Chain Stoppers

[sy_gilana]

Has anyone designed a good chain stopper, before I re-invent the wheel.
The boat is 66,000 pounds (28000Kg) the chain is 1/2" or 13mm.
I have enough space. Here are my design considerations (worries)
1 Must not be light duty like most on offer in the shops.
2 Must bolt to deck in 6 or 8 places
3 Must NOT jam in the locked pos'n (ie not overcentered)
4 Must be able to clear the pawl completely with chain retrieval.
5 Must be able to release under load.

Current thinking is a chunk of 316 ss Channel, weld two bars inside as slide rails, drill sides of channel for pin holding a tri-angular block as the pawl with a lever welded on to raise it. No drawings, yet, just thinking...

[sabray]

I double wrap the windless and insert the hawsepipe pipe plate which is a heavy duty gate. If the snubbers give way that's plenty until I get topside.when underway I tie off the anchor. Not sure a stopper is much advantage. Your design seems good if you don't have arsenate methods. You wNt to be able to release the stop. A gate similar to a gate valve is pretty good at being able release under lload.

[Andrew Troup]

I did one built into bow roller, (pivoted in the forestay chainplate) -- as the anchor came onboard, it pushed the pawl "up and over", and the reverse side of the pawl was shaped so as to hook over the anchor shank (Bruce) and hold it down.

Pawl was plasma cut out of 16mm stainless plate

Good for single handing, as you could get back to the helm quickly if raising anchor in bad conditions, just by putting a single wrap of chain around the bitts, without worrying about the anchor breaking free.

[RabidRabbit]

For a while I was also looking for a really good chain stopper. I came to realize I used a rope snubber almost always, specially when the weather was really bad. I have a 2nd chain hook with a short 6' line I attach on deck, so if by chance the snubber brakes the maxwell winch won't ever see the load. My snubber is 5/8 x 45' but I normally put 20' out. For long term I use a Y bridle snubber with shackle.

[svHyLyte]

Originally Posted by sy_gilana

Has anyone designed a good chain stopper, before I re-invent the wheel.
The boat is 66,000 pounds (28000Kg) the chain is 1/2" or 13mm.
I have enough space. Here are my design considerations (worries)
1 Must not be light duty like most on offer in the shops.
2 Must bolt to deck in 6 or 8 places
3 Must NOT jam in the locked pos'n (ie not overcentered)
4 Must be able to clear the pawl completely with chain retrieval.
5 Must be able to release under load.

Current thinking is a chunk of 316 ss Channel, weld two bars inside as slide rails, drill sides of channel for pin holding a tri-angular block as the pawl with a lever welded on to raise it. No drawings, yet, just thinking...

Why reinvet the wheel. See Maxwell Winch Accessories

[RabidRabbit]

That seems pretty standard. Not sure if it could be released under load. Maxwell makes good stuff though.

[Albro359]

Why would you want to release it under load ?..perhaps someone can explain the need for that, I can't see it.

[sabray]

If the stopper is getting loaded it means your shock loading the chain and connection points I think that means it's ugly out and your snubber has parted. You need to add a new snubber and well if I'm doing that and the chain us loaded I'm putting the snubber up where I can reach the chain and letting off more chain. I wNt to reass the load. Why do you want a stopper?

[arisatx]

another variation:

USCG Chain Stopper, 316 Stainless Steel, Precision Cast

[s/v Jedi]

The Maxwell chain stopper saved our boat during a cat5 hurricane... a better recommendation doesn't exist

ciao!
Nick.

[Nicholson58]

Anchor Accessories

here are a few. Make sure thwy suit your need. I think some of these will be OK to keep the anchor on deck under way.

[Nicholson58]

Originally Posted by arisatx

another variation:

USCG Chain Stopper, 316 Stainless Steel, Precision Cast

at 810 boat-bucks - buy two and keep a spare.

[Andrew Troup]

Some people seem not to be concerned about the difference between a chain stopper of the USCG type and the self-acting, pawl type stopper which the OP intends to fit. The USCG type doesn't need to be bolted to the deck; it's just a more secure alternative to a devil's claw or chain hook. However it's anything but self-acting, so it's not really in competition for many of the same applications as a pawl.

Personally in USCG situations I just use an endless loop of climbing tape, hitched to the chain with a Kleimheist hitch (a prussic is nearly as good, and easier to remember). The advantage is that, apart from being about 0.2% of the cost, and 5% of the weight, it's easier on the chain, and if I have to 'cut and run' (originally a nautical term) I can literally do just that.

Thinking a bit more about this, I don't think my previous post (pawl on bow roller) is likely to be applicable – it was a good idea on a vessel small enough (in relation to crew numbers and strength) that the anchor could realistically be weighed, even in bad conditions, by human effort, provided there was a self-acting and efficient pawl to prevent losing hard won gains, and enable resting between heaves.

