Failing Backstay plate CD27

John Hpiller · Post by **John Hpiller** » Jun 2nd, '10, 12:41

[img]As can be expected with a biggish restoration project I am finding "issues"...

There is significant rust, losing about 2 mm of thickness on the plate that is glassed to the stern to support the backstay. The loss in on the top of the plate, between the plate and deck joint. My inclination is to remove this and replace, either with a similar fabrication (? stainless) or build up the area with carbon (have fair amount left over from another project.

Any one run into this? How did you approach it?

I will gladly post a pic if someone would be so kind as to tell me how...can't find in user instructions. Thx.

Ray Garcia · Post by **Ray Garcia** » Jun 2nd, '10, 14:14

Here is a link from our Webmaster on how to post pictures.
http://www.capedory.org/board/viewtopic.php?t=14638

Without seeing the extent of the corrosion, my first inclination would be to remove and replace with a new bracket. Luckily the hardest part will be to remove the plate. Putting it back should be pretty straightforward. I would be great to see a pic of the plate.

John Hpiller · Post by **John Hpiller** » Jun 2nd, '10, 18:03

Thanks Ray:

Here we go...

John Hpiller · Post by **John Hpiller** » Jun 2nd, '10, 18:09

And another one:
The rust, if one probes around the gap, comes out in big flakes...

Ray Garcia · Post by **Ray Garcia** » Jun 2nd, '10, 20:27

John, I'm glad you got the pictures posted! It really helps to get a visual so everyone can give their assessment.

Not too bad, but there may be a bigger problem. From the pics it seems like there a 2 plates involved. You obviously have an active leak indicated by the rust run from the right side backstay bolt. The problem with mild steel is once corrosion starts the metal begins to expand as the corrosion increases. The bottom bracket looks pretty good. Treated with a rust inhibitor and paint you can probably still use it. Now the potential "bigger problem". Those 2 backstay mounting bolts are stainless steel nylon locking nuts and bolts. With the water intrusion and dissimilar metals too boot, those bolts though they look good from what you can see may actually be ready to fail. I would start by removing those bolts and checking their condition. Unfortunately they are not easy to remove. If they look good you could then tackle that top plate. Depending on how corroded the plate is, you may be able to chip it all out, and try sliding in another plate on top of the bracket. You would also get a look at the top of the bottom glassed in bracket. If your able to get that top bracket out maybe you could insert a piece of fiberglass reinforced board or metal plate to make up the thickness. In the worst possible case you could dig out the glassed in bracket and start from scratch replacing and re-bonding the pieces back in.

On our '81 CD27 the bracket is made out of welded plate unlike your pictured fabrication. I wished Cape Dory had not used mild steel anywhere on their boats but I guess at the time who thought they would ever corrode? I've seen some Cape Dory's with the chainplate brackets made of mild steel bonded to sides of the hull actually deform an imprint on the hull itself which shows through on the outside. This is probably the boats biggest structural flaw.

If you decide to tackle the removal and replacement please takes pics to share your experience. I'm sure others here are facing a similar debate on this project.

John Hpiller · Post by **John Hpiller** » Jun 3rd, '10, 09:14

Thanks for the great insight(s).

Yes I will tackle this...
And will gladly post pictures.

I am planning on replacing the teak toerail as it has worn significantly and is splitting in places which would seem likely to be related to the leak, and these new problems. I had the entire toe rail replaced 5 years ago and was dismayed to show up to pick up the boat only to find they didn't replace this...perhaps most critical...piece. I am sure this will be a larger endeavor than it seems. It seems like if I am going to do the stern toe rail, it would be silly not to replace the bracket as well? I assume the "way to go" would be to fabricate a plate of stainless? I still wonder about making one of carbon?

On we go.

THANKS AGAIN.

sharkbait · Post by **sharkbait** » Jun 3rd, '10, 19:10

I would remove the plate. When you go to remove those stainless bolts do not be surprised if they just snap in the middle and come out both sides. It will not be difficult to cut the rebar out with an air die grinder and a cutoff wheel.

If you have the supplies replacing the unit with one constructed of carbon fiber sounds reasonable to me. When you get the old one out use it as a pattern and build the replacement out of carbon fiber. Then seat the new one in a bed of epoxy and fiber mixed about as thick as peanut butter.

Troy Scott · Post by **Troy Scott** » Jun 4th, '10, 00:29

John,

You definitely need to get that steel plate out. You need to get enough material, both rusted steel and the fiberglass that holds it in place, removed so that you can install something better and more permanent in it's place. I can show you how to build the fiberglass structure that I feel should have been there in the first place. It's pretty simple to do, but it would require drawings and substantial explanation. Do you have structural fiberglass experience? If you are interested, you can PM me.

SPIBob · Post by **SPIBob** » Jun 4th, '10, 02:40

John,

I had a similar issue a couple of years ago. After trying to repair/beef up the pad eye backing, I changed course and decided to go with an external chain plate.

I posted on this project w/pics here: [/url]http://www.capedory.org/board/viewtopic ... c&start=15

I only had a relatively small opening in the aft partition of the cockpit well to work through. I could use one hand only which made the project way more difficult.

If I had it to do over I would cut a bigger access opening. And then make an alcove or storage locker to fit in afterwards.

Troy Scott · Post by **Troy Scott** » Jun 4th, '10, 12:38

John, The hard part is going to be getting the old stuff out. That you need to do no matter what solution you choose. If the solution/part is sensibly planned and built, it should just slip in without much headache or stress.

John Hpiller · Post by **John Hpiller** » Jun 4th, '10, 15:36

Thanks all.

The Bracket is now out...and was a good thing too as the 2nd plate was pretty much mush and one of the welds on a strut had failed. Removal was pretty easy.

Stern teak also removed. That too was good. Despite the 5200 still having a lot of life (ugh...THAT is fun job!) there was moisture under it and some separation @ the outer stern laminate. Did CD lay a layer of glass over the stern that butts up to the deck? This looks too thick to be just gel coat? I was hoping to see how this looks dry today...but it is raining buckets...I think the glass is ok so I hope I can get this dry and reseal with epoxy.

Would ya'll replace the stern teak with similar teak or perhaps rebuild with a laminate? Thinking glass/teak? Not sure this is necessary, but it would be stronger (and might be easier).

The black blobs are all that is left of the 2nd plate:

Weld failure:

PS: spell check tried to change ya'll into yawl

Boyd · Post by **Boyd** » Jun 7th, '10, 08:36

Check out this discussion. Someone else had a similar problem and I posted pictures of how CD solved the problem on the MkII

http://www.capedory.org/board/viewtopic ... e&start=15

Boyd
s/v Tern
CD 30 MkII
Fort Lauderdale, Fla.

The Cape Dory Board

Failing Backstay plate CD27

Failing Backstay plate CD27

FRP replacement for rusted steel structure

backstay chain plate

solutions

I posted this some time ago...