Chainplates and bolts through the Hull

[BuzzLi]

I'm looking at a 1987 Formosa, which needs loads of work, not unusual, and what I've been concerned about is that the Chainplate bolts run right through the hull to the outside. Can anyone please educate me on this being structurally sound and/or a problem? Thanks!

[UNCIVILIZED]

Hi, & welcome to CF!

As to the boat in question, I'm not quite clear what it is that you're asking. So could you expound on your statements a bit please.

In terms of the chainplates, it appears that the ones on the boat in your post are in a location that's akin to those on other boats of the same model. So that if she was built correctly, & hasn't been altered then I'd think that she'll likely be fine. Though of course you'll have such things inspected prior to purchasing a boat.

The caveat or two which goes with chainplates bolted to the hull is that they may be a bit more prone to leaking than ones which go through the deck, & which are then bolted to bulkheads. This would be due to the fact that there are a huge number of skin penetrations created by their bolts, vs. one deck penetration when a chainplate is attached to a bulkhead. So that when the boat & rig flexes, the sealant on the bolts has to work harder to keep things water tight.

This could also create higher odds for crevice corrosion on the chainplates themselves, & their fasteners. Since they'll be immersed in salt water a lot more than the other chainplate configuration.

I hope that that helps, & if you give us clearer questions, the responses will likely be better targeted. And good luck with your search!

[GordMay]

Greetings and welcome aboard the CF, BuzzLi.

External chainplates are very robust.

[HappyMdRSailor]

Welcome to CF Buzz !

Not an uncommon technique, more often than not with plates external...

[BuzzLi]

Thanks everyone, very helpful...I figured leakage was the main concern.

[old frog]

The installation & attachment method is time proven. Crevice corrosion is your main enemy on the backside & oxygen starved areas. Add to that 29 year old Taiwanese stainless. Going on 30 years, it might be prudent to pull, an upper for a random check. Let the results be your guide on how many to check. Do not forget the stem head, bow sprit tangs & back stay c. plates. Some used punched square holes in the plates & carriage bolts to attach. These tend to be more problematic do the the stress risers created by the corners. IMHO, it is worth the time to check as it will help you sleep better at night & when undersail in high winds. Good luck with the project.

[roverhi]

I have the opposite take as Uncivilized. The big problem with inboard chain plates is the through deck area. Sealing this area is an area that's very prone to leaking. That can result in crevice corrosion in the stainless and core rot in the deck. The force on the bolts is in shear which is the strongest. Sealing the bolts is relatively secure as you don't have to contend with movement of the deck. Ideally it would be good to have fender washers under the bolt heads or the chain plates on the outside of the hull. Wouldn't bother me the way it was built, though.

Second 'old frog' recommendation to check all the chainplates and rigging attachment fittings to check for crevice corrosion. Taiwan stainless doesn't have a great reputation for quality and the areas where the SS passes through the deck and hull are the weak point.

[bletso]

Yep! I will second that.

[buzzstar]

Stainless chainplates are not horrendously expensive to replicate (not cheap either, but the adjective are really opinion) and the replication/fabrication can often be done locally, typically using 316 stainless of the proper dimensions. No matter what, check what you have for condition. A visual check is just the start, but it may indicate the need for replacement without going further. When replacing there are many opinions to be found on proper materials. methods and products for replication,installation, and sealants. Welcome board CF, and enjoy the sail.

[Cheechako]

Bolting thru the hull is common and good.

[foufou]

Not only common and good, but a better way for lightning exit the area if it happened along; outside the hull. F

[Akapeterc]

Our Hunter yacht has chain plates on outside

[Formosa46AK]

You can get some answers from Formosa owners at:

Peterson Cutter Website - Welcome

[Hoodsail]

Pulled chai plates that are mounted inboard and thru the deck on my new-to-me 1978 Bristol 35.5 last year. Plates looked brand new with no signs of corrosion. Granted it is Rhode Island SS, but age doesn't always translate into wear.

[Stumble]

Originally Posted by Hoodsail

Pulled chai plates that are mounted inboard and thru the deck on my new-to-me 1978 Bristol 35.5 last year. Plates looked brand new with no signs of corrosion. Granted it is Rhode Island SS, but age doesn't always translate into wear.

No, but age does equate to work hardening. At 30 years they are probably close to their cycle fatigue lifespan even if there is no corrosion.