Looks like a shamrock keel drive. We surf behind a shamrock pilothouse 20, 2 550 sacks, one on each side of the pilothouse, filled with about 400#'s each. One 750 sack on the side being surfed, with about 500#'s in it. We run about 2350 -2450 rpm's. The 750 sack can be rolled side to side in about 5 seconds. The portside is Fantastic and the starboard side is very good, wake on both sides is very steep. I do have a swim platform, but as an experienced surfer, I would have no problem surfing it without the platform.
(Message edited by ruebentown on September 08, 2008)