Gordon,
I have built into my 60' sloop a prop shaft with pressure fed oil bearings
and it drives a Sperry Marine rig that was designed to power winches on
lobster boats. The Sperry Vickers variable volume hydraulic pump drives a
fixed displacement hydraulic motor on the end of an Onen 6 KW 2 pole
alternator. The pump will handle input speeds of 1100 to 4400 rpm. The unit
adjusts the pump volume automatically while monitoring alternator output
frequency and will hold the frequency within 3 Hz. I use a toothed belt to
drive a gearbox and from the gearbox I drive the Vickers pump. At the most
inefficient speed the unit draws 22 HP at 6 KW. The plan is to use the
trailed prop to drive this rig. The 3 bladed prop I am using is 70 CM in
diameter with a 26" pitch and a 70% BAR. It has been sized to drive the
boat. I cannot tell you if it works, I have not tried it yet. When designing
this, I could find no data on the efficiency of props in drag mode. To my
knowledge, no study has even been performed and I asked everywhere I could
think of. I expect when in use the boat will slow somewhat, but how much
only time will tell. The unit will antomatically drop the load, if speed
drops below 1100 rpm. I am sure I will have to do some tuning, but I believe
it will work or I would not have spent all the time and money to build it.
Steve


"Gordon" wrote in message
...
Any recommendations?
Gordon