Rudder Issues on E25 Boats
The centerboard boats (E25 and E23) have their their rudders transom-mounted on long pins so that they can be raised when the boat is sailed in shallow water. There is a cheek block above the waterline on the leading edge of the rudder, with a 2:1 line running from an eye on the stern to a cleat on top of the the transom, or at least there is on all the boats I have seen. The rudder itself is made of two quite thick pieces of mahogany joined vertically to get the necessary width, and wrapped with two layers of fiberglass cloth. The whole thing is shaped in the typical low-speed foil shape (bull-nose tapering to fine trailing edge) that works reasonably well for a wide range of angles-of-attack. It is relatively common for the rudder to be damaged by contact with the bottom, prop interference, delamination/water intrusion, etc. Repairs are straightforward, and involve making sure the wood core is well dried out. Then if damaged areas aren't too large, they can be filled with a good quality waterproof filler - I like to use "gorilla hair" epoxy body filler, as it adheres so well, is strong, and is easy to work. New fiberglass can then be layed over the repaired area, or if the old glass was pretty shaky, the whole board can be reglassed with not that much more effort. I am currently experimenting with using "LDL" construction board for wood cores for centerboard or rudder applications. It consists of 15 plies of tightly compressed and resin impregnated laminated 2Xwhatever and seems to offer a good alternative to the original materials. It is relatively cheap and very strong - the trick is to keep the water out of it, but that is the general issue with any underwater cored construction. So if you need to build a new board, that route might be an alternative to consider.