Unmanned Systems Technology 033 l SubSeaSail Gen6 USSV l Servo actuators focus l UAVs insight l Farnborough 2020 update l Transforma XDBOT l Strange Development REVolution l Radio telemetry focus

to do a fairly accurate assessment of the buoyancy and the weight, so our vessel is therefore somewhat sensitive to weight and the volume,” he says. He explains that carrying something that’s even a little too heavy would turn the buoyancy negative, causing the boat to sink, while something that adds buoyancy would make it float too high so that the righting moment would be insufficient, with the result that the boat would heel over too much. “The physics says it will sail, and it does. It’s not impossible; it’s just a little weird,” he says. Designed using SolidWorks, the vessel has evolved from the original concept, becoming larger and faster and adding a submersible capability and a catamaran variant as options. Minor refinements and improvements have been made over time, arriving eventually at the current Gen6 form. The first vessel built was a subscale proof-of-principle model about 400 mm long. “It was really only to demonstrate that the physics were valid, but it didn’t have enough power to sail in anything other than a millpond,” Todter says. Other proof-of-principle models that focused on other aspects followed, gradually getting larger until one that was more than three times the size of The Gen6 sailing in rough conditions. Balancing buoyancy and weight is crucial – too much weight will sink it; too much buoyancy will make it heel too far in the wind