Of course you can always clap on a line and lead it to a primary winch to multiply the 'human effort', even on a maxi-yacht ... in fact this is what was done on sailing ships when the warp was too big for the capstan drum, and still is on modern maxi racing yachts which don't have a windlass.

However, if you're in this situation, it's usually not that much harder to use two lines and hold with one while shifting the nip of the other – hence no strict need for a pawl-type stopper. (Once again, a Kleimheist sling at the end of the haul line is excellent for this job, on rope or chain – you don't have to untie it to move it, just loosen it)

Seems to me it would pay the OP to add a few more lines to your "brief to self", covering the exact purpose of your intended use, detailing the situations calling for releasing under load, and thinking about contingencies (what if the windlass seizes or strips: how do you lower the anchor under control in deep water or strong wind)

If, for instance, you're into expedition sailing, this last consideration might be quite important to you. In such a case you might want to think about a chain brake upstream or downstream of the pawl, in your channel: one common design is a cover plate, on parallel arms, which can squash down on the chain (operated by chain or lever) to control its runout.

Commercial offerings tend to be only in larger sizes, such as this one from Maxwell, which has a multiplicity of additional features
http://www.maxwellmarine.com/super_a...s.php?deckgear
see "Chain compressor"

IF it's downstream of the pawl, you can consider using a chain brake in lieu of a pawl able to be disengaged under load, saving quite a lot of complication and the need for rather more finesse in the pawl mechanism. In this layout, when your anchor is set, you can apply them both, but leave the chain a little slack between brake and pawl, using the latter solely as a backup if the brake should slip or fail. (And of course as a backup when raising the anchor by whatever means)

[Andrew Troup]

Correction to my post above :
should have read "operated by SCREW or lever" not "chain or lever"

On smaller vessels with lighter gear, the chain can of course be braked, in the absence of a usable windlass, by judicious use of the sole of a sturdy boot.

[sy_gilana]

Thanks for all the input guys. The Maxwell one looks good, and is close to ideal. I would like to make it a tad longer. The deck where I want to fit it, is only 4mm steel with 25mm teak on top. That means that the bolts will not be acting in shear. They will have a bending component, introduced by the soft wood keeping the stopper baseplate an inch away from the steel. The windlass and its associated cleats is on 8mm steel plate, and there, four bolts will be adequate (Maxwell) SO, I would like to have 6 or 8 bolts keeping on the deck.

I think I have enough to go on now, and thanks for the links.

Just to clarify, I attach a photo of the location, this photo was a rare occasion that we had four anchors out because it was a tight anchorage in a current just south of the Phil Foster Bridge (Blue Heron) The locationof the stopper will be where the Teak wear strip is visible under the chain.

To answer a question above as to "WHY", well to prevent a repeat of a situation we had, that could have been a disaster. We usually have a chain claw with 1 1/2" nylon to two deck cleats. We do not use a snubber.

We were in a storm of 60 knots sustained, gusting 80. We were at anchor and sitting quite nicely when a large steel ketch started getting closer from upwind. We decided that we had to move, as we were in his path, and we were not convinced of his ability to correct the situation.

We started engine, and I went up on the foredeck to recover chain while Laura was at the helm, our normal method. It was difficult to judge the way on forward as the sea surface disappears in these winds, covered in a layer of spray. To Laura it looked like we were doing 10 knots, and the engine revs would indicate that too, except that the wind was holding us back. I signalled her to make more turns and she did. Now I was able to recover chain as we motored ahead, so I slipped the chain claw and engaged the windlass to recover chain. Whether by a side gust, or by over-running the chain, we landed up bearing off while the wind was screaming through the rigging, difficult to see, salt in my eyes, we landed up with the chain pulling about 30 degrees off to Stbd. By now the increased windage on the hull cause the boat to sail ahead. I signalled Laura to bring the head to weather. This caused us to fall back and to pull hard on the chain, it was bar-taut as a shallow angle to the sea, and all of that force was on the windlass! The windlass started unwinding backwards and the electricity generated was going to the batteries, but exceeded the amperage of the circuit breaker, which tripped. Now I had to leave the forepeak, crawl back to the companionway, go below, reset it, after applying the claw to a moving chain. Fortunately Laura brought her up to weather and managed to balance engine against wind.

It could have been very messy, and as always its a combination of problems that causes a disaster. We want to prevent this in the future and so, a means of preventing the chain pulling on the windlass directly is the design need. The ONLY time the windlass must 'feel' the chain is when recovering it.

Hope this answers those who asked "WHY"

regards.
Mike&Laura