Sonata Sailing

National One-design Cruiser/Racer

Bulkhead Problem

Sue Watkins

I’ve recently viewed a sonata in the hope of buying her, however, the pre-purchase survey has revealed extensive delamination and blistering of the main bulkhead below the port and starboard chain plates. All indications are that this is due to moisture ingress where the chain plates pass through the deck. It is felt both chain plates will fail/pull from their mounts resulting in a catastrophic failure of the mast supports. Urgent repairs will need to be carried out to the bulkhead prior to putting the vessel back in service.

Having raced on an Impala for 20yrs, I’m no stranger to this problem and unfortunately have first-hand experience of the consequences when we lost our mast last year – the chainplate on the stbd side, ripping up through the deck when the bulkhead mount failed because of exactly this problem.

To have the bulkhead replaced, would cost around £2k (if done professionally)and because of the access issue, would result in damage to/replacement of surrounding structures – bunks/galley joinery. On the impala, we had actually affected a home-made repair to the port bulkhead by replacing a section of the damaged ply to which the chainplate is mounted & glassing it in – this was considered a sound repair by the surveyor who inspected the boat after the de-masting – we just hadn’t got around to doing the same on the starboard side because it was that much more awkward. WORD OF WARNING – THE INSURANCE COMPANY HAVE REFUSED TO PAY A PENNY BECAUSE OF WHAT THEY DEEMED “LACK OF MAINTENANCE”! so the owner has borne the full cost of the repair, i.e. gutting the boat & replacing all interior structures.

I was wondering whether any of you have experienced this problem and could advise on the best (least costly) solution, which will pass scrutiny by a surveyor?

Chris Nolan

I’ve recently viewed a sonata in the hope of buying her, however, the pre-purchase survey has revealed extensive delamination and blistering of the main bulkhead below the port and starboard chain plates. All indications are that this is due to moisture ingress where the chain plates pass through the deck. It is felt both chain plates will fail/pull from their mounts resulting in a catastrophic failure of the mast supports. Urgent repairs will need to be carried out to the bulkhead prior to putting the vessel back in service.

Having raced on an Impala for 20yrs, I’m no stranger to this problem and unfortunately have first-hand experience of the consequences when we lost our mast last year – the chainplate on the stbd side, ripping up through the deck when the bulkhead mount failed because of exactly this problem.

To have the bulkhead replaced, would cost around £2k (if done professionally)and because of the access issue, would result in damage to/replacement of surrounding structures – bunks/galley joinery. On the impala, we had actually affected a home-made repair to the port bulkhead by replacing a section of the damaged ply to which the chainplate is mounted & glassing it in – this was considered a sound repair by the surveyor who inspected the boat after the de-masting – we just hadn’t got around to doing the same on the starboard side because it was that much more awkward. WORD OF WARNING – THE INSURANCE COMPANY HAVE REFUSED TO PAY A PENNY BECAUSE OF WHAT THEY DEEMED “LACK OF MAINTENANCE”! so the owner has borne the full cost of the repair, i.e. gutting the boat & replacing all interior structures.

I was wondering whether any of you have experienced this problem and could advise on the best (least costly) solution, which will pass scrutiny by a surveyor?

Hi Sue,

I’ve just purchased a Sonata with similar problems, worse on the port bulkhead which had completely delaminated under the chain plate. However, the bulkheads on mine are made of two pieces of ply, one something like 3/4″ marine ply for strength and a cosmetic 6mm facing ply with a teak face. I removed the shelf, seat back, switch board and chainplate, then removed the 6mm facing ply using a thin wallpaper scraper (it came off in one piece) and took it home. The structural bulkheaqd was completely sound. I bought a sheet of 6mm marine ply for £30 (unfortunately I couldn’t one with a teak face), drew around the old bulkhead, cut it with a jigsaw, stained it with two coats of woodstain, then gave it two coats of varnish.

I brought it back to the boat, glued it to the structural bulkhead using G-clamps, then replaced all the fittings. It looks really good, and the chain plate is secure. I’m aiming to replace the facing on the starboard bulkhead over the winter and modify the chainplates as suggested on the website.

Having researched different plywood to do this job, I’m not sure the original facing ply is marine ply (hence the extensive delamination). Ordinary ply with a teak face is much cheaper than an equivalent marine ply. Anyway, We’ll see how the new panel lasts.

Hope this helps.

Chris N.