Westerly Oceanmaster 48 chainplate failure

The "A" bolts that lesser Westerlies use fail in the same way We had to replace three out of four on a Berwick some years ago........ We we lucky the one that actually started to lift was outside the galley window and I spotted it while cooking dinner. Not actually sailing at the time.

( the fourth was the one over the locker where I kept my "stuff" ..... when it started to leak I took it out and resealed it. No corrosion at that time so no alarm bells rang)

Any stainless bolts through the deck are likely to suffer in the same way.
 
That type of chain plate anchorage was pretty common on boats of that size and type in period and suffer from the same problem. Javelin wrote up in PBO the repairs he did to a Moody with a similar arrangement. To my mind there are too many fastenings through materials that don't take fastenings well (ply and GRP) and keeping them dry relies on sealing a horizontal seam on an exposed flat area. The sealant either shrinks or the seal breaks through mechanical stress or flex and water seeps in. Add to that the whole assembly is often behind trim so not visible without dismantling.

Much prefer the tie bar system on many more recent boats, particularly when all the connections are visible as on my old Bavaria.
 
I found a similarly broken bolt today when examining why my anchor windlass was moving under load. It was a 10mm A4 bolt. I don't know the size of those bolts on the Westerly but they look smaller than the four 14mm studs that attach the external shroud fittings to the internal tie bar fittings on my 45 foot boat. For any fitting like that I don't like fully threaded machine screws and prefer proper bolts with a plain shank and threads only where needed.
 
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Surely it would be better not to have soggy bits of dead tree anywhere touching the bolts?
But how old was the boat?
What should we expect as a service life?
 
Other than removal of any bolts to check condition, is there anything that can be done in with the mast in situ & afloat to check?
 
scruff said:
Other than removal of any bolts to check condition, is there anything that can be done in with the mast in situ & afloat to check?
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That is the dilemma. The obvious signs of water ingress are staining around the woodwork or signs of movement as in the photo. if water penetration has been going on for a long time you may see signs of delamination. Corrosion of the type shown or crevice corrosion often has no external signs so removal is the only way of knowing.
 
Tranona said:
That is the dilemma. The obvious signs of water ingress are staining around the woodwork or signs of movement as in the photo. if water penetration has been going on for a long time you may see signs of delamination. Corrosion of the type shown or crevice corrosion often has no external signs so removal is the only way of knowing.
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Dragonfly trimarans rely on a large number of bolts (~200) to keep their beams, floats & hinges together & the boat structure in one piece. There's only one way of being sure that everything is sound, & that is periodically rip them all out & replace. Performance trimaran maintenance is similar to aviation maintenance: there is a schedule of replacements from the builder that must be adhered to. Maybe chain plate bolts should be treated in a similar way, replace after 15 years regardless of what they look like.
 
Bit better arrangement on our Bavaria, but similar. The bolts are countersunk ones and the inner backing plate is connected with a ball-ended tie rod to the keel matrix. When I renewed the standing rigging in 2015, there were signs of water leaking inside (there are inspection panels) and I rebedded the outer parts to the deck with butyl tape, including a thin "sausage" of butyl tape under each bolt head. There were no signs of corrosion on the bolts, so I re-used them.

This worked to some extent, i.e. it kept the water out, but the butyl slowly squeezed out of the sides, presumably due to slight movement when sailing / bashing through waves. This attracted dirt and looked icky. I've trimmed the squeeze-out off this year and put a bevel of Sikaflex all around the edges.

I now wonder if I should renew the bolts. They're A4-70 and have been torqued up at least twice in their life.

Photo not from our boat, but exactly the same type of fitting:
Chainplate_on_a_Bavaria_35_Match_..jpg
 
Same type as on my 37 and used on thousands of Bavarias up until about 2009. do seem to be trouble free as even if they leak a bit there is no attachment to wood to retain moisture and cause crevice corrosion. All the loads are transferred to the frame and then to the lower hull. So the deck is only a sandwich between the two halves of the fitting.
 
Tranona said:
That type of chain plate anchorage was pretty common on boats of that size and type in period and suffer from the same problem. Javelin wrote up in PBO the repairs he did to a Moody with a similar arrangement.
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Some (if not all) Moody models have a stainless bar through the deck, attaching the rig to ply bearers. Each has a deck plate which can be unscrewed and lifted for resealing but, a few boats obviously haven't been maintained properly and suffered from chain plate failure although I've not heard of any rig failures.
 
My Sealord had a similar issue when I removed the chainlpates for inspections/replacement. The A bolts had been replaced at some point previously but the angle they were cranked to was not correct so I had new over-sized and cranked A bolts made.

On removal I found that I the bolts that went through the bulkhead were significantly rusty and wasted, a number of them completely failed during removal. I'm guessing that Westerly used A2 rather than A4 stainless fixings. I have some pics of the rusty mess that has now been put right.

Well worth checking but I believe this is a known issue to check on westerlies of this vintage. Otherwise a super go-anywhere cruising boat.
 
"Bit better arrangement on our Bavaria, but similar"


True enough. With the exception of exotics all depend on fastenings through the hull. It pays to take them apart and reseal at the first sign of a leak.

I have just replaced chainplates which seemed ok ish but probably better to err on the safe side.

Good point above, I fitted slightly larger U bolts, cranking them adds considerably to the strength.
 
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I've just unstepped the mast on my Moody s38 with a similar deck plate arrangement.

After 20 years stepped (I guess) there were a few water marks appearing around a couple of the dome headed nuts inside.

The bolts are A4 countersunk M16 x 80, slotted head and threaded along just half their length. In a thread a few weeks ago I asked about sourcing them - Turns out ML in Portsmouth had them on the shelf, together with A4 nuts and matching dome headed nuts.

I have replaced but you can see from the photos the corrosion was just starting..

Moody s38 chain plate bolts

With the mast down they're easy enough to replace although being M16 there was probably a lot of metal left anyway.
 
lw395 said:
Surely it would be better not to have soggy bits of dead tree anywhere touching the bolts?
But how old was the boat?
What should we expect as a service life?
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I agree entirely. The boat has a teak deck with the upper part of the chainplate on top of it, although the real issue to my mind is the total absence of sealant. In Greece it does not remain wet too long but this is the perfect condition for SCC, evaporation concentrating the chlorides.
The boat is 1990 build. The rig has been checked electronically twice but of course this does not include chainplates.
Exclude water and life is indefinite.
 
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