The main factor when using same hull
is the hull rocker, which causes the squatting under power at higher speeds. Depending on the size of boat and design of hull this may be a small or medium issue. If your trying to get to 15-18 knot
range it usually is ok, but try to push sailing hull faster than 18-20 and you will experience squat. John shuttleworth
actuall had trim tabs on his earlier power cats for that very reason.
To give an example the Lagoon
52 cat powers at just over 10 knots with 75 hp Yanmar
w sail drives & fold props, take off the rig and throw in 110hp yanmars with standard prop and shaft and she "should" hit 15knots. She may have a little squat if trying to push faster than that speed. Not bad for a 56,000lb boat. So if you want swift trawler
type speeds go for it, if you want power cat 20+ speeds get proper hull design or modify the existing hull rocker.
We developed a 52ft cat design that can be configured as Trawler
cat 10-12 knot cruise
or performance sailing cat. It's a lighter weight version of the Lagoon
52 at 18,000lbs. Power will be 75-120hp for trawler version. And will top out at 15-18 depending on power.
More info at Maltese Catamarans MP52-trawler.
Side note: have friend who plans on buying
older sail charter
cats for good price and do exactly as you plan.
Reality is that is many places most of these condomorans are used as just big power cats anyways. Maybe actually really only sailed 5% of the time.