New Chain plates on CP-16

[Deebee]

Hello,

Thought it was about time to introduce myself after several years of reading and
soaking up the collective wisdom around here.

My name is Deebee and I have a 1980 CP-16. It demasted last year at the end of
the season when one of the chain plates failed. Fortunately it happened on the mooring
so nobody got hurt.

Has anyone ever replaced their chain plates and if so, have any helpful tips to offer?
I painted the bottom last year but haven't done much else since I bought it. This will be
my first attempt at repairs. I've read about some of the projects that other folks have
completed with a mixture of awe and respect.

Thanks in advance!

[skip1930]

More information is needed for the chain plate failure on a CP-16.

A failure to me means that the actual stainless steel metal strap bolted into the glass matt ripped, allowing he pin/turnbuckle or all other adjoining hardware to 'pop' off the chain plate. Right? The bottom half of the chain plate is still securely bolted into the fiberglass hull. Right?

Everything 'up stream' of the turnbuckle is intact correct? The standing rigging is attached to the mast and all that. If the pin looks like it ripped the chain plate hole open then WHY? Was the pin 'working the hole' and kind of sawed it's way through the metal? That would have been detectable.

Or has the fiberglass parted allowing he bolts to pull out of the fiberglass. Maybe right?

If the bolts pulled out of the fiberglass, I'd guess that the standing rigging was WAY too tight.
That's trying to push the mast down through the cabin top, crushing the compression post or cabin arc and in a sense shove the mast clean through the bottom of the boat. While at the same time adding to the CP-16's already pronounced sheer line, by trying to pull the bow out of the water. Re-arching the boat.  Don't do that.

For example. If the starboard {right} side is heeled into the water, the left side standing rigging {port} is a little tight, and the starboard side is a little wiggly loose. And visa versa.

You don't have a back stay as the port and starboard standing rigging is behind the centerline of the mast.  You do have a head stay and stay does not need to be 'guitar string tight' either. But taught.

Anyway, what the problem with the chain plate? Ripped or pulled?

To replace it, if you have carpeting covering the chain plate from the inside, pull it back. Unscrew and remove all the old fasteners, work that chain plate out past all the caulking, find another chain plate, goop her up {my favorite is 3-M 5200 slow set} but many others use tapes, and other goops...you pick. Slip her back down into the slot and or along side of the hull but under the rub rail and bolt her back in.

If the bolts pulled out of resign impregnated and rolled into a mold using 22 ounce matt fiberglass, that's something different.

skip.

[Deebee]

Hi Skip,

Yes, it was the first scenario that you described. Everything above the chain plate stayed intact.
The metal just gave way above the connection point. I should have been more specific. Not sure
why it failed but I don't believe that the failure was due to the rigging being too tight.

I figured that as long as I'm replacing one I should replace them all as I'm sure they're
original hardware.

Thanks for your advice.

Deebee

BTW, nice dog. Dogs are my first love, then boats.

[Salty19]

Hutchins can you supply you with new bolts/nuts and chainplates that are exact fit replacements.  Yep, replace them all so you know they are good to go.
I never swapped out the forestay chainplate--looks to be much more difficult to access, but doable.

Slather the area around the bolts (backside of plate) and the area where it fits in the slot in the hull/deck joint with Lifecaulk.  I would not use 3M 5200 in this area, that is a permanent adhesive/sealer and not very flexible.  This area of the chainplate flexes, and sometime will need to be replaced again. 5200 bonds stuff together with tenacity...don't use it on anything that someday might need to come off (just about everything).   In fact, I would not use 5200 anywhere on the boat except the actual hull/deck joint during a rebuild.   Cleanup excess Lifechaulk with acetone or rubbing alcohol.

Might need two people here, one inside and one outside to turn the nut and hold the bolt.

Easy project, should take less than an hour.

[Pacman]

Hutchins can you supply you with new bolts/nuts and chainplates that are exact fit replacements.  Yep, replace them all so you know they are good to go.
I never swapped out the forestay chainplate--looks to be much more difficult to access, but doable.

