Anchor snubbers are a very important, yet over looked part of ground tackle. Ground tackle, in its simplest form, is the equipment needed to attach the boat to the bottom in a secure manner.
Most people think of this being anchor and rode. When the rode is rope, this can be the extent of the gear required.
The rope will offer elasticity in the system, reducing the shock of the boat rising and falling back during rough anchoring conditions.
When all chain rode is used, as it is preferred due to the increased weight and reduced risk of chafe, more equipment must be included to make the ground tackle system work properly.
All chain rode offers no direct elasticity, as the chain will not stretch when pulled. It does offer some indirect elasticity, thanks to catenary, which is the parabolic curve that forms in the chain as it travels from your bow roller to the anchor. As the boat pulls back from a large wave pushing on the vessel, the chain will be pulled back under tension. This force them needs to lift the chain up, reducing the catenary as the chain becomes a straight bar. Once the wave passes, the chain will fall once again and catenary will develop again, losing the potential battery for the next shock.
If the force exceeds the stored elasticity in the catenary chain, a strong lurch of incredible force will develop as the boat is snapped by the taught rode. All of this force can dislodge the anchor, causing it to drag, and damage the deck gear.
Chain stoppers are easily bent by this amount of load, and risk ripping or if the deck if overloaded. If no chain stopper is present, all of this load is transferred to the windlass gypsy, running the risk of damaging the gypsy and the gearing inside.
If the bow roller is open, the chain can also fall out of the roller and cause serious damage as it saws on other parts of the boat. If the roller is captive,the chain will not be able to escape, but the forces on the roller are still extremely high!
The solution to the chains downfall is to use a nylon snubber. The nylon snubber offers the elasticity of nylon rode while the strength and weight of chain is still present everywhere else. The last section, connecting the rode to the boat is then completed in nylon rope.
The nylon snubber is attached to the chain rode and to the bow cleats, which are very strong and ate designed to take such abuse.
If the catenary chain is drawn taught, the snubber will still protect all the deck gear while offering elasticity and avoiding the shock load. This also helps ensure the anchor is not lurched and un-set.
Bow roller design is also unimportant, as the snubbers takes over the last connection to the bow. Open rollers are no longer at risk of losing the chain. Captive rollers are no longer at risk of being bent. This is all thanks to the nylon snubber.
As the boat swings around, the nylon snubber pulls on the rode and transfers the force to the cleats. The section of chain between the windlass, chain stopper, and roller, are all slack since all the tension is diverted to the lines of the snubber.
When it comes to snubbers, I have seen many different styles, but I prefer the simplest for a few reasons that I will go over.
Connecting the snubber to the chain can be done by chain hook or by knot. Chain hooks are uncredited convenient, simply slip it on the chain as it runs out and cleat the other end. The chain is instantly captured at the end of the snubber. The problem is the hook can easily slip of the chain, rendering the snubber ineffective. Some companies, like Mantus, have come up with chain hooks that can not easily slip off to negate this problem. The fact that they came up with a better chain hook means that chain hooks were slipping off enough to need improving.
I prefer to tie a knot at the end of my snubber. A good knot will not slip off of the chain like a chain hook, and will hold securely until untied. I prefer a magnus hitch for my snubber since I use both tails, but a rolling hitches would also work.
One last advantage to tying the snubber is you result with two tails. A chain hook only has one tail. This means that a chain hook snubber will pull the boat towards the side the snubber is run through. If it runs through the port chock, the boat will be pulled so that the port side is facing the wind and seas. This also means that all the force is directed onto that one chock and cleat.
When tied, there are two tails, meaning two snubber lines! The lines can be set equally so that the resulting pull is even and the boat faces the weather bow on. This also reduces the force on each snubber line by half, as the load is now shared between both lines.
On a final note, snubbers should be made of Three Stand Nylon, not double braid nylon. Double braid is not as elastic as three stand, and in a situation where elasticity is desired, choosing the least elastic option would be silly.
My snubber is 3/4 inch three strand nylon tied with a magnus hitch and secured with both bow cleats, forming a bridle to the chain rode. This may seem like overkill, but it holds us through all sorts of weather and is easy to untie when we are ready to leave.
Until then, we know our ground tackle is well set.