[PSUBS-MAILIST] Replicas (was: Decisions decisions decisions....)

[Michael B Holt <tlohm@juno.com>]

On Tue, 25 Nov 2003 19:49:50 -0700 Coalbunny writes:
>I have done a lot of thinking about this, and it has literally taken
>several years to make a concrete decision.  I have several ideas for a
>sub, but couldn't figure out which one I was going to build first.  

Not yet at your Carsten Point!

>They were an ambient sub for treasure hunting, a submersable habitat, a
>replica sub and a real go-getter: an animal replica.  The last one 
>would be fun, that's for sure.  Couldn't decide if I wanted it to be a 
rainbow 
>trout, great white shark or the Loch Ness monster.  Ask yourself what
>you'd be thinking if you saw one of those in a lake.  I think you get
>the idea why I like that idea so much!

Hey, I read a great sci-fi story about the animal-replica idea!  It was
written by a French writer in the 19th century.   A good translation
wasn't available until a couple of years ago, but it's a good one even
in bad translations.   The math works in the recent version, though.

Seriously, I did read somewhere that the best 19th-century book
about submarine design was Verne's classic.   Once the math works
right, the boat become a reasonable design.  

>So from the legal standpoint, what are your thoughts on the replicas? 
>My concern is someone going psycho after seeing a great white shark in
>Lake Powell and me being liable for it.  Is that possible?  I think it's
>very realistic in this day and age.  And the liability issue is one of
>the deciding factors.  

I dunno about liability.   That might be a huge problem for an animal
replica.   Common sense and education in natural sciences seem
to have been left behind in the last decades.

When I was a teen, I sketched out a Nessie-inspired plesiosaur
replica.   The long neck held a "sensor suite" of cameras, sonar
and IR stuff (this was before LLTV).   Other than that, it was a lot
like Cousteau's Diving Saucer with a stub tail and fins that ended
in four large electric motors in pods.  

>The other replicas would be of a larger sub.  One in particular I have
>been considering is the USS Nautilus, SSN 571.  One thing to remember 
>is that on a replica, I would prefer staying as close to exact scale as
>possible.  I realize that in some areas this can't be done.  Like the
>c-tower, for example.  For something toliterally be an exact replica, 
>I know the size would be enormous.  

I was thinking about this the other day.   The problem with a replica
properly scaled is that the conning towers of real subs are usually
very small.   To fit the head of a normal human, the entire sub has to
be huge.  A Gato's conning tower -- the part with the people in it -- is
eight feet in diameter.   To fit your head into it, it can't be much
smaller
than two feet across.   That means a properly scaled Gato shrinks to
a terrifying 77.5 feet long.   If the humans fit into the pressure hull
alone,
we're still stuck with a monster 69 feet long (assuming a pressure 
hull diameter of 18 feet).

On the other hand, a Typhoon has a comfortably large sail ... but
the overall boat is huge.   The top part of the sail is about one-third
of the beam of the boat; that means the sail is 25 feet wide.  Taking
that down to 2 feet wide would not quite work because the shoulders
-- attached to the aforementioned head -- would not fit in the wide
part at the base of the sail.  However, if the head sticks up only in
the wide base of the sail, the view is limited to something that would
be good only in a movie (along the deck).   So making the top part
of the sail 4 feet wide means the replica is 156 feet, 3 inches, long.

A few months ago I was shown a Gato replica that was about
3 feet long.  The conning tower was an accurate shape but was
on a hull that was about a third of the correct length.  That might
be a good approach: shorten the hull but keep the shape. 

All this suggests --  to me, anyway --  that the Seehund is the best 
one to replicate in a smaller size.   Reducing a Seehund's 5.5 feet 
beam to 4 feet means the whole thing drops to 28 feet, 4 inches.  
Shorten the hull a bit -- to, say, 24 feet, by removing some length 
forward of the conning tower -- and the thing becomes buildable.

A Biber is pretty good for the same thing.  Reducing the beam
from 5.25 feet to 4 feet -- keeping the right scale -- reduces the
boat to 22.5 feet.  That's even better.  Removing some of the
length forward and abaft the conning tower would be possible
here, too.

I'm going to keep working on the Argonaut Junior, for now.
Holland's first boat is still on my list of boats to re-create,
too.   Both of those can be built full-sized, and still fit easily
on a small trailer.

On the other hand, an 18-foot rainbow trout would be a lot of fun.
Or maybe a turtle or an ichthyosaur.   Hmmm .....

(I have entirely too much time on my hands.   I need a couple of 
new hobbies, or a mistress.)



Mike Holt


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