The 1/4 HP motor on my WH only runs when moving the rudder.
It is current limited to 22 amps max. But that would only
happen in pretty rough seas.

Doug
s/v Callista

"Jim Woodward" wrote in message
om...
How big is Good Intentions, Steve? 1/4 horse is bigger than the
autopilot pump on Swee****er (Swan 57, actual weight about 60,000
pounds in round-the-world trim). I don't remember how strong it was,
but both physical size and power consumption suggest around 1/10hp.

As an extremely rough check on the sensibility of your numbers from
Glenn's formulas, the motor driving Fintry's hydraulic steering was a
2hp 220VDC. She was designed to be bulletproof -- Lloyds 100A1
Maltese, for navigation on the North Sea -- so I suspect that half
that would have done fine. Since rudder area varies as displacement
to the 2/3 power and speeds are probably similar (under 10 knots), 1/4
horse should be good up to around 1/4 of Fintry's displacement, say 37
tons.

1/4 horse is 186 watts, so a perfect motor would draw 15 amps at
12VDC. Your results will vary with reality, maybe double -- small DC
motors aren't very efficient.


Jim Woodward
www.mvFintry.com


"Steve" wrote in message
...
Thanks for the formulas Glenn.

I ran the numbers to get some idea of what I might be looking for.

Seems I should be using about a 2"X20"X1.5" cylinder, 318psi @ .186gpm.

Using a slightly oversize pump at a lower RPM, I would need a 1/4hp
motor to
achieve the 15 sec. hard over time.

Seems do-able on paper. I just don't know what the max current draw
might be
for this motor. I'm sure someone has a formula for this as well.

Steve
s/v Good Intentions