Dagger rudders were mentioned here and I believe their features should be present in the ideal beach cat rudder. 49ers, 29ers and some Malcolm Tenant designs feature this kind of rudder. They are interesting for two reasons:
-The blade can be raised vertically in low wind or for beaching, reducing drag and draft but still allowing effective steering.
- The blade is totally removable, simplifiying replacements and maintenance.
The obvious and serious problem is that the blade does not pivot when hitting the bottom or floating debris.
My proposal is a pivoting dagger rudder - something that would do both tricks: pivot back and retract vertically.
Ian Farrier recently designed one for his F-33, and (correctly) called it kick-back dagger rudder. Unfortunately, his solution is not satisfactory for a beach cat, mainly because it relies on one attachment point only when kicked back - the upper gudgeon.
(It features an additional horizontal hinge in the upper gudgeon of the dagger rudder trunk, and a release mechanism in the lower gudgeon. When the blade hits an obstacle, the entire trunk and blade assembly pivots back, supported only by the upper gudgeon, which will has to support the extreme loads)
This design is very probably unsteerable after the lower gudgeon is released so it is not really safe for a beach cat, like most cats compared to the Supercat/ARC.
I was also dreaming of a pivoting dagger rudder for my boat because it has additional advantages in the particular case of the Catri (motoring in shallow waters with the engine on the rudder).
Then I remebered a very interesting daggerboard design from an old (10 or 15 years ago) windsurfer. As far as I know, it has not been used in rudders, but who knows... Anyway, I adapted that design to a rudder.
It is a simple concept and the rudderhead can be made as strong as necessary to please Bill Roberts, without oversized gudgeons, as in the F33.
The basic drawing is attached. The real plan is almost ready and I intend to use it when sailing in shallow waters.
