bronze vs 316L Stainless chainplates

[chouliha]

Originally Posted by a64pilot

If you have already removed them, I’d try to get them inspected, I’d assume by eddy current or X-ray looking for cracks, but I would not substitute bronze for stainless, maybe Titanium, but not stainless.

Just curious why you would not substitute bronze for stainless especially chain plates? I would think if you use the correct type of bronze it would be far superior in longevity and corrosion resistance.


Regards

Chuck

[strandte]

I'm really pleased with posting this question here on the forum, as your inputs changed my mind. I will certainly keep the bronze chainplates now after all your valuable input. Instead of changing the bronze cp for my main mast I will look into prices for bronze or titanium cp for my new mizzen mast.
Since I have the main mast down now I will inspect all existing cp for pinkey color changes (or was the pinkey color comment actually all about brass?) and cracks, and in the process clean them up to look better than they currently do.

Thanks! I will certainly post some more questions I have, as this was a success on my side. Hope to see some off you on the water in future years!

[a64pilot]

Originally Posted by chouliha

Just curious why you would not substitute bronze for stainless especially chain plates? I would think if you use the correct type of bronze it would be far superior in longevity and corrosion resistance.


Regards

Chuck

I have that backwards, meant substitute SS for bronze.
SS is pretty and stays that way, but it is definitely a time limited item when used as a structural component. For ports lights etc., it’s the material of choice in my opinion

[buzzstar]

Originally Posted by a64pilot

If your replacing, call Allied Titanium and at least get a quote, you may be surprised, Ti isn’t as expensive as it used to be.
Allied Titanium - Affordable Titanium Now

Second the above opinion. Investigate at the very least. BTW, if you do not go titanium or bronze, be absolutely sure the 316 is properly pasivated.

[Jim Cate]

I have no problem with bronze in general, for it is the material of choice for many applications. but i do have a problem with any metals from Cheoy Lee, or other Oriental builders from that era. There are heaps of stories of failed s/s from such sources, so I'm left with a worry about their bronzes as well. There are so many different alloys of bronze, even from reputable sources... who looks after the castings in the boatyard?

Anyhow, what I'm getting at here is the kinda blanket approval granted to the bronze of no known parent... is it valid?

Jim

PS Our now 27 year old 2205 s/s chainplates when inspected a couple of years back were free of any visible corrosion, staining or cracking. Looked essentially as new.

[strandte]

I have also seen online pictures oft ss from Cheoy Lee that have degraded over the years. The ss on my boat does not look this way, and I expect it to be from a refit in 1993/1994. The bronze is also likely from this year.
Thanks for the tip on 2205 ss, I was not aware of this quality of the material.

[CarinaPDX]

I think these concerns for bronze are not supported at Cheoy Lee. I certainly agree that Asian stainless from the '70s and '80s was often substandard, and tanks and plumbing were also a source of many problems. But Cheoy Lee has a very long history of bronze casting and machining. For those that don't know Cheoy Lee has been in the shipbuilding business, now yacht construction, since 1870. They started building teak yachts in the '50s, then later fiberglass. I remember the ads in the back of the old sailing magazines for their beautiful teak sailing yachts. They were notable for having a bronze foundry and machine shop, where they produced all of the bronze parts (including winches and windlasses) on site. That is a lot of experience with bronze.

Unless there are specific reports of Cheoy Lee bronze failures I wouldn't assume that there might be a problem.

Greg

[Jim Cate]

They were notable for having a bronze foundry and machine shop, where they produced all of the bronze parts (including winches and windlasses) on site. That is a lot of experience with bronze.

I know nothing of their casting and alloy quality, but some of their in house designed and built machinery was awful. Friends with an old Offshore 40 had lots of problems with steering gear and winches due to poor fit and poor design.

Chain plates, of course, are not terribly difficult to design or to manufacture. If the ones in question have survived many years without distortion or other faults developing, they are likely quite ok to continue using.

