Hi Rick. My thrusters are steerable but for mounting the actual motor
head, a standard 4 inch schedule 40 pipe has just the right diameter to hold
the motor.
I took a 4 inch section of pipe, split it in half, welded flanges to the
split seam area and drilled bolt holes to re-assemble the pipe.
The Minnkota 101's fit nicely inside the split pipe section. I have a
thin sheet of rubber as an insulator and shock absorber wrapped around the
motor and when the bolts are tightened it holds the motor head snugly.
If you don't want to weld up a mount and your motors won't be swivel type
mounted you could just connect them to the hull with the threaded coupling
that is part of the motor housing.( where the shaft connects to the motor
head)
On the 101's the threaded nipple part has the same threads as a 1 inch
compression fitting. You can buy a "compression to pipe thread" adapter at
most local hardware or plumbing supply stores and simply screw it into the
motor head fitting where the wires come out. Now you have standard pipe thread
and a pipe coupling will attach it to the thru-hull. Put a ball valve on the
inside where the thru-hull penetrates the pressure hull so just in case you
crash into something and break the motor off and the thru-hull starts to leak
you can still shut off the valve and stop any leakage.
You can see a shot of how my motor mounts are made on the psubs
"projects" page.
I used regular steel pipe but will probably upgrade to stainless later.
The dimensions are the same.
I'd like to be able to remove/replace the motors quickly so I made
the mounts so it will be quick and simple to switch out a damaged motor. I
plan on carrying a couple of spares just in case.
Frank D.