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RE: [PSUBS-MAILIST] pressure compensated outboard
Ian! A small diesel genset charging the main battery's for extended running is a better idea.. that’s how trains, ships and subs have done it for a long long time and now car manufacturers are following the same path with hybrid's etc...
If the diesel engine was sectioned off in an airtight internal compartment at the back of the sub... an engine room of sorts... a clutch could be rigged up on the output of the generator shaft to direct drive a propeller shaft... as well as charging batteries etc...
So the sub would have 3 modes of operation then....
1. slow surface running + charging or idling while charging
2. Flat out surface running with no charging
3. running off battery's while submerged..
The only real advantage of having the diesel motor exterior to the pressure hull (pressure compensated) is if you wanted to run the motor off compressed air while submerged! :) I brought the subject of a combustion engine running off compressed air a while ago... with a similar idea in my head... It makes the problem of getting the exhaust gasses out of the hull/motor a bit easier if its pressure compensated... the atmospheric difference between the exhaust gasses coming out of the engine while the whole thing is running under pressure, all you would need would be a gooseneck and some sort of one way valve in the exhaust system :) to stop water flooding back...
Regards,
Stew
-----Original Message-----
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of irox
Sent: Sunday, 27 February 2011 5:16 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] pressure compensated outboard
Hi Brian,
given that almost all submarines that have used gasoline as fuel have met with a horrible end (Doc's bionic dolphin being the only exception, but that only submerges for seconds), I would stay away from gasoline.
You did motivate me to search for diesel outboard, seems like there have been a few, although not a popular diesel application:
http://www.yanmar.com.au/marine/d_series/dseries.htm
I think a small diesel generator powering the main thrusters would be a more convenient set up (and safer).
Also, I would consider making the housing from something that was less flammable that fiberglass.
My 2cent!
Cheers!
Ian.
-----Original Message-----
From: "ojaivalleybeefarm @dslextreme.com"
Sent: Feb 26, 2011 9:19 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] pressure compensated outboard
A Johnson ! I thought the AGMs were good to go, do they have air in them? It would be too much to ask to have the engine cover already set up to work as an ambient housing. I was thinking electric start so as to eliminate the pull cord, but I guess you could work around that. They make these outboards just huge now, I have a friend who has a Yamaha 225 hp. he says they make a 350 hp with a V8 ! Maybe the thing to do is to get a inexpensive one off of craigslist and do a test and try and make it work.
Brian
On Sat, Feb 26, 2011 at 7:23 PM, Alan James <alanjames@xtra.co.nz> wrote:
Not sure about the battery Brian.
I think wet cells are OK but AGM type batteries need a bit of work to enable them to take the pressure.
Was looking at a few motors, & some of them that have the fiberglass motor covers going right down over the motor may be able to be used without enclosing this top section.
The example below has a pull start wich would be a problem.
http://www.trademe.co.nz/Trade-Me-Motors/Boats-marine/Parts-accessories/Outboards/auction-355960445.htm
You would have your ambient system set up with the float down low, maybe in just a tube covering the lower section, so everything above that point would have the air pressure above the water pressure. This would mean that if the motor cover seal (wich you may have to beef up) failed it would be letting air out rather than water in.
With the pull start you could do something like attach a small threaded plug to the back of the pull handle & a female fitting on the motor cover that the plug is screwed in to for diving.
Alan
----- Original Message -----
From: ojaivalleybeefarm @dslextreme.com
To: personal_submersibles@psubs.org
Sent: Sunday, February 27, 2011 11:42 AM
Subject: Re: [PSUBS-MAILIST] pressure compensated outboard
Do those small outboards have a battery inside? The things that would have to be worked out are the starter button, the fuel line, the throttle, steering, air intake ( could be a valve), material to make it out of. I think just using a hardwood like oak for the structure of the enclosure and then just fiberglass and epoxy to do the finish shape. Seal inside and out with epoxy.
brian
On Sat, Feb 26, 2011 at 8:55 AM, Alan James <alanjames@xtra.co.nz> wrote:
I was looking at some small motors on an auction site last night.
