----- Original Message -----
Sent: Monday, October 24, 2005 3:41
AM
Subject: Re: [PSUBS-MAILIST] RimTec
Magnetic Clutches
Hi Byron.
You are right. I should have seen it before I
asked the question! What I was thinking was if you put a minnkota motor
in a metal or pvc pod and then filled the pod
with oil or water that would stop the outside
water pressure from trying to get into the pod. What I failed to take into
account was that the minnkota motor would still
have air inside of it that the outside water
pressure would be trying to get to even though the minnkota was surrounded by
water INSIDE the pod. So then the outside water pressure
would still implode a pod that didn't have very
strong walls as you mentioned it couldn't have for the magnetic clutch
assembly to work. You definately made sense and I must
have been having a blonde moment! Lol. The only
way my idea would work would be to first fill the minnkota with transformer
oil or the mystery "Jesus water" I have heard mention of,
and THEN fill the pod with water. That would
work. But there would be no reason to do that. Because once we filled the
motor with oil it would be equalized and there would be no need
for the pod or the magnetic clutch anymore. I
totally see what you mean't. I guess the answer would be to have a strong
enough magnetic clutch that would go thru a thick strong pod's
walls
so the pod could withstand the outside water
pressure and as you mentioned 6mm would not be enough wall
strength. Perhaps in the future they will come out with a stronger
magnetic clutch
that would go thru thicker material. Thanks for
keeping me straight.
Bill.
----- Original Message -----
Sent: Sunday, October 23, 2005 7:13
PM
Subject: Re: [PSUBS-MAILIST] RimTec
Magnetic Clutches
Bill, if I understand what you are thinking...I
think I see a potential problem. A "waterproof" motor
housing still has air inside it. The motor is not spinning in
liquid, right? But water proof casings may not be the same
as pressure housings. If this is the case, ( no pun intended) then
surrounding the motor with a liquid wouldnt work at any depth greater
than that at which the motor housing is rated. The ambient
pressure of the outside water would just be transferred via the liquid
to the motor housing. It would still flood/leak at the
same depth as it would if you just sank it alone.
the method you mention is used by lots of sub
people to pressure compensate external battery banks, to thousands of
feet. They use a flexible membrane on the top of the battery box and
fill it with mineral oil. However, the batteries themselves are
liquid filled, and not limited by psi.
I hope that makes sense, and
if not, then I probably misunderstood in the first
place!
Byron
Sent: Sunday, October 23, 2005 7:04
PM
Subject: Re: [PSUBS-MAILIST] RimTec
Magnetic Clutches
Hi John.
I was wondering if this idea might be
practical for your applications.
Suspose you rigged your motor to work with
the RimTec magnetic clutches.
Then suspose you filled the inside of the
enclosed casing holding your already waterproof
say...minnkota
motor with either oil or water before you sealed it. Then when you were at depth, the
outside water pressure
would not push against the sealed casing
holding the motor. Then you would not need a thick
barrier between the mag plate and the clutch.
Would that work?
Bill.
----- Original Message -----
Sent: Sunday, October 23, 2005 6:04
PM
Subject: Re: [PSUBS-MAILIST] RimTec
Magnetic Clutches
Hello fellow Psubbers,
I have looked very
closely into RimTec magnetic clutches about a year ago. I encourage
everyone else to check it out for themselves but I found they were very
limited by the type of barrier that one could have between the shaft mag
plate and the mag clutch. Less than 6 mm in most cases which was
not practical for my application and the pressure I was looking to work
with. The barrier has to be non-magnetic of course.
There is also a
significant limit to the torque they can transmit through a barrier this
thick. Since they are
custom made, they are also very expensive. Much more expensive than
building a good quality shaft seal. I was very hopeful at first but do
not feel they would be successful for a 1 AMT psub. Be sure to check
them out for yourself.
John
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