chainplate

[Novachris]

Hi.
I have a 1974 fibreglass yacht.

I am renewing my standing rigging and thought i would check out my chainplates whilst i am at it.

They are not visable on the outside of the hull but stick out about six inches above the side deck.

Anyway after removing lots of panelling inside the boat i found them,or what i think is them, as they are glassed in,not good i thought, so i drilled a small hole in the lump where i thought the chainplate should be and a small drop of water came out.

They are stainless, should i worry?it would be a major job to uncover them.
thanks

 

[alahol2]

To be quite honest, yes, I would worry. A couple of years ago I found a U-bolt type shroud base broken inside the deck where crevice corrosion had got to it. The presence of water + stainless in the absence of oxygen are, I believe, the conditions to create this type of corrosion. Whether the same problem can occur to stainless in plate form I don't know.

 

[Tranona]

Agree. Need to investigate further. Wet enclosed stainless is not good - perfect conditions for crevice corrosion. Doubt they are just bonded in, more likely to be bolted to a bulkhead or web and glassed over. If it is a production boat then an owners association might know if it is a problem, or a surveyor who is familiar with the boat's construction.

 

[Novachris]

Agree. Need to investigate further. Wet enclosed stainless is not good - perfect conditions for crevice corrosion. Doubt they are just bonded in, more likely to be bolted to a bulkhead or web and glassed over. If it is a production boat then an owners association might know if it is a problem, or a surveyor who is familiar with the boat's construction.

thanks,the more i think about it the more it worries me.

 

[HermanD]

Chainplate problems

Alahol 2

Do you know how old the U bolts where?
Where they sealed on top and bottem?
A common mistake it takes longer before you discover the top seal leaks
but in the mean time danger of crevice corrosion.

But i am interested how old they are, and where they
used on salt water?

regards
Herman

 

[Novachris]

Alahol 2

Do you know how old the U bolts where?
Where they sealed on top and bottem?
A common mistake it takes longer before you discover the top seal leaks
but in the mean time danger of crevice corrosion.

But i am interested how old they are, and where they
used on salt water?

regards
Herman

Hi Herman,
i have had the boat for 3 years and the last survey was in 2005,the surveyor said the "chainplates are glassed over so no check is possible".
I need to dig them out for my own piece of mind. the boat is used in salt water.

I think they might have been glassed over to stop deck leaks entering lockers and things.

 

[Bilgediver]

Alahol 2

Do you know how old the U bolts where?
Where they sealed on top and bottem?
A common mistake it takes longer before you discover the top seal leaks
but in the mean time danger of crevice corrosion.

But i am interested how old they are, and where they
used on salt water?

regards
Herman

Herman,,,,


One of the U bolts on my Westerly Chieftain was on the way to failing
and was 30 years old and possibly the deck seal had leaked although there was never wetness in the locker where the U bolt was located.

It actually broke when I was trying to undo a stiff nut so as to remove it for inspection and failed at a relatively low torque. Both were replaced.

 

[yachtorion]

I've just had all the chainplates replaced on my Hurley 22 for the same reason - water dripping from a hole drilled in the encapsulation around the chain plate.

There is some advice around it on the Hurley Owners Association website.

http://www.hurleyownersassociation.co.uk/pages/faqs.htm#CHAIN

 

[Novachris]

I've just had all the chainplates replaced on my Hurley 22 for the same reason - water dripping from a hole drilled in the encapsulation around the chain plate.

There is some advice around it on the Hurley Owners Association website.

http://www.hurleyownersassociation.co.uk/pages/faqs.htm#CHAIN

Thanks for that,how are the plates fixed to the boat?

 

[yachtorion]

The old ones were bolted to a plywood pad bonded to the inside of the hull and then encapsulated in fibreglass. The plate passed up out of this fibreglass/wood pocket through a slot in the deck.

As you would expect to happen over the years the sealant had failed and flexing had opened a gap, and water had run down the plate into the pocket and soaked the plywood pad.

The new chainsplates were fitted by Coates Marine in Whitby. They removed all traces of the old plates, pads and encapsulation, then bonded a new plywood pad to the hull and encpasulated it in fibreglass. Then they attached the plate to the pad using one screw and one bolt right through the pad and hull. The bolt doesn't show on the outside because it's hidden by the rubbing strake.

Hopefully now any water that gets in will just run down the plate and drip off, rather than get stuck in a "pocket" and rot the wood.

 

[alahol2]

Alahol 2

Do you know how old the U bolts where?
Where they sealed on top and bottem?
A common mistake it takes longer before you discover the top seal leaks
but in the mean time danger of crevice corrosion.

But i am interested how old they are, and where they
used on salt water?

regards
Herman

Hi Herman
So far as I am aware the U-bolts were original to the boat (1978). On discovering the broken U-bolt I removed and checked all the others. No sign of problems at all. I replaced both main shroud U-bolts (so that they were a pair) and rebedded the others.
Below decks the U-bolts pass through a pair of stainless webs bolted to a bulkhead. No sign of any water ingress. Yes they have been on saltwater since 'birth'.
I am gradually checking and re-bedding every bolt and fitting that passes through the deck.

 

[Novachris]

The old ones were bolted to a plywood pad bonded to the inside of the hull and then encapsulated in fibreglass. The plate passed up out of this fibreglass/wood pocket through a slot in the deck.

As you would expect to happen over the years the sealant had failed and flexing had opened a gap, and water had run down the plate into the pocket and soaked the plywood pad.

The new chainsplates were fitted by Coates Marine in Whitby. They removed all traces of the old plates, pads and encapsulation, then bonded a new plywood pad to the hull and encpasulated it in fibreglass. Then they attached the plate to the pad using one screw and one bolt right through the pad and hull. The bolt doesn't show on the outside because it's hidden by the rubbing strake.

Hopefully now any water that gets in will just run down the plate and drip off, rather than get stuck in a "pocket" and rot the wood.

Thanks James,it just get worse i bet the ply pads on mine are rotted,i think i will wait till haul out in October and take it from there.