Rudder (Rake) angle

[Boatman]

First off hello everyone. I am going to build a catamaran hull boat and have a question I dont see anyone has covered. I need to pick out my rudder and I allready have an sv27. I notice it has a good negative angle to it. Is this needed for a cat style? I looked at the Jolly Cat pics and being as nice a boat as it is, it doesnt seem to have any angle at all. So I would assume none is needed. Is it just for mono boats?

[Fluid]

You'll have to define your use of the word "rake". Do you mean a rudder with non-parallel front and back edges, a rudder with its back edge not perpendicular to the water when running, or a rudder with caster in the hinge pivot?


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[SJFE]

If you are refering to positive and negating rudder angles in reference to the surface of the water....It's hard to see with out a close up picture but the single motor Jolly Cat has quite a bit of ajustment. With my setup it likes the runnder tucked under full. I have read the same for the SV27. I don't remember how I had mine because I sold it a year ago.

[ReddyWatts]

This is a very good article on rudders, turn fins and more.

http://www.offshoreelectrics.com/inf...s-and-more.php

[ED66677]

I've used rudder negative caster angle on my mono to help the transom to stick to the water in curves, it tends to push the transom downward so it does not "stall", it does, but at higher speed.

[Boatman]

Thanks to everyone for the help. I guess it sounds a little mixed so far. The rudder I was gonna run has no adjustment so I was gonna machine it depending on your thoughts. I perhaps could make some shims and test it in several settings and go from there. I had thought of when cornering that having it tucked under would bring the front down and dig in well for handling such as sjfe spoke of. I also wondered if it would affect iin the straights though. It shouldnt if the rudder is straight and not turning.