I will take some of my off lists comments to Scott public ref personal experience.

First, what Scott says is true, if there is load on the  part of the chain from the boat to the chain hook.  We are very careful to be sure that there is a very large cantary in this part of the chain, so that there will never be any loading on this part of the chain.  The load of the chain hook or plate is actually pulling on the next link up, which becomes the pivoit point.  That is pulling almost directly in the direction of the links (there is a slight vector, but not any where 90 degrees).

Now to real life experiences.  We were in a cove with two similar displacement boats (about 30 tons)  We had our chains out with a 7:1 scope (including the height of the bows--about 7 feet off the water).  I had a 1/2" three stranded nylon snubber on one side of the chain (20 feet from the bow), and a 5/8" three stranded nylon snubber on the other side--but with an extra 2 foot of slack (22 feet from the bow to the chain hook)--there was about 40 feet of chain looped down into the water.  The other boat had just a chain stopper on the deck.  A series of sudden large waves came into the cove and the boats bucked on the chain rode--the all chain with no snubber broke a link--lost the anchor and gear--and only quick starting of the engine saved the boat.  Our boat rode the series of swells easily--no damage to the chain or snubber, although the lines were stressed and we replaced them.

On another occasion I was riding under similar conditions and a squall of 55 knots hit.  The 1/2" 3 strand nylon snubber broke as the rope exceeded its yield strength (at the throat of the splice).

My best guestimate was that this line took a force of between 5,000 to 6,000 lbs to break--this is also near the safe working load of 3/8 HT chain.  The 5/8 snubber line held.  I inspected the chain very carefully, including micrometer measurements of the chain and concluded there was no damage.  This chain continued with us for over 40,000 miles without failure.  If I had wanted to be totally scientific, I should have marked the link, taken several feet out and subjected it to destructive testing--but I did not want to sacrifice the entire chain.  My conclusion was that this load on the chain did not harm it.  The shock load was taken by the snubber--and that is what may have saved the chain.

Is a plate better than a chain hook--most likely.  I have used both.

Yes, chain binders are put on with static loads, and they are tightened with a handle--usually about 30 to one mechanical advantage---depends on the type of device.  However when a logging truck goes around a curve, the forces which are generated are very high and occasionally the chains fail, I do not know if the binder is the point of failure--If they were, I would suspect that another method would be used.

The real weak point in most anchoring systems is the shackles.

Bob Austin

Yes. As I reviewed an excellent force diagram that came with an Italian SS chain swivel, I came to realize that it would be foolish of me to join the snubbers to the chain hooks with ordinary Chinese shackles. So I bought HT, Mil Spec, shackles whose working load matched that of the chain. My local purchase resulted in too high a price. Defender lists 3 different shackle options and their HT shackles were 1/3 the price I paid. It remains to be seen what the country of origin is for Defender's HT shackles.

Ron Rogers
----- Original Message -----
From: Bob Austin

The real weak point in most anchoring systems is the shackles.