Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 19-03-2016, 12:39   #76
Moderator
 
Don C L's Avatar

Join Date: Sep 2014
Location: Channel Islands, CA
Boat: 1962 Columbia 29 MK 1 #37
Posts: 4,381
Images: 34
Re: Challenge: Anchoring on Slanted Bottom

Quote:
Originally Posted by Muckle Flugga View Post
Well, the swivel itself only takes full load if all the catenary is lost. I rate Kongs but they are expensive. TBH failing them I would tend to agree with Boatie. However… they do in fact do a good service, which is to stop the chain roll from tripping the anchor, as can happen if it is heavily bunched up and exerting an axial load on the anchor shank. It also renders the likelihood of bunching somewhat lower.
Yes, I do see the reasoning behind the swivel, but I just have never seen it work out that way in real life. I have never seen an anchor respond to the axial loading more than the actual digging into the bottom, and as the anchor is being lowered, unless it is being dumped as a lump, it has time and length to work itself out, if it is so inclined. If someone is dumping a lump of chain on their anchor, they have much bigger problems than a swivel can sort out, no? I realize when you say "bunching" you are not necessarily referring to a pile of chain on the anchor though. I just think that tangles will probably sort themselves out after 75 or 100', or less, has been laid out. BTW, as I'm sure you probably know, that stud-link chain is made to both increase strength and to avoid the tangles of bunching... not commonly found on yachts though...in fact I don't think I have ever seen it on boats under 100'!
__________________

__________________
DL
Pythagoras
1962 Columbia 29 MKI #37
Don C L is online now   Reply With Quote
Old 19-03-2016, 13:00   #77
Freelance Delivery Skipper..
 
boatman61's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Jan 2010
Location: UK/Portugal
Posts: 20,203
Images: 2
Send a message via Skype™ to boatman61
pirate Re: Challenge: Anchoring on Slanted Bottom

I find the twisting/bunching only happens in certain situations and generally when anchored in one spot for a long time.. weeks on end of 180's with the anchor dug deep into clay bottoms.
In the OP's case however the swivel is at the top and not down on the shank so its not subjected to the wear and tear I described.
__________________


Born To Be Wild
boatman61 is online now   Reply With Quote
Old 19-03-2016, 13:13   #78
Do… or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 9,198
Re: Challenge: Anchoring on Slanted Bottom

Trouble free swivel:


Connecting link G7 rating and passing the windlass without trouble:
__________________
s/v Jedi is offline   Reply With Quote
Old 28-03-2016, 06:12   #79
Registered User

Join Date: Sep 2010
Posts: 844
Images: 1
New "Double Snubber" + Pics

Quote:
Originally Posted by Gone2long View Post
OK,

So everyone has probably heard the various formulas: 5 to 1 rode, more in bad conditions, chain as long or longer than your boat, etc. And, we have heard the various disagreements about some of the formulas.

My challenge is as follows: Lets say, you are going all chain. Its a 40 foot multihull with only 3' draft, and you are in 10 foot of water, with a 35 pound, old style Bruce anchor.

You have 45 foot of chain out and you can't let out more because 45 feet in one direction, the water is only about 6 foot deep, and you are seeing 3-4 foot tides and some rocks on the bottom here and there. In the other direction, the water drops off to about 22 feet, only 45 feet away. You have swung 180 in both directions and continue to swing with radically changing, winds which vary from about 10 -25 knots.

Is your 45 foot of chain enough to hold you when you swing into the deeper water and get hit with 25 knot gusts? If not, what is the solution?

Got some ideas, but hoping to hear from more experienced folks.

Thanks,

G2L
Well, perhaps I should call this a "triple snubber" as one already exists on the main anchor line, lead through the bow roller, as noted in past pics.

That said, I am summoning up the courage to post some upside down photos of the snubber arrangement I am now using after reading some of the advice on this thread, and coming up with a "creative" solution.

Note that this has nothing to do with my original post, but is reacting to some of the "thread drift" that has occurred herein. No problem on my end, if no problem for the moderator(s), since the entire thread has been very informative and greatly appreciated.

So, if so inclined, please check the photos and comment. Note that I'm using two snubbers, rigged from the anchor line to the outer hulls, then aft to port and starboard winches. So far, they have measurably reduced the noise heard in the main hull's forward cabin, and that is the main reason I added them.


