Re: [PSUBS-MAILIST] enquiry - Surface Propulsion

["Emile" <2stroke@hetnet.nl>]

Peter,

If you want to have a high surface speed, be sure the propellor is well
submerged.Otherwise the prop will "pull"air.
Strange but i consider a gas turbine for a small atonoumus sub. I have used
a GPU for in a motorbike. But the complete box (see
http://www.users.zetnet.co.uk/gas/gtp30.htm ) would provide me 28 VDC/ 30 KW
,heating, LP air and good ventilation for the boat. It runs not on gas but
on diesel, kerosineor white spirit

What you mean by temparature stress and insulation? I hope you put the
engine inboard so that wil be no problem. A common 4 stroke diesel is not
kritical on intake/exhaust pressure fluctuations.

Grs, Emile van Essen

----- Original Message ----- 
From: "peter mckellar" <mckellar@earthlink.net>
To: <personal_submersibles@psubs.org>
Sent: Friday, September 19, 2003 1:31 AM
Subject: Re: [PSUBS-MAILIST] enquiry - Surface Propulsion


> Hi Ray,
>
> much good info in the reply, thx.
>
> shame about the gas however, the best (fastest and range) that i've been
able to find is www.incat.com.au that claim a 'theoretical' max of 100knots
with a gas turbine.  true, they are BIG craft but i know they have built at
least one personal size boat.  they claim they have actually pushed up
around 60knots in trials.  they're locally (oz) based too which has obvious
access advantages.
>
> i also noted that they are building (and retrofitting) a number of US navy
transports, so maybe the US navy has changed its policy re gas powered?  or
did u only mean for subs?
>
> i've been investigating gas storage (oxygen and LPG) and it seems the new
solid-state ceramic based methods offer a non-explosive and fire safe method
of storage, but i don't know what happens if the tanks get damaged and leak
fumes (which maybe then would present a hazard?).
>
> do you or anyone else have any knowledge or experience with ceramic solid
state gas storage?  Im guessing they are a type of porous material, but i
don't know it they have a conventional steel/aluminium casing or what :(
>
> thx
> peter
>
> -----Original Message-----
> From: Ray Keefer <Ray.Keefer@Sun.COM>
> Sent: Sep 18, 2003 1:57 AM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] enquiry - Surface Propulsion
>
> Hi Peter,
>
> To surface transit to your dive location you have about 3 options.
>
> 1. Go all electric. Use the same motors to get you there and back that you
use when submerged. The positives are that you only have one propulsion
system to design, build, install, and maintain. Once in you are set and you
have already designed it to handle pressures. The draw back is limited range
and you are using your limited submerged battery power traveling on top.
>
> 2. Go internal combustion engine. The only type I would recommend is
diesel. Why? Proven doable for years in Naval submarines. DO NOT USE A GAS
ENGINE!
> Gas fumes are explosive. That is why the military went to diesel as soon
as
> diesel engines got reliable enough. Positives are plenty of power, good
range, possibilities of powering generators and compressors, oily fumes and
the sweat sickly smell of diesel exhaust. Negatives is added complexity.
Direct drive to a prop requires a pressure seal. Driving a generator gives
you power that you can feed to your submerged propulsion system. The engine
will need air intake piping, exhaust piping, fuel filling, cooling water
intakes and cooling water exhaust. That creates the
> need for more through holes with their compounding safety concerns.
>
> 3. Use a suface tender. Use a surface boat to do the transiting. You can
push, tow, or carry your submersible. With a surface boat you can use
inboard, outboard, or whatever type of engine you want. Diesel or gasoline
is ok. It can be used without the sub for recreation which might be a
selling point to your spouse. With a big enough boat you could put air
compressors and generators on it and be able to turn you sub around quickly
for another dive right there on the dive site. Or you could just
> use a rubber dingy as George Kittredge showed in his video.
>
> If you truely want fully autonomous operations. I would go diesel-electric
with the diesel driving a generator. If you plan to travel more then a mile
or two to get to your dive site, make sure the hull form is steamlined. More
like a WWII military submarine as opposed to the blunt face science sub
look. A sub like Kittredges might get up to around 6 knots with enough power
thrown at it. Any more speed will require more streamlining and wetted hull
length.
>
> Regards,
> Ray
>
> peter mckellar wrote:
> >
> > Hi All,
> >
> > how does everyone provide propulsion when on the surface with a fully
autonomous submersible?
> >
> > At this stage I'm entertaining all options, with maximum speed and range
the preference (though no expectation that either could be adequately met
with the limitations imposed below).  For safety's sake, i'm inclined to
design with a pure electric engine for sub-marine propulsion and a separate
surface engine to get to the dive location.  This leaves it pretty open (for
surface anyway).
> >
> > Something that works in both environments would be great, but I suspect
is out of the question.
> >
> > What sort of considerations would I need to make if i shut down the
surface motor and expect it start again when i re-surface?
> >
> > Some issues that the group may be able to clarify for me:
> >
> > 1.  Pressure proofing/ambient tolerance
> > 2.  Electrical insulation
> > 3.  Corrosion
> > 4.  Temperature stress if submerging when the engine is hot
> > 5.  Safe fuel storage, combustion issues etc
> >
> > Does anyone make engines with these demands in mind?
> >
> > thanks in advance
> > peter
>
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