Oh My God.

[tartansailor]

We are in the process of removing deck hardware prior to refinishing
and this came from the starboard side rear lower shroud backing plate.

It was discovered while attempting to insert a deep draw 1/2" socket.
The socket was obstructed with fiberglass seen on the right of the pic. One good grab and pull resulted in this.

Apparently the steel expanded on rusting and delaminated the encapsulation.

There was no evidence of caulking compound at the bottom of the fitting.

Man, this could have been bad.

Dick



[img]http://i76.photobucket.com/albums/j19/t ... 0_0213.jpg[/img]

[drysuit2]

Yikes!

[Lew Gresham]

I discovered the same problem on my Ty on both chain plates/pad eyes a while back. The steel plate on the Ty's apparently were about 1/4" thick. I cut away some of the fiberglass underneath so I could inspect. Note how the steel plate bled into the fiberglass. My plates are about 12" long and 5 " wide. Good Luck!

[Sea Owl]

Lew;

My CD25 is older than yours, and now I am almost afraid to look at my chain plates...and afraid not to!

I have small (6") circular holes in the cabin wall for access to 'see' the chain plates. I am assuming you had to cut bigger holes to get at them?

Thanks for the posting, hope the fix goes well!

[Lew Gresham]

I was able to get my small air tool with a small cut off wheel in through the original hole. It was tight but, I stayed with it and did a little at a time. I made up a couple of small stainless backing plates to help distribute the forces on the iron plates. I also treated the iron plates for rust, and then painted. As for your backing plates, I am sure they are rusted. My Ty, had never seen or been in salt water. Imagine the condition if in salt water. HTH!

[Sea Hunt]

There was an article several (perhaps many) months ago in a sailing magazine (I think Good Old Boat) about this exact problem on the author's Typhoon Weekender. I think the author's name was Ralph Naranjo but I am not sure. From what I recall, his shrouds actually pulled out completely and his mast almost snapped off. He was a very experienced sailor and was able to save his Ty.

When I bought my Ty, the surveyor said he inspected the area below the turnbuckles, etc. and said they were OK. He said he did this from the two "inspection ports" (removed two wood circular cover plates). He did not remove the large fiberglass section from the inside hull area. He started to but thought it would be invasive and possibly damage some of the fiberglass.

I guess one of my next projects will be to remove these panels and do what I can to see if I have any suspect backing plates, etc.

[henry hey]

I think this thread is a topic that all CD owners keep somewhere in the back of their minds. I remember reading a similar thread over a year ago here. I brought up this issue with several colleagues of mine including Carter. I also recently asked a rigger friend about it.

Some consensus appeared to be that if there is no sign of shape change (deck bulging or anything of the sort) near the chain plates, and that if you have no other signs of problems (staining etc) then it's probably ok.

Of course this doesn't put me completely at ease but it seems that it's a bit of a catch 22 to start inspecting those plates. You can drill in from the bottom to check integrity but the second that you do this, you compromise integrity by opening up the sealed glass to the air.

I just try to keep a close watch over my boat and sail happily.

If anybody has other thoughts on this I would love to hear them.

-h

[tartansailor]

Henry,
What was noticed prior to tearing out the remains of the rusted backing plate was the encapsulating fiberglass under the rusted plate appeared to me to be darker than similar areas on the port side, which was found to be fine.

Now the rusting was extraordinary, like completely through the steel.

A disturbing find was that the next forward fitting (stanchion base)
bolt had rust residue as the bolt was removed.

On that basis one could suggest that a visual inspection using a neon shop light through one inspection hole, and and a mirror in the next hole.

Now if there is still uncertainty, then one could start removing bolts and thereby check for rust coming up with the threads.That would be a good place to start.

Now in my case however, I'm trying to psyche myself up to doing some serious surgery. Uncertainty out in the ocean is not an option.

Dick

[Troy Scott]

Folks,

All this talk of embedded mild steel backing plates is worrisome. As I've mentioned before, my CD36, #152, built in 1988, has long aluminum angles below the hull-to-deck joint through which the shroud hardware is through-bolted. She also has a huge aluminum weldment under the stem through which everything is bolted. I haven't looked under the backstay fitting yet (it's a struggle to get where I can see it) but Ill bet it's similar, with an aluminum plate or angle. All the deck hardware is backed up by aluminum plates as well. I hope this means I DON'T have embedded mild steel in the hull to deck joint. I can't imagine why the boat would need embedded steel AND the big aluminum angles and weldments. I would appreciate any insight into this. Hopefully I don't need to worry about it. I have enough to do. Maybe I should get a big magnet and check for any attraction in those areas.

[tartansailor]

[img]http://i76.photobucket.com/albums/j19/t ... 0_0232.jpg[/img]

This is my first attempt to fabricate a plywood template.
It needs to be a bit wider and longer to the right.