Please forgive the lack of nylon rope - none aboard. Note further, that the use of snatch blocks v. soft shackles is designed to take a bit of pressure off the cleats, which are not that strong. Also, the extra noise they might make is not an issue, since, they have nice, rubber coatings and are on the outside hulls, which make them pretty silent when we are below in the main hull.

Lastly, the dual snubbers are attached below the chain swivel, in order to create some measure of protection, in the hopefully unlikely event that the oversized swivel should snap.

As per some of the advice on this thread, I will be taking off the swivel and one of the shackles next time I haul the anchor, which, hopefully, will be relatively soon. But that's another story.

Tell me what you folks think, but go easy on me, OK? : )

Thanks,

G2L
Attached Thumbnails
Click image for larger version

Name:	+++ snubber photo 1.jpg
Views:	58
Size:	406.1 KB
ID:	121536   Click image for larger version

Name:	+++ snubber photo 2.jpg
Views:	79
Size:	392.3 KB
ID:	121537  

Click image for larger version

Name:	+++ snubber photo 3.jpg
Views:	61
Size:	327.0 KB
ID:	121538  
__________________
Gone2long is offline   Reply With Quote
Old 28-03-2016, 06:22   #80
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: 19,743
Re: Challenge: Anchoring on Slanted Bottom

Quote:
Originally Posted by Don C L View Post
Yes, and somewhere way back in the recesses of my mind I remember reading an article about the strengths of swivels and being shocked how weak they can be compared to the chain and shackles, even if they have the same working load limits, so I haven't considered using them for years. I believe the most common ones usually say something about not being designed to swivel under a load. And are they really necessary? So what if the line and chain spin around a little?
Good swivels (like Kong) are rated for side loads as well as straight line loads. That's what you need to pay attention to. Or else, don't mount them directly to the anchor, but a few links back, where they won't be subjected to side loads.


The need for a swivel is directly related to the balance of the anchor. My previous Rocna anchor was inherently unbalanced -- which is why it needed the roll bar. It naturally came up upside down. It was unusable without a swivel. I would pull it up to just below the roller then turn it around with a boathook.

My present Spade has lead ballast and comes up the right way up. I got rid of the swivel and use a plain shackle with no problems.

In my opinion there is nothing wrong with a good quality swivel, properly sized, and properly used. It needs to be inspected frequently, but a shackle does too. But a normal shackle is less complex -- less to go wrong -- so even better, you your anchor is balanced and doesn't need the swivel.
__________________
"Parce que je suis heureux en mer, et peut-ętre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 28-03-2016, 06:39   #81
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: 19,743
Re: Challenge: Anchoring on Slanted Bottom

Quote:
Originally Posted by Gone2long View Post
Thanks, the graphic definitely helped me better understand the "math" and "geometry" of the situation.

Regards,

G2L
Me too, so thanks to Noelex and others for elucidating the problem.

Sloping bottoms have always held a certain anchoring terror for me and it's good to have some more objective tools to analyze them.

I have learned with time, however, to choose anchorages with flat bottoms, or dropping the anchor in the deepest part of a pool. This has been a particular problem in the incredibly rocky Eastern Baltic. You learn to recognize places where sediment collects and forms a shallow basin or a kind of "meadow" on the bottom, and here are your best places for anchoring in such waters.

I have used Muckle's trick of putting out a kedge to hold you on the high side of the slope, but obviously this won't work if you're being blown in the opposite direction.

So mostly I look hard for a flat spot.
__________________
"Parce que je suis heureux en mer, et peut-ętre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 28-03-2016, 08:50   #82
Registered User
 
wrwakefield's Avatar

Join Date: Feb 2011
Location: Wrangell Island, Alaska
Boat: Nauticat 43
Posts: 861
Re: Better Photo - Shackle Still A Problem?

Hi G2L,

I apologize for my delayed response; I just discovered I'm not receiving an email every time threads are updated, and don't usually go back to threads unless an email is received [like today...]

By now you have moved beyond the questions you asked me, but I embedded some responses below just in case...

It looks like you are making great advancements toward your own security at anchor.