I guess every different motor would present it's own set of problems.
Would be fun having a snorkel & running the sub on outboard just below the
surface.
Alan
----- Original Message -----
From: ojaivalleybeefarm @dslextreme.com
To: personal_submersibles@psubs.org
Sent: Sunday, February 27, 2011 2:59 AM
Subject: Re: [PSUBS-MAILIST] pressure compensated outboard
Nice it's all figured out now, now the only thing left is to build it ;)
On Fri, Feb 25, 2011 at 11:10 PM, Alan James <alanjames@xtra.co.nz> wrote:
Hi Brian,
Yes, epoxy & you need to try it on the polystyrene first, as some additives
in some epoxies can dissolve polystyrene.
Acetone does a good job on polystyrene. Petrol can dissolve it. It dissolves down to a
hard thin layer. Sometimes flakes of it come off, so you'd want to make sure these wouldn't
travel anywhere where they're not wanted.
I was thinking you would need to glue several blocks made of some heat resistant material
like aluminum, around the motor, flush with the level of the polystyrene, so the fiberglass jacket
was left suspended around the motor on these.
A further thought was that you could calculate the volume of air required to counteract any
buoyancy problems caused by the motor at the back of the sub. & incorporate this in the size
of the motor jacket.
Alan
----- Original Message -----
From: ojaivalleybeefarm @dslextreme.com
To: personal_submersibles@psubs.org
Sent: Saturday, February 26, 2011 7:12 PM
Subject: Re: [PSUBS-MAILIST] pressure compensated outboard
I did think of Frank when thinking of this, maybe he's still influencing our thought process more that we know ! so you're saying create a very small amount of an air pocket. Somehow I was thinking steel, but that really wouldn't matter with an ambient situation. A fuel bladder would work also. How does one go about dissolving polystyrene? Actually polyester resin is not compatible with styrene so you would have to use an epoxy - which would be so much the better anyway.
Brian
On Fri, Feb 25, 2011 at 7:18 PM, Alan James <alanjames@xtra.co.nz> wrote:
Hi Brian,
there are flexible fuel tanks that have the advantage in that they would be pressure resistant
& as your fuel level changes your buoyancy wouldn't change; or not significantly.
You could possibly cover the motor with thin sheets of polystyrene then fiberglass over it &
dissolve out the polystyrene leaving a small pocket of air around it.
I'm sure if Frank were around he'd be on to this. He wanted to put an outboard on Git Kraken.
Regards Alan
----- Original Message -----
From: ojaivalleybeefarm @dslextreme.com
To: personal_submersibles@psubs.org
Sent: Saturday, February 26, 2011 3:10 PM
Subject: Re: [PSUBS-MAILIST] pressure compensated outboard
Hi Alan,
That was my first thought, if any components would be affected. I can't see where there would be a problem, anything that has gasoline in it would be safe as far as pressure is concerned. I'm thinking a 20 hp or so outboard, electric start, fuel injected. I think most of those are water cooled so that would be a plus. I would just turn the whole cylinder to steer, and mount the thing in there good. Have a fuel line that could be valved off, the fuel tank might have to be pressure resistant.
Brian
On Fri, Feb 25, 2011 at 5:58 PM, Alan James <alanjames@xtra.co.nz> wrote:
An ambient outboard!
Sounds like an idea with a lot of potential Brian.
I'm wondering if there are any components that may be affected by the air pressure.
How big a motor are you envisaging? What sort of motor controls?
Regards Alan
----- Original Message -----
From: ojaivalleybeefarm @dslextreme.com
To: personal_submersibles
Sent: Saturday, February 26, 2011 12:57 PM
Subject: [PSUBS-MAILIST] pressure compensated outboard
I have an idea for a pressure compensated outboard engine so as to give surface power for my sub. Basically it would be a "can" that would cover an outboard engine with an opening on the bottom. There would be a float valve located near the bottom of the opening so when I submerge, as the water begins to move up into the cylinder, compressing the air, the float valve would inject air. That way it would keep a constant volume of air in the outboard engine compartment. As you assend the extra air would simply expand out the bottom.
Brian
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