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Re: [PSUBS-MAILIST] propulsion
I found a small cheap axial ducted pump similar to wave runners (PWC). I was
planning on using two of them with two 17 HP motors on my unit. I would
have to mold or machine one of them for counter rotation to cancel out
overall torque rotation of the sub (I have equipment to do both). These are
designed for small jet boats and are made of aluminum. The cost rather than
$3k for a larger unit was $700. They are very streamlined. Yes, they do
lose some efficiency due to the surface area of the intake ducting
(friction), but it is minimal. The advantage is that it cuts down on
irregular surface area from a normal prop support. Also, you don't have to
worry about entanglement as much from larger objects since your intake can
be designed large enough to include screens. Even for smaller objects, the
vector flow will tend to clear away objects. If you do get fishing line
sucked in, you can sharpen the props to cut the poly. This would not present
much danger to people outside the sub, since the props are enclosed. I'm not
talking about razor sharp propellers, this would be a maintenance safety
hazard. Just something that cuts easily at high speed.
If any one is interested, I'll throw the web page on the next psub e-mail.
The unit was very hard to find, but it could easily be shaped into a polymer
sub, and be very streamlined.
Suds
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