Westerly longbow, Chainplate deck fitting failure

dazautomatics

dazautomatics

Well-Known Member
Joined
12 May 2006
Messages
173
Location
Northeast england
www.freewebs.com
Hi Guys

helping out a mate here that does not speak English very well.

He has a 1976 Westerly Longbow and experienced a failure of the deck fitting that attaches the chainplate to the rigging while crossing from Las Palmas to the West indies. Can I ask if anybody has had a similar problem and what is a good effective repair for this as he will be taking his boat back out into the deep blue again and is understandably nervous about the other fittings.
I have had a look on line and it is possible to purchase exact replacements from Trafalgar, but he is reluctant to do this as these are expensive, and could the same thing happen twice.
Any ideas on a more robust solution for a cruiser with a limited budget would be very much appreciated.

Thanks for looking,

Darren & Vicki
 
Can you post a picture, or e-mail me one, so I can assist with diagnosing the cause of failure. These boats are very solidly built and a failure must be rare, which points at a problem with your friend's installation. PM me if you want an e-mail address.
 
I don't know if there was such a problem with the Longbow but with some later models such as the Oceanranger there were some failures caused by the original fittings being at ninety degrees to the deck. This was resolved by fitting upgraded fittings that were angled more in line with the rigging. It would be worth a search of the WOA forum or posting a query on there http://www.westerly-owners.co.uk/woaforum/
 
Unfortunately our friend is away from his boat today as he was given the opportunity of a days work. the part in question looks like a "U"bolt but with a much pronounced point like a triangle which bolts through the deck to the chainplates below.
I have found a picture on Trafalgar's website

http://www.westerly-yachts.co.uk/images/chain-plate-FN.jpg

Thanks again

Darren & Vicki
 
dazautomatics said:
Unfortunately our friend is away from his boat today as he was given the opportunity of a days work. the part in question looks like a "U"bolt but with a much pronounced point like a triangle which bolts through the deck to the chainplates below.
I have found a picture on Trafalgar's website

http://www.westerly-yachts.co.uk/images/chain-plate-FN.jpg

Thanks again

Darren & Vicki
Click to expand...

Standard type of fitting. How has it failed? Often suffer from corrosion under the plate where water gets in and sits there. Can also fail from movement if there is not a toggle in the rigging screw. No reason why a straight replacement should not be adequate - after this one seems to have lasted for 40+ years! Need to check that the deck and reinforcement underneath is sound.
 
I do believe from my limited knowledge on these things that from looking at the fitting and where it failed (Just under the deck) that corrosion will have been the main contributing factor to the failure of the fitting. I was just wondering if a stronger solution was out there.
Will pass on all of your input into this and give the poor chap the bad news, that I will be 4 new fitting from Trafalgar. We have looked at "U" Bolts here in the chandlery but nothing will drop in the same holes without widening and elongating the holes that the deck fittings bolt through which will probably weaken the chainplate.

He has had one fitting fabricated by a local company but the quality of the welding is questionable and it was very expensive!

Thanks for your input guys and if anybody has a off the shelf solution that would be stronger than the originals then he would be very appreciative, as the trip back to Europe is going to be a tough trip for him.

Thanks again

Darren & Vicki
 
Don't think there is any problem with strength. Bedding the plate down with good sealant to stop water getting in is the key.
 
alahol2 said:
No off the shelf solution I'm afraid (other than Trafalgar's) but here is a page that explains the ins and outs... http://www.bmse.co.uk/articles/decking-u-bolts/
Click to expand...

That's a very interesting article. One point I would make is that the fracture shown in the photo appears to be transverse to the wire with no necking or obvious corrosion. It appears to me that it is probably a fatigue failure. Fatigue in bolts is almost always the result of under-tightening. There is a page on it on my website. On a boat deck it is difficult to obtain the torque that might be possible when bolting steel components together but providing additional compressive strength using big washers and/or steel plates with epoxy paste against them under the deck can only help. It would be advisable to check nut tightness from time to time.

The lateral bolt loading that is mentioned will make the fatigue situation far more important than if the bolts were loaded solely in tension, so every effort that can be made to get and keep them tight will help.
 
Thanks again guys

As usual the good folks of this forum being very helpful
. I will pass on the information and alahol2's link to our friend and translate over a beer tonight. Hope you all have a fantastic day!

Darren & Vicki
 
vyv_cox said:
That's a very interesting article. One point I would make is that the fracture shown in the photo appears to be transverse to the wire with no necking or obvious corrosion. It appears to me that it is probably a fatigue failure. Fatigue in bolts is almost always the result of under-tightening. There is a page on it on my website. On a boat deck it is difficult to obtain the torque that might be possible when bolting steel components together but providing additional compressive strength using big washers and/or steel plates with epoxy paste against them under the deck can only help. It would be advisable to check nut tightness from time to time.

