Well, then let me be the first cruiser to disagree with you <grin>
An engine is important, but an outboard is enough. I agree with the easy to deploy; so I am not too comfortable with the "sled" concept that Rob has been discussing, but an outboard that just drops down and starts (electric start) is enough for me!
I brought a maine cat 30 from Maine to the Bahamas down the intracoastal. 2 outboards, which was nice for docking, but I only ever ran one at a time. Motoring at 4-5 knots is fine because I only want to do it when the wind is non-existant or directly in front and not too strong.
Back when I had a diesel in my monohull, I had the opposite problem. Diesel died on the way into a lock and I had to madly raise sail and sail into the lock. Exciting! And more rewarding than the reverse <grin>
Give me a boat that is always faster under sail than power and I will be happy. Since I can't do that, just give me enough power that I don't have to paddle the thing.
- Gardner