Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 26-04-2016, 09:20   #16
Writing Full-Time Since 2014
 
thinwater's Avatar

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 4,339
Re: Chain Stopper Vs Devil's Claw

Quote:
Originally Posted by a64pilot View Post
...
I wonder if the average dock cleat would hold? If a Sampson post were very well secured, surely nothing would be stronger than that?
Given that most of the Samson posts I've seen were just bolted to the deck and have more leverage (are taller) than cleats, I would not leap to that conclusion. Back in the day they were timbers taken to the keel, but that will only be the case if you build it that way.

Seems to me, that if you do not trust the cleats, the simplest way to generate massive strength is a flat chain plate on the deck. Obvious, just not typical.
__________________

__________________
Gear Testing--Engineering--Sailing

Writing full-time since 2014.
Bookstore:http://sail-delmarva.blogspot.com/20...ook-store.html
thinwater is offline   Reply With Quote
Old 26-04-2016, 09:43   #17
Registered User
 
Panope's Avatar

Join Date: Sep 2012
Location: Washington State
Boat: Colvin, Saugeen Witch (Aluminum), 34'
Posts: 1,593
Re: Chain Stopper Vs Devil's Claw

In the event that the sampson post is not in the best position, A long, low tang will meet the needed strength (without a pole intruding into the space below) provided the load is horizontal and very close to deck level. A tang like this can be placed virtually anywhere.

Steve

I need to replace this shackle with something cut-able l like a soft shackle.


__________________

Panope is online now   Reply With Quote
Old 26-04-2016, 09:58   #18
Registered User
 
Island Time O25's Avatar

Join Date: Sep 2014
Posts: 2,019
Re: Chain Stopper Vs Devil's Claw

This may sound naive (stupid?) but I'll ask anyway. What if the windlass and the structure it is bolted to are the strongest pieces at your bow - do you still want the load off of them?

When we installed the older heavy duty Nielsen H700 we epoxied several 1/4" layers of G10 (2 but possibly 3, I will check next time I'm at the boat) and the G10 plates were about 3-4" larger all around than the foot print of the windlass. The back up plate is not just around the bolts, it is a large piece which is way larger than the windlass' footprint. We did the same for the cleats but the G10 backing plates were about 1-2" outside the cleat's footprint as there was no space for more. And there is very little room on deck for a robust stopper's backing plate.

For now I am using the method described by one of the previous posters i.e. 2 nylon ropes with hooks which go from chain to cleats. But being a fair weather sailor for now (one of Admiral's requests at this point but I'm working on it )) ) I don't really anchor during severe weather, etc. so this set up for now is fine for short excursions on shore when away from my mooring, etc. But I wonder if being the strongest attachment at the bow, the windlass may not be the worst possible place to use as a stopper in addition to the stopper or is it anyway?
__________________
Island Time O25 is offline   Reply With Quote
Old 26-04-2016, 10:00   #19
Registered User
 
Stu Jackson's Avatar

Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 6,389
Re: Chain Stopper Vs Devil's Claw

Steve, does the windlass lift the chain out of the hook when it is engaged, orr do you have to do it manually? Nice setup, thanks for the pictures.
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
Stu Jackson is online now   Reply With Quote
Old 26-04-2016, 10:06   #20
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2010
Location: Cruising Indian Ocean / Red Sea - home is Zimbabwe
Boat: V45
Posts: 1,282
Re: Chain Stopper Vs Devil's Claw

Interesting......see the last edition of Practical Sailor. There are several caveats about the design of chain hooks including the Mantus which has a 'sharp' edge on the inner face which testing demonstrated significantly reduces the strength of the chain. Scary - proceed with caution!!


Quote:
Originally Posted by Dockhead View Post
Thinking about my still hypothetical future boat, and about the ground tackle handling arrangements.

I'm for sure going to have a massive horizontal windlass with a vertical warping drum, and a sturdy samson post, stronger than the breaking strength of whatever chain I'm using.

