Q: Does chain anchor rode provide any elasticity, like nylon does?
A: Chain can provide great elasticity if used properly. You can attach a nylon snubbing line to the chain near the water surface, and this will add elasticity.
I attach the line to the chain with a chain hook, of proper size for the links, and cleat off the other end of the line. I attach the chain hook just outboard of the roller and then let out chain slowly until all the line is out, keeping the snubbing line tight enough so the hook won’t fall free. Then I continue letting out chain to form a loop, as discussed below. The line should be thin enough to provide ample stretch, but not so thin that it’ll easily break in typical conditions.
If you loop the chain between the point where you’ve attached the snubbing line and the bow roller so the chain loops down into the water (not so far down that it’ll drag on the bottom), you’ll have even more elasticity. This is because the weight of the chain will pull down the snubbing line and hold it down until a strong gust comes. Then the gust must overcome the weight of that loop of chain before the snubbing line is straight, and only then will the snubbing line begin to stretch to absorb additional shock.
Of course, in a strong enough blow or wave surge, the snubbing line may break, but as a backup you can secure the chain to the boat by another, much thicker nylon line, which would not only secure the chain but also stretch, providing some elasticity. If your rode is part chain and part nylon line, as many prefer because of the weight of an all-chain rode, your nylon rode will provide elasticity like a snubbing line, although it won’t provide the effect of that heavy loop of chain hanging down in the water.
Even without a snubbing line, chain can provide considerable elasticity. As it hangs from your prow down to the bottom, its weight forms an arc. When a gust of wind hits the boat, it must blow the boat back hard enough to overcome the weight of the chain in the arc, then straighten that arc before full force is applied to the chain.
There is yet another way in which chain provides elasticity. As it lies along the bottom between your boat and your anchor, it settles into soft material, such as mud. In very soft mud or sand it may even become buried. As the boat moves a little, it may work itself into even harder bottoms. When the gust hits the boat, it must overcome the other characteristics described above. Then it must pull the chain over and/or through the bottom. Chain links sliding on or through mud or sand provide considerable resistance. If the chain has buried itself, the gust will also have to pull the chain up from the mud or sand before stress reaches the anchor. The gust often will be spent before any stress is applied to the anchor.
Of course, it’s possible for gusts to be strong and prolonged enough to overcome all the inhibitors mentioned above. This is to be expected in a hurricane, tropical storm or other storm of such strength. These winds can stretch chain out so it almost looks like a steel bar. This, of course, is not good. However, if you’ve added sufficient snubbing line you may not have a problem in these circumstances. In cases like this, the snubbing line should normally be much thicker to avoid breaking and much longer to increase its elasticity.
As with much of boating, there are risks involved with anchoring. You can suffer serious injury rigging chain or nylon for a blow or during a blow. Applying a snubbing line can be difficult. Among the common causes of injury are catching limbs, digits, hands or feet in the gear; slipping; and falling overboard.
But if you don’t anchor well, you may also face serious — perhaps much worse — risks. It’s best to practice and learn in calm conditions, getting the knack for handling whatever rode and methodology you use, gradually working into more severe conditions. Of course, it’s best to seek a safe marina or haul out before serious weather hits, but sometimes we don’t have this opportunity.