Join Date: Sep 2008
Location: Victoria B.C. Canada
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Re: Caternary & Chain...
"We use a 66lb Bruce with 300' of 3/8" BBB chain."
3/8" BBB chain weighs 1.65 lbs per foot, working load 2750 lbs, coupled with a 66 lb anchor. In lighter breezes there isn't a problem, but when it really blows any catenary disappears and you do or do not drag based on the 66lb anchor alone. If you were to use either a lighter chain or a chain/rope rode with a heavier anchor when it blows you would be relying on a heavier anchor that will not only hold better without the lost catenary but would set better and faster all the time.
G43 chain has a working load of 3900 lbs and weighs just over 1 lb per foot. 300 ft of 5/16" is 198 lbs lighter than 3/8" BBB of the same length. One could use an anchor 50 lbs heavier and still save 148 lbs overall, and have a working load that is 40% larger. Would set faster and give much better holding when that catenary has disappeared due to wind strength. 5/16" G43 is about a dollar less expensive per foot than 3/8" BBB as well for a dollar saving as well based on Jamestown Distributors on line price.
Were one to really get carried away G70 chain of 1/4" size weighs .66 lbs per foot for a chain weight savings of 300 lbs but still has a working load of 3150 lbs, 400 lbs more than the BBB in use currently. Then the size of the anchor can be whatever is desired and there is an even larger total weight savings.
The larger the anchor for a given boat size/displacement the shorter the scope can be if it is necessary in tight places that do not have the swinging room necessary for a 5-1 or larger scope. Of course on a normal basis scope can be 5-1, 7-1 or 10-1 if desired.
Living aboard in Victoria Harbour
Last edited by mitiempo; 11-11-2013 at 12:15 AM.