Swivels, Snubbers & Bridles

Swivels:

Swivels are used to attach an anchor to the chain with the purpose of preventing chain twisting as the boat moves around in the anchorage.  Swivels also help the anchor come up in the correct orientation into the bow roller on retrieval.

  • In the practical sense swivels are often unnecessary unless you intend to anchor for a long time in one spot, further twist usually gets undone as the chain is retrieved with the windlass. If anchored in one spot for an extended period or if designing a mooring system swivels do solve a problem.
  • Swivels are generally considered to be the weakest link between your anchor and the boat.

One issue is swivels often fit directly into the shank and if so can be side loaded (when the anchor is stuck in rocks for example) and fail at much lower loads than the SWL they are rated for. To solve this attach a shackle or a shackle with some chain to the anchor first and then the swivel this will prevent the above mentioned problem with side loading. Further it is often hard to size a swivel for to match the strength of the HI TEST chain, though some well-designed products are available on the market.

One should pay attention to the SWL (safe working load) rating on the swivel as compared to the chain.

 

 

 

Snubbers/Bridles:

 

Why Use an Anchor Bridle/Snubber System?

  • Bridle takes the strain of the chain rode, thus offloading the gypsy on the windlass and reduces the stress on the windlass deck joint.
  • Allow the load to be taken by the cleats that are designed for high loads
  • Reduces the wear on the boat, with all the load on the cleats via the bridle, there is no noise, no chain jerking and snagging on the foredeck.
  • If the bridle is long enough/and or has enough stretch it can absorb the shock loads from waves and wind gusts
  • With the long bridle the chain is lowered below the waterline and offers better effective scope and additional shock absorption
  • It has been suggested by some that when using all chain rode the catenary effect from the sagging chain from its weight will provide sufficient shock absorption. While this might be true for large ships, on average size cruising vessel the catenary effect from the chain does not provide any significant shock absorption, one only has to look at the chain shape under water in a 25 knot breeze to see that the catenary effect is no longer a factor because the chain is oriented in a straight line.

So more simply said the bridle ensures that you anchor has the highest chance of staying put and your boat staying intact.

 

 

 

 

There are different ways of attaching the bridle to your chain:

 

 

 

Mantus hook

 

 

  • The Mantus Chain Hook, or chain grabber securely latches to the chain even when chain is unloaded, making it much safer than standard chain hooks that often fall off.
  • The Mantus Chain Hook has no moving parts, thus can withstand harsh marine environment and is easy to use
  • The chain grabber is safe, designed to be as strong as high test chain
  • Available in 316L Stainless Steel (electro-polished) and Hot Dipped Galvanized carbon steel

Mantus Bridle Line Sizing Recommendations:

The role of the bridle/snubber system is to be able to absorb the shock loads by stretching and yet be strong enough not to fail when exposed to these high loads conditions.  Thus we make sizing recommendations keeping this in mind.

 

  Boat Size

      30 – 40 feet

     40 – 50 feet

     50 -70 feet

Line Diameter (inches)

5/8

3/4

1

Bridle Length (feet)

25

30

34

Effort should be made to protect snubber/bridle line from chafe and inspect it for wear regularly.