From: "Smyth, Alec" <Alec.Smyth@compuware.com>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: RE: [PSUBS-MAILIST] Maneuvering
Date: Thu, 16 Nov 2006 14:15:28 -0500
Agree 100% on all counts. My next boat will have fixed thrusters, but on
the K-250 I had already-built hardware to contend with.
Alec
________________________________
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of
vbra676539@aol.com
Sent: Thursday, November 16, 2006 1:04 PM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Maneuvering
Alec,
I'd be prone to using thrusters of the same size, and carrying a spare
that could replace any of them. The JSLs use them pointed athwartships,
vertically and fore and aft for main propulsion and they're about as
good as it gets for close work (considering the weight). However, it's
power heavy for transits, as you're steering with the maneuvering motors
all the time. Their motors are on and off (1 1/4 hp 28VDC through a
planetary gear turning 14" props in a Kort nozzle).
Rudders and planes are nice for transits. You could build the thrusters
into the things and operate them mechanically from inside (the same as
our side units now). Then a fixed lateral on the bow--four thrusters in
all. Mind you, the most successful builder these days is Phil Nuytton,
and he mounts verticals fixed and steers with the motor controls on his
side thrusters (2 or 4 units), also fixed. It's simple, doesn't require
anything but cable penetrations, and saves a lot of fuss and bother with
rotating shafts through the hull.
The bigger Minn-Kotas all have speed controls and lots of other tasty
options, including battery condition meters, solid state chargers that
could go INSIDE the sub, rather than be toted around, and even a built
in auto-pilot on some models. In fact, they have a dual motor unit
designed to mount to the topside of an outboard's cavitation plate, and
I don't see why that couldn't be adapted to fit them on either side of a
rudder, and wouldn't THAT be a kick in the tail!!! We'll see what they
say, and then look at the price.
Vance
-----Original Message-----
From: Alec.Smyth@compuware.com
To: personal_submersibles@psubs.org
Sent: Thu, 16 Nov 2006 11:52 AM
Subject: RE: [PSUBS-MAILIST] Oil Compensated Thursters
Vance,
Snoopy came with the side thrusters and I added the stern thruster. I'm
not certain how many pounds thrust I have on the sides, but I'd guess
they're about 40 lbs. Those appear very nicely sized, but I'd encourage
you to go with variable speed as opposed to my simple on/off. As you
might have seen in the cable collision video, Snoopy goes a bit too fast
for limited visibility. I wouldn't want them any smaller because they're
just right for maneuvering on the surface, but for UW use variable speed
would be a worthwhile improvement.
The stern thruster is tiny, just 28 lbs. My reasoning for that was that
I was envisioning using it UW and wanted something small to go slowly.
That turned out to be a mistake. The problem is if I'm cruising UW on
the stern thruster alone I have no vertical control, so the main use of
the stern thruster is on the surface, and it's way too small for that.
The side thrusters, because they rotate, are the ones to use submerged
unless you were also putting in a fixed vertical thruster.
Bottom line, I'd go with side thrusters in the 40-50 lb range and a
stern thruster in the 75-100 lbs range.
Ah, and the question about currents. Unfortunately in the sorts of tidal
currents you have down there in South FL, all of the above are useless!
:)
Alec
________________________________
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of
vbra676539@aol.com
Sent: Thursday, November 16, 2006 11:13 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Oil Compensated Thursters
I remembered the conversation after sending the email, but didn't hear
how you had actually done the job. Excellent. Just as plain-dumb-simple
as can be. I just wrote Minn-Kota about this. They've got the 101#
saltwater 36 volters, plus a new electric outboard that is 48 volts.
I'll have to see whether I can afford a box full, as will take at least
four motors to do what I want. Which model did you use for Snoopy, and
how are they in a current?
Vance
-----Original Message-----
From: Alec.Smyth@compuware.com
To: personal_submersibles@psubs.org
Sent: Thu, 16 Nov 2006 10:38 AM
Subject: RE: [PSUBS-MAILIST] Oil Compensated Thursters
That's funny Vance, because you were the guy who gave me instructions on
how to do it!
