Chain plate modification - alternative to glassed in

Hi all,

Finally gone and made an account

Looking for advice about glassed in chain plates. My 1980 First 35 has original glassed in chain plates below deck. Rather than penetrate the deck, they are laminated to the interior hull about 2 feet down from deck level. The plates, rod section penetrating the hull and the deck fittings (where all 3 shroud toggles attach to a terminal) are all original. They seem fine but they are 40+yrs old and... peace of mind, looking to replace.

Would installing a bulkhead for a traditional style chain plate be a good alternative? Might I run into trouble with the hull and deck construction that wasn't designed for a chainplate bulkhead?

Replace the original chain plate location with a laminated-in carbon fibre epoxy chain plate? The angle of upward force peeling away from the hull is approx 20 - 30°.

A boat builder suggested possibly bolting a new parallel plate to the old, bolting through the available protruding glass and plate, with the clevis pin going through both old and new.

Solid GRP polyester resin hull, balsa core decks, displacement approx 5.5 tons wet

Many thanks

 

I've always thought these carbon fibre chain plates were a good solution for worry free installation.
You might get some ideas from this

 

That won't work. Those transversal waves in the laminate visible in your last photo are there for a reason, under them are steel rods that pass trough the middle of the steel chainplate. Unfortunately that's exactly where the bolts for the sister chainplates must also go trough.

For a replacement there are several options:
1. Cut open the laminate over the chainplates, remove and replace. Also replace tierod and deck chainplate with same.
2. Laminate a new composite chainplate over the existing one. Might be difficult to properly sand all that waviness for proper adhesion of the new laminate, and there might be space problems. Again replace tierod and deck chainplate, depending on how you do the work a slight angle adjustment to the tierod might be necessary.
3. Remove a good chunk of the inner molding in the area where the tierod is, remove the lower chainplate, install a big half-bulkhead/knee. Replace the tierod with flat plate bolted to the new knee, fabricate new deck chainplate, reinstall modified interior molding.

For option one you can use either a metal fabrication duplicating the existing one (316, duplex stainless or bronze) or go all composite. The entire job could also be done from the outside, but you would need to fair and repaint the topsides afterwards.

 

Hey thanks for the replies guys.

I've had a second boat builder look at it. Both have said no harm done but very unlikely to need to replace as there wouldn't be moisture creeping in to cause corrosion at all.

Does this hold up with you guys?
Thanks