Deck reinforcement at Chain Plates?

[Knot Stressin']

Here in Michigan our boating season is fast winding down. And so I am thinking about some winter projects on the boat. One thing I am definitely planning is removing alot (probably all) of the deck hardware and reseal as I have some evidence of small water leaks around a few of the chain plates.
I am curious, is it necessary to add something to the decking in that area to stiffen it back up? I only ask because it seems like a highly stressed area of the deck\core. And one that simply cannot afford to be compromised in any way. I mean, who can deal with a pulled out chain plate on a shroud or Safety line stanchion?
Getting some longer bolts and adding a piece of plywood to the underside of the decking seems like an inexpensive and easy way to go......but I am not sure I would be comfortable with "plywood" under there. Although it would help distribute the load.....I would think something as soft as plywood would maybe not be well suited for that.
Have any of you done this, and what material did you use? How did it work/hold up?

 

[capta]

I shouldn't think your chainplates are secured to your decks. There should be waterproof caulking that seals the hole where they pass through in the deck, but their strength comes from an attachment to structural members within the hull.
These passages through the deck do need occasional recaulking as do your stanchion bases, which should already have backing plates in place. If they do not, then it is a good idea to do so.
If you have cored decks and the core material has become saturated with water, then you have a much bigger and difficult project ahead.

 

[Ken Cross]

I have used several methods of reinforcing things (but never had a Chrysler) Chainplates should, however, be by design really stout and usually fastened to a vertical surface. On other things, I've used area washers, wood carved to fit, and plywood. In the case of plywood or carved wood, I covered them with epoxy or fiberglass and epoxy. I've never had a problem with it. This all assumes that appearance isn't an issue. If it's in a visually important area, you may want to paint before you put it in place.

This all assumes you can keep the wood dry. You may also consider stainless area washers with sealant under them.
Ken

 

[dlochner]

Are the chain plates attached to a bulkhead? Or just attached to the deck? Most chainplates are attached to the bulkhead because it is stronger. There is a lot force on the chain plate that most decks con't withstand.

If the chain plates are attached to a bulkhead, the cover is there to compress the bedding compound and make it more attractive. When the hole was cut for the chain plate it was probably not cut neatly.

Remove the cover, then remove the chain plate. Clean out the old bedding compound and inspect the core. Some builders sealed the hole with epoxy others don't. If the core is exposed and dry, seal with epoxy. if the core is wet or rotted, clean it out and fill with thickened epoxy.

Some builders reinforce the stanchion base locations with plywood coring rather than balsa. Others use solid fiberglass. You'll have to pull a a base to inspect it. A fender washer or backing plate should be under the stanchion base.

 

[Knot Stressin']

Being newer to sailing, (and not being overly familiar with the construction of sailboats) I guess I was just curious. I do believe the chain plates are still fastened the way Chrysler built this boat 40 years ago. I am just wondering after 40 years would it behoove me to beef these up a little bit?
You can see in this picture that the shroud attachment points have a pretty significant aluminum angle piece anchoring them to the wood bulkhead inside the cabin. So I guess they are probably not going anywhere. But the life line stanchions on my boat.....I just dont know that I would trust them if I slipped and thats all I had to grab on to. They have small (appx 3" x 3") pieces of flat aluminum on the underside of the deck. But the stanchion base and the flat aluminum pieces I described, seem to be clamping just the deck. And if you push on the stanchion itself there is a slight bit of flexing. I will have to investigate further to know if its actually the decking flexing. Or if its just a loose\damaged base.

 

[Jackdaw]

As long as that wood bulkhead has not rotted from water ingress, you are fine. Once/if it rots however, it's time to replace it. You need to check for solid wood under the thru-screws now, and re-check for water on a regular basis after that.

 

[Gunni]

Since you are turning this into a project, step the mast, have the standing rigging inspected and replaced, pull the chainplates off the bulkheads and inspect for corrosion and cracks. This also gives you a chance to inspect the deck penetration around the shrouds and repair any problems with the deck. Expect you may find that the wood core is wet and in need of replacement. Sound the rest of the deck to look for addition soft spots. A search of “re-coring boat deck” will find lots of guidance.