ENGINE SIZE

hi all , looking for a bit of advice ! , i have a 17ft boat and im looking for a back up engine , what size engine would i need , boat weighs aprox 500 kilos , thanks

Where about are you based and what are the tidal conditions in the area.
Where a 4/6hp might get you home safely in some areas but a strong tidal rip or a dropping tides heading back up an estuary could be a loosing battle.

crosshaven co cork , there can be some strong tides there ,often have to row out in them !

Minimum auxilliary size formula: one HP per metre length. For your boat, that works out at 5.5HP absolute smallest, but sounds like you'd be safer with a 9.9, a fairly easy size to get second-hand.

great thanks ............. anyone got one for sale !

Ask around the inshore commercial lads in your area, a lot of smaller O'Sullivans open boats on the south coast used 9.9s. Just be wary!