please advise as to what grade / kind of stainless steel do i need for my chainplates-- what is the best -- i am going to go to a metal yard for fabrication of some spares and the replacement ones for this boat---
stainless steel expert advice needed, please....
- Thread starter zeehag
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Karen, for plates and non welded things, the best is 316 Stainless.. if anything is to be welded or heat worked, then 316 L Grade is the correct thing to use.. If welds are made, have them dye checked before you pick them up.
304 and 304L is OK but tends to show more rust stains.. again if welded or heat worked, L grade is a must to avoid cracking in later life..
Stuff is not cheap but ya might be able to find some in machine shops scraps.. look around the machine and welding shops that service the refineries in Torrance and Long Beach.. Don't recall shops in San Diego but there may be some that do govmint work that would have this in scraps.. Happy Hunting
304 and 304L is OK but tends to show more rust stains.. again if welded or heat worked, L grade is a must to avoid cracking in later life..
Stuff is not cheap but ya might be able to find some in machine shops scraps.. look around the machine and welding shops that service the refineries in Torrance and Long Beach.. Don't recall shops in San Diego but there may be some that do govmint work that would have this in scraps.. Happy Hunting
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For common 'stainless' use only 316 or 316L grade as its formulation better resists attack by halides (chlorine, etc.) which are the primary 'actors' of crevice corrosion.
Also if possible get the plates sanded & polished to a mirror bright finish, then electropolished if you have the extra $$$$.
... no sharp edges, no 'kinks', etc. even the drilled holes for the bolting attachment should have 'rounded' chamfers --- such will increase the fatigue resistance.
Lastly, go larger in cross section, if you have the extra $$$$ to spend.
Also if possible get the plates sanded & polished to a mirror bright finish, then electropolished if you have the extra $$$$.
... no sharp edges, no 'kinks', etc. even the drilled holes for the bolting attachment should have 'rounded' chamfers --- such will increase the fatigue resistance.
Lastly, go larger in cross section, if you have the extra $$$$ to spend.
thankyou claude!!! i greatly appreciate your information.
handy metal mart is across the bridge and has scraps--is why i am asking--i have to find them meself and then ask for drilling holes etc and if i am nice they do extras.
too bad titanium scraps dont exist lol--
so i need 316L as i need to shape them with bends to fit my spacing--- and as wide as possible and thickness too? so x" -long X x"-wide X 1/8"deep or so?
handy metal mart is across the bridge and has scraps--is why i am asking--i have to find them meself and then ask for drilling holes etc and if i am nice they do extras.
too bad titanium scraps dont exist lol--
so i need 316L as i need to shape them with bends to fit my spacing--- and as wide as possible and thickness too? so x" -long X x"-wide X 1/8"deep or so?
316 SS is the way to go..
Just wanted to introduce a little known fact - plain old zinc plated steel is actually stronger than 316 SS..
Zinc steel could be used no problem.. I use alot of zinc on my sailboat..
Just wanted to introduce a little known fact - plain old zinc plated steel is actually stronger than 316 SS..
Zinc steel could be used no problem.. I use alot of zinc on my sailboat..
Have you checked out Rig-rite for chain plates?
I would bet you can get something from them off the shelf for less that you can have something made up.
www.rigrite.com
I would bet you can get something from them off the shelf for less that you can have something made up.
www.rigrite.com
scrap metal made into stuff isnt really that pricey--and the metal mart is convenient access for me--just across the bridge-- they have goood metals reallllly cheap. i will check out the rigrite-- i think i will still come out ahead--i8 may change the angle of the bend fo the chainplates an the cap.
Ya Rite.. Not too bad if ya don't have to weld and do a lot of shaping.. "Alloy 20" would be really outstanding but it is REALLY expensive..but it does not crevice corrode. We used to use a lot in the refinery around sufuric acids and high chloride corrodents .. but 316 or 304 will stay nice and shiny and last a LONG time .. Be careful of places where water can be trapped on 304 or 316 and remain fliuid and stagnent.. like where a chainplate bolt may go thru from outside to inside and get washed with seawater.. If there is a leak into the space between the plate and hull and the plate and bolts, it will cause crevice corrosion in the stainless.. be sure to seal all that stuff very carefully (Maine's Butyl Tape) to keep from getting water trapped and held next to stainless.. Again, happy Hunting, Karen
quite a few years ago one of my customers showed me a kitchen cabinet door that she had somehow torn the lower hinge from. She was certain that the door was junk. I told her that I could fix it in a hour if she had some wood that I could use. She said "no wood". But she had a pile of fire wood. I selected a piece of oak and with power saw and hand plane cut a piece to fit the door after I had cut away the damage.
Just because a piece of steel isn't called a chain plate doesn't mean that it can't be a chain plate.
Just because a piece of steel isn't called a chain plate doesn't mean that it can't be a chain plate.
i have 2 nearly 60 degree bends if i dont change configuration.. if i run em thru the cap for externals, i dont have the bends. the teak can take it--is thin now-- and i wont have to block them, as i do with the 2 bends..
In case you haven't seen it all.....the guy in the slip next to replaced his chain plates with actual 3/8" SS chain.
In all actuality chain is probably the simplest and elegant method as the entire chainplate system is in PURE tension. Its when one applies bends, kinks, attachment holes, etc. that one radically weakens the load bearing capacity of the base metal.
Of all the builders of production boats, Beneteau who uses a simple stress 'straining rod system' in only pure tension for its chainplates is the most elegantly simple and most efficient stress design and in so doing will avoid 99.9% of the problems of needlessly 'stress complicated' design. As one who for many many years did stress analysis, almost every boat chainplate design I look at is amateurish, doesnt follow good/simple engineering principals, and is thus typically vulnerable to fatigue fracture/failure ... all due to BAD stress design. Beneteau is the only production boat builder who seems to actually 'know what they are doing' when it comes to 'chainplates' ... a chainplate system that is optimized and technically SAFE. Next time you are at a boat show, etc. take a very good look at the Beneteau plate system if you want to see 'good'. Beneteau engineers get an A++ from me.
The chain went through the deck and had silicone to seal it. I didn't see how it was connected inside. A comparable size chain doesn't seem as good as a solid bar chainplate. Chain seems to be somewhat point loaded, where a bolt in a tight hole has more surface area in contact.
Scott,
Point loading only occurs before any load is applied. Once the load is applied the material starts to elastically deform bringing more surface area into contact. Pretty simple math. For point loading the Area is close to zero so Stress = F/A. As A approaches zero stress approaches infinity. Infinite stress assures elastic and plastic deformation until the Area increases enough to handle the load. Stainless is highly ductile so the material deforms easily but it cold works also so once deformed it can't be easily worked any more without heat treating to remove the residual internal stresses. If point loading of a chain concerns you I'd get rid of the chain on your anchor :>) maybe replace it with a cable instead.
Point loading only occurs before any load is applied. Once the load is applied the material starts to elastically deform bringing more surface area into contact. Pretty simple math. For point loading the Area is close to zero so Stress = F/A. As A approaches zero stress approaches infinity. Infinite stress assures elastic and plastic deformation until the Area increases enough to handle the load. Stainless is highly ductile so the material deforms easily but it cold works also so once deformed it can't be easily worked any more without heat treating to remove the residual internal stresses. If point loading of a chain concerns you I'd get rid of the chain on your anchor :>) maybe replace it with a cable instead.
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