The lateral bolt loading that is mentioned will make the fatigue situation far more important than if the bolts were loaded solely in tension, so every effort that can be made to get and keep them tight will help.
Click to expand...

Thanks also to Mr Cox, again you have been more than helpful on numerous occasions, we very much appreciate your time and experience

Darren & Vicki
 
From the article:

...Where the hoop/u-bolt is installed in the fore and aft line, it is often bent inwards at the deck plate during manufacture to allow for shroud angle and deck camber. Some manufacturers however used fore and aft hoops/u-bolts perpendicular to the deck plane but at least most had the common sense to use oversize bar, so few problems were apparent in the early years.

This case study is based on later medium to large Westerly models (early 1980 to early 1990s) which had potential shroud attachment problems arising from this type of U-bolt/Hoop design and placement. Although not proved conclusively, some rig losses were also attributed to the problem.

In the years before its demise, the company was aware of the problem andhad issued advice and arranged for owners to buy new modified ‘cranked-in’ and stronger shroud deck fittings at a knock down price (no pun intended!). Many, but not all, took up the offer. One of the problems was that the rigging not only imposed a pull at an unfair angle on the fittings, but that the metal bar can ‘work’ in the short space between the underside of the fittings’ deck plates and the chainplate bolts, as the rigging was alternately stressed and relaxed under load. This problem is exacerbated by corrosion if moisture is trapped aerobically in the core around the u-bolt holes.

The view amongst class associations for vessels with these fittings is that they should all be checked to ensure they are angled inwards correctly in line with the shrouds. Below decks, the chainplates and bolts/nuts should be checked regularly and the U-bolts themselves inspected every 10 years and ideally be changed if over 20 years old...

It looks like the problem I suggested above. The replacement fitting you linked to is clearly "cranked in", any new fitting should be and the existing fittings should be replaced for the same.
 
dazautomatics said:
Hi Guys

helping out a mate here that does not speak English very well.

He has a 1976 Westerly Longbow and experienced a failure of the deck fitting that attaches the chainplate to the rigging while crossing from Las Palmas to the West indies. Can I ask if anybody has had a similar problem and what is a good effective repair for this as he will be taking his boat back out into the deep blue again and is understandably nervous about the other fittings.
I have had a look on line and it is possible to purchase exact replacements from Trafalgar, but he is reluctant to do this as these are expensive, and could the same thing happen twice.
Any ideas on a more robust solution for a cruiser with a limited budget would be very much appreciated.

Thanks for looking,

Darren & Vicki
Click to expand...

YES

Have had it happn to a Berwick. The bilge keeled version of the Longbow.

It was due to crevice corrosion where the fitting passed through the deck. It had been leaking very slightly for some time but as it was the lower shroud above the galley sink we did not worry too much about it. One day it failed.

The cap shroud one failed when I tried to unbolt it too.

The two the other side were ok because I had resealed them several years previously. (as soon as they started leaking into the locker where I put my clothes)

We had new ones made to match the existing ones. IIRC ones for the lowers are angled differently to the ones for the caps

If you buy from Trafalgar you should get exactly what you want, at the correct angles. If you buy from elsewhere or get them made you will have all the bother of ensuring that they are correct .

Check them all

Seal the new ones and any that are reuseable so that water cannot penetrate and you should not have any further problems with them.


Edit ... Jesus I have just seen the prices from Trafalgar!
 
Last edited:
My intention is to turn the fitting so it is in line with the mast is the caps will be at 90 degrees to the current ones and the after lowers will be at what ever angle is required. I think the canting of the after lowers is a bit of a bodge.
 
rhumlady said:
My intention is to turn the fitting so it is in line with the mast is the caps will be at 90 degrees to the current ones and the after lowers will be at what ever angle is required. I think the canting of the after lowers is a bit of a bodge.
Click to expand...

Is there not a risk that there will then be uneven stresses on the two shafts of the u bolt?
 
l'escargot said:
Is there not a risk that there will then be uneven stresses on the two shafts of the u bolt?
Click to expand...
My Caps U bolts were installed from the start at 90deg to the fore/aft line. Both lowers are cranked U bolts in line with the fore/aft line. I replaced/re-seated all six when one of the lowers' U bolts parted inside the deck from crevice corrosion. They had lasted some 30 odd years prior to that.
 
vyv_cox said:
Can you post a picture, or e-mail me one, so I can assist with diagnosing the cause of failure. These boats are very solidly built and a failure must be rare, which points at a problem with your friend's installation. PM me if you want an e-mail address.
Click to expand...

if the same as the Centaur this may be the usual Westerly through deck design. They do fail if the sealant starts to leak. Probably Crevice???
I checked mine a few years ago by applying torque on the nuts. One failed at a very low torque and the other was fine but I changed both.

If the angled variety then they are available from the chandlery catalogues at a reasonable cost.
 
You must log in or register to reply here.

Share this page

Top