[PSUBS-MAILIST] Dive report - Pickles Reef

[hank pronk]

Marc,
I would think you will need an ac unit on your engine because the engine will generate some heat even with a water cooled manifold.  If you run the exhaust stack inside the air stack it will pre heat the air coming into the engine.  Pre heated air is good in northern latitudes but bad in the tropics.  The heated air will kill your fuel efficiency.  I also would not suck the combustion air through the hull, the exhaust will find its way in.  I would do a short air stack and a tall folding exhaust stack.   A diesel engine in a psub is a great idea.
Hank
 

From: Marc de Piolenc <piolenc at archivale.com>
To: personal_submersibles at psubs.org 
Sent: Thursday, October 10, 2013 8:15:44 PM
Subject: Re: [PSUBS-MAILIST] Dive report - Pickles Reef


I've been following this discussion with great interest. I don't have a 
sub yet, but I do live in the Tropics, and as there's no cold current 
handy to where I live any subbing I do will be in water pretty near air 
temperature. As you might expect, I've given this problem a lot of thought.

My tentative conclusion is that, if I build a sub, I will have to make 
it more autonomous than is the rule on this list. Specifically, it will 
need a combustion engine to ferry itself on the surface to dive sites, 
and to maintain comfort and keep the battery topped off for diving while 
doing so. I started with the assumption that I would need an air 
conditioning unit running off a small industrial diesel, but then I 
realized that, if I use a snorkel exhausting into the cabin, and have 
the diesel draw air from the cabin, I get continuous renewal of the air 
in the cabin without the cost, power burden and safety problems of 
running a Rankine cycle refrigeration system. That's the solution that 
I've retained for the moment. Of course I also need a secure means of 
preventing exhaust gas from being aspirated into the snorkel (I can't 
quite understand how naval submarines manage to combine both functions 
in one mast), but that might be as simple as having the diesel exhaust 
flush with the hull, with some arrangement to prevent water from coming 
in. Since the diesel would only be used on the surface, and the snort 
would only be there to allow a low-freeboard hatch to be kept closed, 
the power penalty would be minimal.

Fuel storage, fuel feed and the like still have to be worked out. Naval 
submarines have very complex arrangements for this, and that complexity 
must be tolerated for a good reason. Even so, I need a simpler way to do 
it that still protects the fuel from contamination and me from asphyxiation.

Marc de Piolenc

On 10/11/2013 1:45 AM, Land N Sea wrote:
> I have been out of the loop for 5 weeks on the mainland on my sailboat
> and I should of read all the emails before responding when I got back. I
> did view the great footage and noticed that my tower looked a little
> taller (good for water ingress) and of course doesn’t have the dome so I
> hopefully won’t have quite as bad of a heat problem as one with the dome
> but I was thinking about Emile’s clear acrylic fairing as an option when
> I heard about the water egress problems with a three foot chop.
> It does get pretty hot here and we are about the same latitude as
> Florida so I will probably be trying Phil’s idea of the frozen pouches
> vest and or the gallon of frozen water and have the air coming out of my
> scrubber blowing against it.
-- 
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