Moorings Guidance

Please Note:

These are only guidelines, the CMMA accepts no liability whatsoever and insists that mooring holders seek professional guidance that relates to their individual mooring allocation, type of vessel, weight of vessel and other factors that might change the mooring configuration and specification required.

Clump

Whilst the CMMA requires a minimum of 450Kg clump, larger and/or heavier vessels might require a larger sinker weight.  The CMMA recommends second hand train wheels for clumps, due to their material, shape and ready availability.

Example Train Wheel:

Ground Chain

The CMMA’s minimum length of 8 metres of 38mm ground chain should suit most vessels. But those with larger vessels may benefit, or require, a larger and longer ground chain, which would offer more weight and better catenary to pull on, as well as anti snatch benefits.

Riser

A ratio of 1.5 - 2  x HAT (Highest Annual Tide) depth at the mooring position  is recommended.

Fixing an anode to your riser could prolong its life and dissuade excessive growth.  Winterising (dropping the riser to the seabed with a rope and small buoy attached) can prolong the life of the riser and buoy.

Buoy

The CMMA stipulates the buoy must be a ‘chain-through’ type, with enough lift to support the riser, here are two examples:

Eye Marine Elastomer 75 & Nofloat M1BS

Bridle

Whilst the CMMA doesn't mandate the exact makeup and method of attaching vessels to the mooring risers, we do mandate that they should be “fit for purpose”. Therefore, there are some good practices we would expect to see, for example:

At least two individual attachments to different fixing points on the vessel, a primary and secondary backup, one of which should be made of chain.

Rope attachments should have a whipped braided thimble whenever possible, certainly at their connection to the riser.

Using ‘Green Pin’ shackles is recommended, as these are tested and rated.

When using larger shackles they should ideally be of the bolt, nut and split pin variety.

Example of Green Pin Bolt & Braided Metal Eye:

When using standard screw pin shackles, the pin should be seized (secured) to prohibit the pin coming completely undone in the event of it coming loose.  Common methods of seizing pins include one, or a combination of, the following: Loctite (thread glue), Monel wire and cable ties. The consensus is that good quality cable ties are the most reliable method.

Examples of seizing;

Generally the use of stainless steel shackles or chain in moorings and bridles is not recommended. 

Regular inspection, maintenance and renewal of the bridle elements is going to be the single most important factor in securing your boat safely.

Going forward the CMMA will be taking a more proactive role in ensuring and helping its members secure their vessels, please don't hesitate in seeking help or advice.

What follows are some photos of example bridle setups, with examples of pickup buoys.