http://image.rcuniverse.com/gallery/...s/lg-38398.jpg is my latest boat. she has 'flaps' just under the 'armpit' ( behind where the stantion meets the fuselage) for the same reasons. for your boat, being a pusher, I would suggest attaching adjustable flaps onto the prop cage, or even on the rudders. They can be on the fly adjustable, but that would require a 3rd channel on the radio. simply make them adjustable, as you would trim tabs for the hull, and do a series of test runs, adjusting the flaps in between each run. See what works best. http://rcairboats.net/v-web/bulletin...pic.php?t=1337 this thread shows (somewhere) similar flaps. these are on the fly adjustable, if I remember correctly. as far as shape, I would say neutral lift (symetrical top to bottom). Good luck! Sean