Anchor to Chain Connection Guide
Look around any marina, harbour or anchorage and you will find a multitude of different methods employed to join a yacht’s anchor to the anchor rode.
There is no right or wrong way to attach the two together, but there are some general principles to follow which should lead to a successful conclusion.
Applying the following principles to the decision making process should lead to the optimum set up of any individual anchoring system.
How to choose the correct anchor shackles and connectors for my yacht or boat and how to fit them together in the proper manner.
Galvanised or Stainless Steel
Generally speaking, it is better to avoid contact between dissimilar metals because of the eventual corrosive reaction, but the widespread use of stainless steel connections on galvanised anchor systems indicates that the deterioration is either very slow or manageable.
Therefore, with the right precautions, a combination of the two metals is definitely acceptable where required - read more on Dissimilar Metals
For stainless steel anchors and chain, the decision is fairly straightforward - use stainless steel fittings to join the two together. There is a wide range of different makes and models to suit all budgets - Purchase Anchor Connectors
For galvanised anchors and chain, a galvanised connection is the natural choice. However, the options available are realistically limited to shackles only - Purchase Anchoring Shackles
Galvanised Dee and Bow shape shackles generally feature a protruding head with a hole drilled through it for a. Tightening and b. Securing the pin. It is worth noting that any protrusion may cause snagging or jamming through the stem head roller. Flush fitting pins are mostly found on stainless steel shackles.
Correct Alignment of Load Bearing Surfaces
Spread the load by matching the length and shape of the two bearing surfaces as close as possible e.g. a round pin in a snug round hole with both parts the same length. Avoid pin point loads.
There is always the possibility of an ‘awkward’ force being exerted on the anchor shank and/or the connection to the anchor chain when the anchor is being retrieved i.e. not a straight pull.
The anchor connection therefore needs to be capable of coping with a wrench from any direction.
Allowing or Encouraging Rotation
An anchor will not successfully dock into the stem head fitting if is facing up the wrong way. An anchor swivel connector will allow the anchor to rotate as it approaches the bow roller. There are also connectors that are designed to actively twist or flip the anchor into the correct plane for re-entry.
Strength and Quality
Components that are rated with a manufacturer minimum break load will provide reassurance. The integrity of any anchor system can be compromised by one weak link.
The working life of each part will depend on the quality of the base metal and the finish.
Steel should be a minimum grade 40 and treated with hot dip galvanising. N.B. Electroplating will not last very long in a marine environment.
Stainless steel should be a minimum grade 3, marine quality A316.
Couple shackles together ‘back to back’ i.e. with the two crowns bearing against one another.
Fit the largest diameter pin possible through the end link of the chain for the strongest possible joint.
Fit the largest, shortest pin possible through any ‘square cut’ hole e.g. the slot in some anchor shanks.
Use the more open rounded shape of bow shackles to allow more freedom of movement where required.
Use D shackles, especially those with a flush head to the pin, to achieve a narrower fitting.
Take advantage of the oversize bow shackles which are factory fitted to some brands of anchor e.g. CQR. These shackles often feature a flush pin head with the thread permanently welded.
The Dee shackle in this example appears superfluous - this type of connector provides for rotation and lateral loading but is not readily available with a manufacturer guaranteed breaking strain.
This shackle is not correctly aligned on the anchor slot, but is oversized to compensate and facilitates unilateral movement in the correct location.The Osculati Twist Connector has a long banana-shape body to flip the anchor in to the right position for docking on the stem head and incorporates a swivel for rotation.
Use a Maillon Rapide (Chain Repair Link)
Pros: a good quality chain repair link should be as strong as the same size chain, streamline attachment with no snagging, sympathetic bearing surface for chain links or pins at both ends.
Cons: the thread may require a little filing in order to fit through calibrated chain, requires a thread locking compound because seizing is not possible, in this instance, it does not allow lateral movement on the anchor connector.
Joining shackles together ‘pin to pin’ - this will result in the bearing edges sliding from side to side.
Fitting the crown of a shackle through a ‘square cut’ hole so that the shackle bears on two unsympathetic stress points.
Freedom of Movement
Fixing an anchor connector directly to the anchor shank with no freedom of lateral movement. The use of this method is extremely widespread, looks very neat, but there is a strong possibility that at some point it will result in some sort of damage or even failure when the anchor is trapped on the seabed.
Anchor without articulation
Anchor Swivel with no articulation