----- Original Message -----
Sent: Wednesday, June 01, 2005 2:36
AM
Subject: Re: [PSUBS-MAILIST] Trying
again, Help a newbie
Hi Brandon.
There are others at this forum more knowledgable
than I that might help you with certain technical aspects that I cannot, but I
will endeavor to help and advise you as best I can.
First let me say that you must be dedicated to
building this sub completely. Otherwise it will wind up an unfinished project.
Even a susposedly simple wetsub can be quite complicated actually. I know. I
own one.
I will address your concerns and question in
order.
1. You do not need a dry suit to have audio
communications. You just need a full face mask with communications built into
the mask.
2. If you want to do barrel rolls you cannot use
cheap, easily available car or marine deep cycle batteries. If you roll
frequently you will spill your acid out into the interior of your battery
compartment using those types of batteries so you will
have to use more expensive non lead acid
batteries in your design if you want to barrel roll the sub. Also you want
stability in your wetsub so that means you need most of your buoyancy high and
your weight low. Most people put their
batteries and ballast low in order to keep
stability and to keep from rolling over inadvertently. Rolling might sound
like fun but why? In order to design your sub to roll it will cause you more
design work and problems with the batteries and ballast
weight. Most battery powered wetsubs are keel
heavy for stability so they will not roll over. You can build a rolling
wetsub, but it is more complicated.
3. Trolling motors are made in other
voltages besides 12 volts. My 74lbs thrust minnkota is 24 volts.
Trolling motors companies like minnkota will only
guarantee their products to 33ft. They are not made to go to deeper pressures.
Now you get into either oil filling your trolling motors or air equalization,
or have special ceramic prop shaft seals made to keep water
pressure out of
the motor. You will have to decide which system you want to use.
Or you could strap a couple of sea scooters onto your sub that are
already rated for at least 100 ft and believe me you might want to seriously
think about that since you would not
have to go thru the whole ceramic seal/air
equalization/oil filled trolling motor thing. Also there is the hydrogen explosion problem from the batteries and
isolating the motor from the battery gases going thru the wire strands and the
tubing from the battery
compartment to the motor. By the time you get
thru messing around making a trolling motor work to 100 depth and
adapting that motor and building a battery compartment and either oil or air
equalize it, then making sure you vent the battery compartment
properly to let hydrogen out when you
charge....AHHHHHH! Trust me, think about scooters strapped to a wingtank. Then
you could barrel roll all you wanted without a heavy battery pod under the
sub. If you don't have that heavy battery pod keel then you might
have
a tendency to roll inadvertently. You could
install ailerons on the dive planes to correct that roll when you are at
speed, but you might not be able to control your rolling when you were
stationary since you would not have a heavy keel for stability.
Since you cannot dive to 100ft for 2 and 4 hours
because of dive table preclusions, I assume you simply want that much battery
time for multiple dives. Most times I will only dive two times on a given
dive. Sometimes 3. You really do not need that much
battery time and will only add unnecessary weight
by needing more and larger batteries for that length of time. Two good quality
(read that EXPENSIVE) powerful sea scooters with around 90 minutes of constant
run time is all you really need.
Two weeks ago I dove to 55ft spearing grouper on
a reef. I used my sea scooter on two of my three dives that day. It
has a run time of 90 minutes on full speed. If necessary I can surface and
quickly and easily change out batteries and get another 90
minutes.
You can't do a rapid battery change using a
battery pod on your sub's keel. Trust me on this one and consider using dpv
scooters as propulsion for your wetsub.
4. Why do you want wings? They are not necessary.
They do not hold you up like they do an aircraft. Dive planes will suffice.
Possibly ailerons on your dive planes if you want to barrel roll. Let me ask
you.....will you ever get out of the wetsub while underwater?
What if you see something you want to retreive?
