[PSUBS-MAILIST] Luxury submarine yacht - how would it shape up if experts were involved

[Marc de Piolenc <piolenc@archivale.com>]

A lot of derision was recently heaped on a submersible luxury yacht 
concept bruited by an Italian shipyard and reported by CNN. But 
something in the article struck me as a challenge to those "in the 
know." A spokesman for the shipyard said that they were looking for 
consultants.

What if one or more of the leading lights of the personal submarines 
networks were tapped to advise these builders? What would he/they tell 
the yacht designers about the concept they have now, and what 
modifications would he/they recommend, and why?

Although I am NOT a leading light in the field of personal submarines, I 
have fantasized for decades about a personal submarine large and 
comfortable enough for cruising, or even living aboard, and even done 
some calculations and formed some opinions. I would like to try 
launching the discussion, which I hope will be fruitful. Referring to 
the CNN report:

http://edition.cnn.com/2010/TECH/innovation/07/01/concept.yacht.designs/index.html?fbid=owi0rlu2C1-

It's fairly clear from the graphics that the outer hull of this thing is 
the pressure hull (portholes visible), not a "soft" external casing, 
which means that ballast provisions must necessarily be "hard" and 
located inside the pressure hull. That, and the sheer size of the round 
wiewports located just aft of amidships tell us that this beast, as 
conceived, is meant only for shallow submergence. The absence of 
internal stiffeners and bulkheads in the interior drawings reinforces 
this, and also dictates the use of an inherently stiff, thick hull 
shell, possibly of sandwich construction.

That said, what advantages would the ability to submerge to a modest 
depth give the submarine yacht that might justify the vast additional 
cost of building a huge submersible? The most obvious is the ability to 
sightsee, to view the wonders of the shallows: reefs, lagoons... But 
this could probably be adequately provided by a glass-bottomed surface 
vessel. Handling rough weather is another advantage - one that 
absolutely requires the ability to submerge. Equipped with a snorkel, 
the yacht could use the full power of its diesels to make a rapid 
passage through even the roughest weather. Even though, snorkeling, it 
could not submerge below the convection zone of large surface waves, the 
power of its propulsion system, allied with powerful hydrovanes and an 
automatic stabilization system, would iron out most of the bumps and 
allow a fair body like the sub to power through a storm at over thirty 
knots. If the hull shape were optimized to minimize wave-making near the 
surface, it might do better still.

There are disadvantages, of course, besides the greater expense of 
building the beast. Like water ballast, all fuel tankage must be 
internal, which makes venting, and protecting the passengers and crew 
against fuel fumes and spills, a major design task. At snorkel depth 
there's no problem because there is a continual influx of fresh air and 
aspiration of interior air into the engines and expulsion out the 
exhaust. With the boat completely buttoned up and on electric 
propulsion, the problem gets more complicated.

The big viewports will have to be altered - I don't know of any outfit 
that could mold a one-piece acrylic port that large. The result would be 
mullioned, and might resemble a rose window more than a porthole.

Best,
Marc




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