Nobody can answer this question simply from photos posted here. You would need a micrometer and measure your worst case link-At a minimum.
dj
Anchor chain corrosion - cause for concern?
- Thread starter skunther
- Start date
dj
I'm not sure what Jim is implying with his statement.
For another application, I looked into the effect of wear on shackle strength, essentially the same idea. There is not a linear relationship between strength and diameter because strength is based on the diameter of the link, as more link wears away the strength of the link decreases exponentially. Thus, if 25% of the link is gone, the actual loss of strength is much higher. The key to strength is the cross sectional area.
The math is pretty straight forward, calculate the cross section area (π * r^2) of the designed diameter and calculate the area of the link's actual diameter. The ratio of the 2 numbers will estimate the remaining strength.
To make the math simple, assume a 1" diameter link, the cross sectional area I 3.14 square inches. If the link diameter is reduced by 25% to ¾" the cross section area is 1.77 sq inches. The ration is 1.77/3.14 = .56. The chain will have about 50% of is strength when the diameter is reduced by 25%. Note these are back of the napkin calculations as such they are rough estimates.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,224
Inspect for the weakest looking link and then measure. You can always double up a rope to the chain to get you back home then swap the chain out rather than see it as an emergency purchase away from good resources.
Since a few do not click on the Blue Links to read them. This is accurate info still today from this SBO Link
https://forums.sailboatowners.com/t...ilboatowners.com/threads/anchor-chain.186253/
from that link [pun intended
]
__________
This is Fortress Anchor guide...
Safe Anchoring Guide - The World's Best Anchors!
Chain link info...
1) The size of chain is by the diameter of the steel rod used to bend into the link. example: 3/8th chain is 3/8" rod.
2) The USA standard of tension strength has 125% over design, or you can corrode away 25% of the diameter and be at design loads. Thus the strength of chain is only as good as it weakest link.
3) Stainless steel chain is stronger in tension than carbon steel for same rod diameter.
4) Galvanized Chain is for show and not for much else. Why? Zinc coating scrapes off and how many hours in water versus a dry anchor closet. Water is needed for grounded electrochemical reaction (corrosion). Rusted dry steel is a good thing, but ugly.
_________
Please read above.
Jim....
https://forums.sailboatowners.com/t...ilboatowners.com/threads/anchor-chain.186253/
from that link [pun intended
]__________
This is Fortress Anchor guide...
Safe Anchoring Guide - The World's Best Anchors!
Chain link info...
1) The size of chain is by the diameter of the steel rod used to bend into the link. example: 3/8th chain is 3/8" rod.
2) The USA standard of tension strength has 125% over design, or you can corrode away 25% of the diameter and be at design loads. Thus the strength of chain is only as good as it weakest link.
3) Stainless steel chain is stronger in tension than carbon steel for same rod diameter.
4) Galvanized Chain is for show and not for much else. Why? Zinc coating scrapes off and how many hours in water versus a dry anchor closet. Water is needed for grounded electrochemical reaction (corrosion). Rusted dry steel is a good thing, but ugly.
_________
Very bad assumption, Sorry Dave.
Please read above.
Jim....
By 1" I meant 1" rod. It is really easy to calculate the area of a circle with a 1" radius and I did make a mistake and said 1" diameter, when I meant radius.
Look at this chart from this website
A ¼" chain is 80% of the diameter of a 5/16" chain, following your reasoning, it should have 80% of the strength of 5/16" chain, but it doesn't.
Using G30, the working load limit of ¼" chain is only 68% of the 5/16". Looking at the math from the other direction strength of 5/16" chain is 146% of ¼" while only being 25% larger. The point is diameter is important and the relationship between strength and diameter is not linear. The loss of strength due to the erosion of the chain (rod) is disproportionally greater than the amount of erosion considered as a proportion of the rod diameter.
In an article I published in Good Old Boat Magazine a few years ago, I found shackle size (rod diameter) to account for 98% of the variance between mean breaking load and cross section area while diameter alone only accounted for 94% of the variance.
That's a great thing to do, but you have more energy than me! BTW, when I do muster the energy to do so, I also use Saltbuster (Salt-X), which really blows the salt off things. As a testament to its effectiveness, the Navy Seals use it when washing their dive gear, and flush their outboards with it.
The way the sentence was written, yes, it should be 25%. It was easier to edit the 125% to 25% than to rewrite the sentence.
