Re: Trolling Motors

[Martin Sanderse <sanderse@ingenuitygroup.com>]

Albert Long wrote:
> 
> 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 !!!

On the risk that Albert is just trolling us for emotional responses:

How about testing it without risking your health first?  OK guys, let's think of a good 
testing method before we have a long post-mortem discussion.  That way if he wants to 
kill himself his family can't say he didn't know how to test the thing.

Umm. . . .   we could always test Albert too.  Perhaps giving him a revolver with one 
bullet in it on a dare would deflect the cause of death to poor judgement rather than to 
PSUBS. 

> 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
> > >
> >
> > ______________________________________________________
> > Get Your Private, Free Email at http://www.hotmail.com

-- 
Martin Sanderse
---------------
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