UNDERWATER EYES

Wi-Fi underwater is amazingly simple: Strip off 6.25 centimeters of shielding from coax cable and duct tape the center conductor to the back of the camera. Strip the other end and tape to the back of the smartphone or tablet. You can even leave the core insulation in place.

trical conductivity, and there can be a lot of variation in that, resulting in speeds as slow as 0.3 ten-to-the-eighth meters per second. So like, it would probably be best to put the coax inside a small square tube full of air, and tape that to the back of the camera housing. But never mind the theory, it works okay just like this." Lee was making multiple passes over the same area of the bottom, not too far from the waterline on the south side of the boat where the sun had provided perfect conditions for a very tenacious layer of algae. "Light-colored bottom paint also helps," she noted, "so you can see where the hull is clean. But like, it would be better if there were a way to measure and transmit smoothness directly, instead of having to infer smoothness from the visuals." "You get sound with the picture, no?" I suggested. "Maybe scrape a probe of some sort over the surface so you can hear the bumps and the roughness."

"I'm working on it," said Lee. "But like, this hand-powered brush stuff is just a transition. What we're all waiting for — especially with the way bottom paints are getting less toxic and need more brushing — is an automated device, sort of a robotic snail." "A Roomba for the boat bottom?" " 'Zactly. It's not a hard problem for any self-respecting AI drone. It will have to have a local navigation system, probably sonar -based, and it will have to be smart enough to teach itself the shape of the hull. And agile enough to

swim back to the boat if it falls off, or to swim to the charging station when the boat goes sailing." "The divers in the hull cleaning business are not going to like this," I predicted. "No way, they'll love it," Lee countered. "The divers will be the first to invest in these hull-cleaning drones, and they'll use them to expand their business. Cost goes down, volume goes way up. One bottom-cleaning drone could service a whole row of boats. Hulls get cleaned way more often and we'll all be sailing faster. And like, the owners get a 3-D image of their hull with a contour map of bottom smoothness before and after the cleaning. Much value added." "That's better info than a business card," I said nervously as I glanced down the dock to see if my diver had arrived. "Hard to believe that we don't have any products like that on the market already." "They're here, mostly designed for ships or other industrial applications, and they cost mucho bucks. But they still need, like, a human driver, and they still need a tether so the video signal can get to the display for the human driver to see. A few are aimed at mega-yachts, and they give them cool names: Keelcrab, Hullbot, Hullbug, Remora, Hulltimo." "If these things are really smart," I speculated, "and if the local positioning system is precise, they could map the hull accurately enough to produce a lines plan for an ORR rating. No more of that hokey 'wanding' to get your hull measured." "And it knows where the waterline Fish-eye view of a partially cleaned rudder. Always choose a light color for bottom paint.

November, 2018 •

Latitude 38

• Page 93