Trolling motor?

[thegadgetguy]

I don't really know either. In theory, it should be a problem, but theory and reality are often two very different things. I don't really think many people would have a problem with salt water, as most people operate in freshwater, but it would be an interesting theory to test.

[manhattan]

Soul,
Agree with your post and but think we are a bit off context here. The question was if the trolling motors were brushed / brushless and if they could dive 500-600. Pretty convinced that brushed can be run underwater, they used to be broken-in underwater. However I still doubt that the motors in question will survive 30m yet alone the target of 200m.

http://www.homebuiltrovs.com/mayfair750test.html

I think that if the trolling motors were opened they would dive deeper but it would not be fair to green to have him spend 35$ X ? to still our curiosity. Let’s face it, 600 feet depth is difficult DIY. I was also previously looking at “beyond scuba” depth but now I will celebrate if I reach 200 feet in salt water..lol.

And yes, water is a poor conductor but unless we plan to dive in 200 meters of distilled water, factors like uw particles (conductive), electrolytes (salt-water), drag and rust will definitively be relevant to us. Yesterday I ran my brushless (motor only) on 14m depth for 10min (lake) and it worked well. Waiting to see side-effects. If none, next test will be serious..lol..

[soulreaper]

Manhattan I dont have any knowledge of Salt water conductive properties. I dont know anything about salt water period. The link you posted was a pressure test of a sealed motor. As I understand it ( I could be wrong) but the conclusion was that the pressure caused grease to be forced into the motor which caused the higher amp draw. Water Pressure will not cause more drag on any object passing through it or swimming through it. (exception concerning light which cant penetrate deep depths) As a former diver, and this forum has people that currently dive, I move the same speed whether I'm 10 feet underwater or 70 feet underwater. I miss understood Greens post. I thought he was asking if he filled the troll motor with water or oil if it would be able to go deeper. My apologies if I have misled anyone.

Manhattan your right about Saltwater http://wiki.answers.com/Q/Is_salt_water ... then_water

[manhattan]

I am in on way correcting you Soul, as I said you are fully right-on with your post. Also I am the noob here as you can see in my intro. I started with 0 knowledge in rc, rov, controllers etc.

The drag that was referred to (I think) was on the motor armature of a brushed motor which would create more drag in the motor then BL setup.

[greenkarson]

Thanks for all the feed back. I'm going to go ahead and order the motors in the morning. I know that i will lose some power with the oil filled motors. But not enough to worry me. As long as all the air is out of the motor the external pressure of the water will have no effect on the motors abilty other then the oils resistance.

karson

[SoakedinVancouver]

Try not to leak oil in the water though. Using vegetable oil might be better for the odd leaks (Not "if" but "when")? Anybody with some more knowledge on that?

Also, having a bladder let the oil be at the ambient water pressure. Less escape forces...

[Stoic]

Trolling motors will work, if you're willing to put in the time to adapt them, but I would suggest that they might be overkill, unless you're doing a very large ROV. They will put out a ton of thrust compared to a bilge pump motor. The guys over at psubs.org have been known to use two or more to propel their submarines, although they usually custom build oil-compensated pods for them.