I guess most sailboats of some size have an emergency steering tiller that can be coupled to the rudder if the other steering systems should break or fail. There is usually some kind of hatch that can be opened to get access to the top of the rudder post. On the Privilege catamarans of our model and others of the same age, the access is through a "screw-in" hatch in the transoms.
I have had to use this one time in calm and nice conditions when a rudder got stuck and thus was disconnected, leaving the other rudder available only to the autopilot or the emergency tiller. Going into a harbour, the autopilot was no option. Since that I have been thinking that if I ever have to use the system offshore in more than moderate waves, seawater is certain to enter through the hole. Underneath is the shore power charger and some other stuff, so seawater is not welcome in that area. But I did not do anything about it. Likewise, the tiller itself has been stored under some sails in a locker, and not easily accessable. Quite complacent. So I have now made a more accessible storage position for the tiller. And also made an arrangement to plug the hole when the tiller is in use. It is not completely water proof, but will prevent open flow into the hull. The charger will still have to get some kind of top hood to protect it fully.
In addition, a tiller extension was made out of a carbon tube. The forces on the rudders are great, and I fear it will be hard to steer the boat in open sea.
Simple materials, the plug from some styrofoam-like sheet (a bit softer) and the cover from canvas. Joined together with polyurethane glue.
I hope we will never have to use these things.