Each trolling motor has two little plastic elbows screwed into the
casing, one on top and one below. I have about a foot of clear plastic
tubing that is wrapped around the can and ends in each elbow. The tubing
being flexible will compress if there are any small air bubbles left in
the motor (I've found it impossible to eliminate ALL bubbles, there's
always a small one that shows up in the tube). The reason the elbows are
on the top and bottom, as opposed to say the sides, is to make it easier
to fill with oil. I disconnect the tube from the top elbow, raise the
open end of the tube above the level of the motor, and add oil through
the tube until it flows out the top elbow.
Obviously to install the elbows you need to take the motor apart,
because drilling and tapping the holes creates metal chips that would
ruin the motor in short order. You also need to make sure you're
drilling in between the magnets, which come glued to the inside of the
motor can.
I hope that description is clear. If you see the actual HW it's
ridiculously simple.
thanks,
Alec
________________________________
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of
vbra676539@aol.com
Sent: Thursday, November 16, 2006 10:17 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Oil Compensated Thursters
Alec, How do you compensate the oil? I'd love to try some of those 36
volt Minn-Kotas. They've got a ton of umph, and might get me back a
couple of hundred pounds of payload from George's Model-T Rex style
thruster cans. And it would be cheap, too. Vance
-----Original Message-----
From: Alec.Smyth@compuware.com
To: personal_submersibles@psubs.org
Sent: Thu, 16 Nov 2006 9:39 AM
Subject: RE: [PSUBS-MAILIST] Oil Compensated Thursters
I had an email conversation with Carl about a year ago on that topic.
They're just straight air compensated, with Swagelok SS fittings tapped
into the trolling motor casings. The reason I'd contacted him was to ask
whether he was using air, because some on here maintained that at his
depths, the partial pressure of O2 in air would be a fire hazard. I
think his sub demonstrates it's not.
BTW Snoopy's trolling motors started out air compensated and are now in
their second season with oil compensation. I have nothing at all against
air compensation, and would go with that if my air bottles were outside
the hull. But the way it was implemented on Snoopy the air was passed
through the shafts from the cabin, and there just wasn't space to do it
properly along with the cables. What's been interesting about the switch
to oil is I can't notice ANY difference. The motors seem to pull just as
strong, and even sound exactly the same as before.
cheers,
Alec
________________________________
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of
vbra676539@aol.com
Sent: Wednesday, November 15, 2006 11:17 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Oil Compensated Thursters
Oil compensated DC motors work just fine at moderate depths. Alvin had
problems originally with brushes arcing, but he Hymak 5 hp motor used by
Hyco on nearly everything they built was a serious workhorse. You get to
tear it down and change brushes periodically as they wear faster, and
they'll get the oil dirty, so you'll have to watch that. I was on Karl
Stanley's web page last night and it looks to me like his Idabel is
using about a case of trolling motors, and they must be compensated, as
the sub is rated for 3000 foot service. Maybe we ought to ask him what
the secret is, if any.
Vance
-----Original Message-----
From: DJACKSON99@aol.com
To: personal_submersibles@psubs.org
Sent: Wed, 15 Nov 2006 10:35 PM
Subject: [PSUBS-MAILIST] Oil Compensated Thursters
Can anyone support this statement: "Scripps has tried to fill the DC
motors with oil, but the oil gets between the brushes and the
commutator, where the insulation properties of the oil causes problems.
Although it would be possible to use high voltage to break through the
oil film, the high voltage is a safety hazard for the divers."
-- www.empiremagnetics.com/articles/deep_sea.htm
I was thinking about 24 or 36 volt oil compensated brushed trolling
motors, but after reading the above I looked and could not find any
examples of oil compensated brushed motors under 100 volts.
What are your experiences and thoughts?
Thanks
--Doug J
www.submarineboat.com <http://www.submarineboat.com/>
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