And please keep the perspective of my replies in mind: What I'm sharing is from decades of higher latitude experience with relatively heavy monohulls. I have no experience anchoring multi-hulls, and very little experience dealing with relatively shallow anchoring. Therefore some of my approaches may not scale/apply to your circumstances or vessel.

You should feel good that you have made some worthwhile improvements to the security of your vessel at anchor; a never ending endeavor from my experience...

Cheers!

Bill

Quote:
Originally Posted by Gone2long View Post
Thanks Bill. The links were especially helpful. But, wouldn't a direct connection of the rope to the chain cause twisting and potential chafing, if not other problems?

When using the snubber with an all chain rode, and when the chain is adequately slacked- keeping all the load on the snubber- there is rarely any twisting or chafe at the rope-chain attachment point(s).

The latest photo should show that we have an admittedly ancient connecting swivel, and, connected to that is the shackle holding both the main anchor rope and the secondary "snubber" - the purpose of both ropes only being to absorb a bit of shock, and to create less racket than the chain does in the anchor roller, when we are hit by a bit of swell and winds up to 25knts. The "snubber" is also there to protect against a possible break in the main anchor rope.

In fact, I inherited the chain, swivel, shackle and spliced main rope configuration from the previous owner who has never made himself available to comment on any of this. Consequently, I am trying to learn, after the fact, how much of the set up that I inherited make sense, and how much doesn't.

I appreciate your comments and links, and tell me why you think it might be a bad idea to have the swivel and/or the shackle.

When I mentioned simplifying the rope-chain connection, I wasn't worried about the swivel as much as mentioning a way to introduce some more stretch to the rode [3-strand or 8 plait nylon] and eliminating all that hardware that needs to be inspected/maintained/seized.

That said, the swivel at that connection point is not very useful anyway in my experience. Closer to the anchor allows you to rotate the anchor more readily for stowing on the bow roller if it comes up backward... [I prefer no swivel and just twist the chain from on deck to rotate my 80 lb anchor when this happens...]

Practical Sailor recently published a study of how effective swivels are [or aren't...]


As noted previously, I think that the intent of the shackle attached to the swivel at the end of the chain was to make it easy to connect various lengths of rope, and perhaps more chain (which we also have aboard) to the chain line, as varying conditions might warrant.

That is a perfectly reasonable argument in favor of using a shackle for the rope-chain attachment point- if you don't have a windlass...


The versatility that the shackle creates would seem to be worth any possible problem it might create, no? Furthermore, the shackle should be somewhat stronger than either rope connected to the chain, no?

Your logic is sound- unless one is using a windlass...

It is a matter of preference, and boat hardware. There is nothing wrong with a shackle connecting the rope and chain if you are not using a windlass. Is it more secure than a direct rope-chain splice? Not likely, as shackle or chain link, you still want to use a splice vs. a knot to maintain maximum line strength...

The rope splice to a shackle would only be better than a direct splice to the chain if you include a crush-proof thimble in the rope eye that connects to the shackle...


I know; I am presenting lots of rather involved issues here, and they probably bring up a number of additional variables, but any comments you might have would be sincerely appreciated.

Fast forwarding to today [28-Mar-2016] and seeing your post with your triple snubber with the outboard legs led to primary winches looks like a nice improvement. Well done.

I have described that arrangement on my monohull on related anchoring threads. We always set the bridle, and if anticipating inclement conditions, lead it through the bow chocks [with chafe protection] aft through sheet return blocks to primary wenches. This way the bridle can be longer if needed, kept off the bottom in shallow anchorages [rare for us...] and adjusted from the safety of the cockpit.


Thank you for your detailed responses.

G2L
__________________
SV Denali Rose

Short on opinions; focused on research, facts & experience [yours and ours...]
wrwakefield is offline   Reply With Quote
Old 29-03-2016, 00:00   #83
Registered User

Join Date: Sep 2010
Posts: 844
Images: 1
Re: Better Photo - Shackle Still A Problem?

Thanks,


Once again, very helpful.


Regards,


G2L
__________________
Gone2long is offline   Reply With Quote
Old 29-03-2016, 00:08   #84
Moderator
 
JPA Cate's Avatar

Join Date: Nov 2011
Location: aboard, cruising in Australia
Boat: Sayer 46' Solent rig sloop
Posts: 10,673
Re: Challenge: Anchoring on Slanted Bottom

Gone2Long,

How about summarizing your takeaways from this discussion that you have not yet been able to implement?

