First time questions regarding thrusters

[tyrantbb]

Hey all, first time poster here, so I've been researching ROVs for about a month now and decided I should first work on getting a good thruster setup, at the moment I have a non waterproofed brushed DC motor with a 40mm prop, and it puts out about 3/4 lb of thrust @ 2.5A. My questions are...

-Is there any real benefit in waterproofing these DC motors? I don't plan on ever running this in salt water, and from what I read on other threads the main benefit of waterproofing is to keep the motor running in a less viscous fluid to keep the current down, but the friction from a shaft seal seems like it would be just as bad as running it directly in water.
-Is 3/4 lb of thrust enough to sufficiently maneuver a ROV? I plan on either using a 50' or a 100' tether so I expect the thrust to only be about 1/2 lb... this is kind of a subjective question so to phrase it better how long would it take for a ROV to dive to 50' using only one thruster at 1/2 lb of thrust?

[bikerbones1968]

You can run brushed and brushless underwater without waterproofing. Even in fresh water only just make sure you rinse them off well with clean water, blow dry with compressed air and use a non conductive lubricant to ward off any corosion.