Chainplates bearers sheared
After repairing the keel last year we have managed to shear the starboard bulkhead where the chainplates are attached. During the Fastnet the only thing securing the starboard shroud was the deck structure. The damage happened in a North Sea storm ofF Rotterdam where the furler swivel sheared and the No. 3 shredded itself as we recovered it. unfortunately the damage only became apparent at he of the Fastnet when the joinery under the starboard pilot berth split! Thank God they were built strong!! Has anyone had similar experience?

Crack under pilot berth

The chainplate loads are taken by GRP reinforcements on the plywood partial bulkhead. The reinforcements continue out on the topside, and it is likely that the laminate suffered damage if the bulkhead can move.
A detailed inspection of the area, and particularly the transition between bulkhead and topside is needed. Does the crack close if shroud tension is released?
Kind regards
Lars

The chainplate loads are taken by GRP reinforcements on the plywood partial bulkhead. The reinforcements continue out on the topside, and it is likely that the laminate suffered damage if the bulkhead can move. A detailed inspection of the area, and particularly the transition between bulkhead and topside is needed. Does the crack close if shroud tension is released? Kind regards Lars

Hallo Lars
The mast is in the process of being removed. I will take the liberty of passing your message onto the surveyor and boatyard (osmotech). I attach pictures from the yard.
Regards

Thank you for the information.
As far as I know you have a Swan 47 with Mk II interior, and the main shrouds are attached to the partial bulkhead showing in the first picture.
The yard picture shows woodwork only?
Kind regards
Lars

This was just an intial look. The joinery is to be stripped out to get.a beter look at the damage

This was just an intial look. The joinery is to be stripped out to get.a beter look at the damage

All is now stripped out. The plywood bulkheads have sheared on both sides level with the post at the base of the pilot berth. The surveyor believes this is simply the weakest point in the bulkhead where a corner cutwas made when built and that it has simply failed the test of time albeit after 30 years.. The starboard bulkhead went first and the port one seems very recent. The laminate appears to be intact. The proposed solution as checked by a naval architect is to glass in the cracks and spread the load with swathes of glassfibre in different directions before reinserting a much extended stainless steel chainplate base going down past the area where the crack occurred. I have the design drawings if anyone is interested. (A word of warning - it is not cheap but, as the surveyor said, that is the price of owning a beautiful old Swan!).

All is now stripped out. The plywood bulkheads have sheared on both sides level with the post at the base of the pilot berth. The surveyor believes this is simply the weakest point in the bulkhead where a corner cutwas made when built and that it has simply failed the test of time albeit after 30 years.. The starboard bulkhead went first and the port one seems very recent. The laminate appears to be intact. The proposed solution as checked by a naval architect is to glass in the cracks and spread the load with swathes of glassfibre in different directions before reinserting a much extended stainless steel chainplate base going down past the area where the crack occurred. I have the design drawings if anyone is interested. (A word of warning - it is not cheap but, as the surveyor said, that is the price of owning a beautiful old Swan!).

I'm not sure how freely you're willing to share the drawings. I have no need of the repair, but I am interested in seeing how the revised design was brought forward from an engineering point of view and just to learn a little. Plus, my boat did have her chainplate knees stiffened, so the subject is of general interest from that point of view, too.

So if you can share for this purpose, by all means I'd love to see the drawings to: valveman at sbcglobal dot net. If not, I understand too. Either way, best of luck with your work - spread the loads more, make the repair heavier still, etc. Belt and suspenders while you're in there, as there's no better time.

Fair Winds,

Geoff
Corazon, 411 #41

Will get the drawing on the forum and send it to you in the next week!

Attached the chainplate strengthening drawing

Chainplate strengthening

I can not see

Can i send it to you directly to upload?
Regards

Can i send it to you directly to upload?
Regards

Thank you, it is possibile that I am not managing to download from my IPad.
It might be useful to compare with my case about 4 years ago.
I do not know if I had the original system, it looked overdimensioned. I do not have pictures, anyway, I hope to remember correctly. There are two large plates, around four mm thick, bolted on both sides of the bulkhead with not least than 12 bolts of 8-10 mm diameter. All this looked very solid and perfectly integer (probably too much rigid).
The problem was underneath the bulkhead, where a vertical fiberglass stringer was connected to the bulge and keel area. Here was the weak link of the chain. There was a crack of about 5 mm running very closely to the hull.
I have already written about this problem in a post regarding the horizontal uneveness of the topsides.
I hope that my experience may be useful, probably the system of x-yachts is better engineered, excuse me for the provocation...
FW,
Matteo, Grampus, 47/016