Hi Alan! I’m doing some investigative work into ROV’s and surface autonomous vehicles at the moment… and I’m contemplating designing my own motors for the surface autonomous boat… Ive also been into building RC planes for quite a while… Brushless RC motors = what is exactly needed… The magnets are mounted in the external stator and inside the motor is 3 coils mounted at 120 degree’s apart… and a controller works out which of the 3 phases to energize to make the motor rotate at the demanded RPM… This design means that an insulator/isolator can exist between the stator and the coils(as long as there is a slight clearance for oil or possibly even sea water to cool the motor… if the coils and magnets can be sufficiently insulated/corrosion proofed Only the magnets/magnet housing/bearings and other drive components need really be waterproofed! J From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Alan James Hi, Came across these underwater thrusters. They are "rim driven" with one moving part. It looks like the kort nozzle or duct is the stator & the propeller is the rotor. They are rated for any depth. Am awaiting a price, got an idea they aren't cheap. Alan |