Starcraft o/b to i/b jet

[Muskrat]

Hello,
I have a 22' Starcraft MR 220V. This past year I have completely rebuilt the boat from the bottom up, stripped it to the bare hull,(foam had become a sponge),coated the inside of hull with bed liner,refoamed,and new decking and new composite transom. Have done alot more for comfort and ease of use but they aren't important for my question.Now with all this done I was ready to get a new O/B, except just yesterday I bought a 1979 Arrowglass Jet Boat.It was a killer deal that I couldn't pass up. The engine is a 455 Olds(suppose to be built to about 500hp) with Berkley pump. The motor and pump are rebuilt and still in their crates. They never made it to the boat. The Arrowglass would need alot of work to be sea worthy. Now here is my question, how feasable would it be to install 455 and pump into Starcraft. I don't think the weight would be a problem, the Olds and pump weight about 710lbs and the O/B that I have hanging on the back now weights about 580lbs. I'm not an engineer but I do have the facilities, tooling and working knowledge to do this swap. Any input would be helpful. Muskrat

[Black Swan]

There are a number of things to consider. First of all there may be some structural issues. Certainly your target hull may be well built, but if it was originally designed for an outboard, the stringers may not currently be beefy enough to support that nasty 455. Fortunately, the transom will probably be OK since the jet's propusive effort is primarily exerted there, though some of the stress is shared by the jet intake block. As far as the 455 being 500HP... whew! It would be common for a "go faster" builder to tweak that engine to that level. The Berkley pump is a time-tested design, and there are lots of aftermarket improvements that can be "bolted on" to improve performance. Sounds like you're in for a lot of fun!

[Muskrat]

Black Swan,
Thank you for your input. I knew that I would have to do something about the stringers. I figured on running a 1/4" thick sheet of aluminum to the inside of the existing stringers with a space of 1 1/2" between, then run them about 8' from the transom forward. I'll weld them in and then fill gap with liquid composite. After this I'll still have about 24 1/2" between the stringers. Where the engine and pump will be the stringers will only be as high as they need to be which at this point of time I'm not sure what that will be. From the front of the engine forward to the end of the added stringer it will be to the bottom of the decking which will be about 16". Also currantly my fuel tank sits under the decking in the middle of the boat from about 2' from the transom forward to about the middle of the boat. I plan on turning it around so my fuel inlets are in the same place under the decking then forward. This will put the tank about 18" past the center of the boat toward the stern and about 3 1/2' toward the bow from center of boat. This is a 50 gal tank. Oh by the way I'm speaking of the theoretic center of gravity bow to stern not the physical center bow to stern. Muskrat

[Black Swan]

Hamilton and Ultrajet websites have a lot of good info on "suitablility" of hulls to jet application. From the description of the stringer exercise, it sounds like you may have a "deep vee" hull there. They both caution builders about this hull design. Have at 'er!

[Muskrat]

I have contacted about all the jet pump companies and the most help I got was from American Turbine. They even had a document that I down loaded from their web site that gave me all the diagrams that I needed to do the conversion. I talked to the Pres. of the company (Ron) and he was very helpful in what I needed to do to make it all work.
Some of the companies even told me it was a hair brain idea to which I would ask if they possibly wanted my business or not.That got a little more info out of them but still not as much as I needed to make a good decision to go ahead or not.
After talking to American Turbine it's full steam ahead. Well when the weather cools a little here. My shop is heated but not air conditioned. If there is an interest in this project I'll post my progress after I get started.
Thanks for the info that was provided from all. A special thanks to Black Swan for the encouragement to check more into this project.
Muskrat