CD30K chainplates

[JD-MDR]

CD 30k Chain plates, Help! I've been wanting a CD for a while and got this one for a little more than salvage . It looked really good. But after close inspection.the chain/backing plates are catastrophic looking. the iron plates look like baklava. I hauled out two days ago and am starting the process of stripping the bottom and servicing the shaft etc. Can anyone recommend how I should go about the chainplates. Should I rebuild the same way with iron and rebar I think It's gonna be a nightmare. The cabinetry was so nice I hate to damage it.

[David van den Burgh]

You could always go with external chainplates. Not exactly the streamlined CD look, but probably a lot less invasive than reconstructing from the inside.

[Bill Goldsmith]

This is a common issue on the older CDs. The factory used mild steel for the rig padeye backing plates and any seepage over time caused severe rusting and deterioration. One of the few weak spots on these boats. Having said that, I think I am correct in saying no one has ever reported a rig failure as a result of this issue. These are backing plates, and not actually taking the rig tension load. The rig tension load is taken by the bronze padeye fitting and the bolt. The later CDs utilized aluminum backing plates.

As mentioned, some people have simply abandoned the CD padeye design and installed external chain plates. Your choice. To retain the original CD/Alberg design, you would need to replace the backing plates with aluminum or stainless plates. On a 30K that's a lot of work because you have two rigs. But the external plates involve work as well. If it were me, I would replace the backing plates and keep the original design. But it's your boat. Let us know what you decide!!

-Bill

[Keith]

JD,

I reconstructed my bow plate with 1/2" G-10 it is stronger and lighter then the original 1/4" mild steel and will never rust. Several other have done the same or similar. Check in history there are many photos or if you want I can send photos directly to you. My side and stern chain plates are in great shape with no rust. I would suggest that you use the G-10 to replace your rusted ones.

Keith

[JD-MDR]

Hi Keith. Did you change the side plates also? I'm trying to find out if it is gonna be necessary to cut some of the bulkheads . The plates go across both bulkheads and the bulkheads are fit tight.
John D.

[hilbert]

John, I did not need to cut the bulkheads in order to remove the plate.
All the backing plates on my boat had rebar attached to pass the load on to the topsides (sides of the boat between the waterline and the deck).
The hull to deck joint is only held together by mish-mash and a few screws and bolts.

These cracks were above the backing plate, but they were mostly hidden by the toe rail.
I don't feel that the rig was ever in danger of catastrophic failure, but the deformation did allow water to enter and hasten the deterioration of the mild steel backing.


I changed over to 316 stainless external chainplates. However, if I were to do it over I would give serious consideration to using silicon bronze.
http://www.sailfeed.com/2012/03/diy-cha ... materials/

Also check out this link, click "Rig" on the side menu:
http://www.sbastro.com/FeNIX/Projects/P ... temsFS.htm

Jonathan

[Pembquist]

Going by the various Capedory drawings I have seen the steel/rebar chainplates are not just backing plates, the rebar hooks that are glassed into the hull are supposed to carry the load from the shrouds into the hull. The drawing with aluminum backing plates shows extra laminations of unidirectional glass laminated to the hull and underside of the hull deck flange. Just replacing the old steel with a backing plate doesn't provide a load path to the hull. I have seen pictures of repairs done with half knees and repairs done with external chainplates. When I do mine, (maybe never,) I would like to use composites and keep it internal. Make sure you have an oscillating multi tool.

[JD-MDR]

The yard installed the new bow plate last week of g-10 and are preparing to do the sides also w/ g-10 and g-10 knee braces where the rebar was. I installed the new sprit. I'll figure the roller later and I didn't bore the hole for the chain. I'm not sure if its in the right place. One photo shows a mock up with cardboard knee braces. Oh, the backer plate is not shown with the braces but it will fit above the braces just like the iron one was. I hope its gonna be good. I won't be able to do the rest of the chainplates this year. I'll replace the bolts though and hopefully launch soon. I should have time to run the boat a few times in the bay to iron out the kinks, which probably will be many. One question: The yard manager advised me that they weren't painting any of the interior . Does the new glass work on the inside need to be painted?

[hilbert]

That is a permanent fix, great job!

The picture is blurred so it is difficult to get a feel for the total thickness.
It looks like there was a lot of filling in to create a level surface below the hull/deck joint.
What was the thickness of the G10 and what is new thickness from the top of the deck to the bottom of the new bow plate?

Jonathan

[JD-MDR]

Hi Jonathon, Its sure nice to get feedback. The guys aren't there on weekends so I wasn't able to talk to them. Hopefully there is 1/2" plate to level the surface where those flanges are on the sides then another 1/2" plate below. That would really be strong. I kinda doubt they went to that extreme. I'll have to ask what they filled it with. Its about 1-1/4 " plus the 1/2" deck at that point. I'm pretty much trusting them. They work on a lot of modern tech stuff and seem to know what is best.
do you know if I need to paint it? I'll try to get a better photo.

[hilbert]

I've used a lot of composite fiberglass below deck.
When it is not exposed to sunlight, I see no reason to paint it.

[JD-MDR]

Got hauled out today and removed the plates in the galley lockers for the mizzen shrouds. It took about an hour each to remove the iron. The yard will do all the grinding and install 1/2” g-10 with knee braces to replace the rebar. I guess it's not rebar just 1/2" rod. The stbd side looks good but the port is wasted same with the backstay plates. There is about 1/2” filler material that wont come out easy. Its like a marine tex stuff. I'm thinking of just grinding the surface and bonding the new to it. I don't think that bond is so important as the braces going down the hull because they barely had any bond at all. There was'nt any glass on it. I thought what little bond it had was just to hold it in place during installation. ( I might be wrong). I twisted a bolt of the stanchion and it snapped so easy. I guess that means I need to replace all the stanchion bolts and rebed them.

[hilbert]

John, good to hear that you were able to find a yard to fabricate the G10 chainplates. 1/2" G10 will be be very strong and will easily outlast us all.
Please post a picture of the completed work.

"Mish-Mash" was used as a filler in the hull deck joint and between the top of the metal plates and the underside of the deck.
This was typically polyester resin with fillers for thickening and strength. A note of caution, it was not uncommon to use asbestos as a filler in the seventies.

Re-bedding stanchions is a project that can be done one at a time, when convenient. I wouldn't count on the original sealant and there are significant forces trying to pry up the base, everytime someone grabs hold of a stanchion. At least few fasteners have likely been compromised by exposure to moisture and deprivation of oxygen. Also, some of the inboard bolts might pass through the balsa core (these holes should be sealed with epoxy before rebedding).

[Kickin Bears]

Following this thread; awesome info!

Any chance you have pics of the bow plate before and during removal?

Really appreciate the pics and info!

[JD-MDR]

They are in there somewhere in “Leoma posts. I not good at computer stuff. Try to find “Leoma update 3/20/17. I just got back from the boatyard. It looks like they are doing a good job cleaning the surface for the new plates . The first photo is for the backstay and aft mizzen shroud combo there will be two knee braces and you can see the filler material at top. I am leaving that in and bonding the new plates to it. The other photo is for the plate for forward mizzen shroud will have one knee brace. It shows some rust stains. If I go there tomorrow I'll get another look to see if that is a problem.