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2025-03-07 This is an interesting article about how to use ambient wave energy and currents to get through the water more efficiently, though their actuators (conventional propellers) are not very good. I find that when I am in the fishBOOT, I feel and interact with ambient waves to perform exactly this function. It is easy to feel and do. When a boat goes by, producing a wake, I can interact with the wake to help propel myself, regardless of my direction of travel, relative to the direction of travel of the wake. I suspect that the sensing system they describe in this article is wildly over-built. Fish use a lateral line of nerves, down both sides of their bodies, to do this, not an inertial measurement unit (IMU). There are low-cost, low-power, durable water flow sensors that could be used, rather than an IMU.

2021-10-05 The Oceans are DEEP! Checkout this video to get a sense for just how DEEP the oceans are.

Deep water (below about 750 meters) creates problems even for simple components, like driveshaft seals. A driveshaft seal keeps water from coming up the driveshaft into the motor. When the water gets deep enough, pressure will push past any seal. You can use a labyrinth seal, but it will increase friction and reduce operating time. You can use a magnetic coupling, between a driveshaft on one side and the propeller on the other, but they have problems, including reduced peak torque transfer, additional bearings, alignment, and system complexity. You can also flood the motor with oil to keep water out, but oil really increases motor friction and reduces efficiency.

Even simple components, like driveshaft seals, are problems at depth. The fishBOAT does not have a driveshaft seal and should be able to operate at great depth.

The Air Force Is Going to Navigate Jets Using Earth’s Magnetic FieldIf adversaries destroy American GPS satellites in wartime, the U.S. military must have a backup.

2021-07-09 This is REALLY important. Navigation through use of the Earth's magnetic field would open up an alternative to GPS under the water. The magnetic field still needs to be mapped, but this report about the US Air Force suggests it is possible! A fishBOAT could be used to map the magnetic field.