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Well, actually I got the
instructions for this from Vance who posted them way back. Since doing my own
thrusters with those instructions, Greg Cottrell came over one evening
and we did his with the Vance method as well.
1. Take the motor apart.
You want the can with nothing else attached, because when you drill holes in it
there'll be chips, which should not be allowed into coils or anywhere
else.
2. The magnets are glued
to the can, so you can't remove those. Drill two holes on opposite sides of the
can, making sure you miss the magnets. Choose the hole location so that once the
thruster is installed, one hole will be at the motor's highest point and
the other at it's lowest.
3. Tap the holes and
install threaded plastic elbows for 3/8" clear vinyl hose.
4. Clean up the chips and
put the motor back together.
5. Connect about 6-8" of
vinyl hose to the lower elbow. Use a funnel to fill the motor with oil through
the hose until it flows out the top elbow.
6. Wrap the hose around
the motor (mine loops once around the shaft) and connect to the top elbow. You
want to do this trying to avoid air bubbles, which means you make the connection
quickly with oil flowing -- a puddle on the floor is unavoidable.
The hose has two
functions; it comes in handy for filling the motor, but more importantly it's
compressible. A tiny bit of air is unavoidable (barring a bathtub full of oil to
assemble the thruster submerged) so the flexibility of the hose keeps the seal
from being squeezed by compression of that remaining bubble.
That's it for oil compensation. Each motor should take
you about half an hour to do. The other question that comes up is what kind of
oil to use. I've used Marvel Mystery Oil and this time I just refilled with
WD-40.
Now as for sealing up the
cables, that depends on whether the motor shaft is going through the hull or
not. If it is not, as on my stern thruster, then you've not got any significant
pressure differential across the cable seal. I've just got that one sealed with
marine silicone around the cable jackets. But on the side thrusters it's a whole
different matter. Look at Emile's project, he's got a photo showing really super
workmanship on a trolling motor penetrator. What you want to do is
connect a section of solid conductor inline with each cable, to
prevent pressurized oil from wicking along the strands. You have to pot those
solid conductors with epoxy inside the thruster shaft. The shaft should have a
groove or thread on the inside to give the epoxy something to hold onto. The
tricky bit is the lack of space. You have to keep those conductors apart so they
don't short out, but also have to keep them from touching the shaft
wall. As you can see Emile did it with a plastic insert that acts as a spacer.
Be as generous as space affords with the cable diameter -- you don't want to pot
a space heater that melts epoxy.
good
luck,
Alec The contents of this e-mail are intended for the named addressee only. It contains information that may be confidential. Unless you are the named addressee or an authorized designee, you may not copy or use it, or disclose it to anyone else. If you received it in error please notify us immediately and then destroy it.
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of
ShellyDalg@aol.com
Sent: Tuesday, June 16, 2009 12:23 PM To: personal_submersibles@psubs.org Subject: Re: [PSUBS-MAILIST] Side Thruster Options Hi Alec. Could you explain in more detail how you switched over to the oil
compensation of your thrusters?
I remember the past thread and drilling a new hole in the thruster casing
was made for the addition of the oil.
How is the existing hole with the wires sealed up?
I found some brass compression fittings at the hardware store that the
threads on the Minnkota motors match, and the original supplier also had an
aluminum fitting with a rubber compression grommett that screwed into the nipple
where the wires exit the motor. What parts and methods have you got on
yours?
Frank D.
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