Stainless Bolts

[IdoraKeeper]

Hello all,
I am replacing the chain plate bolts on Idora. She is an all wood Ingrid so the bolts are open to the air. What type of stainless should I be looking for when I buy fasteners?

Todd

[Cheechako]

316L would be best I think. However, where they go thru your hull they are not exposed to the air right? and being inside the wood they might be damp. Bronze might be nice..... Whats the size and length?

[casual]

Just did the same thing on my Cabo along with chain plates.I,used 316 stainless bolts and locking nuts.How many do u need,I,bought 50 as that was the only way Fastall sold them.`Give me the size and quanity,I,will never use them.

[Stumble]

Todd,

In closed areas like this where there is a possibility of water being trapped against the bolt, 316L is almost required if you go with stainless.

Of course I will try to sell you titanium, since it eliminates corrosion as a concern, and is much stronger. Plus our MOQ is typically 1, not 50, so they may actually be cheaper.

[Tristan]

Originally Posted by Stumble

Todd,

In closed areas like this where there is a possibility of water being trapped against the bolt, 316L is almost required if you go with stainless.

Of course I will try to sell you titanium, since it eliminates corrosion as a concern, and is much stronger. Plus our MOQ is typically 1, not 50, so they may actually be cheaper.

Titanium have ultimate tensile strength of about 63,000 psi (434 MPa), equal to that of common, low-grade steel alloys, but is 45% lighter.
T.

[clockwork orange]

I agree with Cheechaco, go with silicone bronze rather than SS, about the same strength without the corrosion issues, a great marine metal that is often overlooked.

Steve.

[Cheechako]

3/8 x 2.5 bronze Carriage bolts , about $3.20 each if you buy 50. (the price of bronze blows me away any more, what is the deal with copper prices?) Hex heads may be less.
Ti would be very nice too!

[Stumble]

Tristan,

I was actually thinking of CP2 which has a yield of 40,000psi vs 316L stainless at 29,700psi. But we could certainly go with G5 with a yield of 128,000psi for a little more. Siliconized bronze btw has a tensile strength of around 25,000psi depending on exacally which alloy you use.

Cheech,

Our MSRP price for a CP2 3/8-16 x 2 bolt is $8.54, for the same bolt in G5 it would be $10.33. Of course if you are talking about a quantity order, OR have a business you can order thru I can do much better pricing for commercial vendors, but I can't make those prices public.

So figure (if you need 12 bolts)
50x3.20=$160
12x8.54=$102.48
12x10.33=123.96

The break even point (where the bronze would actually cost you less) on this would be 19 bolts for the CP2, and 16 bolts on the G5.

I was going to price out some 316L bolts, but other than a few custom places I couldn't find an online price. I would guess they would be a little less than the bronze.

[Stumble]

I would also warn you about using siliconized bronze as chainplate bolts. Because SB is more anodic than the stainless plate and rigging, you could have a galvanic problem attacking the bolts. Ideally in a galvanic series you want the smaller part to be the cathode, and the larger to be the anode, since this spreads the corrosion over the largest possible area.

You have reversed this, with the smaller part taking the damage.

It is likely find forever, but I would keep an eye on it.

[clockwork orange]

Stumble, out of interest, what is the shear strength of, say, a 1" dia G5 bolt ?

Steve.

[Cheechako]

Originally Posted by clockwork orange

Stumble, out of interest, what is the shear strength of, say, a 1" dia G5 bolt ?

Steve.

enough to lift the whole boat!
I was assuming he's doing all chainplates (at least eight with maybe 5 bolts each?) Not sure..... In the end, Stainless makes sense. Probably last another 20+ years.....if installed well.
I dont think the shear strength is really a big factor whether Ti, SS or Bronze. For Instance, a 3/8 316SS bolt is listed at 10900 lbs. (one bolt) Most chain plates have 4-6 bolts.... so it's easy to see the redundancy. Probably more important that there are enough bolts to keep the plate secure to the hull without any movement. Incidentally, most data show 316 about the same strength as 304 in bolts; 40k yield and 80-105k ultimate for 316, and 40k yield and 85-125k ulitmate for 304. It does depend on whose data you look at though.

McMaster Carr 316 SS Hex Head 3/8-16 x 2.5" $10 for 5

[Stumble]

Originally Posted by clockwork orange

Stumble, out of interest, what is the shear strength of, say, a 1" dia G5 bolt ?

Steve.

Steve,

I haven't run into this question before so I would want to run it by an engineer to be honest. The best information I found is that the ultimate sheer strength is 79,800psi. So check my math, but...

A=(pie)r^2
A=3.14*.5^2
A=3.14*.25
A=.785

So 79,800*.785=62,643lbs.

I would absolutely not rely on these numbers. I am not an engineer, and didn't even stay in a Holliday Inn express last night.

[Cruiser2B]

Originally Posted by casual

Just did the same thing on my Cabo along with chain plates.I,used 316 stainless bolts and locking nuts.How many do u need,I,bought 50 as that was the only way Fastall sold them.`Give me the size and quanity,I,will never use them.

When I replaced my chainplates I used 304 SS. Mainly because they were not exposed to elements, and quite a bit cheaper than 316. One thing to watch for and I was worned was that not all 304 /316 bolts are equal. As with many things much of what we buy is sourced from China, SS hardware is no different. I went to a local specialized fasten dealer, B&S Bolt in Norfolk. They supply much of the military around these parts with mil-spec fasteners. A third party warned me about fastener from "chain" stores. They also sold me pieces in what ever quantity I needed not bulk which i think saved me money in the long run.
I am only posting this so you get good quality hardware. not some cheap stuff that won't last. My 40yr old 304 stainless hardware(i assume usa made at the time)came right apart when removing the chainplates. I upgraded the size of the bolts or else I would have reused the originals. just FYI for OP

[gjordan]

A slight thread drift, but maybe important? Is there an easy way to tell if your existing SS is 304 or 316??? I would assume replacing like for like would be OK. If it is Taiwan SS , all bets are off.____Grant.

[Cruiser2B]

Originally Posted by gjordan

A slight thread drift, but maybe important? Is there an easy way to tell if your existing SS is 304 or 316??? I would assume replacing like for like would be OK. If it is Taiwan SS , all bets are off.____Grant.

My 304 and 316 hardware had it engraved in the top of each bolt