Go Back  The Hull Truth - Boating and Fishing Forum > BOATING FORUMS > The Boating Forum
Reload this Page >

LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

Notices
The Boating Forum

LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

Old 02-25-2006, 11:05 PM
  #1  
Senior MemberCaptains Club Member
Thread Starter
 
Join Date: Jul 2004
Location: Louisiana Gulf Coast
Posts: 875
Likes: 0
Received 1 Like on 1 Post
Default LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

Hey guys, what is the ratio of anchor line to water depth. I have always gone by the old rule of 6 to 1, meaning 6 foot of anchor line for every one foot of depth. Just wondering what your thoughts might be on this subject. Thanks in advance, Doc of the Bay
Old 02-25-2006, 11:10 PM
  #2  
Senior Member
 
Join Date: Mar 2005
Location: panama city fl
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

7 to 1 is the "by the book" standard, 10 to 1 in foul weather. This number is open to a lot of interpretation. An all rope rode and a light anchor will need a lot more scope than an all chain rode.
Old 02-25-2006, 11:13 PM
  #3  
Senior MemberCaptains Club Member
 
Join Date: Nov 2005
Location: seattle, wa
Posts: 5,934
Likes: 0
Received 22 Likes on 13 Posts
Default RE: LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

yeah thats how it works and i have heard 1 to 7. i have been thinking abuot anchoring and camping this coming summer. is all this line really neccesary? does anyone have any tips to anchoring so you dont float away?

anchor alarms on gps are cool, is that all one would need for safety through the night (besides an anchor light)?

whats the best way to know what the bottom surface is like and which type of anchor should be used?

thanks
mike
Old 02-25-2006, 11:15 PM
  #4  
Admirals ClubCaptains Club MemberPLEDGER Admiral's Club Member
THT sponsor
 
Join Date: Feb 2003
Location: (snowbird in training) Lake Erie Un-salted water and shark free!
Posts: 7,335
Received 709 Likes on 376 Posts
Default RE: LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

Here's a good source.

http://www.boatus.com/boattech/casey/34.htm

I've used as little as 4-1 in calm(er) conditions with a muck bottom. It all really depends.......
Old 02-25-2006, 11:27 PM
  #5  
Senior MemberCaptains Club Member
 
Join Date: Feb 2005
Location: Oakland, CA, USA
Posts: 1,450
Likes: 0
Received 0 Likes on 0 Posts
Default Re: LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

Depends on a lot of things: How long you're going to be there, what you're going to be doing while you're there, wind and wave conditions, bottom composition, etc.

For instance, if all you're doing is hooking up to eat a sandwich on a clear, calm day, 2:1 will probably do it. Even if the anchor drags, you're on board to notice and correct.

OTOH, if you're anchoring in high wind and swell, and leaving the boat unattended, a 7:1 or greater ratio would be called for (as would multiple anchor rigs.)

What you want to do with scope is to ensure that the pull on the anchor is as horizontal as possible to prevent it tearing out. That also will assist it in resetting should it happen to drag.

Anchor alarms are a good thing, but as far as relying on one rather than proper anchoring, I'd hate to have to explain how I slept through it.

jky
Old 02-25-2006, 11:52 PM
  #6  
Senior MemberCaptains Club Member
 
Join Date: Aug 2004
Location: Baton Rouge, LA
Posts: 2,437
Received 173 Likes on 107 Posts
Default Re: LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

Depends a little on the anchor, a little on the chain, a little on the size rope, and a little on the weather. I anchor on the lump in 200 feet of water with 600 foot of 1/2" rode. I have 30 feet of anchor chain and use an 11 lbs. anchor. My boat weighs in at around 8000 lbs. loaded. I have set the anchor in 5 foot seas and never had a problem. Always bites immediatelyand have never pulled the anchor. I have 20 feet of 1/4" chain and 10 feet of 5/16" chain. I won't use such a heavy setup when anchoring in shallower water. That is the length of rode that most boats that fish the Lump use. I imagine there would be pulled anchors in really rough stuff, but I will be home before it gets much worse than that.
Old 02-26-2006, 01:05 AM
  #7  
Senior MemberCaptains Club Member
 
Join Date: Oct 2005
Location: Newburyport, MA
Posts: 1,747
Likes: 0
Received 0 Likes on 0 Posts
Default RE: LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

Yep, I have read anywhere from 3:1 to 10:1, all depending on conditions.
Old 02-26-2006, 01:22 AM
  #8  
Senior MemberCaptains Club MemberPLEDGER
 
Join Date: Nov 2004
Location: Oregon Inlet, NC
Posts: 2,660
Likes: 0
Received 2 Likes on 2 Posts
Default Re: LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

7 to one is the norm, get a good anchor (fortress) and keep at least 20' of light chain on it. Sea anchor should also be included in the locker.
Old 02-26-2006, 08:56 AM
  #9  
Senior MemberCaptains Club Member
 
Join Date: Apr 2004
Location: MD.
Posts: 13,564
Likes: 0
Received 2 Likes on 2 Posts
Default Re: LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

The problem with anchoring in deep water in heavy seas is stuffing your bow.To get the 7:1/10:1 in acouple hundred ft. of water you would need some serious amount of rode.A sea anchor would probabaly serve ya better.
Old 02-26-2006, 09:07 AM
  #10  
Senior MemberCaptains Club MemberPLEDGER
 
Join Date: Nov 2005
Location: Central Jersey
Posts: 7,961
Likes: 0
Received 1 Like on 1 Post
Default Re: LENGTH OF ANCHOR LINE TO DEPTH RATIO ??

Regardless of the scope, you need the apropriate anchor for the bottom. In Long Island Sound, my Danforth never failed; in the Chesapeake the same anchor has a hard time grabbing on those oyster reefs, because the flukes get fouled and it can't dig in.

I carry 200' of 1/2" line and 8' of chain, BTW.

I don't sleep out on this boat, so I'm there to watch it now. I'll get an aluminum Mighty Mite grapnel for the foul bottoms this year.

If I slept out on the hook, I'd get a CQR or a Bruce.

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 On
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.