Reduction in anchor scope with chain use - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > General Interest > General Discussion (sailing related)
 Not a Member? 


Like Tree5Likes
Reply
 
LinkBack Thread Tools
  #1  
Old 10-17-2012
sailak's Avatar
Crealock 37
 
Join Date: Apr 2007
Location: Alaska
Posts: 488
Thanks: 13
Thanked 14 Times in 14 Posts
Rep Power: 8
sailak is on a distinguished road
Reduction in anchor scope with chain use

Tonight in our Coast Guard Boating Safety course the instructor gave a "rule of thumb" that 1 foot of chain equals 10 feet of line.

His example was anchoring in 50' with a scope of 7 to 1 you would need 350' of line. But if you had 25' of chain (equal to 250' of line according to his rule of thumb) you would only need 50' of line -- 75' total rode.

I'm new to boating but have never heard this rule of thumb. I agree that chain can reduce the amount of rode needed to safely anchor but have to wonder if the advantage is as great as he is saying.

Anyone heard of this?
__________________
Dale

S/V Elnora
Pacific Seacraft "Crealock" 37 #312

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #2  
Old 10-17-2012
Senior Member
 
Join Date: Feb 2012
Location: New Orleans Louisiana
Posts: 1,927
Thanks: 6
Thanked 43 Times in 41 Posts
Rep Power: 3
Stumble is on a distinguished road
Re: Reduction in anchor scope with chain use

That may be the stupidest thing I have ever heard.

Chain can reduce the amount of rhode needed in mild weather, but you still need at least 3:1, preferably 5:1. For storm conditions 10:1 is recommended in both chain and line.
__________________
Greg Rubin
Attorney
Reply With Quote Share with Facebook
  #3  
Old 10-17-2012
bristol299bob's Avatar
Senior Member
 
Join Date: Apr 2011
Location: Oriental NC
Posts: 214
Thanks: 22
Thanked 16 Times in 11 Posts
Rep Power: 4
bristol299bob is on a distinguished road
Re: Reduction in anchor scope with chain use

no, of course that is not right. by that logic, anchoring 5:1 in 50' of water requires only 25 ft of chain. Chain gives you lots of benefits but warping space time is not one of them :-)

I measure chain and line the same, and sleep well at night.
dacap06 likes this.
Reply With Quote Share with Facebook
  #4  
Old 10-17-2012
Geoff54's Avatar
Senior Member
 
Join Date: Oct 2011
Posts: 692
Thanks: 0
Thanked 6 Times in 6 Posts
Rep Power: 3
Geoff54 is on a distinguished road
Re: Reduction in anchor scope with chain use

The rule of thumb that I remember is that chain is about 10 times the weight of nylon but that example makes no sense.

My rule of thumb is all chain, minimum 5:1, extra long nylon snubber, sleep well.
Reply With Quote Share with Facebook
  #5  
Old 10-17-2012
blt2ski's Avatar
Senior Member
 
Join Date: May 2005
Posts: 6,694
Thanks: 0
Thanked 21 Times in 20 Posts
Rep Power: 10
blt2ski will become famous soon enough
Re: Reduction in anchor scope with chain use

So this guy is saying 1.5-1 ratio?!?!?! The "ONLY" time I have seen this ratio is for a permanent anchor point. And one is using usually all chain, plus and anchor/wad of wt at the bottom that is multitudes more than one would use normally. IE 350-500 lbs of anchor vs 25-50 lbs. So the scope, while important, not as important as it would be in normal anchoring situations.

I personally want at least 2 if not 3-1 minimum.

Marty
__________________
She drives me boat,
I drives me dinghy!
Reply With Quote Share with Facebook
  #6  
Old 10-17-2012
Senior Member
 
Join Date: Nov 2009
Location: Vancouver BC
Posts: 201
Thanks: 0
Thanked 4 Times in 3 Posts
Rep Power: 5
delite is on a distinguished road
Re: Reduction in anchor scope with chain use

Call the instructor out on that one. I cant imagine anyone anchoring in 50ft of water with only 75 ft of chain out. Likewise unless there is a storm most people dont have 7:1 scope, especially in a crowded bay.
Reply With Quote Share with Facebook
  #7  
Old 10-17-2012
chef2sail's Avatar
Senior Member
 
Join Date: Nov 2007
Location: Maryland
Posts: 6,964
Thanks: 29
Thanked 54 Times in 50 Posts
Rep Power: 7
chef2sail will become famous soon enough
Send a message via AIM to chef2sail
Re: Reduction in anchor scope with chain use

Make him show you where he got this information or guidence when the minimum I have alwasy seen is 5:1
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
___________________________
S/V Haleakala (Hawaiian for" House of the Sun")
C&C 35 MKIII Hull # 76
Parkville, Maryland
(photos by Joe McCary)
Charter member of the Chesapeake Lion posse