Dick

[Troy Scott]

Dick,

Are you planning to put a piece of stainless steel or aluminum back to replaced the rusted mild steel you removed? I am sure that would work just fine. However, I would like to share my experience with some very handy stuff I bought from MSC. It's fiberglass "pre-cure". I think they call it FRP in sheet form, but I've been calling similar stuff pre-cure for a very long time. I buy it like plywood, in 4' by 4' or 4' by 8' sheets 1/4" or 1/2" thick. They have other thicknesses as well. It's great to have around the shop for use as backing plates for seacocks or deck mounted hardware. I stacked up three thicknesses of the 1/2" stuff to make the blank from which to machine the bolster for my windlass. It saves me an enormous amount of time. It doesn't rot or corrode. It's dense and it would be very difficult to crush. It's also very stiff. I believe this material would be ideal for reinforcing the chainplate area. If anyone here knows some engineering reason why this material should be avoided in this application, I would like to hear it. Otherwise this is my official recommendation:
I would remove all the old mild steel. I would seal the affected area with brushed on epoxy resin. I would cut a piece of pre-cure large enough to distribute the load over a greater area than that which has been weakened by the deteriorating mild steel. I would bond this FRP plate in place using epoxy thickened with mill fiber, taking care to mount this piece in a plane parallel to the deck surface. The pre-cure should be sanded before installation because the surfaces are smooth when you get it, and there may be remnants of mold release on the surfaces. There should be no voids between the deck surface and the bottom of the backing plate. Then, taking care to drill perpendicular to the deck surface, I would use the original holes to locate new holes through the newly created strong points. Lightly countersink the new holes on top to provide a place for the bedding compound to make a good gasket. You will probably need longer SS bolts in this new setup. Use SS fender washers and nylon locking nuts. You will never have to worry about rust with this plan. See my post in the topic "important safety issue".

[Carter Brey]

Dick,

Are you planning to put a piece of stainless steel or aluminum back to replaced the rusted mild steel you removed? I am sure that would work just fine. However, I would like to share my experience with some very handy stuff I bought from MSC. It's fiberglass "pre-cure". I think they call it FRP in sheet form, but I've been calling similar stuff pre-cure for a very long time. I buy it like plywood, in 4' by 4' or 4' by 8' sheets 1/4" or 1/2" thick. They have other thicknesses as well. It's great to have around the shop for use as backing plates for seacocks or deck mounted hardware. I stacked up three thicknesses of the 1/2" stuff to make the blank from which to machine the bolster for my windlass. It saves me an enormous amount of time. It doesn't rot or corrode. It's dense and it would be very difficult to crush. It's also very stiff. I believe this material would be ideal for reinforcing the chainplate area. If anyone here knows some engineering reason why this material should be avoided in this application, I would like to hear it.

Troy,

Yes, vinylester FRP is an ideal choice for backing plate material, and I have used it for this purpose. It is extremely tough and utterly inert.

As a stanchion base backing plate:

[img]http://pws.prserv.net/cbrey/6-8-040002.jpeg[/img]

As a deck organizer backing plate:

[img]http://pws.prserv.net/cbrey/4-15-040003.jpeg[/img]

The only drawback to it is (as you implicitly point out) that it needs to be used in greater thicknesses than materials like aluminum or, of course, stainless steel. This results in some difficulty in lining up machine screw holes if it's impossible to use a drill guide in a particular location. The FRP used in the above applications is 3/8" thick.

I suggested aluminum to Henry with this in mind, although your point about further swelling of rusted mild steel is well-taken. As you say, there is a quick fix for someone short on time and in need of immediate results, and there is a longer-term fix which would make greater demands on a DIY owner's time.

If using aluminum backing plates, be sure to use TefGel to isolate the different metals.

Have fun,
Carter

[tartansailor]

Troy.
Thanks for the heads up on FRP. The plan is to use FRP
for future deck reorganization hardware.

Carter,
That is some neat installation!

1/4" mild steel was removed, and 5/16" 316 SS is the
replacement.

Honestly, if I knew then what I know now, I would have
cut the deck and worked from the top. The bottom of the
deck is very uneven, and somehow we need to figure out a
regimen for an inelastic bedding.
Additionally a portion of the back liner needs to be replaced.
All the more reason to work down from the deck.
The 2nd template fits fine.

Dick

[Bob Owens]

Last year I was alarmed to discover rather soft plywood-type backing plates beneath the winches on the side decks of my CD27. I still can't believe that CD would use such crummy stuff. Thanks to the generosity of Carter, who bequeathed me the remnant of his 3/8"-thick FRP sheet, I made new FRP backing plates for the genoa winch bolts. Other than requiring 1/2" longer hex bolts, it was an easy substitution, since they are not glassed in place. I am very pleased with the FRP, and plan to use it for all backing plates from here on. (I would encourage everybody to check your winch mountings. They carry a load, especially if you have a large genny.)
Bob

[Troy Scott]

Carter,

I'm pleased to hear that folks are using better materials. I always try to make repairs the way I wish the work had been done originally. Often a better method is no more difficult and hardly any more expensive. It's in all our best interests to keep up and improve our Cape Dory boats. The value of the whole fleet increases as they become generally better. This board is a great place to share knowledge and techniques. I know it has been a terrific resource for me! That's why I try to help if I can. And, as most of you know, I ask LOTS of questions