I'd borrow a motor, and hang it on the boat, and see how well it clears. Anything else is speculation. Easy enough to do out of the water.
Our boat has the OB in the lazarette. Originally was a short shaft. That made it possible to be tilted out of the water when racing. I have since gone with a long shaft 9.8 Nissan, and don't tilt. Definitely stays in the water better in the long swells of Lake Ontario. Don't notice much increased drag, though I'm sure it's there.
Regarding 6 hp vs 9.9, etc... All new small OB's in the US will be 4-strokers. In the Tohatsu/Nissan/Mercury lineup, the 4/5/6 family is a one-cylinder. The 8/9.8 family is a 2-cylinder, and available as electric start if desired. At idle, the 2-cylinder units are much smoother. As a Tohatsu dealer/mechanic, I would opt for the 8 or 9.8 if buying a new 4-stroke. Remember that Tohatsu makes the Tohatsu, Nissan, and Mercury (30 hp and under) OB's. Only difference is brand recognition and price. Oh, yeah, our HR28 could use a bigger motor than the 9.8, but the next family up is the 15, which weighs 30 pounds more, and is Huge. The 9.8 is adequate, don't get me wrong, but I have seldom seen a sailboat with too much aux power when a storm is on.
Paul Van Voorhees
Certified Tohatsu TLDI Technician
Mgr, Obersheimer Sails
Buffalo, NY USA
Last edited by pvanv1; 03-01-2009 at 01:13 PM.