Re: O/B replacement
First off Happy New Year !!!
Now the engine stuff. Your main consideration between 2 and 4 stroke motors will be primarily a weight issue with the 4's coming in a little bit heavier. If I had the boat bucks I'd really look close at the new E-Tech motors. I've read nothing but good about them but in the same vein you just can't beat the 4 strokes.
I run both two and four stroke outboards and the difference is vast between them. I know I just might be comparing apples to oranges but they are two different beasts.
Once again, consider your weight factor - could be a make or break point with that 18 footer.
Do some comparisions on the net between all of the motors, i.e. weight, cost, ( complete with controls ), etc. and go from there. You will need to include a new set of them ( controls ) as nothing will match up with your existing Force except maybe an old Merc.
Hey, it's only money !!!!!!!!!!!!