Our blog-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


“Sailing is just the bottom line, like adding up the score in bridge. My real interest is in the tremendous game of life.”- Dennis Conner
Reply With Quote Share with Facebook
  #8  
Old 10-17-2012
Junior Member
 
Join Date: Aug 2011
Location: Queensland
Posts: 21
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Mike Banks is on a distinguished road
Re: Reduction in anchor scope with chain use

There is only the rule of common sense. The weight of chain rather than length is important--but in deep water you have to use nylon or you will simply not be able to recover all the chain if it is heavy short link chain--which is the best to buy.

If you have such chain, you need to put out as much as you can in the circumstances. I know that is stating the obvious, but after reading the first post the obvious seems to have been overlooked. The comparison in weight of chain and nylon is completely irrelevant. The weight of chain is relevant--because you need to ensure you put out no more than your winch can handle in a vertical lift plus the force necessary to pull the pick out of the mud plus the weight of said pick and an angel of you use one. If you put out more than that you will be unable to get it back. If you regularly set anchors in deep water fifty feet of heavy short link chain with an angel of about twenty pounds set in the chain about ten feet from the rode end, then a five-to one scope to the end of the chain with the angel fitted is a minimum and ten is better. What pulls out the anchor is the weight of the boat and the speed it builds up as it surges backwards between waves in a storm, because when the chain pulls taut this is transferred to the ground tackle. An angel plus chain softens this and the elasticity of a 20mm nylon rode softens it still further. Even so--such an anchor can still drag--sometimes anchors land on sea beds where they will not grip. In such a situation, if the water is shallow, say twenty feet or so--the more chain you can let out the better.

My boat weight five tons, and with stores and fuel more than six when cruising. My anchor is sixty pounds and I use at least thirty metres of 13mm short link chain, to which is lock-spliced one hundred metres of 20mm hard woven nylon rode. Even so, I would hate to have to ride out a storm at anchor. I am just experienced and pessimistic enough to realise that if I am wearing cast-iron pants, fate does not often try to kick my arse.

Last edited by Mike Banks; 10-17-2012 at 03:24 AM.
Reply With Quote Share with Facebook
  #9  
Old 10-17-2012
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,338
Thanks: 11
Thanked 120 Times in 88 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
Re: Reduction in anchor scope with chain use

Quote:
Originally Posted by sailak View Post
Tonight in our Coast Guard Boating Safety course the instructor gave a "rule of thumb" that 1 foot of chain equals 10 feet of line.

His example was anchoring in 50' with a scope of 7 to 1 you would need 350' of line. But if you had 25' of chain (equal to 250' of line according to his rule of thumb) you would only need 50' of line -- 75' total rode.

I'm new to boating but have never heard this rule of thumb. I agree that chain can reduce the amount of rode needed to safely anchor but have to wonder if the advantage is as great as he is saying.

Anyone heard of this?
Sounds like this guy should be TAKING not teaching this class.....
jrd22 likes this.
__________________
______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Reply With Quote Share with Facebook
  #10  
Old 10-17-2012
chucklesR's Avatar
Senior Member
 
Join Date: Sep 2007
Location: Pasadena Md - Magothy side
Posts: 5,978
Thanks: 10
Thanked 30 Times in 30 Posts
Rep Power: 10
chucklesR is a jewel in the rough chucklesR is a jewel in the rough chucklesR is a jewel in the rough
Re: Reduction in anchor scope with chain use

So in ten feet of water I can toss out 10 feet of chain and call it the same as 100 foot of rode.

Stupid. The rule of thumb is chain weighs 1 pound per foot (3/8) and rope (5/8) weighs 1 pound per ten foot. That has nothing to do with anchor rode or scope.

Seems he has his thumb in the wrong place.

Scope is about angle of pull on the anchor, the less the better. Heck to pull a anchor up you shorten scope!

I wouldn't even use his ratio for a mooring ball, lunch hook, or to prevent drift while fishing.
__________________
Lessons learned are opportunities earned.
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Anchor Rode and Scope for Marker Buoy jetdrvr393 Gear & Maintenance 3 05-13-2012 02:00 PM
G5 5/16 HT Anchor Chain interlude44 General Discussion (sailing related) 4 12-21-2009 08:10 AM
Anchor Chain TxLnghrn Gear & Maintenance 9 12-24-2008 05:03 PM
Anchor chain geoffr98 Gear & Maintenance 4 07-29-2007 04:09 PM
anchor chain SteveCox Gear & Maintenance 11 07-22-2006 07:39 PM


All times are GMT -4. The time now is 01:53 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.