5hp? why so little?
You are quite right that 20hp is far too much; even 30' keelboats have 15hp inboards. But I run into people all the time who get used boats that come with 4-5-6hp motors who have a 'marginal' experience and decide they need to move up despite the expense. On reading the archives, looking at the specs, and recalling some hairy conditions, I would now say about 7.5hp and not more than 10. Less is fine for flat water, docking, lakes with little current, etc. Calling the 22 a displacement boat is a little misleading as it is incredibly shallow; its grip is minimal and steerage depends solely on thrust in some conditions. Since you are here on the Bay, you may have been caught out against strong current, punishing wave action and adverse winds simultaneously with a less than clean bottom, possibly motoring while all-standing thru a narrow channel. Its about margins of safety, too.