I am particularly curious as to your considerations about deciding where to place your anchor initially, and your strategies for using additional anchors in the future. There will always be trade-offs when you start using a secondary anchor, and part of that is my wondering how you view these trade-offs at this point. I think writing it all down will help organize it for you, and therefore make it easier to explain clearly to crew.

Ann
__________________
Ann, with Jim, aboard US s/v Insatiable II, in Oz, very long term cruisers
JPA Cate is offline   Reply With Quote
Old 29-03-2016, 00:52   #85
Registered User

Join Date: Sep 2010
Posts: 844
Images: 1
My Takeaways: Anchoring on Slanted Bottom

Quote:
Originally Posted by Ann T. Cate View Post
Gone2Long,

How about summarizing your takeaways from this discussion that you have not yet been able to implement?

I am particularly curious as to your considerations about deciding where to place your anchor initially, and your strategies for using additional anchors in the future. There will always be trade-offs when you start using a secondary anchor, and part of that is my wondering how you view these trade-offs at this point. I think writing it all down will help organize it for you, and therefore make it easier to explain clearly to crew.

Ann
Hi again,

if you mean that you would like a summary here, I will provide a quick one below.

As per two anchors: I won't use them. Will use my heavy anchor and add more chain. Will tie off to shore when absolutely necessary to limit swing, instead of using two anchors. I have a good cyclone anchorage in mind and will be there by the time that season hits. Will probably spider web to shore, along with the heavy anchor and extra chain, then hope for the best. Probably will not use the snubber as the leads are not strong. Will tie a very heavy (1") mooring line to the mast and run attach it to the anchor line, which will run through the bow roller. Spider lines will come off the winches and maybe the forward cleats.

I don't feel that two anchors is so impossible to do, and I am sure they would be worthwhile in certain conditions; I just don't trust myself to learn how to do it right at the moment (too much other stuff on my plate), and we don't need two at the moment and shouldn't need two into the next month or so. That said, I actually have used two recently to keep me from swinging toward a rock overnight. Used the dinghy to carry out a 15-20 lb Danforth, and dropped it. Then, we hauled on it to set it. Worked well in light wind conditions.

On where to place the anchor: In the future, I will take folks' advice and look for a flat space whenever possible, find a lee shore and anchor from the bow. However, I doubt that I will find many such places where I am now, so I will stay put on this sometimes scary windward shore.

Right now, we are holding well, and the wind is dying as we enter a relatively windless transition period, and one where we should not swing too much. As mentioned previously on the thread, we have sufficient swing room.

The anchor chain wrapped around some coral, when we did a 180, or more, a few weeks ago, but it recently swung free and we have a straight line of chain out to it at the moment. Went down to dive it recently and it looks very good. With less swing likely in the near future and the new snubber, we should continue to have a nice looking rode and catenary.

Lastly, I assume that you have seen my latest post on the "double snubber" which I can partially credit to your suggestion that I be creative. Also, I've learned a lot from other folks sharing their snubber systems on this thread.

Thanks again to you and all the other helpful folks on the thread.

Best Regards,

G2L


PS- I don't remember you ever telling us why Jim doesn't like swivels; perhaps I just missed that detail, suffering from info overload : ) As noted in an earlier post, I plan to remove it, next time we pull the anchor and at least check it. Probably will remove it altogether.
__________________

__________________
Gone2long is offline   Reply With Quote
Reply

Tags
anchor, anchoring

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
Challenge: Wake Up The Mechanics - Outboard Challenge Ex-Calif Challenges 37 04-04-2016 09:55
To Bottom Paint, or Not to Bottom Paint (or Just a Touch-Up) OrangeCrush Monohull Sailboats 40 28-03-2016 05:56
Bottom Blasting and Bottom Painting, New Jersey, PA, DE and MD. AtlanticGreenPro Vendor Spotlight - Great Deals for CF Members! 22 27-08-2013 15:13
Bottom Paint For Textured Bottom chas5131 Construction, Maintenance & Refit 2 29-08-2012 01:07
Challenge: A Real Challenge Solved by a Forum Member Soft Air Challenges 10 27-03-2009 09:59



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:48.


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.