Slather the area around the bolts (backside of plate) and the area where it fits in the slot in the hull/deck joint with Lifecaulk.  I would not use 3M 5200 in this area, that is a permanent adhesive/sealer and not very flexible.  This area of the chainplate flexes, and sometime will need to be replaced again. 5200 bonds stuff together with tenacity...don't use it on anything that someday might need to come off (just about everything).   In fact, I would not use 5200 anywhere on the boat except the actual hull/deck joint during a rebuild.   Cleanup excess Lifechaulk with acetone or rubbing alcohol.

Might need two people here, one inside and one outside to turn the nut and hold the bolt.

Easy project, should take less than an hour.

+1!

Yup.  That's it!

[carry-on]

Deebee,
Any pictures of the failed chain plate? Seems unusual for the plate to fail.

[ahmch]

This thread is a bit disconcerting.  I have only had my compac out in a strong wind twice and felt quite comfortable.
It is a '78.  Maybe I should just replace the chain plates all around.  This could be disastrous.
Pics of the failed part would be fantastic.

andrew

[Craig]

Pictures would be really helpful. I would not obsess about the'78 chain plates. I would however, inspect them carefully and as mentioned  above, make sure your rigging is not over tightened and the fasting bolts tight.

[jpfx]

if it's just the top came off then why not drill a new hole further down and round off the top? a longer turnbuckle might be necessary.
I certainly wouldn't bother replacing the rest unless there were obvious signs.
I can't see this failure happening unless the the plate tip was folded/straightened and suffered from tensile failure, or perhaps 40 years with the wrong size pin cutting a groove.
my leeward stay isn't taut at all once the wind is in the sail.

[Deebee]

I will post a picture once the weather permits. All the metal above the hole is gone. The
day it happened was calm, although there had been stormy weather the days that preceded
it.

[Deebee]

Not the best picture but you get the idea.

Salty, I have already ordered the parts from Hutchins. I agree with your advise to avoid 5200.

There were no obvious signs of impending failure and no groove. . I'd rather just replace them and err on the
side of caution.

[mandolinut]

Happened to me some years ago on a larger (32') boat with much larger chain plates.  Mine snapped in half where one of the bolts went through the chainplate and hull.The boat captain in the boat next to me in the marina was a metallurgist with Pratt Whitney that contracted with NASA. He explained to me about "metal fatigue".
I had another neighbor sailor that lost his mast one day when the braided stainless cable supporting the mast snapped. Same metal fatigue as a cause. It is one of those things you do not see coming.

[carry-on]

Deebee,
Thanks for the picture. Many folks will be looking at their chain plates!
The failure slot looks somewhat narrower than the clevis hole. A small clevis pin would increase the psi on the chain plate, but quite a load would be required to pull through the chain plate. Would expect other parts like the hound assembly or shroud to fail before the chain plate.
Can you tell from the discoloration in the break if it happened all at once? If gradual wear, would expect more corrosion toward the clevis hole and shine at the upper end of the failure.
Good luck with repairs.

[Deebee]

Carry-On,

I believe that it did happen all at once. There wasn't any evidence that it was
about to fail. I went to work in the morning and the mast was in place and when
I came home that evening it was in the drink. As I said earlier, it was a calm day.

It put an early end to my season. I would have hauled it shortly after that as Sandy
was due to arrive.

[Bob23]

DeeBee:
  You mention Sandy- are you in NJ? I hauled my 23 just 2 days before Sandy arrived so she was safely in my driveway during the storm.
  I've followed this thread...I'm very happy to have 3 chainplates per side on my 23. Part of the beauty of the 23 is the 8 stay rig- a bit overkill for a boat this size but a little extra insurance can't hurt either, eh? 
   I'll be inspecting my chainlates before Koinonia is  splashed this spring. Maybe it 's not a bad idea to replace 'em all after a number of years. Sometimes metal fatigue gives no warnings.
Bob23