dropping a mooring

I too have laid a couple of moorings using Old Harry's and Day Dreams's technique. The only difference is that I use a purpose built frame that accepts 2 large 210l barrels. At low tide I tie the weight to a fixing point with sacrificial rope and allow the rising tide to float the sinker - usually a steel railway wheel (nice and flat with a bit of concave shape to it). Tow it out over the mooring point, let loose the riser and ground tackle and then cut the rope.
Every couple of years I use the reverse technique to lift the moorings to check/replace the swivel. It is amazing the power the tide has.
Ps make sure you wire the shackle pin!
 
Jabamusic said:
I too have laid a couple of moorings using Old Harry's and Day Dreams's technique. The only difference is that I use a purpose built frame that accepts 2 large 210l barrels. At low tide I tie the weight to a fixing point with sacrificial rope and allow the rising tide to float the sinker - usually a steel railway wheel (nice and flat with a bit of concave shape to it). Tow it out over the mooring point, let loose the riser and ground tackle and then cut the rope.
Every couple of years I use the reverse technique to lift the moorings to check/replace the swivel. It is amazing the power the tide has.
Ps make sure you wire the shackle pin!
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Only problem with that is that 420 litres only displaces 420 KG. If you can lift it free from the seabed then the railway wheel has not had much of a hold.
 
Daydream believer said:
Only problem with that is that 420 litres only displaces 420 KG. If you can lift it free from the seabed then the railway wheel has not had much of a hold.
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To be fair, the seabed is like a viscous fluid. A steady pull of 420kg will shift a sinker which won't budge from the normal forces of waves on a yacht, even if the yacht is adding jerky forces peaking at a few tons.
But around here, we get the boys in to lay a clump consisting of a couple of tons of concrete and some grown-up bits of chain.
Concrete and steel are cheap, once you're comparing it with the costs of big boys with their toys. And it's good value, knowing your mooring would hold a small coaster.

A 400kg sinker will probably resist 600kg of pull on a 1.5:1 scope?
A 40ft yacht in a gale probably only needs a mean force of 200kg to keep it in place?
But the peak force can be seriously more.
 
lw395 said:
To be fair, the seabed is like a viscous fluid. A steady pull of 420kg will shift a sinker which won't budge from the normal forces of waves on a yacht, even if the yacht is adding jerky forces peaking at a few tons.
But around here, we get the boys in to lay a clump consisting of a couple of tons of concrete and some grown-up bits of chain.
Concrete and steel are cheap, once you're comparing it with the costs of big boys with their toys. And it's good value, knowing your mooring would hold a small coaster.

A 400kg sinker will probably resist 600kg of pull on a 1.5:1 scope?
A 40ft yacht in a gale probably only needs a mean force of 200kg to keep it in place?
But the peak force can be seriously more.
Click to expand...

Yep
 
Is it possible to have a fore and aft mooring? I did, for outside porthleven and used much less weight, but plenty catenary. I had a 4ftx4ftx1ft concrete one end, an old anchor about 250kg, laid flat the other, but 10m chain and 10m nylon rope each end. 14.5 ton boat. Advantage is no swivels, and each end good alone if one failed, which was unlikely. Also, dropped every time, so no jangle damage to chains.
pics here, but little idea of location, you can see how long the bow rope is, out tight in 24ft water.
https://www.google.com/search?q=st+...UIEygD&biw=1280&bih=910#imgrc=9_FigM_69BuvkM:
 
lw395 said:
A 400kg sinker will probably resist 600kg of pull on a 1.5:1 scope?
A 40ft yacht in a gale probably only needs a mean force of 200kg to keep it in place?
But the peak force can be seriously more.
Click to expand...

People tend to forget that a 400Kg sinker will only weigh 235Kg when in water.
Experience has shown us that this would be seriously under valued, in even light winds especially coupled with a current of a couple of kts. Might be Ok for up to 25 ft boat in an exposed site. (ours is)
However, add another tonne to that and it is OK for 40 ft provided the bottom is reasonably muddy.
 
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we have a mooing barge with crane for the morings at the club im with. the ground chain is held in place with anchors at each end of the run
 
Before you do that you need the permission of the owner. The seabed to 12 nautical miles is largely owned by the Crown and managed on its behalf by the Crown Estate Commissioners as is much of the foreshore. The remainder is in a mixture of public and private ownership.
 
Daydream believer said:
People tend to forget that a 400Kg sinker will only weigh 235Kg when in water.
Experience has shown us that this would be seriously under valued, in even light winds especially coupled with a current of a couple of kts. Might be Ok for up to 25 ft boat in an exposed site. (ours is)
However, add another tonne to that and it is OK for 40 ft provided the bottom is reasonably muddy.
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A 400kg steel sinker will be 350kg to lift due to the buoyancy.
I've heard of round sinkers moving a lot on rocky seabeds.
I've seen moorings lifted where yacht have sat through some weather, and all that comes up is a few metres of rusty ground chain.
Divers go down looking for the sinker, couldn't find it.

Sometimes the limit of what you can get away with depends on the space you have. Sometimes a light mooring will drag a few metres in a real gale. That may only matter if it means the boat hits another.

Even a light mooring sinker can be held by a bigger area of mud than a fairly serious anchor.

In the absence of proper science, we fall back on brute force. It's worked for me anyway!
 
KellysEye said:
Before you do that you need the permission of the owner. The seabed to 12 nautical miles is largely owned by the Crown and managed on its behalf by the Crown Estate Commissioners as is much of the foreshore. The remainder is in a mixture of public and private ownership.
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Err. dont think they own the seabed round West Kerry and Dingle do they! But somebody does, and you may need permission. In England You need seabed owners consent, and a licence from the MMO, which requires an environmental impact survey before you can lay a new mooring! Ask local clubs and mooring contractors.

Moorings vary enormously with the make up of the seabed, and whether you can actually dig the sinker in. It's always strongly advisable to find out what actually works in your locality. I had a mooring which comprised a 20 metre ground chain with 25kg anchors at each end, all buried at least 50cms in to firm sand (which later built up over one end to around 1m when the river channel shifted) . It never ever moved in the 10 years I had it with the boat on it all year round. The same arrangement would be useless in Chichester harbour's soft mud, where I am now. Find out what the locals use, and dont compromise unless you want to lose your boat. Sooner or later you will get caught out by a sudden change in the weather, and your insurers will be only too happy to refuse a substantial claim because the mooring tackle was inadequate.
 
KellysEye said:
Before you do that you need the permission of the owner. The seabed to 12 nautical miles is largely owned by the Crown and managed on its behalf by the Crown Estate Commissioners as is much of the foreshore. The remainder is in a mixture of public and private ownership.
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:) i dont think your queen would have too much interest in what im doing, we have enough queens (leo and michael) running our country thank you very much
 
JumbleDuck said:
My 4 ton boat lives moored to a standard railway wheel. The contractor who services the mooring considers it sufficient, bit only just. I am sure he would want a LOT more down there for ten tins.
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North West Marine laid my mooring in Loch Etive and specified a 2t concrete block + heavy ground chain for my 10t ketch and all year round use.
 
Any fish farms nearby? Could be a good source of anchors, chain, and a boat to help lay it all.

Btw if this is just an occasional mooring, consider not having a swivel. Depends on local conditions (like everything else to do with moorings) but it would eliminate the biggest weak spot.
 
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