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Re: Trolling Motors
Well guys, have you ever heard the expression "the proof is in the pudding"
?
also "If it ain't broke why fix it !!!"
All I know about this is, don has been using the evinrude for some time now
at depths of 700 ft. !!!
Even the guys that made the dam thing would probably say, "your kidding, 700
ft."
It works... That's it...
I guess you either try it or you don't... I'm going to try it, when I do I
will let you know how it works for me, of coarse im only going 150 or so but
at least I know its been to 700.
I'll just consider the difference as a safety factor !!!
STEVE McColman wrote:
> I agree with you Ken! Why would evinrude use such a high quality,
> pressure proof, "expensive" shaft seal for a motor thats not meant to be
> more than 3 feet under the water???
>
> Steve McColman, Vancouver Island
>
> >I use on my Sub a Minnkota 70 pound thrust 24 volt Trolling Motor ($169
> each).
> >I examined the shaft seal and found it is a simple "Cup" seal in which
> the
> >shaft rotates in a rubber seal. Thus the shaft does abrade the rubber.
> This
> >degradation is a function of differential pressure across the seal and
> for low
> >pressures is long lasting.
> >
> >When I was talking to Minnkota, they stated the seal wasn't good for
> much more
> >than about 30 feet of fresh water before it could leak. I believe his
> response
> >was conservative but their seal certainly would not work at 700 feet
> and if it
> >did it wouldn't last long. I ended up pressure compensating my motor
> with a
> >somewhat simple SCUBA regulator such that the differential pressure
> across the
> >shaft seal was less than 2 feet of seawater and was positive. This
> means that
> >any leaks would leak air out and not corrosive seawater in. At least I
> hope
> >so, I still have not made sea trials yet although the my Wet Sub is
> ready.
> >
> >The point of this is that since the Evinrude Trolling Motor is in the
> same
> >competitive market I personally doubt that their shaft seal will
> reliably
> >operate with 700 feet of sea water differential pressure. Pressure
> >compensation, I believe, will be required.
> >
> >If someone is planning to use the Evinrude Trolling Motor, it would be
> >critical to call the vendor and get real data on their shaft seals. I
> know I
> >did on the Minnkota Trolling Motor. I spent about $20 on the phone
> calls. I
> >also got design information on the Motor Controller I designed. High
> surge
> >currents can demagnetize the Trolling motors permanent magnet stator.
> >
> >Good Luck,
> >
> >Ken Martindale
> >
>
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