Marrying Lifeboats Up - The Push Me Pull You

BoatRenovationPeople

BoatRenovationPeople

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Hello folks, new to the forum.
I'm sure it's been covered but I'm interested in the possibility of taking two GRP 30ft life boats, slicing them up into 1 hull. Have people tried similar things, obviously there are major structural considerations, buoyonancy and weight distribution at play. Feel free to tell me I'm a fool.

I've rebuilt boats from composite core in the past, it's more the other elements. Use would be a live aboard, occasional cruiser, coastal.
 
It would have to be chopping the bow of one and chopping the stern off the other. You'd loose overall length but you'd still end up with an ample base for a live aboard.
 
Do you have a picture of the boat ? You would need parallel lines to join together cleanly.
 
I could deal with some slight discrepancies but ultimately they'd need to marry up well yes. I'm just in the research stage - just seeing if its viable. Have the access to space, cranes etc and a good amount of experience with composite. I can imagine the pain in the *** would be cutting through a keel.
 
I think the joining is more difficult than the cutting, if you have something that has a long constant hull section it might work out, otherwise not.
 
Lifeboats are usually quite tubby things, so would it be feasible to simply chop one in half amidships, and then add a length of parallel mid-body?
This would give you more room inside, and also make the boat effectively skinnier, with a higher L/B ratio.
Would you keep it as a motor boat, or would you want to put a sailing rig on it?
Be aware that for the cost of buying a lifeboat and the cost of the materials and labour to do the conversion work, it would probably be much easier / cheaper / less stressful in the long run to simply buy an existing boat that hopefully comes close to what you want your boat to be capable of achieving.
 
The typical lifeboat isn't designed for much in the way of long distance motoring, just safe custody of people abandoning ship. They are quite stubby-ended which helps with internal room and overall stability. I guess if they are built with a long constant section, it lends itself to grafting two together, better than most boats, but the end result is always going to be not quite ideal for purpose, unless the purpose is not too demanding. Perhaps you should define the intended use.
 
The sides are not quite parallel and the bottom isn't horizontal. Joining them will let you with a useless piece of bow and stern, and a lumpy hull. The longer hull will have increased stresses that may exceed the original design. Further, it will cost you more than buying a 40 foot boat ready to cruise.
 
In the absence of a sizable parallel midsection, splicing boat to increase LOA is not theoretically possible.
 
gonzo said:
The longer hull will have increased stresses that may exceed the original design.
Click to expand...
I assume you are talking about the longitudinal strength of the ship-girder. If so, keep in mind that boats of such a small length are very unlikely to have problems of this type. That would probably not be a reason to discard the job. The modulus of the main transversal section should be checked and, if there is such a problem, it can be solved by adding some longitudinal reinforcement. It has been done many times.
DogCavalry said:
In the absence of a sizable parallel midsection, splicing boat to increase LOA is not theoretically possible.
Click to expand...
It may be possible but, probably, it does not look very pretty.
 
Actually TANSL, I'm referring to the joint itself. Imagine joining 2 eggs to make 1 longer egg. The connection can't be made fair or strong.
 
I'm visualizing an unmanageable concentration of stress at the sharp concave intersection. I suppose with enough epoxy and cabosil it might get a large enough radius to survive, but it seems a bad idea.
 
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