Top Gear

Please note that a swivel shackle is now a mandatory requirement

Members are responsible for top gear and must inspect it regularly and ensure it remains safe throughout the season. It must be removed at the end of the season when you remove your boat. When removing your top gear you MUST NOT remove the buoy shackle, if this is done the mooring will be lost and you will be charged for its recovery.

You must have at least two mooring lines, each independently shackled to the top of buoy shackle or a strong swivel.

The mooring lines can be rope and/or chain, it is recommended that rope is used. With rope it is important that you protect any chafe points (eg fairlead or bow roller) with plastic tube or other suitable protection. The chafe protection should be secured so that it is always located over the chafe point and cannot move up or down the rope to expose the rope to chafing. Your chafe protection needs regular checking and replacement.

The rope thickness must be such that it will safely hold your boat in strong winds and the end that is attached to the buoy must use a metal thimble. It is recommended that you use 20mm rope for boats up to 22 feet and 24mm rope for boats up to 29 feet . Above 29 feet you should use as large a rope as possibly (but not less than 24mm). You should check that the rope size (and chafe protection) will fit your fairlead or bow roller. If your bow roller or fairlead is too small for these rope sizes you should consider replacing these fittings. Although smaller rope sizes will be sufficient when new a smaller rope will part with only a small amount of chafing.

You MUST NOT pass your mooring rope through the top of buoy shackle, ropes can wear through very quickly, even if you put a turn around the shackle.

The boat end of the rope bridle should be a spliced soft loop. The soft loops should be safely secured to the cleats on your bow. Obviously since a cleat could possibly pull out, a second cleat is the preferred method of attachment. The soft loop should be prevented from releasing from the cleat by using a short thinner line to lock the loop on the cleat.

Any cleats used must have backing plates and not simply be screwed onto the foredeck.

The ideal length of line from boat to buoy should be as short as possible, it is acceptable to lift the buoy out of the water by a few inches when you secure your line. All our moorings are designed to reduce shock loads as part of the mooring system, you do not need lines that reduce the shock or put snubbers in your lines. An additional advantage with short lines is that when the boat rides up on the buoy, the buoy does not scuff down the side of the boat.

Previously we have recommended a line that is no longer than 1.5 times the height of the bow. You may still use existing lines at this length but please replace them with as short lines as possible.

Longer lines can get twisted, can twist under the buoy and increases the swinging circle of your boat with the potential for interfering with other moored boats.

All shackles used should be kept moused with wire to prevent the pin from working loose, cable ties can be used in addition to wire but should not be the only means of mousing (“mousing” Definition:- Mouse or Mousing (screw pin shackle) is a secondary securement method used to prevent screw pin from rotation or loosening.) Other means of locking the shackle pin are acceptable (eg hole and split pin or lock nut). Mousing is particularly important for stainless steel shackles as these tend to shake loose, even at the end of the season.

Chain Top Gear

Chain can be used for mooring and suitable strong chain is hot dipped galvanised 8-, 10- or 12-mm chain depending on the size of your boat. If you use chain, it must not be your primary connection to the buoy. Your primary connection must be rope and it must be possible to remove the chain whilst the boat is under load on the mooring. The reason for this is that occasionally we get riser chains trapped under the mooring block. When this happens, the bow can be pulled under (especially with smaller / lighter boats). To release the mooring, it is essential that the chain can be removed first. Once the chain is removed the rope is then released (or cut) to prevent the bow being pulled under. Although trapped risers are rare, if your boat is secured primarily with chain and it cannot be released, it is possible for your boat to be pulled under.

Regular Checks

You must regularly check your top gear to identify early signs of failure. Common failure modes are: -

1. Shackle pins working loose: This is more common with stainless steel shackles. The solution is to mouse the shackles with wire. Do not rely on cable ties and note that wire can often become cut during the season so check your mousing regularly. MBOA has wire for mousing shackles in store 3, allow around 40 - 50cm (16 – 18 inches) per shackle.

2. Frayed lines: This is usually insufficient chafe protection or a poor lead through a fairlead. Note that a line may be fine for weeks but can fail very quickly in bad weather.

3. Unsuitable or worn mooring fittings: Use as large a fitting as you can, check regularly for wear or failure (especially if you cover your buoy fittings with a fender). The most common unsuitable mooring fitting is that they are undersize, closely followed by worn fittings. Note that stainless steel fittings do not show the same signs of wear as galvanised fittings so have the potential to fail without warning. It is recommended that you replace stainless fittings every 10 years.

4. Insufficient lines: Each year we get boats held by just one line. This is not acceptable.

Shackle sizes and Swivels

The shackle on the top of the buoy is a ¾ inch (19mm) “Bow” shackle, so your attachment to this shackle must have a large enough jaw to be able to fit over the buoy shackle. If you are going to attach two lines direct to the buoy you will need to ensure that both shackles will fit onto the buoy shackle. The diagram below shows dimensions of the most recent shackles purchased but please note that we still have some older style shackles with similar but not identical dimensions (A and B dimensions are the same for both old and new shackles).

Previously we have recommended a swivel to prevent lines from twisting. If you use a short, tight line to the buoy the swivel in the mooring chain appears to work all season so a swivel is not required. This also means that you can put two independent lines onto the buoy shackle which eliminates the single point of failure that the swivel introduces. If you do decide to use a swivel, it is critical that both pins are moused or otherwise secure as a failure at this point will be a failure of the mooring (single point of failure). If you are using a swivel, consider using a jaw-jaw swivel not an eye-eye swivel, this eliminates two shackles per line so is safer and cheaper.

The photos show a jaw-jaw swivel (with pins) and an eye-eye swivel (without pins).

If you wish to put a third line onto the buoy it is unlikely that you will be able to attach three shackles to the buoy shackle. Your best option is to attach your third line to one of the shackles that attaches one of your first two lines.

Galvanised shackles and swivels should have their pins greased when they are fixed to the buoy, only a small amount of grease is required but it makes removal at the end of the season possible. Stainless steel components must not be greased.

Useful sources of mooring equipment

Useful sources of mooring equipment include:-

Handy Straps (www.handystraps.co.uk) – although a web based company they have a unit at Burringdon Industrial Estate in Plymouth and give you even better prices in person.
Gael Force Marine (based on the fish quay) we use GF for our mooring chain, shackles and swivels.
Mount Batten Boathouse are convenient, useful in an emergency.
Force 4 Chandlery at QAB stock most items.
Marine Bazaar have a stock of items and are particularly useful for protective tubing.
Bogie Knights at Mutton Cove may or may not have what you require, they are good for 3 strand mooring rope.
Marine Bazaar and Mount Batten Boathouse will give MBOA members a discount on most items.

Other

An example of a mooring setup with swivel. Note the shackle pins have been moused with wire, the eye-eye swivel could have been a size bigger, but this is sufficient for the smaller boat on this mooring.

This chafing is due to the rope protection not being fixed in the right place, one of the three strands has parted, a new line is required.

Mooring lines badly twisted, either a swivel or shortening of the lines is required.

Missing shackle pin. This pin was not properly moused, on this mooring the shackle pin is moused with wire, but the other swivel pin is not moused.

The stainless ring has failed at the weld (very top right of the photo), stainless components can fail like this without warning so need to be checked frequently.

Created with