CD Chain Plates & What to look for

[DaveR]

I'm currently looking for a CD27-28 and reading up on what to look for as I do an initial inspection. I found this old post on another forum today and was wondering what the good folks here think of this alaysis:

https://missionmariah.wordpress.com/201 ... te-design/


In defense of the Cape Dory chainplate design
Posted on March 11, 2014 by Bow Sineath

One of the biggest complaints Cape Dory owners have is the design of the chainplates, specifically the mild steel backing plates.

For those that don’t know, the Cape Dory chainplates are basically a bronze piece on deck, thru bolted to below the deck, and through a mild steel backing plate that runs along both sides of the cabin. The design sandwiches the deck between a large steel plate and the external bronze piece. On deck, they look like this:

More at the link above

[jbenagh]

You want to see where the steel is and assess if it's corroding. Peter Hunt (surveyor and CD employee) thought that some boats used what was available which may have been bronze (BONUS!!!). Some are SS but most are not are mild steel. On most CD's there are access panels (plywood) that let you look at where the chain plates are. You will need a flashlight and an automotive inspection mirror; your surveyor should have these items and use them; if not run from that inspector!!!

You'll want to look at fore stay, back stay and both shrouds. Sometimes different material used for each so be vigilant!

There's a lot more info in the archives so I recommend a bit of search feature usage. If that's not enough I'm sure we're happy to help.

Jeff

[jbenagh]

PS depending on your skill level replacing chain plates is not hard, per se. It's just REALLY time consuming and messy

[Jim Walsh]

I'm thankful that the CD31 used aluminum backing plates. I've checked mine and they are intact with no indication of corrosion or water intrusion. The use of bronze backing plates would have been fantastic! I recently rebedded one of my boarding gate stanchion bases and it also had two aluminum backing plates. Both were cleaned up and reused as they were in fine shape.....not bad for a boat born in 1984.....thank you Cape Dory!

[Pembquist]

One important thing is that a lot/most of the time the thing called a backing plate is not just a backing plate. Would that it were so as than you could just replace it. It is a weldment where the "backing plate" is welded to rebar hooks that go down along the inside of the hull and are glassed over. Some designs, as shown in owners manuals, (I don't have first hand knowledge,) are aluminum backing plates and the structure is shown as being reinforced by unidirectional glass at the hull deck join but I think the majority of them were the rebar hook type, though it might depend upon which size CD.

Unfortunately the weldments were not designed to be removed so replacing them or using a new method to reuse the pad-eye system requires a lot of messy deconstruction. Most of the repairs I have seen via the web are replacements of the Cape Dory system with old fashioned chainplates on the outside of the hull bolted through the side with some heavy glass reinforcement where the holes are made. Looks sort of nice and traditional but I would like to do mine by making a glass angle at the hull deck connection and than have a backing plate of some sort (G10?) but I haven't yet found out how to know what would be a safe layup for this, also I would have to remove a bulkhead and cut out the liner at the rearmost shroud, so I will probably just wait till the mast falls down.