Re: [PSUBS-MAILIST] Propane sub

[CWall@swri.edu]

Sure, Ray. I was really fishing for some hidden "gotchas"...and as I mentioned,
 I did find one that I will report Friday if no one figures it out.   

Since this is a very shallow-diving boat, and most dives will really only use a
 small ballast change, I don't anticipate a big loss of propane with each
diving cycle.  I could even see using manual pumping for bouyancy control, and
when surfaced there are even other ways to build up freeboard. 

What attracts me to the concept is the potential for a very lightweight sub
when dry, with very few systems- I'm looking at a clean hull shape to get very
low cruising power requirements; the original inspiration was Blondie Hasler's
powered submersible canoes. I just want to increase the capability a bit to go
to a dry design, sacrificing payload and stealth.

As I said before, it's really not much of a stretch. The use of propane may or
may not be novel, but it is a common fuel available nearly anywhere, and I
already have a number of projects using it, so it was a natural design element
to consider.

I certainly wouldn't compare this boat to a serious submarine, but that was
never the intention.  And if anything ultimately strikes the viewer's eye
(assuming it ever gets built), it won't be the propane- it will be the hull
shape, which will be reasonably graceful both in and out fo the water.   That
would have very low priority with a working sub, but in my case it translates
to economical surface cruising. 

  One of the failings of most of the subs I see is that they cannot cover long
distances. Another is the need for support to do anything, so there is very
little incentive to get long surface range in any case. The potential for a
lightweight design is (as far as I can see) largely unexploited, and since you
pay for materials by the pound, the light overall dry weight translates to some
 extent into materials cost reduction.  This is not a major point, however.

For me, it is another design exercise, and I have already reaped some rewards
even if I never build it.   

I'm getting the itch, though. Originally I was giving myself about a 25% chance
 of starting on it, but that is rising somewhat. I'll know more after some more
 models and some tank tests, but that won't happen quickly. I have several
other projects to finish first.

Craig
---------- Original Text ----------

From: "Ray Keefer" <Ray.Keefer@west.sun.com>, on 11/13/00 2:25 PM:
To: Incognito2@CTC@SwRI26[<personal_submersibles@psubs.org>]

Hi Guys,

I just got back from a trip and man what a bunch of flame mail.

Yes, I'll be honest. My first reaction was "Oh my god you don't really want
to use propane." Guess what, it will work. A long time ago in the PSUBS
forum there was a thread that went something like this, "with the proper
design and cautious approach you can make a sub out of anything, even
popsicle sticks." Look for popsicle sticks in the archives.

It sounds like Craig has done his homework, knows what he is doing and
most of all has accepted the challeges to make his design work.
So go for it.

As for myself the the only propane I have played with is on the Bar-B-Que
so I won't mess with it. Mostly due to lack of experience.

Propane should make a useful fuel, but I wouldn't use it for ballast because
I would want to use it to produce energy. The ballast tanks can be
filled with exaust gases. I guess my attitude comes from being a tight
wad and would hate venting a gas into the air that I paid money for.

The only drawback I can remotely come up with is if you are operating in
cold water the propane may not gassify well or may freeze up an orfice or
pipe. Again Craig would have a better opinion on this then me. My
experince is limited to small propane camp stoves.

Craig, please keep in mind that you asked a bunch of guys with far less
experience in flammable gasses then you have for opinions. I doubt most
of us would have the knowledge set to give any real comment. We can
discuss our fears. We can discuss how to build a sub. However, detailed
specifics on how to design for use of propane is beyond us. So I guess
any further discusssion is pointless since we have all had our say. 

Now that I have weighed in with my two bits, can we put the flame war to
rest?

Regards,
Ray