Brushless DC Motors suitable for Underwater?

[Kunniez]

Hi people,

im new to this forum. I'm currently working on a underwater ROV for my school project. We did a experiment recently on the performance of our ROV. We met up with some problems on the motor & the propeller for the thrusting. The motor stalls just after 5secs. So I am thinking is there any wrong with our motor? Cuz I am afraid that our brushless DC motor might not be suitable for underwater usage. The motor we bought is "Oriental motor Brushless DC motor" model BLM5100k-A. Is there anyone had tried making a ROV using those motors? Pls advise. Any help will be very much appreciated!

Thank you
Kunniez

 

[berkeman]

The motor is sealed in a water-tight enclosure, right? The motor doesn't know it's underwater, or at least it shouldn't. What do you mean by "stalls"?

 

[Kunniez]

Yup it in seal in a high density plastic material called delrin with O rings & rubber seals at the opening. It is already a water proof seal so I am sure there wun be any water that could leaks into the motor. I did a experiment on the motor & driver mounted wif a marine propeller in the water. Everytime i on the power supply, the propellers starts to spin smoothly for the first 5secs. After that it will stop automatically. I am suspecting is it whether the motor couldn't run at consistent pressure in the water. Cuz when i tested the motor & propeller on air, it works perfectly fine. Or is it becuz there is not enough current or is there other extra components to make this work. Eg, like a potential meter. Pls advise...