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IN thinking of a slight overpressure inside, would a small 12v auto
tire pump hooked to an empty
scuba tank solve the problem? I know they go to 250lbs, and the
volume should be ok
Dean
In a message dated 6/15/2009 3:17:56 P.M. Central Daylight Time,
Alec.Smyth@compuware.com writes:
Simple solution... just put a T in your pressure gauge line, and
a little check valve of the kind that's a SS ball seated by a spring. You can
get them for maybe 10 bucks on eBay and they work like a charm. I know, a
small instrumentation line isn't large enough to relieve huge
volumes of air. But what you're contending with is pesky little small
leaks that go unnoticed. Also, install a barometer in the
sub.
Hello
Alec,
Your reminded me of one reason I didn't wish to go with
air compensated thrusters. It was a slow bleed into the interior of a K-250
that George was running, that made the hatch dome pop out when he started to
ascend, and he was lucky to of survived. This is also why I plan to install a
over pressure valve much like the larger one that is installed on the
KSS. Except I'll be mounting mine in the bottom of the sub so it can
also be used to drain the sub after a wet exit training exercise.
Regards,
Szybowski
Subject: RE: [PSUBS-MAILIST] Side Thruster Options
Date: Fri, 12 Jun 2009
09:14:20 -0400
From: Alec.Smyth@compuware.com
To:
personal_submersibles@psubs.org
Hi Dan,
I recall a past thread in the past on this topic, it
must be in the archives. Mine were air compensated when I bought Snoopy
but I switched to oil because the way the air compensation was originally
implemented, a little air bled into the cabin raising the interior
pressure. So I've run the same exact motors in both air and oil. I cannot
tell the slightest difference. They seem to have exactly the same power, and
even make exactly the same sound. In retrospect, I wish I'd measured the
current draw so I could compare that, but I'm afraid it's too late. Either
method works just fine.
thanks,
Alec
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If I were to do it again I would
also go with a Minkota or similar for me thrusters. I built mine
from standard DC motors. They're ambient pressure inside and have
ceramic shaft seals. It was a lot to go through and not cheep when all
was done. The worse is the weight of them.
Speed controllers aren't really
necessary on fractional horse powered thrusters like side thrusters because of
the mass of the sub. It doesn't react fast. Just pulsing them on
and off is sufficient. Where I do recommend a speed controller is on the
rear thruster so you can slowly cruse, skimming the bottom.
Has anyone done any
experimenting with oil filling thrusters to determine if there is an increase
in electrical current draw or reduction in thrust do to the drag of the
swirling oil and maybe some floating of the brushes?
Dan H.
----- Original Message -----
Sent: Friday, June 12, 2009 5:05
AM
Subject: Re: [PSUBS-MAILIST] Side Thruster
Options
Hi
Brent
I am also planning on using
Min Kota 's on my K350 I am also thinking of splitting my front mbt for
better view of my hydraulic manipulator you got any
thoughts.
All the best
glen south
Africa
----- Original Message -----
Sent: Friday, June 12, 2009 12:23
AM
Subject: [PSUBS-MAILIST] Side Thruster
Options
Greetings James,
I'm also
planning on installing small mostly off the shelf thrusters on the sides
of my K boat to reduce drag and simplify things. I've been planning
on using 36 volt Minn Kota 101 saltwater thrusters, like Frank, and I
believe Vance are using and oil compensate them. Last I checked
those thruster were running $250 each with the speed controllers going
for $150 each.
I'll have to check my notes, but I
believe Karl Stanley is using 6 of the 36 volt Minn Kota saltwater
thruster that he has oil compensated, and has used down to 2500 fsw.
Two for vertical thrust and four in the stern. Are you expecting to go
that deep James. ;}
I like the idea of using the existing flexible
shafts on some motors that Alec mentioned. I expected that I would clamp
mine on in a similar manor as Frank has done, since I'm not sure of the
long term saltwater durability of my favorite brand of duck tape.
I
see the need to beef up the side thru hulls, and was planning on looking
closely at how Dan beefed his up. With the new tangle guard configuration
I'm planning, I don't expect the thrusters will sustain any real damage
unless the Euronaut or the like plays to rough with my
sub.
Regards,
Szybowski
> Subject:
RE: [PSUBS-MAILIST] Subdate
> Date: Thu, 11 Jun 2009 17:46:21
-0400
> From: Alec.Smyth@compuware.com
> To:
personal_submersibles@psubs.org
>
> Hi James,
>
> 1. Do people just buy the standard Minn Kota outboard motor
complete
> with the bracket, leg, controls, handle, battery etc and
just modify the
> motor part? or can you get just the motor and prop
on its own?
>
> AS: You can buy just the parts you need
cheaper than the whole thing, I
> recommend
www.trollingmotorparts.com.
>
>
> 2. Whats the through
hull design? A straight forward twin O ring
> through hull on the
outboard shaft?
>
> AS: I would not go with the standard pipe
because it just isn't strong.
> In fact some motors come with
plastic pipes designed to be flexible so
> the shaft bends when you
hit something, rather than break off. On the
> side thrusters, I've
got heavy through-hulls. I did use the stock pipe
> on the stern
thruster, because that one doesn't go through the hull. The
>
through-hulls are just a SS bar stock with an external shoulder to
>
prevent the thing from being pushed in, and bored to whatever
minimum
> inside diameter you need for the cables and potting. Do
not just pot the
> cables, you have to put in solid conductors so
the pressure doesn't wick
> along the cable strands. I'd recommend
machining some vice flats on the
> through-hull too, for the day you
need to unscrew a thruster that's been
> on there a few years.
>
>
> 3. Compensation. Oil, ambient air pressure
regulator?
> I've had both but like oil compensation the best
because it's the
> simplest (not a single moving part). I just
changed the oil a couple of
> days ago. I expected it to be laden
with carbon deposits, but it came
> out looking like new despite
being in there for 4 years. Admittedly I
> put very few hours on the
sub, but it still surprised me that the oil
> came out looking as
clear as the day it went in. And yes, it WAS oil not
> water that
came out...
>
> :)
>
> Alec
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