convert ib to ib/ob w/ jackshaft

[beached]

Has anyone converted a straight inboard to an ib/ob with a jackshaft? I like the idea of having the motor in the center of the boat allowing more room on the deck, but don't want a straight ib, and might prefer not having ob's hanging off the rear.
I'm considering all options, advantages, costs, etc. for my future (hopefully 23'classic CC)project.
Any thoughts?

[Rich]

Do you have an inboard now?

[rudders_midship]

Naval rhibs are set up that way the 2 that are on DDG's are about 23' with cummings 220 turbocharged inline 6 b model set up with a jackshaft to an outdrive I belive its a odd outdrive I can look tommorow I do know they use a huge prop like a 19 square

[deepsushi]

Converting a straight inboard to a jackshafted I/O outboard I think would be a very difficult project. The inboard seacraft has a prop pocket or "tunnel" where the running gear /prop sits. If you look take a look at either Craig Miles or Capt. Skip's inboards you can see the half moon curve of the tunnel which runs from the transom up approximately 1/3 of the way up the keel. The bottom of the v of the keel is in reality "missing" as this is where the shaft /rudder/skeg sits. I would think that this tunnel would create cavitation which would prevent either an I/O or an outboard from getting enough clean water for the props to get a good "bite" on the water. However, like the saying goes "anything is possible" and I guess it could be done with a a huge amount of hull modifications.

If your looking for a jackshafted seacraft, they do in fact exist, however, they are as rare as hen's teeth. A while back I believe there was a thread called "seacraft trivia" and if I remember correctly Trayder posted that the number of jackshafted I/O Potter seacrafts numbered in the single digits (3 total?).

If you are determined to undertake such a major project, it would seem to me you would be better converting a hull that was all ready an I/O and figuring out how to move the engine forward under the console.

However, as a wannabe seacraft inboard owner I think it would be a crime to convert a straight inboard into either an I/O or outboard.... [img]images/icons/shocked.gif[/img]

edit: you can see the prop pocket here:

http://www.theboatzone.com/gallery/miles01

[ February 19, 2003, 09:37 PM: Message edited by: deepsushi ]

[Briguy]

When I thought about repowering my '78 23' cc I first looked at doing a Jackshaft 260hp inline 6 Yanmar. I spoke with a naval archatect and we agreed it could be possible mounted like an Albermare. Our thoughts were to NOT mount it under the console but to make a box starting at the leaning post. That way the transom would be clear and the 1100lb diesel would be far off the transom allowing an even weigth distribution. My problem. COST. 5k to do the transom work and install the motor, 23k for the motor and outdrive. Gas tank? Where the heck that would go was a mystery. I really wanted to have a CC with a full transom and open console. No dice. My twin 115hp suzuki's were the best decision as they were about 15k fully installed and ready to run. Oh well, I'll save the Diesel project when I retire or win the lotto or when Amazon goes back to 300.

[Briguy]

As an added comment. The Silverhawk comes with a 230 hp yanmar io diesel as an option for not much more than 55k brand new. Check it out as its a copy of a seacraft 23 and its actually 24'. I would consider it over a new sc 23'.