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Re: Other: Another rudder query
By:Bill Hamm
Date: 11/19/2011, 4:46 am
In Response To: Other: Another rudder query (Craig Robinson)

: hi All,
: I am building a timber surfski and am currently playing around with
: the rudder setup. I have a CF rudder that I removed from my
: current surfski. I belielieve that it is designed for weed
: shedding but is useless for anything but flatwater. i replaced
: it with a 9"elliptical surf rudder (Epic) which is great.
: Main problem is the placement of the post, so I cut off the
: original post to move it back so that rudder was more balanced.
: From this;
:
: [IMG]http://i124.photobucket.com/albums/p23/CraigMel/17112011520.jpg[/IMG]
: to this;
:
: [IMG]http://i124.photobucket.com/albums/p23/CraigMel/17112011521.jpg[/IMG]

: It occured to me that it might be beneficial to reduce the front
: angle while I am at it. The surf rudders are not as raked back
: to this;
:
: [IMG]http://i124.photobucket.com/albums/p23/CraigMel/17112011522.jpg[/IMG]

: this image shows the difference between a universal rudder and a
: surf rudder.
:
: [IMG]http://i124.photobucket.com/albums/p23/CraigMel/WeedlessRudder.jpg[/IMG]

: There are some smart blokes on this forum and was hoping that
: somebody would know if reducing the rake?? of a rudder intended
: for openwater, downwind and surf is beneficial and why?

: The ski is based on a clc pax20 so being hard chined and having a
: fairly defined keel/stern, I expect that it will track very well
: with or without a rudder.
: cheers

Hi Craig,

You lose effective span on a raked rudder, so rudder at closer to a 90 degree angle to the bottom will be more effective for it's size, but I'd bet the effect would be tiny and not sure you'd ever notice a difference. Long narrow wings are the most efficient, also prone to easy stalling and are structurally difficult. Also will be far worse if you do find a weed.

Bill H.

Messages In This Thread

Other: Another rudder query
Craig Robinson -- 11/17/2011, 8:55 pm
Re: Other: Another rudder query
Craig Robinson -- 11/17/2011, 8:58 pm
Re: Other: Another rudder query
Bill Hamm -- 11/19/2011, 3:01 am
Re: Other: Another rudder query
Bill Hamm -- 11/19/2011, 4:46 am
Re: Other: Another rudder query
Craig Robinson -- 11/20/2011, 5:34 am
Re: Other: Another rudder query
Bill Hamm -- 11/20/2011, 9:21 am
Re: Other: Another rudder query
risto -- 11/21/2011, 4:35 am
Re: Other: Another rudder query
Craig Robinson -- 11/21/2011, 6:07 pm
Re: Other: Another rudder query
Craig Robinson -- 11/21/2011, 7:09 pm
Re: Other: Another rudder query
Bill Hamm -- 11/22/2011, 12:48 am
Re: Other: Another rudder query
risto -- 11/23/2011, 4:36 am
Re: Other: Another rudder query
Craig Robinson -- 11/23/2011, 6:10 pm