Hi Ron... The 4hp should do it for you, depending on where you sail. I sail on Lake Lanier, Ga., and a 3hp does just fine... no current to buck, and few strong winds. I've even moved my M-17 with a 36 pound thrust electric when the first motor was being repaired. However, if it's possible that you will be bucking headwinds, or strong currents, a 6-8 hp motor might be in your future. I'll stay out of the 2 vs 4 cycle argument, only saying that 2 cycles are lighter for their power, and unless you plan on doing a lot of motoring, the oil in the gas won't add much to the pollution. My two Seagulls are 2 cycle, and of the last generation with 50-1 gas-oil mix. I use synthetic oil which is bio-degradable and smokes a bit less then regular oil. Harvey/ Ga M-17 Stargazer #294