[QUOTE=Fenlander;654282]From my experience with a 15hp on a T35 I would agree with the comments above. These alloy floor Honwave models are great boats but heavy and do not perform as well as a smaller/lighter SIB for any given outboard size.
To have reliable performance 4 up (assuming adults) on the plane you will need a 20hp really.
What do you mean by "cruise" though? Most of us would mean a comfortable speed the boat will easily maintain once on the plane... perhaps 15kts. The problem you may have with a smaller (than 20) outboard is that it may be capable of maintaining this cruise once it gets on the plane but you may find a 20 is needed to easily push it over the "hump" onto the plane 4 up.
When 2 up a 15hp should be OK but a 9.9 may be too small.[/QUOTE
If your gonna have a 20hp 2 smoke you may aswell go for a 25hp it's the same weight and the extra would be a noticeable improvement on a 20hp.Not that different in fuel either.