hull flexing in forward cabin

[jamesminge]

I’m redoing the interior of my 1980 424. I’ve read some articles indicating that in a seaway the sides of the hull in the forward cabin flex disturbingly. (1) has anyone had experiences with such flexing? (2) has anyone found a relatively easy way to reinforce that area? Jim

• This topic was modified 10 years, 9 months ago by Site Administrator.

[quent]

Hi Jim-
Are you concerned with the hull between the caprail and the v-berth or the space just aft of the v-berth?
If you search the forum, there is discussion of “oil canning” deflection of the hull in the first area. Bill Shaw actually addressed this in the old National Pearson organization newsletter. He suggested several layers of woven roving and mat fiberglass sandwiched with balsa core to stiffen this area.
Regarding the second area, at least one well used P-424 required repair/ reenforcement in this area.
On Clairebuoyant, we also repaired some of the bulkhead tabbing on the port side galley/salon area.
I think it all depends on how hard you have used or intend to use the boat.
Quent
Clairebuoyant, #132

[jamesminge]

Thanks for the info and great leads. I bought the boat just three months ago and it has been in the yard the entire time, mainly because of engine, v drive and generator issues. The area of concern is the hull between the shelving and the v berth. Now that I’ve stripped off the paper and foam, it is apparent just from tapping, that the hull is not very thick in this area. Could I get by with just reinforcing this area (mat, balsa or plywood, mat and roving), or must I address the bulkhead between the v berth and salon as well. No signs of stress so far, but the previous owners didn’t really sail beyond the shallows of Lake Pontchartrain as far as I know. Once the boat is rehabbed I would like to take her to the windward islands and who knows where else. Would plywood work as well as balsa for these purposes? sure would be a lot easier. Jim

[quent]

Hi Jim-
Well, welcome to the P-424 community. You might want to take this over to the mail list as the chit-chat does not get as much attention. There are probably as many opinions on the suitability of this boat for offshore as there are owners. Many owners have made extensive voyages as you have probably noticed.
Regarding your question, the area over the v-berth and below the shelf is slightly concave on the interior. The balsa (1/4″ will do) serves only as a spacer between two layers of fiberglass. It conforms to the shape easier than plywood would. The schedule if I remember correctly was one layer of mat, then balsa covered by another layer of mat, then a layer of woven roving. Fore and aft edges of the balsa should be tapered to avoid a hard edge. Not a terribly big job. If you already stripped off the vinyl and foam, you might as well do the fix.
I think our boat was used a bit harder than your boat. I would suspect that if she surveyed OK, that you are in good shape.
We also had some repair work on the transom where the backstay chainplate attached. Clairebuoyant is a sloop and has one centered backstay chainplate.
Quent

[jamesminge]

will do, and thanks much for the advice, which i will follow, jim

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