This topic is one that most of us ignore until it is forced on our unwilling attention. The sailing books don’t mention what lies beneath that orange buoy, and I’ve never heard of any teaching on the subject other than how to approach and pick up or drop and sail away from the buoy. I recently had a crash course in mooring maintenance which I shall pass on in the spirit of the confessional so others may profit.
The first sign of trouble was a call from Trevor Greenslade that Amadeus had escaped her chains and drifted downriver. Luckily she was safely returned unharmed and the mooring buoy retrieved. This was left on the Topsham Sailing Club slipway for all to see. The evidence was clear, the poorly maintained riding chain or riser had finally parted when the links wore to less than a fuse wire in width. There was some disbelief among the owners of the boat as one of them had just reported that on returning at low tide three days before he had inspected the chain and found it to be in good order! I wonder if he had the wrong mooring or the wrong spectacles.
Luckily help was at hand. With advice from Trevor Greenslade and Tony Bradford a new riser was prepared with a swivel six feet up from the bottom, and the shackle pins moused with cable ties.
Those of you cognisant with what lies beneath will know that most moorings are secured to a ground chain which is attached firmly at either end to something heavy like a buried concrete block or a large anchor. The riser is lighter in weight and should have a swivel fitting to allow free rotation as the boat swings. At the top is the buoy and sometimes a pickup line.
The size of chain suitable for a swinging yawl mooring on a fast flowing tidal river like the Exe has been defined by the Topsham Moorings Owners Association, and probably this would suit all but the most exposed coastal moorings. They disclaim responsibility for loss or damage suffered!
The dimension of riser and link chains should be no less than 5/16” above the swivel fitting. In length the chain should be not more than 1.5 times the maximum depth of water at its point of connection to the ground chain. (In our case this was 1.5 x 14 =21 feet). The buoy should be at least 12 inches in diameter and capable of supporting the weight of the rising chain at maximum water level whilst floating at least half its’ diameter. Pick up buoys if used should be no less than six inches in diameter and attached to the buoy with rope or chain which shall not exceed the height of the bow above the water in length plus the distance from the bow to the mooring cleat.
The ground chain of a swinging mooring should lie along the direction of tidal flow. The ground chain on a drying mooring should be 3/8” and 1⁄2” on a non drying mooring. (This should also apply to the bottom 6 feet of the riser chain). The length shall be not less than 4 times the maximum depth of water ie 4 x 14 =56 feet. The weight of blocks should be 200lbs or anchors 60lbs. Is that all clear?
The next part was exciting. Towing the dinghy containing the newly assembled chain and various tools I set off up the river in drysuit and wellies with waterproof gardening gloves. Walking at low water springs up the gravel river bed I strolled nonchalantly past the queue for the Topsham ferry. I looked for the spot the boat usually occupies and saw a pile of chain and tree branches. Disentangling these showed the riser was most corroded in the upper part exposed to the freshest water, and still in good order where it lurked in the mud. Two other old riser chains added to the tangle. I took a hacksaw to these and tidied up the ground chain. The next surprise was to find that this massive chain, still thick and strong, had parted from its’ anchor at one end because the shackle had perished. Luckily I had a spare to reconnect it with. The shackle at the other end is on the list for next time. Once the new riser was attached I strolled around a little to admire the unusual view of the river. Swans were courting noisily and rivermen with spades were digging in the main channel standing only knee deep. I took a few photographs and admired the undersides of the local cruiser fleet. As the water rose I walked back down to the Club smelling of that characteristic river mud perfume that hangs around for days. There was some shock that the male owners had left such an important task to me, but then again, they were the ones who had allowed the chain to reach its’ fragile state! Definitely a job to carry out annually, perhaps on the April Spring tides before trusting your pride and joy to the river.