90 or 115 ETEC for 18SF?

[Bushwacker]

HP/liter is an excellent way to assess how durable or "high strung" an engine will be. When I bought my Seafari back in 1975, there were no V-6's; choice was between a 115 and 135 V-4 (same 100 cu. in. powerhead, just carb and exhaust tuning differences.) After one old time mechanic, who used to provide motors to the local commercial kingfish fleet, told me that a 115 would outlast "about FIVE 135's!", I went with the 115 and never regretted it. Speed difference was supposedly about 3 mph, which I considered a small gain for big loss in durability!

A lot has changed in 35 years however, and all of the E-Tec's appear to be very durable, so either the 90 or 115 would be fine. If you're running in a rough chop, I'd vote for the lighter motor because boat will plane at a lower speed with it and ride better, and it'll still push the boat faster than you can comfortably run anyway! Just make sure you prop it so it turns max revs with max load. Might also consider a 4B prop. The extra blade provides more stern lift and the additional blade area will provide a great hole shot if you get the right dia./pitch combo.