I used a 2009 Tohatsu 3.5, a 4 stroke. The weight is about 43 lbs. You don’t save any weight by going down to the 2.5, they are the same engine with different carburettors. The only new engine that is much lighter seems to be the Honda 2.5.
This link includes some pictures which show the mounting on the boat.
The rudder clears the prop when the outboard is straight ahead. This makes for very nice cruising as I set the engine dead ahead, set the throttle, and then steer with the main tiller. Being able to use the Wayfarer’s rudder gives much better directional stability than the alternative of having to remove it. Dropping the centreboard a little or completely also helps. With board down the boat steers like a keelboat, very stable. I tried seeing if the centreboard slows the boat down, the gps showed only by 0.1 knots.
I think we”ll start to see more restrictions on 2 strokes – we already have a couple of lakes here that don’t allow them, only 4 strokes.
Fuel economy is a plus, 45 mins on a litre at full throttle. Half throttle still gives 5 knots and 1.5 hours per litre. Full throttle gives 5.7 knots with the bow up by 6 inches – a little planing going on!