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Hi Vance. I haven't fabricated the tanks yet, so I have estimated the total
weights and volumes. The tanks are made of 12 gage 304 stainless sheets and the
support frames are made of 2 inch mild steel pipe. The back plate is 3/4 inch
steel plate which supports the outboard motor, two Minnkota rear thrusters,
swivel linkage, and prop shroud/rudder assemblies. The tank will weigh
approximately 124 pounds with a capacity of 86 gallons. The rear support frame (
3 legged) and back plate weighs 82 pounds. I haven't weighed the motors
etc. but a rough estimate for the motor assemblies, extra scuba tank,
outboard, and miscellaneous parts and pieces should be around 180 lbs. The
fiberglass rear fairing weighs about 60 pounds and is mostly 3/8 inch thick
except where a little extra was used at areas of high stress like the hinge
area, rear "bump" zone, and side "bump" rails where it's 1/2 to 1 inch
thick.
The front tank will weigh approximately 118 pounds with a capacity of
54 gallons. The front fairing weighs 52 pounds and the tube support frame ( 4
legged) with heavy nose piece weighs about 79 pounds.
The larger capacity rear tank is needed to "float" the extra weight of
the two thruster/rudder assemblies and spare scuba tank.
I built a scale model of the sub and used it to size and locate the tanks,
fairings, weights etc. This proved invaluable as I had to increase the
front tank capacity so the model would sit level while at the surface. This
was a balancing problem that took quite a bit of adjustment so that the
submerged balance (front to back) remained equal.
I will be making further adjustments on the balance using the drop
weight and internal ballast weights to fine tune the front/back balance after I
float the sub on it's first "wet test".
I'll have two hard ballast trim tanks inside the sub to further fine tune
the buoyancy while diving. the "Lite" propane tanks look to be the best way to
go for these as I can visually see how much water is in them, and they are
corrosion proof.
I made the steel tube frames so I can fill them with oil or argon
gas, and if needed the lower legs can be filled with a steel shot/oil
mixture for a little more weight.
Here's a sketch of the rear assembly and if you click on the other pictures
you can see the scale model and front tank as well.
The final configuration of weights/balance will become apparent when I
float the sub during it's first "wet test"
This will determine the exact location/capacity of the drop weight and
internal lead brick ballast.
The displacement of the pressure hull is 6750 lbs. I estimate a
total lead weight around 1800 pounds.( inside lead ballast and exterior drop
weight) Frank D.
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