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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