scarab kv with speedmaster drives
 

I have a 88' 38 scarab kv (non notch) that i bought without power and drives .I purchased a set of ssm3's to use on the boat and my 600hp motors out of my 30 scarab II. My question is what x dimension (running surface to prop centerline) are these boats happy with ? I plan on using 12" ext boxes (still yet to purchase) with the ssm'3s .I have read a lot of posts on the x dimension subject but need to know what setup the guys with the kv"s and ssm's are running?Future plans for boat are ssm 3a's with bigger power . Any information would be greatly appreciated.
thanks mark

On my Excalibur hawk, very similar bottom, 3" below the running surface with a 17" diameter prop works VERY well. That's a 21.311" x dimension. If your using boxes go up 1"

I wouldn't go any higher than 21 1/4 because the weight of the bow you might have problems getting on plane if the boat were a Larry Smith Scarab then you can go higher the production boats were very heavy in the bow. That put your prop shaft 3 Inches down. I would start with 17.5 to 18 Dia props we have found that the big V bottoms like more Dia.

The boat has minimal cabin, padded bench seats carpeting thats all . No cabinets , fridge or sink . The 3 " is that with or without ext boxes ?
Mark

Yes that's with ext. boxes The problem is Wellcraft used plywood for everything all bulkheads stringer benches and deck core that's what makes them heavy in the nose. We rigged a 2000 38 with number Vs and we had to be 3 inches below the bottom to get it on plane in under a minute. Wellcraft didn't know how to build a light boat.

Thanks for the information guys , now i can get busy looking for 12" stellings ext boxes .