Chainplate Inspection

[01kiwijohn]

I have an old Cascade 36, with the chain plates embedded inside the hull, and secured within the roving/ mat material.
I was just reading the story of Bob & Carolyn MeHaffy (?) losing a chain plate on their Hardin 45.
Gasp! I have the same type. So, is there any way to verify their integrity without surgery to remove the covering roving and pull the plates out through the slot in the top of the deck>
Looking from the inside, there is just a slight trace of rust around several of the little "stubs" that protrude through the roving?
Or, am I just being too cautious?

[mike d.]

If you see rust down in/through the laminate, I would be very apprehensive to put a load on the plates. It's a pain the @$#SS to do but the you should really get into the laminate/plates for a thorough inspection/replacement. If you replace I would not bond into the hull again. I would through bolt the plates, which allows relatively easy removal for inspection/rebidding. You don't need big wide plates to replace the old. I redid my chain plates on my Gulfstar 37 (they are through bolted). The originals had some corrosion, so I made new ones out of 316 strap. 1/4 by 2inch for the lowers, and 3/8 by 2 inch for the main stays. I beefed up the mains, from 5/16, to 3/8, only because the shop I got the stock from was out of 5/16. I drilled them, radiused the ends, then put the shroud angle in on a hydraulic press.

[Stu Jackson]

Very good advice from Mike.

Chainplates should be considered part of NORMAL periodic maintenance.

Rust is a telltale.

Deal with it now.

Good luck.

[billknny]

You are not being too cautious.

You have the disadvantage of having a boat that was built with construction expedience in mind, and not longevity or maintenance.

The only way to inspect stainless steel chainplates is to pull them out and look at them. If you are really lucky you can find the guy who decided it would be a good idea to glass them into your hull and give him the grinder!

When you reinstall them, DO NOT glass them back in the hull! Better yet, just plan on replacing them with bronze or titanium and then you won't ever have to worry about them again.

More information about chainplates and what they are made of here:

The Worst Possible Chainplates - All At Sea - Southeast

[Stumble]

I will repeat this in every chainplate thread ever. Buy titanium nice, and you never have to deal with chainplates again. You could encapsulate them permanently in stagnent salt water and it wouldn't matter. For a job that is going to take a lot of man hours, the small price increase in the materials is absolutely worth it.

[billknny]

Originally Posted by Stumble

I will repeat this in every chainplate thread ever. Buy titanium nice, and you never have to deal with chainplates again. You could encapsulate them permanently in stagnent salt water and it wouldn't matter. For a job that is going to take a lot of man hours, the small price increase in the materials is absolutely worth it.

Titanium certainly works, and is worth the price difference over SS, but what practical advantage does it have over good bronze?

Weight--sure. But the weight savings doesn't matter to the average boat, especially at deck level.

Bronze is as strong as stainless, so you can use the same scantlings, and it can be easily worked by the average diy boat owner.

If you do the machining yourself, bronze is a bargain over stainless since it does not need electro polishing to achieve its corrosion resistance.

My suggestion: if you are hoping to do the machining yourself go with bronze, if you are paying for machining anyway, go with Ti and be the coolest boat on the dock!

Again, not an argument against Ti, just a potentially more convieient alternative.

[boatpoker]

If you see any corrosion staining at all, replace them.

ABYC Certified Corrosion Analyst.

[Stumble]

Bill,

The major issue with bronze isn't an alloy issue it is a foundry problem. To start with naval bronze and magnesium bronze with are the common marine alloys are actually brass and have too much zinc. So to use bronze you need to use siliconized bronze. Which is fine, except that it is primarily cast, and cast parts used in tension structures like rigging MUST be load tested and X-rayed to ensure there are no casting defects. This is a pretty expensive proposition for a set of chainplates, though it is certainly possible.

Secondly bronze turns green if you don't polish it regularly.

Third, titanium last time I priced it was running about 15% than si-bronze for bar stock. So the price advantage isn't really that much.

[boatpoker]

Originally Posted by Stumble

Bill,

The major issue with bronze isn't an alloy issue it is a foundry problem. To start with naval bronze and magnesium bronze with are the common marine alloys are actually brass and have too much zinc. So to use bronze you need to use siliconized bronze. Which is fine, except that it is primarily cast, and cast parts used in tension structures like rigging MUST be load tested and X-rayed to ensure there are no casting defects. This is a pretty expensive proposition for a set of chainplates, though it is certainly possible.

Secondly bronze turns green if you don't polish it regularly.

Third, titanium last time I priced it was running about 15% than si-bronze for bar stock. So the price advantage isn't really that much.

I think you mean "manganese" bronze and "silicone" bronze.

[Jim Cate]

I think you mean "manganese" bronze and "silicone" bronze.

And I think you mean silicon bronze, not silicone.

Silicone bronze brings up the image of a well tanned bimbo, not chainplates!

Jim

[boatpoker]

Originally Posted by Jim Cate

And I think you mean silicon bronze, not silicone.

Silicone bronze brings up the image of a well tanned bimbo, not chainplates!

Jim

You are correct ..... slip of the finger

[goat]

Where does one buy Ti chain plates? And tanned bimbos for that matter?

goat


Sent from my SGH-I257M using Cruisers Sailing Forum mobile app

[boatpoker]

Originally Posted by goat

Where does one buy Ti chain plates? And tanned bimbos for that matter?

goat


Sent from my SGH-I257M using Cruisers Sailing Forum mobile app

I hear you can get them both on Craigslist

[goat]

Thanks BP, I'll have to look them up. Hopefully better quality than eBay. Chain plates too.

Sent from my SGH-I257M using Cruisers Sailing Forum mobile app

[Exile]

According to Stumble, you can buy Ti chainplates from a co. called Allied Titanium. I looked into it, along with bronze, but am now leaning back towards SS. I am in the process of pulling all of mine now and having them professionally inspected. AFAIK (and therefore have to assume), they are original and almost 30 yrs. old. Thus far, they have all checked out fine. I think if good quality to begin with & properly bedded (butyl tape in my case), SS can survive a very long time.

Bronze can be difficult to source & have properly machined, and identifying the proper type can also be challenging as we just witnessed above! Ti can also be difficult to source, and machine shops who can deal with it aren't exactly commonplace. Allied sources & machines all of their Ti from China -- not necc. a bad thing & they seem to have a good rep, but I think I prefer the idea of walking into a local machine shop and having them make exact duplicates of what has already done fine in my boat for the past 30 yrs.