From: vbra676539@aol.com
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Minn Kotas
Date: Sun, 19 Nov 2006 19:33:06 -0500
Perry built subs a quarter mile north of the Palm Beach Inlet. What do
you think? Vance
-----Original Message-----
From: joeperkel@hotmail.com
To: personal_submersibles@psubs.org
Sent: Sun, 19 Nov 2006 6:45 PM
Subject: Re: [PSUBS-MAILIST] Minn Kotas
Vance,
"maybe we ought to be thinking PC-14. Use a 3 hp golf cart motor through
the right reduction gear and turn a big wheel".
......I took a quick look at PC-14, was this designed to transit long
distances along the bottom?
A large slow turning prop is more efficient than a small fast one, I know
this from aviation. Something like this would certainly fair better in a
current than thrusters, make transits much easier and, this whole rig could
pivot on the existing rudder bar system.
Alvin initially had this big wheel rig. But Alvin is more suited to
hovering with fine buoyancy control and bursts from her thrusters which is
what I have in mind also.
But, let me ask you this, for our coastal environment, with that prevailing
northward current that can get quite troublesome, would some combination of
a large efficient stern wheel and some fixed fractional hp thrusters be
ideal?
Joe
From: vbra676539@aol.com
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Minn Kotas
Date: Sun, 19 Nov 2006 14:25:04 -0500
Joe,
George settled on 3 horsepower after experimenting with several other
combinations, including smaller trolling motors. I don't know if the thrust
calcs from Johnson Outdoors is static or dynamic, and those results would
make a substantial difference. However, I'm thinking that if you used three
of the 101s from Minn Kota, two reversible units forward on a common shaft,
one on the stern, and one fixed lateral on the bow, then the boat ought to
do pretty well.
However, I'd miss that big old slow turning wheel from Perry, and I have to
tell you, I have never found anything quite as good in all the other
configurations I tried, horsepower be damned. I can remember having the
1201 trimmed dead neutral on the bottom skirt of the CDP-1 platform in the
North Sea oil patch, and moving the boat slowly along while we filmed with
the main motor on its minimum setting. The prop was going so slow that I
could actually see little jerky movements as the SCR fired!!!
The 12-boats weighed 8-tons, mind you. At dead slow RPM we weren't using
much horsepower, but that big 3-bladed fan in back was doing all I wanted
it to do, thank you, and it was a beautiful thing to see. Looking at it
that way, maybe we ought to be thinking PC-14. Use a 3 hp golf cart motor
through the right reduction gear and turn a big wheel. It's heavy and
cumbersome and takes a lot of room and puts out a lot of heat and blah,
blah, blah. But man, you will love it. Guaranteed.
Vance
-----Original Message-----
From: joeperkel@hotmail.com
To: personal_submersibles@psubs.org
Sent: Sun, 19 Nov 2006 2:03 PM
Subject: RE: [PSUBS-MAILIST] Minn Kotas
Vance,
Interesting comparison here, perhaps you can comment. The WHOI user manual
for Alvin specs 150 lb thrust for ea of the 6 thrusters....(Alvin weighs
35k)
http://www.whoi.edu/marops/vehicles/alvin/userman_subsystems.html#propulsion
Minn Kota specs the following for their saltwater outboard mounted
motors...
ModelVoltsThrustShaft Lengths
Engine Mount RT202/EM36202â??
Engine Mount RT160/EM24160â??
Engine Mount RT101/EM36101â??
Engine Mount RT80/EM2480â??
Engine Mount RT55/EM1255
The Busby manual says power requirement selection is based on a velocity
-vs- resistance formula. What's your best intuitive guess for a K-sub to
hold it's own against a prevailing 2-3 kt current?
Joe
From: vbra676539@aol.com
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Minn Kotas
Date: Sun, 19 Nov 2006 12:41:11 -0500
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