TxHawk

iTrader: (2)

Hopefully I worded this title correctly for the discussion. I've dealt with 3 credible fiberglass shops all having done some sort of structure work for me on older boats. I have gone back myself and fixed and maintained most of their work. Small cracks, popped tabs etc.
In discussions, it was said that I needed to leave some flex in the boat. This came up when talking about attaching the bulkhead behind the fuel tank with some knees into the side of the boat vs only attaching to the bottom of the hull and stringers. It came up again when I wanted to add hull to deck sold bulkheads in the bow ahead of the helm. I guess the discussion I am looking for is, do you go back with similar structure in an older boat or beef it up with additional structure.

Currently I am fighting the same reoccurring cracks at the bulkhead behind the fuel tank. The current bulkhead extends up the hull (V) but stops short of the hull sides.

Hope you guys still beating on old hulls chime in.

Thanks.

ren3

If your are adding a bulkhead, keep the edges of the bulkhead away from the hull so you do not create a hard point. The tabbing if done correctly will fasten everything together without creating stress points. Use overlapping tabbing to spread the load properly, and I would suggest vinylester or epoxy resins. All structures have some flex.

sailtexas186548

I have been wondering this also, I am restoring the hull structure in a 1980's hull that has 7 bulk heads, no stringers forward of the engine bay, solid fiberglass bottom, and cored hull sides. I want to add stringers and extend the bulkheads up to the bottom of the deck (like the knees you describe) but the hull is crack/issue free so I am reluctant to change anything.

Like your hull my bulkheads are not attached to the hull sides there is a 1/2" gap and no tabbing...

ren3

Post some pictures and model info. I do not know what is keeping the bottom of your hull forward straight without some longitudinal reinforcement. Do the existing bulkheads extend to the deck level. Without being tabbed to the hull sides I don't know how they function. Maybe someone can explain.

resurrected

I have added one bulkhead to my cabin area with the intention of two more
Its balsa core throughout, I placed a layer of 1708 first then added the the 3/4" plywood bulkhead bedded in thickened resin with wide coves (about 5/8") to spread the load. The bulkhead was then glassed in with 2 layers of 1708, and mat at the difficult corners. I believe with the balsa core it will reduce the risk of stress risers at the connection point, I may be wrong but will find out.

TxHawk

iTrader: (2)

1980 27' Excalibur. It seemed to have had stringers changed in it before I got it, and we basically copied what was there. I've seen some others like it that have different size keel and engine stringers with more substantial "knees" or outbound structure between the stringers and the hull sides. This just in the bilge area. I have never pulled the cockpit floor. The tank looked good from internal inspection and the floor is tied into the cockpit and deck in 1 piece. I hate to cut it.

The deck is solid in the bow with no signs of stress. I don't think I need to do much in the bow. The hull sides are not cored, so I don't think I want to tie in anyway.

I am considering making some changes in the bilge this off season to see what might work better, so trying to get a game plan.

ren3

If it's been around since 1980 and is still solid then I wouldn't worry about it either. I am guessing though that you do have stringers under the cockpit floor. Post some pictures when you have time. I have always thought your avatar is exceptional!