Tuesday, March 3, 2009
Wooden Boat with Twin Jet Drive
This was my attempt to power a small skiff with simple & cheap Jet propulsion. The boat is a Bolger / Payson designed 15" Diablo. I built the hull in about two month working weekends and evenings. Boat was built close to original plans, only minor changes to suit my drive setup.
Power is from a pair of Pacer Trash pumps. Engines are 5.5hp Briggs & Stratton. The pumps are direct driven from the motors and made of some near indestructible black plastic and uses 2" pipe fittings.
The output from the pumps is from the top of the housings. Looking at the pic you can see a Blue handle, centered on each engine. This is my forward -neutral- reverse control, I have full independent of each pump. Opposite side of the Tee from the control valves is for hookup to a fire hose or a pair of fire nozzles I added later that would shoot water almost straight up about 50' (just for fun;-). Forward thrust goes through the clear hose you see going forward, it then goes under the engines and exits through a pair of modified antique fire hose nozzles that have an opening of about 1". Reverse jet is a simple 90 degree 1" copper fitting that faces forward. Intake is from a 2" floor flange fastened to the bottom of the hull. Steering is from a sailboat style tiller.
I put a lot of though, money and work into the jet drive only to end up removing all of it a couple of years later. The tiller steering and separate control of each jet worked great, at full throttle I could instantly reverse one drive and make the boat turn within its own length. The main problem was lack of forward movement. Measured with a handheld GPS I could only get about 6 mph ! The pumps were not designed for pressure, so I was just pumping tons of water out the back. Tried reducing the nozzel diameter, but no help.
After a couple of years I removed and sold the pumps in favor of an 18hp 1957 Evinrude outboard.