Francis fired this volley in
:

Any idea how much power an *unloaded* radial piston pump would use up?
I'm asking because I am wondering if I can leave the motor/pump
connected to the propeller shaft all the time or if I have to devise a
physical connect/disconnect mechanism to reduce overhead.

What is the lowest-loss hydraulic pump type, anyway - anyone???

Well, they all have friction losses, and unless of the variable-
displacement variety, they must move fluid even when unloaded. Friction
losses of the fluid circulating also add to the total loss.

But most pumps in the under-20gpm range absorb only a small fraction of a
horsepower at "idle". Stiction torque at startup is fairly high, but
idling torque is low.

LLoyd