Outboard/inboard dilemma

Just lift it up and boom no drag.  Too bad an outboard on the back of a Contessa looks like shite.  If you have a two blade prop, after you shut the engine down, you can turn the propshaft so that the prop lies in the lee of the keel.  Better than having a folding prop because it will back up better.  Not that you could swing a folding prop on a Contessa anyways.

As for the weight?  A Honda 9.9 longshaft weights 110 lbs.  A Yanmar 1GM10 weighs 170 lbs.  In a Contessa that 170 lbs in in a better position along the centreline of the boat, and low slung in the hull as inboards in these boats are, than any weight hanging off the back of the boat.  That, and an extra 60 pounds won't make the boat sail all that much worse.  Really.

Personally I'd rather have the inboard.  I mean, that's a lot of space that could be filled up by beer, but an outboard really does screw up the lines of these boats......

*weight figures are approximate.  The Honda really weighs 108 or 111 pounds depending, and the 1gm10 is specd at 167.  I added a bit for carbon in the exhaust elbow....

Not much of a dilemma at all.  First, let’s get realistic about prop drag and its effect on speed.  The drag of a Campbell Sailor (sailing at 5kts) is around 12 lbs for a two blade and 18 lbs for a three blade.  As mentioned above, the two blade can be hidden and one blade of the 3B could also hide (dropping its drag to around 12 lbs).   My guess is that at the most, you’d lose maybe 0.10 kts.  That isn’t significant for a cruising boat. 

Hanging 100+ lbs off the transom is just where you don’t want the weight.  Loading the extreme ends of any vessel promotes “hobby-horsing” in heavy seas.  This almost insures that the prop will be batting air just when you don’t want it to be doing that.  A diesel down below gets the weight in a better position being more forward and below the LWL.

Gas tank?  If you install a permanent tank with deck fill and venting, etc. you’re fine.  If you use the portable tank that comes with the engine, you have a placement problem.  You can’t keep it anywhere in the interior where fumes could accumulate.  It’s got to be in a sealed but vented locker or outside where any spills or vapors from the vent cap can go over the side.  Fuel usage is another concern for a cruiser.  My 2GM13 gobbles up a little over a pint/hour at 5kts.  My 10 gallon tank gives me roughly 60 hours of steaming.  No outboard can come close to this.

If engines were only used for motoring in light air and seas, the outboard would be fine.  But that isn’t always the case.  Driving into a heavy wind with nasty seas is not a job for any stern hung outboard.