Re: [PSUBS-MAILIST] "Frankenboot"

[Paul Kreemer <paulkreemer@gmail.com>]

Joe, just writing to put in a plug for Dan's suggestion: that you first
consider the displacement of your minimally sized dry compartment and
then treat the rest of the vessel as a fairing.  The fairing would
add some displacement, especially being built of plywood but you'd have
to get the whole thing into your target displacement.  The first
step would be to choose your desired dry weight and/or crew compartment
volume.  (10,000lb? which is almost 160cf.)

You could add in your maybe 30% reserve buoyancy (48cf) for good
surface operation but those are just variable ballast tanks, mostly for
surface use and emergency surfacing, right?  They wouldn't add to
the displacement of the boat and the whole thing really would weigh
10,000lb on a trailer. 

This seems like a better way to describe a WWII-style homebuilt that
will be good on the surface - a modest pressure compartment with a big
free-flooding fairing.  You could do a big deck and superstructure
like on that nice S-44 replica, but you would need some propulsion
power to move such a rig submerged!

Please correct me if I'm wrong on this - certainly there are different ways to approach the design process.


Paul

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Dan H. wrote: 

Maybe
your only planning to build a small pressure hull with a big  fairing
for your subs appearance.  If so, then your displacement is only your
pressure hull and the fairing can be free flooding and not part of your
displacement equation at all.