Figuring out the shape of a harbor bottom has always meant putting a boat on the water with people standing on it. You pay for the boat by the day and the crew by the day, and you pay either way, whether the job takes six hours or six weeks.<\/p>\n
So companies have spent the last few years shrinking the boat and leaving the people on the beach. Most of the ones that reach the news are military, like the 17-foot aluminum drone boat that ran two weeks of a Navy electronic warfare exercise in Michigan<\/a>. This one’s a commercial survey boat, which is a duller job and, I’d argue, a much bigger market.<\/p>\n An Italian survey contractor called Subsea Fenix has one working now, and on September 7 its British builder showed us what the thing brought back.<\/p>\n The boat’s called USV Fenix 01. It’s an 18.7-foot aluminum catamaran with batteries and a generator aboard, built by HydroSurv<\/a> in Exeter, England, and it’s the first vessel the company has sold into Italy. It came out of commissioning in August, and the first bathymetry came off it during that same phase.<\/p>\n Bathymetry is just the shape of the bottom and how far down it is. If you’ve ever watched the depth reading tick over on a boat’s display, you’ve collected one point of it. This boat collects a whole fan of them, up to 50 times a second, while it moves.<\/p>\n Depends on the day. The hull takes interchangeable payload skids, and the survey skid holds a Teledyne SeaBat T51 multibeam echosounder, an Innomar sub-bottom profiler for seeing under the mud, an EdgeTech 4125i towed side-scan sonar and a Sonardyne MiniRanger 2 for tracking where gear is underwater.<\/p>\n Pull that skid out and an ROV skid goes in, carrying a Saab Seaeye Falcon and the winch gear to put it over the side. Same boat, different job. It’s the same idea behind those swappable weapon cassettes on a British military drone boat<\/a>, just pointed at survey contracts instead of targets. Only the survey half is finished so far.<\/p>\n Subsea Fenix leads with that number, and it decides whether any of this pays for itself. A multibeam echosounder fires sound at the bottom and times the echoes coming back across a wide fan, so a single pass gives you a strip of seabed instead of a line of dots. Surveyors call that strip a swath.<\/p>\n Seven times the water depth means that in 30 feet of water, you’re mapping a strip about 210 feet wide. I ran that ratio back through some trigonometry and it’s a fan roughly 148 degrees across, which sits between the two swath figures on Teledyne Marine’s datasheet<\/a> for the uncrewed version of this sonar.<\/p>\n Subsea Fenix CEO Stefano Mancini says the detail “does not cost you mission hours.” That’s the trade he cared about. If a sharper sonar makes you run twice as many lines, you’ve paid for the sharpness in boat time.<\/p>\n HydroSurv says the sonar’s running in its 700 to 800 kilohertz band, which is the high end. High frequency buys you detail and costs you reach, because high-pitched sound gives up faster in seawater. Teledyne’s sheet puts the normal working depth in that band at about 197 feet.<\/p>\n So why not drop to the lower band and see deeper?<\/p>\n You can. The same sonar head runs a lower band too, where the normal working depth jumps to roughly 525 feet. You’ll just stop resolving the small stuff, and the small stuff is why anyone pays for a nearshore survey. Cables, rock, scour around a pipe, the boulder somebody needs to not drop an anchor on.<\/p>\n This year’s version of the hull gets twin steerable 11-kilowatt pod drives. They’re rim drives, so the motor sits in the ring around the propeller instead of behind it, and the thrust doesn’t run through a shaft at all.<\/p>\n Call it 22 kilowatts total, or about 30 horsepower, which is less than you’d find hanging off the back of most bass boats. Top speed is 7.5 mph, so it’s slower than a bicycle.<\/p>\n The pods earn their keep standing still. Two of them steering independently let the boat hold a heading against wind and current without an anchor, and hold a straight line while it drags a sonar fish along behind it. Both of those matter more than speed when you’re getting paid for clean data.<\/p>\n HydroSurv’s own REAV-60 page<\/a> still lists 8-kilowatt pods, incidentally. The August announcement and the September writeup both say the 2026 platform moved to 11, and I’d take the vessel documents over a product page, though a spec page running a year behind the hardware is pretty ordinary.<\/p>\n The electrical side got rebuilt too, onto a 48-volt architecture with separate AC and DC generation. That doesn’t sound like much until you look at what it’s feeding. HydroSurv’s platform page lists a 100-gallon fuel tank on a boat you could park in a two-car garage, and the sonar processor sitting on top of all that draws about 90 watts.<\/p>\nSo what’s it actually carrying?<\/h2>\n
The sonar covers seven times the water depth<\/h2>\n
The pods are new this year<\/h2>\n
The ROV work is still a plan<\/h2>\n