Jim

[danhunt]

I have a Cascade 42, the stainless chainplates are embedded in the fiberglass hull with only the top 4 inches or so exposed. As a precaution I would like to replace them, which means exterior plates bolted through the hull. Has anybody have experience with this kind of rigging project? I don't think drilling through the embedded plates is plausible considering my experiences with stainless and how it hardens when drilled. The other option that later Cascades came with is a cast Aluminum toe rail, they attached the standing rigging directly to that but I heard the mold was broken years ago and no new pieces are being made. I know someone who got them off of two 29 footers and installed them on his 42, but he just lucked out finding them it seems.

It seems if they had only the foresight to use bronze I would not be thinking about this right now.

Thanks for any help.

[CarinaPDX]

Are there any signs of corrosion? While it is a bad idea to deny stainless steel oxygen by sealing it up in anything, unless corrosion has started it is a small risk. OTOH if there is any rust coming out of the sealed area then concern is justified. I have not noticed that construction technique in the Cascades; my friends who built 42's used the large extruded (not cast) aluminum rails, and they were strongly bolted through the hull, but I know this was not the way in the earlier boats.

As for drilling stainless, it is a PITA but certainly not impossible. It is best to invest in cobalt drill bits; otherwise you will go through a lot of Ti-plated HF drill bits. Don't waste your time with high-speed steel unless you have the proper sharpening equipment and like spending a lot of time. The trick is to drill a modest hole first, then gradually ream it out with progressively larger bits in small increments. You must use cutting paste or fluid generously, and don't let heat build up.

If it were me and I saw any rust from or in the sealed area I would remove them to prevent damage to the hull from the swelling caused by iron oxide. And if there is no sign of corrosion then I would just keep an eye on things. YMMV

Greg

[a64pilot]

A trick to drill stainless, is low speed, high pressure. Tap magic and other drilling lubes didn’t seem to work well, but some kind of wax did help some, but the main thing was low speed to keep the heat down.
Stainless work hardness easily and that is what happens when you try to drill it fast, you work harden it and it gets real hard, harder than some drill bits.
“Titanium” gold colored drill bits are I think some kind of marketing gimmick. My experience is that plain ole good high speed steel bit is better, but cobalt is a different animal.

[CarinaPDX]

@a64pilot: I would add that the best thing to do is use a large drill with a 1/2" chuck, and a second grip. They will often have a slower speed available than a smaller drill, and have the torque and leverage to get the job done.

I have found that the titanium-plated bits do a good job for up to a few holes in stainless, then they are worthless. The underlying steel is inferior to quality high speed steel so once the plating is gone they round over. Cobalt bits are the best, but the expense justifies investing in a sharpener as they do eventually dull going through stainless.

Greg

[danhunt]

Thanks for the advice.

Since my first post I found a lot of information when searching using the words "glassed in chain plates". There are no humps where the plates are glassed in, so I am not sure how deep I would have to go into the hull to reveal and remove them, that and one is where a major structural bulk head is tabed to the hull. What I might do is partially open one that is easy to get to and see if there is any rust happening. It appears that the plates stuck out of the hull the height of the wood toerail and then another inch or so for the turnbuckles to attach. the previous owner had fiberglassed over the toe rails and covered the chain plate as well. I removed the fiberglass at the chainplates exposing the plate and there was some surface rust coloration there. That part looks fine and there has been no return of the coloration, so I hope the water did not penetrate into the part buried in the hull. But I have no way of knowing without a specialist of some sort.

Anyways it is possible to remove them, but it would be months of work, dismantling the interior that I have more less just gotten to where I like it. I need to electrically bond/ground the plates for lightening protection any way, so opening up some inspection holes might be useful. I have double aft stays, to get to them I would have to remove the decking as they are inside a very narrow stern locker that houses the propane bottle.

I have been trying to get Cascade specific advice about this for about 4 years, this is the closest I have come. The toe rail used in later models that also functioned as the stay anchor point instead of chain plates is not available from anybody at this point, only toe rails that fasten only to the deck which of course is not strong enough. it seems the prudent thing to do is leave the plates in the hull and put exterior mounted ones either over them or just beside them.