Eric, here is a short reply I received re: your question:
"Re: the Tartan 37 rudder: Tere is a false skeg that is only a water foil ahead of a spade rudder which is designed to break away at the lower support bearing rather than endanger the rudder tube and surrounding hull structure near the transom in a hard grounding at speed...this is good and bad. I gently drifted back onto a coral head and that started the structural weakening of the rudder that eventually caused it to fall apart without further trauma 4 months and 400 miles later. Feel free to give your friend my email address and I''ll be glad to answer any specifics."
You can contact Larry for further info by using email@example.com.