But what's the best way to belay the chain? A chain stopper is the obvious answer, but it seems to me that it might be hard to achieve the desired level of strength, since it's just bolted to the foredeck. Maybe it's better to use a devil's claw made off at the samson post? That's certainly the way it would be done on a commercial vessel. Add a hyfield lever to it and it will also hold the anchor in the roller. A bit more work than a chain stopper, though.

What do you guys think?
__________________
Bulawayo is offline   Reply With Quote
Old 26-04-2016, 10:48   #21
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,057
Re: Chain Stopper Vs Devil's Claw

Quote:
Originally Posted by thinwater View Post
Given that most of the Samson posts I've seen were just bolted to the deck and have more leverage (are taller) than cleats, I would not leap to that conclusion. Back in the day they were timbers taken to the keel, but that will only be the case if you build it that way.

Seems to me, that if you do not trust the cleats, the simplest way to generate massive strength is a flat chain plate on the deck. Obvious, just not typical.


I think due to hull geometry and the backing plates, my cleats are strong, but I don't think that is always the case, I've seen thin fender washers on some.
Far as Sampson post, here I believe we are talking about Dockhead designing a custom boat, and one assumes due diligence would be done as far as structure, to mount a Sampson post on my boat would not be practical I don't think as there just isn't enough space, I'll just have to rely on my cleats.

I was interested when I heard someone had busted anchor chains, I've asked that here and got no response, and I've asked around if anyone has stretched chain to the point of it being un-serviceable as of course it stretches before it breaks, I've stretched many a chain with a Bulldozer, but never seen it with anchor chain.
My concern being with a 25,000 lb boat, is my chain that is only good for half that, enough?
__________________
a64pilot is offline   Reply With Quote
Old 26-04-2016, 11:36   #22
Registered User
 
Panope's Avatar

Join Date: Sep 2012
Location: Washington State
Boat: Colvin, Saugeen Witch (Aluminum), 34'
Posts: 1,593
Re: Chain Stopper Vs Devil's Claw

Quote:
Originally Posted by Stu Jackson View Post
Steve, does the windlass lift the chain out of the hook when it is engaged, orr do you have to do it manually? Nice setup, thanks for the pictures.
Thanks, Stu. The windlass will not lift the chain out of the hook. What happens, is the hook pivots and follows the chain. I disengage the hook by first relieving the tension with the windlass, and then give a quick kick to the chain with the bottom of my foot. Hook falls right off and I don't even have to bend over.

Steve
Panope is online now   Reply With Quote
Old 26-04-2016, 12:31   #23
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,751
Re: Chain Stopper Vs Devil's Claw

Quote:
Originally Posted by Panope View Post
In the event that the sampson post is not in the best position, A long, low tang will meet the needed strength (without a pole intruding into the space below) provided the load is horizontal and very close to deck level. A tang like this can be placed virtually anywhere.

Steve

I need to replace this shackle with something cut-able l like a soft shackle.


An excellent foredeck!

In all respects. Very much what I want my next boat's foredeck to look like. Where does the second chain go? Is that a hawse pipe?

Advantages of metal construction very evident here.
__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 26-04-2016, 12:50   #24
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,751
Re: Chain Stopper Vs Devil's Claw

Quote:
Originally Posted by a64pilot View Post
I think due to hull geometry and the backing plates, my cleats are strong, but I don't think that is always the case, I've seen thin fender washers on some.
Far as Sampson post, here I believe we are talking about Dockhead designing a custom boat, and one assumes due diligence would be done as far as structure, to mount a Sampson post on my boat would not be practical I don't think as there just isn't enough space, I'll just have to rely on my cleats.

