Spade rudder, skeg rudder or keel mounted rudder. It all depends on how it is built. There are many skeg mounted rudders where the rudder post is strong and the skeg is weak. If you go to a big boatyard and look at the boats on the hard you will find that in some cases the rudder is strengthening the skeg, not the other way around. Shake a few and you will see what I mean, especially the ones with a smaller skeg. While a spade is vulnerable to damage from a good hit while sailing, if it is designed and built properly it should not be a problem. As for an emergency rudder, which is a good idea on any offshore boat regardless of rudder design, some self steering vanes like the Monitor can be used as an emergency rudder.