Things to consider
Things to consider. A 15" shaft will be too short except when in flat water and crew in the cockpit. Motor bracket sounds like it is in the right position. 6 HP should be adequate. 4 HP minimum (ideal depending on other factors) and 10 HP max. 20" shaft engine with F, N, R. My brother has 6 HP on Mariner, friend with 7.5 HP on Cape Dory 25 - both are more than adequate. Best? 4HP 2 cycle with 20" shaft F, N, R shift -alternator optional. This will have low weight assuming you only need aux power to go a 1 mi or less. If you need to typically power 1- 2 miles to / from sailing then 6 HP. Bigger engine only if cheap. 4 cycle engines are quiet, cost and weigh more. Extra weight negatively effect sailing performance. Small flexible solor panel to charge battery nice - even if the engine has an alternator.
