I have a mac 224 and want to replace my turnbuckles, i sail only in fresh water. 304 turnbuckles i can get for under $6 a piece vrs 316 are $27 a piece from what ive read theres no strength difference only that 316 has the molybdenum which is an xtra corrosion resistant. Big deal or not going with 304
304 vrs 316 stainless
- Thread starter sailnewbie
- Start date
Figured that just how fast i wonder, i can by 5 sets for the cost of one, something to think About
Still looking into that, from what i first read there the same except 314 having the xtra non corosive but no problems with strength
How strong should be strong enough? Looking at various choices (bronze, 304, 316) which is mechanically strong enough including a safety margin? I've seen exposed 304 tarnish but not rust away. I'd be worried about tendency to gall. That I've experienced first hand with 316.
i thought 316 is weaker but more corrosion resistant. So a tradeoff. He is in freshwater so corrosion resistance is much lower priority I would suppose.
304 SS has the best strength to corrosion resistance ratio of all stainless alloys. 316 gives up strength for improved corrosion resistance. On a freshwater boat 304 would be my choice.
in practice, it doesnt work quite as simple as that.... when you place ANY material that rusts against 316 stainless, which doesnt normally rust by itself or in contact with other 316 components, the corrosive part WILL induce the 316 to start rusting... and once it is induced, it is then contaminated and extremely difficult to stop, so it will continue to rust/stain and corrode even if the original contamination source is removed.
so, the chainplates and rigging ends will become a source of rust stains on the boat.... going cheap on the turn buckles now, is only costing you more later...
Why not chrome plated bronze like Hayn? Personal opinion - born of too many stainless fails: There ought to be a rule prohibiting any stainless component subjected to stress and moisture allowed in rigging including chain plates.
Talk with Rigging Only or other similar.
Charles
Edit: Also - use open body turn screws not the closed ones
Talk with Rigging Only or other similar.
Charles
Edit: Also - use open body turn screws not the closed ones
Last edited:
304 is stronger than 316, period. Yes, 316 has better corrosion resistance. Lube the threads with TEF 45, it will keep any water out of the crevices for quite some time. In a fresh water environment I doubt you will develop running rust that quickly.
I have some Robship Turnbuckle covers I got on clearance, size small. I haven't used them yet but they seem very well made; durable with an inner vinyl sleeve that keeps any lubrication off the fabric cover. The argument against these would probably be that they would trap moisture on the inside. I suppose that is true if they get wet from rain or soaked by splash, but in general good weather they should keep moisture in the air from settling on the turnbuckles.
The small size is on sale @ defender for $10 each (these will cover 1/4" an 5/16" turnbuckles);
http://www.defender.com/product3.jsp?path=-1|619045|1970797&id=3250143
The small size is on sale @ defender for $10 each (these will cover 1/4" an 5/16" turnbuckles);
http://www.defender.com/product3.jsp?path=-1|619045|1970797&id=3250143
For turnbuckles, and I may be wrong on this, I thought open body chromed bronze with SS studs were preferred. The reason is that if it were a SS body and SS studs, the SS could start to gall, especially with 316 SS. But the bronze body with SS studs, the bronze kinda lubricates the threads. Of course I've seen had had all SS bottle screw turnbuckles, and got rid of them for open body because the open body were easier to adjust.
Can anyone else confirm that 304 SS thread on 304 is more resistant to galling than 316 theaded SS on 316 SS?
Can anyone else confirm that 304 SS thread on 304 is more resistant to galling than 316 theaded SS on 316 SS?
Brian, your assumptions are correct for the most part. The choice of chromed-bronze open bodies has less to do with galling that it does with ease of manufacturing. Bronze is much, much easier and cost effective for casting and machining. Stainless, 316 much more so than 304, is very hard on tooling. The mills that finish the bodies and create the threads have to run at a slower feed rate to avoid work hardening by overheating while the cutting edges wear out much faster. Also, stainless is much less ductile than bronze, so when it fails it will snap without warning where a bronze body will stretch and deform before it parts.
In terms of galling, I can only speak from personal experience... stainless threads will gall on anything, not just stainless to stainless. I have had (more than I'd like to admit) a few SS screws or bolts gall in mild steel or aluminum, this was in custom or race motorcycle builds. If you have SS studs and SS barrel or open-body turnbuckles, simply use turnbuckle lube or TEF 45. The TEF 45 is much stickier than turnbuckle lube-oil, but is superior because its actually purpose is a high-load/extreme pressure/anti-sieze/actually waterproof grease. Just apply sparingly to the threads with a brush.
Hmm... TEF 45: http://www.forespar.com/products/marelube-tef45.shtml Basically Teflon powder grease. Probably much like the Ultra Tef Gel that I use on SS to AL mating (insulates the materials from each other to limit galvanic corrosion) though Forespar states that they have a higher percentage Teflon to grease than other products. http://www.tefgel.com/ (Sorry, it's a Flash based site, so no direct linking to the product.)
I have heard of people using anhydrous lanolin for similar SS to AL insulation. And I've heard they found it at pharmacies. I went around to 5 local pharmacies once, from big ones like CVS to local mom-and-pop, and no one knew what it was. (I needed some that weekend to do repairs, and didn't have time to wait for an order online.) It is available on Amazon. What I wound up with at that time was "pure" lanolin from a wholistic health store (what I call a hippie store.) I put some of this on my bronze open body turnbuckles like 3 or 4 years ago, and they still spin freely. Mind you, I'm in fresh water, and my rig is very lightly tensioned. Of course, there is also Lanocote: http://www.forespar.com/products/boat-lubricant-lanocote.shtml
So, as usual, what I learned at the bike shop holds true: all threaded surfaces get either grease, oil, or Loctite, depending on the application.
I have heard of people using anhydrous lanolin for similar SS to AL insulation. And I've heard they found it at pharmacies. I went around to 5 local pharmacies once, from big ones like CVS to local mom-and-pop, and no one knew what it was. (I needed some that weekend to do repairs, and didn't have time to wait for an order online.) It is available on Amazon. What I wound up with at that time was "pure" lanolin from a wholistic health store (what I call a hippie store.) I put some of this on my bronze open body turnbuckles like 3 or 4 years ago, and they still spin freely. Mind you, I'm in fresh water, and my rig is very lightly tensioned. Of course, there is also Lanocote: http://www.forespar.com/products/boat-lubricant-lanocote.shtml
So, as usual, what I learned at the bike shop holds true: all threaded surfaces get either grease, oil, or Loctite, depending on the application.
I was going to offer my two cents but geeze, we sure got off the question of 304 vs 316. But 304 is stronger, and 316 is more stain resistant. Remember stainless means stains less.