I was interested when I heard someone had busted anchor chains, I've asked that here and got no response, and I've asked around if anyone has stretched chain to the point of it being un-serviceable as of course it stretches before it breaks, I've stretched many a chain with a Bulldozer, but never seen it with anchor chain.
My concern being with a 25,000 lb boat, is my chain that is only good for half that, enough?
For whatever it may be worth, the proportion between mass of my boat and breaking strength of my chain is about that same as that. You're not going to lift your boat with it; it only has to resist the maximum force of wind and waves operating against the maximum holding power of your anchor, plus a margin for snatch loads.

I don't know about your cleats, but one would surely hope that they would hold a few tons without ripping out. Otherwise they're no good for mooring to a dock, either. Island Piglets have a very good reputation for strong construction, and I've never heard of any problems with cleats or any other structural issues of any kind, so I'm sure you're fine using your cleats.


Metal construction sure simplifies many of these structural issues. I just spent a couple of thousand dollars having Lallows construct permanent twings for my blade jib -- which required through bolting and all kinds of nonsense (the bill also included redesigning and rebuilding my stanchion gates, however, so it wasn't all twings). If my boat were metal, I'd have had solid twings with 10 minutes of welding, plus strong padeyes basically anywhere I need them.
__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 26-04-2016, 15:29   #25
Registered User
 
Panope's Avatar

Join Date: Sep 2012
Location: Washington State
Boat: Colvin, Saugeen Witch (Aluminum), 34'
Posts: 1,593
Re: Chain Stopper Vs Devil's Claw

Quote:
Originally Posted by Dockhead View Post
An excellent foredeck!

In all respects. Very much what I want my next boat's foredeck to look like. Where does the second chain go? Is that a hawse pipe?

Advantages of metal construction very evident here.
Thanks Dock. Yes, that is a hawse pipe for my old school, hairy chested, no bendy, Forfjord anchor. Does not get much use.

I've said it before and I'll say it again: The reason to have a metal boat is not because of the hull. The reason to have a metal boat is because of the DECK

Steve

Panope is online now   Reply With Quote
Old 26-04-2016, 15:37   #26
Registered User
 
Snowpetrel's Avatar

Join Date: Jul 2012
Location: Hobart
Boat: Alloy Peterson 40
Posts: 3,071
Re: Chain Stopper Vs Devil's Claw

Quote:
Originally Posted by a64pilot View Post
I was interested when I heard someone had busted anchor chains, I've asked that here and got no response, and I've asked around if anyone has stretched chain to the point of it being un-serviceable as of course it stretches before it breaks, I've stretched many a chain with a Bulldozer, but never seen it with anchor chain.
My concern being with a 25,000 lb boat, is my chain that is only good for half that, enough?
We broke my folks chain twice when I was a kid. Big 20 tonne gaff ketch. We only had 30 or 35 meters of very dodgy old longlink chain. I suspect the welds weren't very good, because the broken link seemed to just open up without much distortion in any other links.

Back then nobody was using snubbers, and in both cases it was anchored in open roadsteads in very nasty conditions with a huge danforth in sand, and not really enough scope out. We lost the anchor once, the other time miraculously the link didn't open up fully and we spotted it as we raised the anchor.

A friend also broke 6mm chain on his 28 footer, but I think it was just plain undersized.
__________________
My Ramblings
Snowpetrel is offline   Reply With Quote
Old 26-04-2016, 17:03   #27
Senior Cruiser
 
Jim Cate's Avatar

Cruisers Forum Supporter

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 11,461
Re: Chain Stopper Vs Devil's Claw

Chain failure is pretty rare in the cruising world. We've only seen it twice in all our years. One case was a world-class cheapskate who bought the chain from a Mexican shrimper who had retired it due to excessive rust (go figger!). The other was on a 72 foot ferro cement square rigger of unknown but massive displacement. The chain was 1/2 inch, attached to a huge Danforth buried in firm sand during cyclone Lisa... 60 kts sustained, big bullets from cliffs around us... and NO SNUBBER.

Both of these cases are well outside normal practice... in fact approaching idiocy, and fail to convince me that chain breakage is a likely event for the prudent cruiser!

