I've had 2 seagulls- the really simple ones with no clutch or recoil starters. They were dependable and hell for stout but crude. I had one on a 16' ply Great Pelican, and it seemed to go as fast towing a 20' inboard/outboard as lone boat! The thing that wouldn't work today is the starting procedure. The instructions said to press the brass button on top of the 'carb' until you see a sheen on the water. I say 'carb' because I was told by someone who knows that it isn't really a carburetor but a mixing valve, sort of like a model airplane motor. The 'shear pin' was a spring of about 3/16 wire that wound 3 or 4 turns around the prop shaft and had the ends turned out to engage the prop & shaft. If you get one be REAL careful not to hit anything- Heaven only knows where you could find another. If memory serves, the mix was 10 to 1. Especially since they are out of production, I don't think I would buy another.
Best regards
Alex