Rick, you were not instantly convinced by the rudder up/down traveling prop combination for the Seabbatical design.
The Promas design http://www.rolls-royce.com/marine/products/stabilisation_manoeuvring/promas/index.jsp treats this issue, although in another context. An alternative setup also shows a rudder with a flap.
For the Seabbatical what about a Speer like foil with the side with the prop fixed acting like a board and allowing the prop&pod to travel up/down, and the other side act as a flap/canard depending on direction?
It does seem simpler to build than the original.
Needless to say, I don't have the numbers ;)
Luc
PS: thank you for the numbers on hull fouling. It makes sense in hindsight.
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