Rudder

[Alan Wheeler]

OK so the Boat is a 46 ft Hartley Tahitian @ 26Ton. Full Keel, big engine with a large Prop. (I have some photo's, but I can't work out how to make them below the allowed 1000bytes)
The previuose owner had allowed 18months to pass before she was lifted from the water. And the Anode was gone, along with nearly the Rudder. It had bad pits in it and the rudder shaft was not too healthy looking either. As we are not doing anything to seriuose yet, we dcided to leave all that alone. But they day of reckoning will soon be upon us, where I will need to make sure the shaft is fully repaired. Here is the main question though.
The rudder is plain simple steel plate. Flat, no shape as in, no hydrodynamic foil shape. I was wondering if their would be any benifit in making a foil shape as a replacement. Or do I just keep it a flat plate. Like, will it make any difference to the feel of the steering, which is hydraulic by the way and will it make any difference to drag??
I think the original will be OK with some holes filled with the welder. I will need to weld a section to the shaft. But it is halfway down the rudder, so it is not under severe stress. The section of rudder stock up to the steering arm is in good condition.

[yona]

You can use a free utility from this web site to reduce the pics' size:
http://bluefive.pair.com/pixresizer.htm

Yona

[BC Mike]

A foil will have less drag. The rudder provides about 10% of the lift. I am not sure of the construction you have but a normal proccess would be a round stainless steel shaft with a flat plate welded to it. The foil surrounds this. BC Mike C