Rudder shape

[Larry Ludwig]

Does anyone consider the old more streamline rudder a better choice than the new max-sized squared off rudder? It seems that almost all the boats I see these days are either retro fitted or OEM with the larger rudder. I still have mixed feelings about the subject.

What about changing rudders? Anyone doing that? Certainly easy enough to do. We have many many light air days here...and racing can easily become a drifting match in the Summer time. When the temp is 100+ it is normally accompanied by a flat calm. Does anyone feel that having too much rudder surface acting as a brake makes for excessive drag when you need it the least?

[Philip Whitley]

Hi Larry,

Good topic, Here in New Zealand most of our boats are mostly all fitted with the square or barn door rudder. Having sailed boats with both types of rudder.

It is my belief that the larger rudder works better in light air, A we bit of trim on the rudder increases the lift in light air, were as the smaller ruddered boat slips slightly side ways. For me it's the square rudder[;)]

Phil

[Matthew Houghton]

Larry,

This is only my opinion but...

Go with the barn door. It works in a larger range of wind conditions. Use less throw for lighter days and more throw doesn't hurt as much in heavier air days. No need to switch back and forth.

My 2 cents.

Matt

[Larry Ludwig]

I have 4 different boats that I am testing with, and I am just not that impressed with the larger rudder. The chance of braking being so great... it kills the speed on the boat in a hurry that is for sure. I know a great deal of people have switched the older boats over.. I am still running along traditional lines.. I have an old Dumas and Reynolds with old style against two of my own hulls with a full size and almost full size. I need to make some waterline changes and try that and then change the balance on the rigs to see the whole picture.

Thanks for the input, it all helps.

[Matthew Houghton]

There is one other thing and I may be way off base. All of the "standard" rudders that I have seen have a very rounded trailing edge. Seems to me that, unless faired nicely, that kind of trailing edge may lead to cavitation. If I was going to use a "standard" rudder, I'd probably try to fair it to a sharper edge for better water flow.

What do you guys think?

Matt

[PegLeg]

Matt
The better trailing edge (my opinion) is one that you could shave with.

Larry
When you test the design varriations you should make sure that the linkage arms are identical in length both for the rudder heads and the servo arms, Also be carefull to evaluate (Nullify as much as possible) the rotaion rates for both the servos and the transmitters. One twitch on A might equal a full throw on B.

[Rick West]

Hi Larry. How are things on the Brazos?
My feeling is that rudder (thumb) control is more critical than the rudder itself. The helmsman can screw up a good rudder and often does. I use a concave shaped barndoor with a knife edge trailing edge for the best flow across the surface without boundry layer separation. (I know you know what that is). I think this produces the best rudder that I can have within reason.

To me the money is then in the TX. Using one with exponential servo control is a God send to the nerves. Inputs are so small to be hardly seen....Rick

[Larry Ludwig]

Heheheh... Brazos? Gotta go further South than that Chief... past the Colorado, Guadalupe, down to the Alamo! We are WAY down there.

I agree... that the TX control is the most important thing. I am not convinced that the extra surface is required. Maybe I should rephrase...

Does anyone consider a standard old style rudder a disadvantage? I guess it has been already answered by a few here that consider the larger rudder of more value.

[philair]

Does the shape of the Rinehart rudder (the cutout) improve performance? I've heard pros & cons but it seems to me that a the smoothness & fairing to a fine trailing edge is more important.

[Larry Ludwig]

If there is a difference, it would most likely be so small that the impact would be equally small. I consider those things... while <u>needing to be considerate of them</u>... well.. lets just say I can screw up once and make a lot more impact on the speed of my boat than the shape of the rudder will all day combinbed.[|)]