Jim
__________________
Jim and Ann s/v Insatiable II , lying Port Cygnet, Tasmania once again
Jim Cate is offline   Reply With Quote
Old 26-04-2016, 17:39   #28
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,057
Re: Chain Stopper Vs Devil's Claw

Good to know about the chains, I had assumed chain failure was very rare based on I haven't seen any stretched, and good chain will stretch so that you can hold several feet of it straight out before it breaks, and that was grade 70 transport chain, which ought to be more brittle than grade 40.

Dockhead being metal does not necessarily mean strength, yes you can weld to it, but unless there is significant structure, you may just peel the deck back, and overbuilding of course means excessive weight. I know you know this of course.
Being a an oilfield contract welder in my youth, I really wanted a steel boat myself, I like steel, give me a decent Tig machine and I could fix anything on a steel boat.


Sent from my iPad Pro using Cruisers Sailing Forum
__________________
a64pilot is offline   Reply With Quote
Old 26-04-2016, 17:48   #29
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Re: Chain Stopper Vs Devil's Claw

A chain stopper is not quite the same as a strop with a chain hook. The latter is a perfectly satisfactory arrangement, but a chain stopper works differently and acts like a rope clutch. It will allow the chain to be pulled in with little resistance, but locks as soon as the chain tries to move in the other direction.

The major advantage of a chain stopper is when trying to retrevive the anchor with some wave action. In some situations it can be difficult to avoid a high load on the windlass. A chain stopper solves the problem, allowing the windlass clutch to be left reasonably loose.

The drawback is that a chain stopper needs to be very strongly mounted to perform this task. There also needs to be enough room between the windlass and bow. The chain stopper needs to be to the rear of the shackles or swivels. It also (very slightly) adds some wear to galvanising each time the chain is retrieved.

The Muir chain stoppers have the option of a Devils Claw. This is used to tighten the chain when the anchor is on the bow roller.

__________________
noelex 77 is offline   Reply With Quote
Old 26-04-2016, 19:40   #30
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Boat: Outbound 44
Posts: 4,583
Re: Chain Stopper Vs Devil's Claw

Quote:
Originally Posted by a64pilot View Post
Burst strength for 5/8 nylon three stand I think is about 12,000 lbs. I run two lines but I know load is not always split evenly.
I believe the WLL for grade 43 5/16" chain that I have is 3,900 lbs and that breaking point for grade 43 chain is three times WLL? If so that means my chain is only good for 11,700 lbs. or about the same as the line.
Either way I don't think a stopper will hold against anything that will burst the nylon line, gotta think the shock load would rip it out if nothing else?
I would think a second line would be the way to go, first line bursts, second catches it, allowing you to set a third?
I wonder if the average dock cleat would hold? If a Sampson post were very well secured, surely nothing would be stronger than that?
A,
Using the burst strength of the various components is a large simplification. In reality the system is dynamic, not static. If you burst your snubber, then it has absorbed a lot of energy in the process. Maybe enough to save the chain and then fallback to the chain stopper -- till you can get another snubber in place. I've snapped 5/8" brait snubber before, while all the other components held fine and were undamaged..
__________________

__________________
Paul L
http://svjeorgia.blogspot.com
Paul L is offline   Reply With Quote
Reply

Tags
claw

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Who likes their chain stopper? I need a recommendation for 3/8's chain... Pipeline Anchoring & Mooring 16 06-08-2014 13:00
Chain stopper for anchor chain sbrin Construction, Maintenance & Refit 8 19-07-2014 03:26
For Sale: Chrome chain stopper- 5/16 (8mm) chain Bristol30 Classifieds Archive 7 12-12-2012 08:41
Looking for a Devil's Claw with Positive Lock KevinE Anchoring & Mooring 60 13-08-2011 15:30
Does Chain Stopper Wear / Damage Chain ? nitpik Anchoring & Mooring 29 25-02-2010 12:51



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 08:46.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.