep the water is in exactly that zone, and what’s sitting on the bottom waiting to open up a hull. So for a week this month, an Army coastal lab in Duck, North Carolina sent a robot boat into the break on purpose, to find out what it could map in there.<\/p>\n
The boat was Ocean Power Technologies’ WAM-V 8<\/a>, and on paper it reads more like sporting goods than a survey vessel. It’s 8 feet long and 4 feet wide, weighs 340 pounds empty, and runs on two 1,100-watt electric motors fed by lithium-ion batteries. It draws 4 inches of water. You can load it in the bed of a pickup, or take it apart and check it as baggage on a domestic flight.<\/p>\n So what was it doing in the surf?<\/p>\n The Army Engineer Research and Development Center’s Coastal and Hydraulics Laboratory put out a call<\/a> for drone boats that can keep moving where the waves break and the currents run, right into the mouths of coastal inlets, and map the seafloor while they’re at it. The target scenario in that solicitation is breaking waves of more than 3.3 feet (1 meter), folding over on top of a boat that’s 8 feet long. ERDC picked its participants through a competitive technical evaluation and hosted a week of live testing at its Field Research Facility in Duck. Running drone boats close to shore isn’t a solved problem for anyone: a 24-foot British navy drone boat put a gouge in a 55-foot racing yacht<\/a> inside Portsmouth Harbour.<\/p>\n Why does the Army care? Two reasons. The Corps of Engineers keeps channels and inlets dredged, and you can’t dredge what you haven’t measured. The military also has a mission category called logistics over the shore, which is exactly what it sounds like: landing fuel, food and equipment straight across a beach when there’s no port around. Before anyone runs landing craft onto that beach, you’d really like to know where the sandbars and the sunken junk are. The surf zone is the gap in the charts, because it’s the one place survey boats don’t like to go and divers like even less. Farther offshore, this kind of mapping already belongs to machines; two 242.5-pound drones drove themselves out to a mooring off California<\/a> to photograph the water column ahead of a research ship.<\/p>\n OPT said on September 9 that it was taking part, and on September 18 it announced the week was done, calling it a formally evaluated demonstration. Testing covered sensor performance, vehicle configuration, and how you actually get a sensor in and out of the water in conditions like these.<\/p>\n Here’s the two-sentence version of the trick. The WAM-V 8 is a catamaran with two inflatable pontoons, and the platform holding the electronics doesn’t sit on them directly: it stands on legs, and the front legs connect to the body through spring-loaded ball joints that let them pivot as a unit, while the rear legs stay rigid. The pontoons ride up and over each wave, and the sprung joints soak up a good chunk of that motion before it reaches the deck.<\/p>\n That matters because sonar hates movement. A multibeam sonar builds its picture of the bottom from whatever it’s bolted to, and when that platform pitches and rolls, the data smears. Keep the deck steady and you get a clean map. Let it slam around and you get noise. It’s basically a camera gimbal holding up a sonar instead of a GoPro, and frankly it’s a neat piece of engineering to find on something the size of a kayak.<\/p>\n The suspension exists because one man spent a sailing trip throwing up. Ugo Conti crossed oceans on a 50-foot ketch in the 1970s and, according to Uncrewed Systems Technology<\/a>, was chronically seasick the whole way. That misery eventually turned into the idea of a platform that adjusts itself passively instead of fighting the water, and the company he and his wife Isabella built around it now belongs to Ocean Power Technologies, which bought it in November 2021.<\/p>\n The design got simpler over time. Early versions carried suspension front and rear, until the builders concluded the front end was doing most of the work and deleted the rest. They also added a rigid ski on top of each inflatable hull, which let them drop the air pressure in the tubes from about 7 psi to between 1.5 and 2.5 psi. A soft hull squishes over a wave instead of slapping it, so the tubes themselves became part of the suspension. Which is my favorite kind of engineering: the fix that removes parts instead of adding them.<\/p>\n Honest answer: we don’t know yet, at least not in numbers. Neither of OPT’s two announcements gives the wave heights the boat actually faced that week, how many days it spent in the water, or any performance figures, and as far as I can tell the Army hasn’t published anything about the demonstration on its own. The 3.3-foot breaking waves in ERDC’s paperwork were the target, with a note that conditions would depend on whatever the ocean served up during test week. Keep that in mind, because right now the entire public record here is two company press releases.<\/p>\n What OPT did say is where the data goes. Jason Weed, the company’s chief operating officer, said the week gave OPT “valuable insight into how we can advance our platforms” for customer operations, and OPT says it’ll feed the lessons into its bigger boats: the 16- and 22-foot WAM-V platforms<\/a>. The 22-footer’s a different animal, weighing 2,500 pounds against the 8’s 340, topping 20 knots, and running on gasoline outboards rather than electric motors.<\/p>\n So far, nobody’s committed to buying anything. OPT’s own announcement notes that taking part isn’t a procurement contract or any kind of US government commitment, and ERDC’s said promising technologies may be considered for follow-on testing, subject to funding its solicitation listed as not currently available. That’s pretty normal for a program at this stage, and I’d guess a drone boat that can hold a sonar steady in whitewater will find plenty of civilian survey work even if the Army never buys one.<\/p>\n OPT announced the completed evaluation on September 18, nine days after saying the boat was headed into the surf at Duck, and says the results now feed the development of its 16- and 22-foot platforms.<\/p>\n","protected":false},"excerpt":{"rendered":" Boats hate breaking surf. If you’ve ever watched somebody try to punch a small skiff out through the waves, you … <\/p>\nThe Army wants maps of exactly that water<\/h2>\n
So why does a boat need suspension?<\/h2>\n
Seasickness started all of this<\/h2>\n
So did it work?<\/h2>\n