Chain Stopper Install

[Terra Nova]

If they are counterbored holes they must fit Allen head cap screws.

[Frankly]

If you get back into the practical world where the chain stopper is to keep the anchor in the roller rather than an end of the world chain anchor termination, then might want to consider "bonded fasteners". This is a technique developed by the Gougeon Brothers (West Epoxy Fame). My copy "The Gougeon Brothers on Boat Construction" dates back to 1979. They list the SHEAR withdrawal values for a 3/8" machine bolt bonded in wood as 1374 lbs (detectable movement), 2180 lbs (movement less than pencil line), and 2638 lbs (1/8" movement). That bow structure is marine grade fir plywood sandwiched between heavy glass layup with 3/4" teak on top. Multiply those numbers by 4 and you are in the chain ultimate BS ball park. The bonded fasteners also eliminate the water intrusion issues into a location that IP used a wood core that is not repairable (no small consideration).

A later copy of the above book is available free on line from West. Not sure that all the original fastener load test info made it into the later editions.

Coat the machine screws with mold release and you can remove them later just like they were tapped in whatever.

Frankly

[geoleo]

I had a chain stopper POS!

[a64pilot]

Frankly,
This is what someone else posted, amounts to I believe if you have 6" 3/8" bolts to drilling a 3/8" hole slightly deeper than six inches, then coming back and drilling say a .5" hole 5.75" deep, threading in the threaded end of the bolt into the wood to hold it straight and pouring the cavity full of epoxy? Thing is the bolts would have to be removable as I don't see any way the epoxy could be poured with the stopper installed, you would have to pour with just bolts, then remove them and install the stopper. Maybe thread on an insert first, then put the two in the hole, that way you have a threaded insert epoxied in?

I see the logic, sort of building your own insert, but which Epoxy specifically? No kind of filler I assume? I am paranoid of water intrusion, in truth the fear of wet decks had a lot to do with my choice of boat.

I checked with the Machinist here at work and they have drill guides they can lend me, essentially a 2" thick bar that you place hardened inserts into, I think I can drill straight holes with that as a guide.

[Frankly]

With a drill press and a piece of 2" wood you should be able to make a accurate enough drill guide. Just clamp the drill guide on top of the teak cap and drill the pilot holes for the bolt diameter. Then come back and drill the oversize holes at a little less depth. 6" for 3/8" fasteners strikes me as overkill depthwise. If you coat the machine bolts with a good wax or mold release then you can back them out after the epoxy cures. One other little trick for the shear case is to include a flush mounted machine nut in the top of the pour. If you don't get it filled the first time do it in two stages.

I have used the original West epoxy for more years than I can remember. Mixing portions are critical (Use their pump attachments) and the plastic syringes are handy for this type of op. Get everything ready before mixing and if you have not played with epoxy might run a test project before you attack the yacht. I would tend to stay away from the new Gflex stuff as it is intended for different applications.

Download a copy of the book from their website and read the chapter on hardware bonding. They hang keels on yachts with this stuff and no backing nuts.

I added a 12" SS cleat right in the middle of my bowsprit. My teak runs a little father back so my windlass is aft and the cleat is probably just about where your windlass is located so it is thru bolted. I still jumped through the epoxy loop because there ain't no replacing that wood in the bowsprit.

A proper cruising yacht should carry a little epoxy for whatever.

[a64pilot]

I've done a lot of work with Epoxy, and even have tubes of it here at work that is sort of strange looking, you put them into a side by side caulking gun that presses both tubes and the resin and hardener run through a swirl tube that attaches to both tubes so it comes out mixed. We attach the Hopper gatebox on our airplane with Epoxy as Epoxy is resistant to almost all chemicals.
So regular West is I assume slow set, thin Epoxy, pot life of at least an hour?

The 6" number came from nowhere, just an example.
How, or why would you put a machine nut at the top? And I assume this would be a nut that the bolt does not thread through unless you use all thread?

I'm thinking also to Epoxy in all thread and essentially have studs that you put nuts on as opposed to bolts? I generally dislike all thread though, I believe it is weaker, but four 3/8 pieces in shear ought to be stronger than a 5/16" chain in tension.

I need to ensure a nut will fit into the counterbore first though.

[Frankly]

In shear the likely failure mode is wood (teak in this arrangement) in compression. WEST Epoxy was originally developed to improve on the structural features of wood and the Gougeon brothers did a lot of testing to see what they had. Does that mean that any epoxy won't work, probably not. WEST stands for wettable epoxy saturation technique and the standard 105 is pretty fluid to penetrate the wood cells.

Just glued (epoxied) some black walnut for a rocking chair this morning. Waiting for it to cure as I type this.

The idea of the recessed machine nut is to enlarge the compression area of the teak, not the toughest wood around. The hole for the nut could be slightly larger but just counter bored to the nut thickness. Yes the machine screw or all thread would thread through the nut.

If you geometry can make all thread work with top nuts that would be the easiest. Life will better if you get your hands on 316 SS whatever the outcome.

[a64pilot]

The Stopper is investment cast 316, I have some all thread I ordered that is 316, but I think 5/16" for the Windlass install.
It's not very expensive at all. No reason not to do 316.
West 105, that was what I was looking for, which West Epoxy?

I think I will use All Thread and make them function like studs, if the counter bore is too small for a full sized nut, I believe I can have it counter bored so one will fit.

[a64pilot]

Local Fastenal will have three ft of 316 SS fine thread here on Fri. for $16.
No reason I can see to not use 316

[Three Sisters]

I've done this type of installation before with bronze backing plates upper and lower. Drilling both plates clamped together was key. The epoxy slurry ran all over the place below during installation but provided the intended outcome.

Is this your chainstopper ? It's an 8mm.

[a64pilot]

No, it's this one, now I'm concerned that a 3/8" nut which I believe will take a 9/16 nut will not fit into the counterbore and if I shim it up with washers, if it will interfere with the chain.
I'll figure something out, not much goes as planned

http://www.lewmar.com/node/11663


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[model 10]

Originally Posted by a64pilot

Local Fastenal will have three ft of 316 SS fine thread here on Fri. for $16.
No reason I can see to not use 316

I didn't catch you were using fine thread. Get some "reduced wrenching" nuts from your parts dept.

[a64pilot]

what are reduced wrenching nuts?
I like fine thread, since I can chose I went that way.
I may have to go down to 5/16 if I can't get a nut into the counter bore.


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[a64pilot]

OK looked them up, used them all my life and never knew the name, but your right, they may just be the ticket, and the high temp ones that are silver plated may be corrosion resistant. I don't know why I didn't think of them myself.
Thank you.
Heck you guys have come up with a solution to all the issues so far.


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[Three Sisters]

Your concerns were clear after viewing the link. Looks like you are approaching installation. All the Best.