Ok someone asked me (Jim) where I?m going with this so here is the
concept broken down by area so far. Group input is solicited and greatly
appreciated.
As I read more and look into the subject, I can see that modern
epoxy-ply boat building techniques and a dry ambient pressure design are a
match made in heaven for my intended application. As to the question of size,
I am working out several options each with it?s own set of compromises. In any
case, the project will be a significant investment in time and
money.
General
Concept
If I want to keep in scale with the Disney - Goff boat and have some
degree of comfort, it looks like with frames / stations spaced at around two
feet, this would be something in the order of 36? L.O.A. (rough estimate).
That is trying to keep her less than 10,000 lbs surface displacement if
possible; again I have yet to do the calculations. The idea is a submarine
cabin cruiser with some pretty serious panache, and if I can?t make it work,
accidentally sink her, or get too old for diving (45 now I?ve got time I
hope), the whole shebang can be converted to strictly surface use still with
the underwater view ports. Really nice options here.
If I can?t keep her to scale and have to take a little ?creative
license?, the one requirement is to have 6? standing headroom in the
pilothouse for two; sitting for too long can be dangerous (peripheral
circulation) and uncomfortable. In the main saloon area one may have to duck
through in order to keep scale and the size reasonable. A convertible dinette
to starboard and a galley to port, each centered under the round Plexiglas
view ports and Victorian era décor right down to fake rivets on the interior.
A porta-potty finds a home somewhere.
One problem that I see for me with this hull design is draft at D.W.L.
is looking to be about 5 feet. If I run propulsion at an angle out of the
bottom I could ballast her higher and lower in the water at will but I lose
the efficiency of the straight shaft as well as the spirit of the
design.
Another option is to go tiny, shrinking the cost and complexity as well
but forget about any family members feeling comfortable about it and that?s no
fun. This vessel as conceived, would be suitable for long distance surface
travel throughout the Florida Keys and maybe even an occasional ?patrol? to
Bimini to sink a fishing smack or two. :)
Machinery
At that weight she would require a little diesel in the order of 25 hp
to move her at hull speed (maybe a little more with all that drag), I have no
idea what the electric motor requirement would be at this point (group input
here) and I envision some type of coupling system to the main shaft so both
motors can take their turn. I don?t need too much underwater endurance (motor
wise), just some degree of control as I envision putting the boat on the
bottom (sandy patches), most dives.
The little motor might not turn a big enough alternator to charge the
battery requirements (group input) so a small gen-set may or may not be
required. Then there is the question of charging the air cylinders and you see
a real engine room emerging. And in Florida, in a black / gray submarine with
a grand total of two hatches topside, a 5000 btu marine air is a
requirement on the surface. The design has to work the first
time out, flood her and everything has to be torn down for rebuilding. Did I
mention time and money?
Batteries (non-gassing)an lots of em, need to be as low in the
hull as possible and may possibly be split into two banks fore and aft if not
in the bilge centerline, depending on ballast tank arrangements.
Ballast
and Air
I intend to follow the technology of the WWII fleet boats and await the
NAVPERS manuals I ordered from www.history-on-cdrom.com
which are quite detailed. The
Nautilus hull appears to lend itself nicely to the same conceptual arrangement
however, the problem of size (beam) arises here. I do not yet know the size
requirements of the ballast system; its relationship to interior volume, and
more research is needed in this area.
The same goes for the high-pressure air requirements and placement of
those bottles may pose a problem for Nautilus depending on size and quantity.
All controls run to a manifold in the pilothouse controlling both ballast and
life support with one isolated secondary safety system having sufficient
capacity to surface the boat. I do not yet know if a drop weight system is to
be incorporated or not. The system may be sufficiently complex enough to
require two crewmembers to control the boat when diving.
I noticed that the fleet type boats placed their bottles low in the
hull and this may pose a problem for me configuration wise. There would be
some space under the top deck (not much) but this would be too high for
stability reasons. Perhaps in the ballast tanks themselves, this still needs
to be worked out.
Some type of pressure relief valve(s) is required to vent cabin air
overboard and keep Davy Jones at bay. I do not yet know where these are
available, how many, flow capacity requirements (group input) or how they
function (mechanical or pneumatic). Some manner of precise cabin airflow
regulation is also required.
Hull
Design
Here again more research is needed. I want to get away with as minimal
possible hull material and still maintain a reasonable margin of safety and
sea keeping ability. I see her going together on a strong back, plating over
frames and bulkheads, standard stitch and tape epoxy construction, chine logs,
butt blocks, etc. Lloyds certified marine ply throughout saturated with epoxy
and exterior surfaces either glassed with GRP or another material I believe is
called Dynel. Interior surfaces saturated with epoxy and painted to
suit.
Someone mentioned to me "oil canning" of the hull and started me
thinking about a lag in pressure compensation going both ways. The Gorgean
brothers have done extensive research and stress analysis of marine plywood
and cycling stresses so that work in conjunction with what I learn about
ambient pressure hull design, will determine the specifics of materials and
framing. I envision something like four bulkheads at this length among the
frames with longitudinal requirements yet to be determined.
The exterior will be in keeping with the spirit of the design, right
down to the 19,000 or so fake rivets on the hull. Did I mention time and
money? In fact, I don?t need to bother hiding the glass tape on the panel
joints either, take a good look at this surface. http://www.vulcaniasubmarine.com/The%20Eleven.htm A whole lot of wetted surface but I don?t care
about going fast and the diesel will be efficient enough despite
this.
Safety
In all my years of diving, I have never felt the desire to do
saturation diving nor is that likely to change. I have plenty to see at less
than 50 feet. The boat would never submerge unless those aboard are scuba
certified, pony bottles would be secured to the bulkheads clearly marked and
lit. She would never initiate a dive in greater than 25? and never venture
where the bottom is greater than 50?.
And finally in the event there is a failure of the ballast tanks to
blow or some other failure, a provision to flood the boat and exit one of two
hatches would be made. Static stability would be designed to ensure that those
hatches remain upright. The hatches themselves would be robust enough
(Freeman) to ensure that any potential warping of the hull leaves them
operational. As a last resort, the transporter could just ?beam? you ashore!
(Just kidding?maybe:)
So there it is, my very own mad scientist project! I even have my own
version of Vulcania as a building location.
Regards
Joe