Empathy List Archives

FM

Faure, Marin

Wed, Aug 30, 2006 12:32 AM

To settle an argument, I am looking for an all chain rode anchoring

scope table.

The Bruce website has a chart of sorts
(http://www.bruceanchor.co.uk/cast.htm ) At the bottom of the page is a
statement that in "rough weather" with all-chain rode (and a Bruce
anchor) the recommended minimum scope is 4:1, for a nylon/chain rode a
minimum of 7:1, and for all-nylon a minimum of 10:1. This is if the
winds are expected to kick up. The 4:1 all-chain recommendation seems
way too short to me. I have always heard it said that with all-chain a
5:1 scope is okay for "normal" conditions, but if things are expected to
get rough a 7:1 or more is what you'd want. If it's going to get really
windy put out everything you've got.

If you have access to a copy of Earl Hinz's book "The Complete Book of
Anchoring and Mooring" there may be a chart or at least a description of
the information you're looking for.

C. Marin Faure
GB36-403 "La Perouse"
Bellingham, Washington

>To settle an argument, I am looking for an all chain rode anchoring scope table. The Bruce website has a chart of sorts (http://www.bruceanchor.co.uk/cast.htm ) At the bottom of the page is a statement that in "rough weather" with all-chain rode (and a Bruce anchor) the recommended minimum scope is 4:1, for a nylon/chain rode a minimum of 7:1, and for all-nylon a minimum of 10:1. This is if the winds are expected to kick up. The 4:1 all-chain recommendation seems way too short to me. I have always heard it said that with all-chain a 5:1 scope is okay for "normal" conditions, but if things are expected to get rough a 7:1 or more is what you'd want. If it's going to get really windy put out everything you've got. If you have access to a copy of Earl Hinz's book "The Complete Book of Anchoring and Mooring" there may be a chart or at least a description of the information you're looking for. ______________________________ C. Marin Faure GB36-403 "La Perouse" Bellingham, Washington

RR

Ron Rogers

Wed, Aug 30, 2006 12:44 AM

From a Don Casey article:

"Tests have shown that the correct size anchor of any reputable design
pulled horizontally, is more likely to hold than an oversize anchor pulled
upwards."

and

"In normal conditions, a safe minimum anchor scope ratio is 5 to 1 (warp or
chain length to depth). (In heavy weather 7 to 1 or more). Depth is the
depth of water at high tide, plus the height from water line to the bow
roller. Scope is the actual amount of anchor line paid out when the boat is
safely anchored. For example, if high water is 20ft deep and your bow roller
is 5ft above the water, you need 125ft (i.e. 5 times 20 + 5ft) of scope to
anchor.
Remember, putting out too little scope is one of the most common mistakes a
skipper makes when anchoring."

He is not making a distinction between rope and all chain.

Ron Rogers

>From a Don Casey article: "Tests have shown that the correct size anchor of any reputable design pulled horizontally, is more likely to hold than an oversize anchor pulled upwards." and "In normal conditions, a safe minimum anchor scope ratio is 5 to 1 (warp or chain length to depth). (In heavy weather 7 to 1 or more). Depth is the depth of water at high tide, plus the height from water line to the bow roller. Scope is the actual amount of anchor line paid out when the boat is safely anchored. For example, if high water is 20ft deep and your bow roller is 5ft above the water, you need 125ft (i.e. 5 times 20 + 5ft) of scope to anchor. Remember, putting out too little scope is one of the most common mistakes a skipper makes when anchoring." He is not making a distinction between rope and all chain. Ron Rogers

T

trawlerphil

Wed, Aug 30, 2006 1:30 PM

In reality, there's no cookbook answer to this question. It all depends on
the anchor, the holding ground, the boat's structure, and the weather. Until
you get experienced, put out all the chain you've got room for in the
anchorage. Get into the habit of setting your GPS alarm and if you are in
the Bahamas, dive on your anchor to make sure it is set before going to bed.

As you gain experience, you'll know which anchor to use and how much scope
is reasonable for the holding conditions. The Keys and Bahamas are different
from the Chesapeake which is different from New England.

Use high test chain and keep getting a bigger anchor on your bow until
people laugh at you. Once they laugh at you, you've got the right size
anchor for extended cruising.

                                      Regards....

Phil Rosch
Old Harbor Consulting
M/V "Curmudgeon" MT44 TC
Currently lying Bond Creek, NC

In reality, there's no cookbook answer to this question. It all depends on the anchor, the holding ground, the boat's structure, and the weather. Until you get experienced, put out all the chain you've got room for in the anchorage. Get into the habit of setting your GPS alarm and if you are in the Bahamas, dive on your anchor to make sure it is set before going to bed. As you gain experience, you'll know which anchor to use and how much scope is reasonable for the holding conditions. The Keys and Bahamas are different from the Chesapeake which is different from New England. Use high test chain and keep getting a bigger anchor on your bow until people laugh at you. Once they laugh at you, you've got the right size anchor for extended cruising. Regards.... Phil Rosch Old Harbor Consulting M/V "Curmudgeon" MT44 TC Currently lying Bond Creek, NC

trawlers@lists.trawlering.com

All chain rode scope question.