|
Hi Joe.
Paul wrote....
"What we need is a clever trick like that used in water ballasted sailboats
- just fill the tanks before sailing to increase your displacement. But of
course that doesn't help a sub, unless you look at flooding most of your crew
compartment while diving. Maybe you need a sand ballast keel
system. :-) Run along in shallow water scooping up sand until you've
got the two tons or so that you need.".
How do you run in shallow water scooping up sand in
a trolling motor ambient sub? How would that be accomplished without the
friction of some kind of scoop attached to the sub stopping the sub dead? It
would be like running into a sandbar wouldn't it?
I like what Paul said about looking at flooding
most of your crew compartment while diving though. The buoyancy problem is why I
went with a wetsub rather than an ambient myself. Wetsub allows super
lightweight since there is no air bubble to force
underwater. Even in Kent Markham's silent
runner 2 (plans and pics at psubs homepage) which is a semi dry ambient
that only allows from about your chest up to be dry, it still takes a lot of
weight to keep that little sub's canopy bubble underwater.
But compared
to other ambient subs the Markham silent runner 2
is not as heavy because it doesn't have as large of a dry compartment as most
ambient subs do and therefore does not require as much weight to get underwater.
The only problem with Kent's design (and he told
me this himself), is that the
integral motors/diveplanes do not allow for turning very well at
all. When Kent sent me the plans he told me he should have used a rudder
and if I was going to build it I should install a rudder also. Have you seen the
BOB ambient sub?
It is basically an underwater scooter that you
ride on like a bike and your head stays dry in a acrylic bubble. Like
sticking your head in an underwater fish bowl that has fresh air supplied. Not
much air bubble to shove underwater and lightweight. Both Kent's sub
and
the BOB show how semi dry (but mostly wet) subs can
be lightweight yet still free you of the diving regulator mouthpiece and
facemask. Have you even considered a semi dry wetsub with a small ambient
bubble for the operator? It just might be that the answer to your
buoyancy and weight problems is to NOT have much
buoyancy and weight. Just some suggestions.
Bill.
----- Original Message -----
Sent: Monday, November 07, 2005 1:01
PM
Subject: Re: [PSUBS-MAILIST] Re: Some
issues
Joe,
So mainly there's that one unpleasant reality of
submerging a volume of air: it has a lot of buoyancy! 63 lbs/cf of
seawater adds up pretty quickly into a too-heavy-to-trailer submarine.
And the fact that you're considering an ambient sub doesn't really help your
displacement, right? The construction is easier in that you don't need a
1 inch thick pressure hull but unfortunately the boat needs to weigh just as
much as if you did.
I've liked the DeepFlight two person sub
(model 502) which has a separate pressure compartment for each occupant.
It really helps to reduce the cabin air volume but it also locks you into a
small space which is very different from your original dream. And does
anyone know why it's been decommisioned now? I think they built that one
for their pilot training program. Maybe they didn't get many people
buying the training? http://deepflight.com/subs/dfa.htm
What
we need is a clever trick like that used in water ballasted sailboats - just
fill the tanks before sailing to increase your displacement. But of
course that doesn't help a sub, unless you look at flooding most of your crew
compartment while diving. Maybe you need a sand ballast keel
system. :-) Run along in shallow water scooping up sand until
you've got the two tons or so that you need...
take
care-
Paul
On 11/7/05, Joseph
Perkel <joeperkel@hotmail.com>
wrote:
Rick,
Thank you for the info and support. With further research my initial
exuberance has now been tempered a bit by reality. Something I am quite
sure all of the newbie's must experience at the beginning.
My main issue at the moment is material density and it's effects on
buoyancy and ballast requirements, in this case of course, ply composites
for this ambient design. Lead is my friend in this case but still there are
some hurdles to overcome.
Pat Regans boat has a "proper" pressure hull underneath but it is tiny. I
want a compromise between size and the necessity of having to be launched by
crane, so my belief is that an ambient design could be light enough to be
trailer able and still give some reasonable interior volume but therein lies
the technical hurdles.
I am looking at aluminum again as I did last year for a surface yacht
(see the attachment for the quote)...outrageous! This could quite possibly
be riveted as in the old 'R" boats but that of course presents it's own
problems. One would use lighter gauge alloy than what you see in the quote
so welding would not really be an option.
I must admit though all these technical hurdles are quite fun to try to
figure out.
Joe
|