Mary,
Here are the basics on beach cat rudder heads. The pivoting rudder blade type rudder head has proven itself to be the most practical rudder up and down system for sailing off the beach, through surf, running aground by surprize, etc on beach catamarans.
For this type system to work well, the rudder blade must be submerged into the rudder head the same depth whether the rudder is up or down or halfway up or down. This places the rudder pivot bolt approximately in the center of the rudder head pivot chamber. This means that the rudder head is as wide fore and aft as it is deep vertically. With this rudder head framework, the rudder blade is well supported in the horrizontal position, in the vertical posion or anywhere inbetween. SuperCat, Aquarius Sails makes such a rudder head.
Today's so called 'modern boats' have gone away from the 'off the beach type rudder head' on their beach cats. Today's 'modern beach cat' has a rudder head with no rudder head framework aft of the pivot pin. This means that when the rudder blade is in the up position, there is insufficient rudder blade support. If you try to steer the boat through the surf or across shallow water,POW, you break the top of the rudder off or split the rudder head casting. This 'modern boat' rudder head design has eliminated the aft half of the rudder head support box in a weight savings effort. The net result reduction in rudder head weight is somewhere between one pound and one and a half pounds per rudder head.
Beach cat sailors down hear in South Florida don't appreciate this new design because we sail off beaches and sometimes a sand bar slips up on us.
The shortcomings of this 'modern boat' rudder head design were demonstrated very thoroughly at the Jensen Beach stop in the Worrell 1000 Race about three years ago. More than half the fleet lost their rudder steering systems in the surf due to broken rudder heads and blades.
Good Steering,
Bill