Skip Asay

"Well Skip without actualy owneing one of these great subs you are as usual venturing."

It's not necessary to own one of these boats to understand how an electric motor works.

"No Skip again you don;t see the point ,its not a mater of haveing to cool the thing its just a beter way or a good insurance to do so,keep the little bugger happy and cool,it keeps the air inside of the casing cool so that it won't expand ,it also increases the efeciency of the motor quite a bit as I myself found out in several experiments."

All unnecessary as long as you're using the right motor/reduction/prop combination. My Type 56" XXIII, which is now 30 years old,has had the same motor for all but the past 2 months and the original motor is still going strong. BTW, I bought that motor used. The only thing I've ever had to do is put a drop of oil on the bushings every couple of years. And it's NEVER gotten hot or even warm for that matter. I'll disagree with your claim of increased efficiency with water cooling unless you're getting the motor so hot it will boil water.

The reason I've replaced the motor is to prove that a little 385 size motor WILL drive the 2 3/4", steeply pitched 3 blade prop very well. And it only draws ONE AMP at full speed.

"My motors are are just as common as yours ,simple can 12 volt units ,but I gear them down to as you even said with yours ,to 3.5 or 2.5 to one depending on the prop and how fast I want her go."

Now this opens a can of worms (pun intended). I've seen the master Mabuchi catalog and let me tell you, there are literally HUNDREDS of 375/380/385/400 size motors. The number "3" tells the diameter of the can while the 75/80/85 number tells the length. But the windings inside are all over the place. To cut to the chase, I've seen 380 size motors which draw only 50 milliamps and turn less than 5000 RPM (unloaded,@12 volts) all the way up to a 35,000 RPM screamer that draws 3 1/2 amps UNLOADED and this was only at 7.2 volts. So to say that you're using a "can" motor tells me nothing.

"yet most of the surface high speed boats have it standard every time"

Let's stick to the application at hand. We're talking subs here, not high speed boats.

"So please think about it its prity much so a no brainer the wy that I have cooled my motors is super inexpensive,simple to make and lasts a long time."

I'll stand by my original statement - "If water cooling a sub's motor is necessary, you're doing something wrong."

"Also remember that why would marine engineers and manufacturers of boat engines go threw all that expense just to keep the engine cool why? Its makes them last longer by far."

Again, I'll say "Let's stick to the application at hand." We're talking about electric motors not internal combustion engines.

"Of course you may build a sub without cooling there is nothing wrong with that but just remember that alot of the batery power yor toting around is going to be lost in heat build up caused by a motor that is warm or getting hot,the hotter it gets the worse the loss of effeciency ,look it up its all there."

For the most part, the heat generated by an electric motor is caused by the amperage going through it. Keep the amperage down and guess what? You don't have to cool it.

Skip Asay