On Mon, 15 Dec 2003 14:19:01 -0500, Glenn Ashmore
wrote:



Brian Whatcott wrote:

If you are visualizing what I am visualizing, then two single acting
rams can substiture for one double acting ram. /snip/

Actually, there is a difference and two pushing cylinders make it worse.
Think force vectors for a second. Lets assume we have a 72º hard over
to hard over rudder angle and with the rudder amidships the ram
intersects the centerline of the rudder at 45º. /snip/

I am evidently not visualizing what you are visualizing, Glenn.
Why would a ram be set at 45 deg to the long axis of the hull?

If I visualize an aft rudder, with a forward facing tiller. I can fit
either one double acting ram acting from side to side.
Or two single acting rams.
I could place these two rams transversely (like the double acting
ram) but I *could* consider an arrangement that places each ram
connecting to the tiller at 36 degrees aft of the transverse
direction.
Then, at either hard over position of the tiller, the ram is acting at
90 degrees to the tiller, the most advatageous position.
But with moderate hydrodynamic balancing of the rudder surface to
moderate the steering forces is this such a problem?

Brian W