Chain Stopper Install

[Dockhead]

Originally Posted by noelex 77

This is a good option, but it is not quite the same as the sort of chain stopper that A64 is considering fixing. A bolt-on deck chain stopper has the advantage that it is a one way clutch. It is always in place, preventing a snatch load on the windlass, a bit like a rope clutch that leads to a sheet winch.

There are times when this can be useful, such as when retrieving the anchor with a lot of wave action, or if the chain is stuck under a rock, or if the windlass fails and you have to retrieve the chain by hand/sheet winch.

With a bolt-on deck chain stopper, it will automatically lock in place even when a few links of chain are retrieved. It is often not practical to adjust a strop and chain hook like this.

There are also some significant disadvantages to a bolt-on deck chain stopper. It needs a very strong deck connection and a very strong bowsprit. If it locks in place while the anchor is being retrieved at a short scope with some wave action the loads on the chain stopper and bowsprit can be enormous if a wave lifts the bow. Most fibreglass boats do not have a strong enough attachment point and bow roller for this. There is also some wear on the galvanising of the chain and finally, the distance between the end of the anchor shank and the windlass is too short to install a chain stopper on many boats.

However, if you have a bolt-on deck chain stopper, you can always pull the pin on the paw disabling it, so you have the advantage of both options.

I also agree that in A64's case, the bolt-on deck chain stopper may be more trouble than it worth. Weakening of the bowsprit, even slightly, needs to be considered.

I agree with all of that, and it's an advantage of chain stoppers vs strops that they stop the chain automatically while you are retrieving the chain.

I've cruised 15 years with a chain stopper and 8 years or so with a strop, so have a good bit of experience with both. In my experience, the lack of automatic action of a strop is not a big disadvantage. It is not a big deal to put the hook back on when you need to back down on the anchor or start breaking the anchor out. Meanwhile the windlass clutch -- if properly adjusted! -- will protect the windlass.

[Tayana42]

a64pilot, with all the good advice and technical engineering suggestions you've gotten I hesitate to add anything, but... In my case I don't have room for a bolt on chain stopper so I use a chain hook on a rope taken back to a strong point to take the load off the windlass every time before backing down and as a back up to my snubber(s). Cheap, easy, strong, no holes through my deck (or your bow sprit).

On edit: I see Dockhead beat me to it regarding use of a strop.

S/V B'Shert

[Terra Nova]

no--good post.

Originally Posted by noelex 77

...you can always pull the pin on the paw disabling it, so you have the advantage of both options...

Most/all chain stoppers provide for their own disabling by simply flipping the claw out of the way. And so it isn't required to remove anything, just flip a lever, usually. Just like a circuit breaker...ON/OFF.

[a64pilot]

The four snubbers or twin bridles would only come out in the event of a major storm, normally I use one bridle and since I leave the loops on the ends, takes just seconds to attach to the bow cleats.
In truth is was a way to try to not have a chain stopper from ever being deployed, I just have to think with nothing absorbing shocks, failure of something would be imminent.

Why Dynema, isn't that shock wise sort of like steel cable?

On edit I found out yesterday when breaking out the anchor that I had set really well, that my windlass clutch will indeed begin to let chain out with my engine at 1500 RPM, well below what I think the windlass is capable of standing, so the clutch is a fuse of sorts.


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[Dockhead]

Originally Posted by a64pilot

. . .Why Dynema, isn't that shock wise sort of like steel cable? . . .

Yes -- Dyneema no good as a snubber.

But Dyneema is highly chafe resistant, easy to splice, and very strong, so perfect for a strop.

[a64pilot]

OK the holes in this thing using calipers measure .415" , so unless it's something metric, I assume it's meant for 3/8" bolts, that should be .375? Seems to be a lot of clearance ?


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[Terra Nova]

It is probably meant for 10mm fasteners. But 3/8" will be close enough.

[a64pilot]

OK I can see Dynema used if your trying to break it out, any other time you would want or need a strop for an anchor?
Normal anchoring I can break it out pretty easy, just that night before the Hurricane I did everything I could to dig it in, a couple of min full throttle reverse moving heading as much as I could to get it dug in, bottom had a lot of mud, and buddy let me tell you, it dug in . I had a shackle and 25' of line and a small bumper tied to the line as a float just in case I couldn't get it back, idea was to winch it out backwards. But a little throttle and changing heading pulled it free.


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[a64pilot]

Originally Posted by Terra Nova

It is probably meant for 10mm fasteners. But 3/8" will be close enough.

I'm going to take it to work and see if I can't talk a machinist into making me a drill guide out of aluminum, I figure a 4' block of aluminum with a matching hole pattern and I should be able to drill straight holes so I could use a backing plate. Sprit is not 8" either, that was a guess, but now I'm here it looks to be more like 5 or 6, but tapered on the bottom


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[stillbuilding]

Have had to use the sheet winches to pull a heavy anchor up several times. A chain stop makes this much more effective than moving fore and aft to clamp the chain, reattach the line and then pull again.


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[jongleur]

I agree with whoever said that drilling
through your sprit might change the
strength/dynamics of it. Especially
4 holes so close to one another.

Also, the base of the chain stoppers
I have seen require a countersunk
head of a bolt to allow the chain to
run fair. No allthread and nut could
fit in that space.

Would be nice to see a pic your bow
set-up so we can get a better idea
of what you're up against.

[Terra Nova]

Originally Posted by jongleur

...drilling through your sprit might change the
strength/dynamics of it...

Not on his boat (IP38).

[Steve Bean]

I recently made ten flat-head bolts using SS all-thread for my sheet winch installation. I ground the nuts to match the shape of a flat-head bolt, sawed a slot in the end of the all- thread so I could hold it with a screwdriver, and installed the nut on the all- thread. Then I peened it to secure the nut.

[Terra Nova]

Originally Posted by Steve Bean

...I ground the nuts to match the shape of a flat-head bolt...

I would not do this on anything subject to high loading.

[a64pilot]

The holes are counter bored pretty deep, I feel sure a bolt head and flat washer will fit in the counter bored holes, although it may take a very thin walled socket to hold the bolt heads, or even the screwdriver trick, but I'd rather a socket fit, cause one day someone may be removing this thing
I'm going to drive on with thru bolting it, I just don't like lag bolts and keeping it water tight.
Best photo I have, I took it with the 40 kg Rocna to see what it looked like, but it gives an idea anyway.


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