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  #1  
Old 10-11-2006
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bulkheads and strength

hello all,
looking for some design/structural opinions or advice. I realize that the bulkhead partitions have some function towards stiffness and flexing of the hull but I would like to open up the interior of my Beneteau first 345 a bit after seeing some cool interiors at the Annapolis show. The question is can I increase the size of - or remove altogether the bulkhead doors and frames leading to the quarter berth and forward cabin without compromising the structural integrity of the hull.
thanks in advance
stephen
s/v Enfin out of Oxford MD
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Old 10-11-2006
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Yikes! Want to take away a structural member eh.

Well im sure you know that you cannot simply remove a support like that. However, you may re-engineer the support. By this I mean remove the member and rebrace it in a way that is less obtrusive. For example if it is simply a fiberglass or wooden bulkhead you could fabricate a truss like aparatus or bracket out of stronger materials but you must remember how certain material characteristics change with fatigue, temp. , & etc.. I wish I could be of more help but its hard to really say anything without knowing the boat.

Also check if the bulkhead is a cover/facade of a load bearing support. In that case you might be able to remove the facade oppening up more room.

Sounds like a fun project. Keep us updated.

Last edited by kananumpua; 10-11-2006 at 10:52 AM.
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Old 10-11-2006
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Significantly altering the original layout is a sure way to harm the resale potential and value of the vessel. In other words, it is going to cost you money in the long run.
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Old 10-11-2006
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Any boat where the position of bulkheads and furnishings is set and dictated by the existence of liners and molded parts will be difficult to modify in a way that is attractive or sufficiently strong.

In an older design or a semi custom one where the bulkheads and stringers are glassed in, it is possible, but a major project, to remove, redesign and reinstall such items to create a new layout. Special care must be paid to supporting chainplates and rig loads in any such redesign.

I would guess that the Bene 345 is not a boat that can be easily modified, and in any case as stated above, changing a recognized and fairly popular design may well harm eventual resale potential
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Old 10-11-2006
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Well...Beneteau US has a reputation for anwering the phone and talking to owners, you might want to get their opinions first.

They have a reputation for not overbuilding a boat (i.e. using the space frames and doing a lot of engineering up front, ignoring the "BendyToy" nickname) and they could probably tell you which bulkheads were structural--versus just a "plan option" in the boat.

FRAMES leading to the 1/4berth I'd worry about. The cockpit is typically supported by those, but many designers offer berths (one or two) versus lockers versus something else--so again, Beneteau may already have options to suggest to you.

I saw an Albin Nimbus, a nice flush-deck Baltic style 42 footer, some years ago. It was "almost new" but one of the mods the first owner had put in, was to chop a foot out of one of the primary stringers in the keel "so the bilge would drain better". Ahuh, just slice the structural ribs out of the boat with a chain saw. (Some people just shouldn't be allowed to buy OR use power tools.)
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Old 10-11-2006
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Hellosailor has some good points. We contacted J/boats about a structural question we had - whether the ladder leading to our forward hatch was actually holding up the deck. The answer was... maybe. Cutting holes in a bulkhead may not be a problem until the wind hits 18.347 knots. The boat may then fold in half and sink in 18.347 seconds. Ask your insurance company what they think. (Do you want to triple or quintuple your policy quote?) Designers and builders put "safety factor" engineering into boats for a reason. Remove it, and you could end up like the America"s Cup boat that's sitting in pieces under the water off San Diego.
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Old 10-12-2006
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Quote:
Originally Posted by chefmango1
hello all,
looking for some design/structural opinions or advice. I realize that the bulkhead partitions have some function towards stiffness and flexing of the hull but I would like to open up the interior of my Beneteau first 345 a bit after seeing some cool interiors at the Annapolis show. The question is can I increase the size of - or remove altogether the bulkhead doors and frames leading to the quarter berth and forward cabin without compromising the structural integrity of the hull.
thanks in advance
stephen
s/v Enfin out of Oxford MD
Why not just do it and report back
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Old 10-12-2006
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We've all heard them referred to as Bendyteaus, now we could really see some action. The worlds first origami cruiser. This cannot be a good idea.
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Old 10-12-2006
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"The worlds first origami cruiser. This cannot be a good idea."
But just think of the savings on dockage!

"Yeah, it's a 42, but it fits in only eight feet after we fold it!"
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thanks all for your helpful words, I guess I should have been more specific. The existing bulkhead partition (which encompasses the door frame) is 1/2" plywood aprox. 4500 sq. in. Of that, aprox. 1400 sq. in. (or 32 per cent) is doorway. In home construction when you poke a hole in a wall you add headers, however in this bulkhead partition there is no additional or beefed up bracing. Thus my question should be more correctly can I increase the size of the doorway by 10-20 or 30 percent. I posted the question because maybe there is someone out there who has done something along the same lines. As far as resale value goes I'm not that concerned because just as you customize your house or car it can turn out for the better, after all these things are boats, not precious antiques. Calls to Beneteau by the way were not helpful.
stephen
s/v Enfin
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