Chainplate Material ?

[sneuman]

I am looking at 316L stainless vs. Grade 2 Titanium

-- the 316L is about half the cost of the Titanium, but has a rated "yield strength" (is that the important strength consideration?) of 25K - 42K psi

-- the Grade 2 Titanium has a yield strength of 40K psi

is there any reason not to go with the stainless?

The current plates are 30-year-old 304 SS. My replacements will be bit oversize to add some heft.

[rebel heart]

I'd go with stainless. It's much more common and if you get a hairline crack and need one temporarily patch welded it will be no big deal.

[zeehag]

use the stainless and make sure to have spares-never hurts. ye should still be able to sail in a hurrycame with ss 316. is what i am going to use on my formosa 41.

[sneuman]

Thanks for replies. I was leaning toward stainless, too. Always nice to bounce ideas off the others though.

[afmstm]

Chainplates are typically hidden in at least some areas. Being hidden and in areas with poor air contact, they are frequently subject to crevice corrosion which attacks stainless rapidly and invisibly. Pulling them for inspection is a chore that often gets skipped. I think I read somewhere that 40% of dismastings are due to chainplate failures, and crevice corrosion is a leading cause of that.

Take your existing chain plates and inspect them with a magnifying glass in areas that are not exposed to fresh air - so look where they pass through the deck or lie against a surface. And if they are painted, beware that paint can lift off creating perfect crevice corrosion sites (never paint stainless). Look for small pits, 1mm or less in diameter. Especially look for clusters of these. Then, take a dremel tool and start digging like a dentist. You'll find these pits just go on and on, often changing course, and often exploding out creating planes of failed material. Dig them all out and see how much you have to remove to stop the rot. You can remove a few percent of the cross sectional area of your chainplates without worrying much about loss of strength. I suspect after you do this you'll reconsider Titanium as it does not suffer from this.

So, I'm planning on replacing our chainplates with Ti when the time comes. My machinist friends tell me it's not hard to weld (not that I'd want to rely on a weld to fix a crack....) and is easy to machine.

FWIW, Brion Toss - a rigger here in the PNW who's written a nice book called the Rigger's Apprentice - also suggests Titanium. The cost of materials is not much higher than SS and anyway, most of the cost is likely to be labor.

Good luck,

Van

[zeehag]

i am in process of externalizing my internal ones--will allow me to replace easily and will lend more flexibility for foresail handling-

[capt_douglas]

And stainless polishes so much nicer than Ti.

[zeehag]

if the ss chainplates the boat was born with lasted this long, the new ones will prolly last longer--especially as you will be checking on htem regularly-- do yourself a favor and externalize the internal ones.

[Jim Cate]

G'Day all,

I'm surprised that in this learned discussion, no one has mentioned 2205 duplex stainless as chainplate material. This alloy is stronger, stiffer and more corrosion resisitant than 316L, and is ideally suited to chainplate fabrication, especially if said plates are to be buried or sealed in way of deck penetrations. While a bit pricier than 316, is is far cheaper than Titanium.

Cheers,

Jim

[Christian Van H]

316L should last a LONG time with proper care and good sealant (consider butyl). If you will be doing the drilling, consider condensed milk as a cutting/coolant fluid. It has a nice nutty smell while machining, and your tool will last a hell of a lot longer...

[rebel heart]

Russian submarines back in the day were made out of titanium instead of HY 80 steel because it was "better". It was actually far inferior for the application and the boats couldn't be submerged anymore. I deviate from what everyone else is doing when I've done tons of research and understand the issue. There just aren't enough people using titanium in rigging long enough to draw conclusions. My $0.02.

And in regards to welding, welding a plate to stainless is easy and plenty strong. Certainly strong enough to get you from A-B. I have a small welded patch on my masthead and it's working fine. Pull into some backwater port and poll the welders for who has gas and experience for titanium vs stainless.

[Christian Van H]

Originally Posted by rebel heart

Pull into some backwater port and poll the welders for who has gas and experience for titanium vs stainless.

I dont want to be anywhere near a welder who has gas...

[zeehag]

rofl..... is an excellent idea-- i just need a free welder..lol.. wont feed him beans either..LOL

[redmirage]

Mine are all stainless but I do not know what grade, they still look like chrome on my 1978 island trader. I understand that 304 stainless is stronger but 316 has more corrosion resistance. I have seen some really old boats with bronze which last a long time in a marine environment.

[IceMan]

If you are going to buy TI which is pricey, why not go with Aluminum/Silicon/Bronze. Less in price than TI, will never corrode. Right now I am replacing all my toggles on my standing and running rigging with 17-4PH stainless. Its working strength is almost 4 times that of 304/316L stainless. And I don't know where you were pricing TI but from everywhere I've looked, TI isn't even close to the price of 304/316.
If you don't want 304/316 because of lack of oxygen problems, go with 17-4PH. Just my 2 cents worth.
WD