Steve, the 260 and 26 motor mounts are...
...completely different. SOME manufacturers 15s are the same motor (same weight) as their 9.9s and some are quite a bit larger. The 260's seem to have a weaker mount, stainless steel on the 260 vs. heavy teak block on the 26. As far as exceeding hull speed, it's possible even under sail but unusual needing exactly the right conditions. As I said below a larger motor, unless powerful enough to overcome the bow wave, will not increase your hull speed with respect to the water. So ,under usual conditions the boats OVER THE BOTTOM SPEED against your 4.5 knot current will be about 2 knots. A larger motor will counteract chop and wind. My 26 under no current, wind, and chop conditions with an 8hp at wot goes the same speed (GPS) as my friend's 260 with a 9.9hp Did you get your speed from a GPS (over the bottom speed) or from a true knot meter (through the water speed)? It's physics. Anyway, when my old johnson 8 becomes an anchor, I plan on getting a 15 four stroke. I enjoy sailing under exciting conditions and want the extra charging and other goodies. I guess it should be stated that in the end, hull speed is theoretical based on calculations. Actual through the water speed depends on water conditions and attack angles. The more powerful motor will get you a very slight speed increase. The operative word is slight until you start climbing over the waves your boat makes which takes a much larger motor that won't fit on these boats. alan