Re: [PSUBS-MAILIST] Side Thruster Options

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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From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Dan H.
Sent: Friday, June 12, 2009 8:08 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Side Thruster Options

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 -----

From: glen brown

To: personal_submersibles@psubs.org

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 -----

From: Brent Hartwig

To: PSUBSorg

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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