My dad wanted a trailerable boat for short cruises, and traveling across the country and exploring different waterways. He didn't want it to be any longer than 20 feet, because that would be the largest size he could fit on the trailer he has. (We baught a used trailer to launch "Heart of Gold" with.)
He wanted a comfortable berth, and sitting headroom in the cabin, and an enclosed stand-up pilothouse. We started with a design close to Sam Devlin's Surf Scoter, but when it was shortened to 20 feet, the pilot-house and the cockpit were both too small.
We decided on the pilot-house/cockpit combination, with an extended hard top. The sides and back will be enclosed with canvas.
Speed was not a priority, so it will have a semi-displacement hull. A 50 horse 4-stroke is the bigest motor contemplated, which will give a comfortable cruising speed of about 12-13 knots. (rough estimate) A 25 horsepower motor is more likely, which will push it about 9 knots.
Originally, the motor was going to go in a well, but we decided to mount it on the transom to make more room in the cockpit. There will be a watertight bulkhead 2 feet forward of the transom.
The cockpit sole will be below the waterline for headroom,(6'6") so it will not be self-bailing. there will be a sump and a bilge pump for rainwater that might get in.