small rudder angle?

[ticomic]

Yo! On this forum, I learned about prop side-thrust or whatever it is called complicating backing up in one direction especially. Someone also pointed out to me that if I welded a plate in front of the rudder pivot shaft, I would gain better control, because only half the prop had a piece of rudder catching the water. I did. Now, I realize the the hydraulic steering turns the rudder 45 deg. max either way. If I drill a hole in the pivot arm closer to the rudder shaft, the piston will make the pivot arm travel further, won't it? All I will have to do is lenghten the rudder safety chain, right? But is 45 degrees a must or can I give it maybe 60? A friend says docking would be much simplified by adding 15 degrees of rudder movement each side. Any no-no's a junior like me might have overlooked?
Gary. Québec.

[Phil Young]

Hi gary. Not sure I know the answer. I'd think there might be some engineering issues with additioanl rudder area and tighter angles-might place some big forces on parts not built to take them. Tell you a story though. I once bought a tumlaren-very fine double ended 27' sail boat. Small engine with forward and neutral, no reverse. First time I took her out I got really worried, she had an extremely small arc of rudder movement, and therefore a huge turning circle. Turned out I had to lift the tiller a little, it was hinged on the rudder head, to clear it past the cockpit sides! problem solved. On another issue, I posted a while ago looking for a small primary school, in Quebec, that my children's school could correspoond with by email. Seeing you are from Qubec, can you give me any pointers?
Thanks
Phil

[ 08-17-2004, 10:25 PM: Message edited by: Phil Young ]

[ion barnes]

Hi Gary,

There is nothing to be gained after 35 degrees, because of the rapid increase in drag and decrease in change of direction. The arguement changes when you insert outboard for rudder, and thats another story.

What is of concern is the water flow across the rudder form and the resulting pressure change that gives you a direction change.

Adding a tab ahead of the rudder shaft reduces the effort to move the rudder against the water pressure (resistance) but does not affect the response to rudder change unless the rudder was undersized to begin with.

What can also happen by changing the ratio of arm lengths is the number of turns of the wheel from center to full rudder deflection.

So, what was the problem you wanted to correct?