Re: 23cc transom rebuild and f350 repower
 

The f350 is very smooth and quiet at both idle and cruise. If the 23 can handle the weight it will be a very sweet set up.

Re: 23cc transom rebuild and f350 repower
 

I'm not really worried about the weight since I'm getting a hermco twin bracket. I am worried about the performance through choppy seas, I had a friend with the same boat with armstrong bracket and twin 200hp mercs. He said it rode better when the twin mercs were on the boat transom rather then on a bracket. I can't get a hold of the guy and last I heard he sold his boat. Any advice is greatly appreciated.

Re: 23cc transom rebuild and f350 repower
 

That's because he shifted the CG of the boat aft by moving the motors aft by whatever the bracket setback is! It's elementary physics; boat with a bracket will tend to run with bow higher with less of the higher deadrise forward sections of the hull slicing the waves. He may have picked up 2-3 mph at WOT, but I bet his min planning speed also went up!

You SHOULD be worried about the weight of that big V-8 motor! CC's are already a little stern heavy compared to a Sceptre or Seafari, so more engine weight just makes it worse. The big floatation tank of the Hermco twin bracket only helps at rest or at slow speeds. It does NOT eliminate the CG shift when you're up on plane with the flotation tank out of the water! Check out the big block 250/300 E-Tec's. They're quiet too, but much lighter, simpler and cheaper to maintain. My 150 is actually QUIETER than the equivalent 150 4-strokes at 30 mph! It has so much more mid-range torque that it doesn't have to rev up as much for same boat speed.

Your friend should investigate switching to stern-lifting 4 blade props and possibly a Doelfin or equivalent on cavitation plate to improve the ride and low speed planing ability. Those changes on my rig dropped min planning speed from 18-20 mph down to 11-12 mph! Since the 20' hull starts to go airborne at about 20 mph when seas get over about 3', that low speed planning ability makes a huge difference in ride when conditions get real snotty!

Re: 23cc transom rebuild and f350 repower
 

All great points...I think adding a Yam 350 from scratch would be easier. You could adjust the CG by postioning fuel tank and the console further forward. As mentioned, weight is weight...it's the planing speed that would be my concern.

Re: 23cc transom rebuild and f350 repower
 

I know its not a seacraft but I have a 23ft contender and recently put a Yamaha 250 on it.
It needs a little prop work but with the old 225 merc prop she runs 45 mph top speed fully loaded.
The cruise speeds are off due tot he wrong prop but I fine it plenty to push this hull.

No problem getting on plane with 4 adults and 5 kids with lots of coolers and toys we take to Egmont Key for the day.