You can't do that if you are slightly positive buoyant. The sub would float to
the surface. Also I am not nuts about a slightly positive buoyant wetsub. When
you do your 3 minute hang at 15 feet for no decompression
diving, how are you going to do that once you
stop the subs forward movement and the dive planes no longer hold you down?
You will not like having a wetsub you can never park on the bottom. What you
need are a couple of bladders or small ballast tanks that
you can vary your buoyancy with. Put one in the
bow and one in the stern. Have seperate lines going to them from your air tank
so you can trim the boat. If you do not barrel roll, then you can drill a hole
in the bottom of the ballast tanks to make sure you never
overill and burst them. Also think about
this....if you are in a bow up attitude, your air will go the the
uppermost portion of your bow ballast tank right? Suspose you want to drop the
bow to make the sub level called trimming the boat. You would want to make
sure
your air release valve or hose on the ballast
tank was built into that end of the ballast tank, otherwise the air would be
trapped above the valve or hose and not exit the tank.
5. Although once certified as a diver in the U.S.
you are always certified. Your diving certificate does not expire here.
However if you have not done it in a long time I would recommend a refresher
course definately. It is suicidal and foolish for anyone to operate a
wetsub
without being a diver first.
6. How much will it cost? That depends on your
design. I would recommend a military surplus kevlar wingtank from a helicopter
that is 15 ft long, about 1/2 inch thick and very strong. Cut out your
cockpits, install your pivoting dive planes, rudder and sea
scooters.
You could avoid dive planes altogether and just
use pivoting sea scooters in place of dive planes. Make the scooter removable
so you can detach them and use them for normal diving without the sub.
Then install your buoyancy bladders or ballast
tanks. It will be as expensive or as cheap as you make it. But I guarantee if
you make it correctly you will have more than a few thousand dollars in it.
Figure what you THINK it will cost. Then multiply
that number by 3. That will put you about right.
Hope this helped.
Kindest Regards,
Bill Akins.
----- Original Message -----
Sent: Tuesday, May 31, 2005 9:27
PM
Subject: [PSUBS-MAILIST] Trying again,
Help a newbie
Hey I just joined your mailing list. I saw a sub on a TV
program and
it sparked my interest, now I am looking into building one. I
was
wondering if you guys could help me get a better understanding of
what
I am getting into and the overall cost of such a project. The sub
I
saw on TV was always positively buoyant and 'flew' around
underwater
using a reverse hydrofoil to allow it to descend thus
eliminating the
need for a ballast tank/system. I think that's a pretty
cool idea.
What I have in mind is a WET sub, 2 man, powered by 2 12v
trolling
motors and deep cycle optima batteries. Air would be provided by
2 or
4 (haven't decided) scuba tanks and both the pilot and the
passenger
would use a scuba regulator (possibly a dry suit setup so we
can
communicate)
I plan to sit the pilot in the rear with the
passenger below and in
front of him in some sort of plastic bucket seat
with a 5-point belt
like a race car, control would involve pitching both
motors up and
down for ascent and decent and also for roll control (what
good is a
sub if you can't do barrel rolls) and either one large rudder
or 2
small ones attached to the backs of the motors. I would like a
run
time of aprox 2-4 hours and a depth of 100' Add on some
powerful
lights and a camera etc to the power budget. I would like to tow
the
sub on a trailer.
Also this thing has to look COOL. Since I am
going to have wings of
some kind I want to make it look like some sort of
space fighter jet
on steroids or like a POD racer from starwars. Sub is
for recreation
only.
I have done scuba diving in the past but
would have to re-cert
(something I plan to do anyways) and I can weld and
fabricate pretty
well (I have a 4x4 that some would consider at the
extreme end of
custom)
What kind of cost am I looking at for
something like this, I think I
am saving alot of money by having a WET
sub and no ballast system.
Safety factor is high because the sub will
return to the surface in
the event of failure as it always remains
marginally positively
buoyant, and I plan to have an emergency pony
bottle between my legs
in case I have to abandon ship.
Where
to
start....
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