ORIGINAL: martno1fan

why have you moved to another thread to repeat your questions?,my airboat is a flat bottomed hull it has a 46 la engine 11 "prop,more than enough power for that boat arround the same weight.yours is a tunnel design which should be faster id say stick to a 46 any will do but the ones with ball bearings are best.more expensive unless as i said you get the sc ones or similar priced ones like thunder tiger etc.os engines are very expensive and no better than sc in my book.my os 46 la has no barings but its a cheap reliable engine!!.the la ebgines are for trainers so they need to be reliable but they arent powerfull although should be ok for your boat for a bit of fun.i dont think a 61 is too big though it will certainly shift ,if it floats .check out this site see what everyone is running on theire tunnels.
[link]http://www.rc-airboats.com/gallery/[/link]