Moving engines forward
 

We are still in the planning stages of our repower and wondering if it would be beneficial to move the engines forward a few inches? 40ft Hustler single step hull switching from Yanmar diesels to Cummins. Currently spinning 32 pitch 5 blades on #8 Arnesons. One issue the current setup has is it starts porpusing when trimming up. It'll run flat then a small boat wake can set it off and I have to bump the tabs or drives down to make it stop. If you let it continue it'll start hopping the boat out of the water. Would moving the new engines forward make it better or worse? Currently cruise at 70 to 72 with drives at zero with no porpusing. Top speed 83 but thats trimmed way up and hopping her fat heavy ass out of the water. Lol I have roughly 12 inches of room to move forward.
https://cimg4.ibsrv.net/gimg/www.off...d8fb30c390.jpg

Is there a weight difference between the two motors, that might factor into that also.

have you tried adding weight in the nose in the current config, moving engine location affects several things......... if the manufacturer is still in business Id be getting them on the phone

They both weigh 1,400ish give or take a few pounds.

I'll give then a shout next week. I'm curious what should I expect in moving forward? The engines are heavy so a minimal movement could make a big difference for better or worse.

The two biggies I see is drive coupling and exhaust reconnect, I assume this is a side by side

I don't think moving them forward +/- 6 inches will have any significant results. I would lean toward trying different props with more rake.

I'll be the one doing the swap and fabrication. The turbo design is completely changing so exhaust already has to be redone. The coupling will just require a longer driveshaft.

A friend of mine had a 1995, 46' Post. Twin 6v-92's. Moved the engines forward one foot. He was very happy with the performance.

ya I keep forgetting its a repower.........:ernaehrung004:

I agree, exhaust all prop possibilities first.

The hustler 388 slingshot was known to have too much hull lift at the transom for speeds higher than what Merc 500s or 525s could achieve. Some guys shortened the lifting the strakes to get the rear to settle down. I’d rather do that than move engines. My glass/gelcoat guy down here is the cheapest maintenance I get done on my boat. Every other type of work is more expensive.