Moorings - What lies beneath? by Naomi Anderson
To me a mooring was a rope disappearing into the water with a buoy attached.
I started wondering what was attached to that rope and that’s when I decided to spend a few days at trying my hand at being a deckie with Peter Wherry from Jubilee Marine. The idea of wearing jeans and a t-shirt to work instead of the high heels and a skirt was most appealing.
There is a definite science to laying and servicing moorings. The size of the craft, tides, weather, depth, type of sea bed and fetch (size of waves the area is exposed to) are all factors in the laying of a secure mooring.
Firstly there is a concrete block sized according to the size of the vessel that is to be secured to that mooring. During high winds a block that is too small could easily be dragged along the sea bed.
From this block is a huge ship’s chain which also acts as an anchor as well as a spring. Next a swivel is attached; the swivel allows the wind to turn the mooring chain 360 degrees and stops the chain getting twisted which allows the boat to swing in the wind. Attached to the swivel is a lighter chain known as a ‘wear chain’ and this is attached to the mooring rope, that length of mooring rope is determined by the depth of the water and tide.
So why do you need to have your mooring checked each year when the rope looks to be in good order?
Chains don’t rust underwater because there is no oxygen to cause rust but they do wear and the reason they wear is movement. Sydney harbour has a two metre tide, so apart from the up and down movement of the waves the chain is being subjected to during normal weather; there is also a two metre movement with the tide. When you see your boat bobbing around on top of the water, imagine what’s happening below the water, those chains are absorbing a lot of that movement.
Peter Wherry’s mooring barge and examples of wear and tear.When we hear of a boat that has broken its mooring the main reason is the ‘wear chain’ or the swivel has worn through.
Why not use a heavier chain I asked? If you did, it would be so heavy on the rope you would not have the strength to pull the rope up from the buoy to attach it to your boat at high tide.
When Peter services a mooring, he ties the moored boat alongside his boat and pulls the whole mooring up from the bottom with the winch and checks the wear on the chains, swivel and ropes, cleans the ropes of growth and replaces any worn chains, swivels or ropes.
I learned a lot in those few days. You have to be a master at manoeuvring a boat around and in between other craft, it’s dirty, it’s hard yakka. I also learned how to retrieve a mooring from a boat using a boat hook without falling in and the best part … I learned to tie a bowline.
There is more to laying and servicing a mooring but Peter said if he told me everything he would have to tie me to one of the mooring blocks so I couldn’t talk.