Mahogany will work
Mahogony is a pretty wood. It is a bit softer than teak so denting may be a problem. You will have to finish it. I like varnish but that statement will start a war with the cetol following. If you keep up with the finish, you will have no problems. If you let the finish go, you may start having some problems.Don Evans did his rudder out of mahogany and it's under water all summer.I think he made his rudder about three years ago. I think he used a polyester resin for protection. Anyway the mahogany is holding up.I also made new rails. I used teak and changed the configuration and glued the pieces with Gorilla Glue. It stands a little higher so that it is usable. You can get your hand around it. If you want I could post a photo.r.w.landau