Hello Group, [snip]
Then I came across both the Venture craft
Sportsub and several other commercially available designs and the thought of
an ambient pressure diesel-electric boat has been swirling about ever
since.
The Sportsub was originally fabricated here in BC, a
suburb of Vancouver called Surrey. It was directly based on a semi-dry
ambient sub designed by another Floridian by the name of Kent Markham.
He was a high school teacher, I believe, and it was originally intended as a
school project if memory serves correctly. The sub was featured in the
June'71 issue of Popular Mechanics. Plans are available online.
Try PSUBS.
In terms of a diesel-electric, wooden submarine, your
heart's in the right place! We have many islands up here and surface
travel without a support boat sure is nice. Have lunch and dive when you
get there. Just don't guzzle any softdrinks.
[snip] know some of you will be horrified at
the thought of a "wooden" submarine but, modern epoxies and quality marine-ply
should make it doable for an ambient pressure design. With proper
consideration of scantlings, I believe the ship would be robust and seaworthy
[snip]
Absolutely correct. Keeping in mind that the
hull is just for hydrodynamics and sea keeping, materials and building
techniques don't have to be anything esoteric. Plywood/epoxy is
fine, especially if you lay up your layers perpendicular to each other [two
layers] or at 45's [if three layers]. The diesel, of course, is not used
for propulsion, just battery charging like the fleet boats.
Operational rules would be as
follows.
#1 The boat never submerges unless those
aboard are certified divers. Internal pony bottles and at least two points of
egress would be provided. (Most likely Freeman hatches).
IMHO, Freemans are overkill in an ambient boat. Two
points of egress ain't a bad idea. Pony bottles are a must. In our
cold water, a neoprene hood and dive mask are essential for a safe
swimming ascent.
[snip] #3 The
boat never initiates a dive in water depth greater than 30' nor ventures where
the bottom is greater than 50'.
If all aboard are divers, then you could start your
dives deep(er) and gradually ascend. Certainly what you describe is a
conservative policy and well worth following during the break-in period (of
the captain, as well!)
In S Florida, that means most of the premier
diving locales in N America are within a short distance and quite
accessible.
Um, mind if I edit that? ;-) I have
some flag waving to do, and, yes, it is sub related.
That would be some, not most of the premier diving
locales, and that would be America, not N America.
Out here on the Wet Coast of Canada, we have very
accessible areas called the Strait of Georgia, Desolation Sound,
Vancouver Island, Barclay Sound and more. Use GoogleEarth for some
fantastic imagery.
Much of it has vis of well over 30 metres in winter,
oxygenating currents that provide tremendous volumes of plankton for sea life,
of which consists of, but is not limited to, sea urchins, huge octopus, orcas
(killer whales), huge sea lions, dolphin, shark, harbour seals, anemones,
coral, big big crabs, grey whales, jellyfish, huge schools of fish, wreck
diving par excellence, forests of beautiful kelp diving, wall diving to
blow your mind, and, well, more.
Submarines out here would have a field day. That's
why your particular affliction for what I refer to as a touring sub appeals to
me.
[snip] How
much airflow in cfm is required to maintain ambient pressure from the surface
to 50'?.
None with regard to maintaining ambient pressure per
se. It is not a function of rate except when descending. What you
do need to calculate is your cabin air volume and the rate of flow from your
low pressure valves. If the cabin oil-cans a little you'll be mighty
uncomfortable :-)
Once at depth, the only rate to be concerned with is the
life support air flow. I will be using scuba regs for breathing so for
me it's a moot point. I will, however, have a dehumidifier.
Cabin compensation will consist of a gang of six
scuba regs with the mouth ends inside the cockpit. The six regs will
provide a very large volume of air if needed, not to mention redundancy.
As the sub descends, water pressure will force the diaphragms
inward. The partial-vacuum in the cockpit will draw air from the
regulators into the cabin area.
#2 Does some manner of scantling rules exist
for GRP designs?
Yes. Consider wave action, walking on deck, support
for cleats, anchor chain stowage, etc. The usual found in conventional
boats.
What you and I, and other dry-ambient types, are looking
at is essentially what you so aptly described as a fleet boat going down for
an occasional dip. Having said that, my Typhoon will have a very robust
cockpit, mainly to handle pressure differentials from large wave
action over my head and, um, errors in depth keeping where the regs
may not be able to keep up.
#3 Has anyone else built an ambient
design of marine-ply?
As above, the
Sportsub. Well, actchalee, it's GRP. BTW, you don't need marine
ply if it's going to be sealed by epoxy AND it won't be living in the
water.
[snip] I envision this being done with "off
the shelf" components but, if I am overlooking something unworkable I may
stick to the surface design.
Off-the-shelf will be more than adequate. As I
pointed out above, ordinary scuba regs will suffice for cockpit compensation
and life support. The down side, btw, in using special pressure
sensitive valves mentioned in other posts (not exactly
off-the-shelf) that detect ambient pressure, is that they will release
air into the cabin through one orifice generally. That will be a large
volume of air screaming into your cabin. That's why I've elected to go
with what I know: several scuba regs. By their very nature, they are
pressure compensating.
Incidentally, another Hurricane, (Wilma) is
heading my way tonight. We are shuttered up and hunkered down so I may not see
any responses until after power is restored (could be a week or more). I thank
you in advance in that event.
Good luck - we do not envy you.
Rick Lucertini
Vancouver, Canada