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Hi Brian,
I presume all of the submarines Ian mentions with
petrol engines were inboard.
The issue of petrol fumes in an enclosed space
with compressed air may need looking at.
The Johnson I linked you to was just a random motor
I came across with a deep motor cover.
I agree with the idea of starting off with
something small & cheap & experimenting with it.
Maybe track down a manual first & see if there
are any foreseeable issues.
I'm thinking that it may be a matter
of finding a particular motor that lends itself to this
conversion, rather than just grabbing anything
& doing a lot of hard work.
I can imaging all these K250s retro fitting ambient
outboards.
A K250 with a 350 hp V8 ??? You could run it just
under the surface with a snorkel.
Alan
----- Original Message -----
Sent: Sunday, February 27, 2011 6:19
PM
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.
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 -----
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 -----
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 -----
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 -----
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 -----
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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