4 sinkers, one mooring- how best to use them?

[Kelpie]

I'm planning on laying a swing mooring for my Wayfarer. I've got two cast iron manhole covers, big and flat and 75kg each, plus two engine blocks as well if I need them. In addition, I've got 4m of 13mm chain and 8m of 10mm.

The ground is soft mud with occasional large stones, not very deep, and there are a few other boats close by so I don't want to be swinging through too big an arc.

Now, am I best laying a single ground chain with two weights on it? Or should I lay all four separately going to a central riser? Or is that much weight overkill for a 16ft dinghy?

 

[boatmike]

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Or is that much weight overkill for a 16ft dinghy?




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Yes! Two manhole covers shackled together with a single chain riser long enough to reach the surface at HWST is quite enough I would have thought.

 

[sailorman]

dont forget a "Swivel" on the riser then go to rope after the swivel this will be kinder to your topsides

 

[Kelpie]

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Yes! Two manhole covers shackled together with a single chain riser long enough to reach the surface at HWST is quite enough I would have thought.

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So basically, the length of chain should be the depth of water at HWST? Then add a swivel and rope to extend it by how much- three times HWST or something?

Are the manhole covers better sinkers than the engine blocks? I think they weigh more, but I'm not sure how to attach the chains to them.

 

[TheBoatman]

Rob
A couple of things to bear in mind.

The two manhole covers would be sufficient to hold a w/farer.

You said that the bottom was soft mud so laying them in tandem might give you better holding because of the "suction" effect.

Don't forget that your mooring buoy has to "lift" the weight of the chain without sinking.

If the mooring is not subject to a serious ebbing spring tide then 1.5 times depth on MHWS should be OK. I.e. max depth of water @ MHWS is (say) 30' x 1.5 = 45' of chain.

If you use something like a Hippo buoy then bring your chain riser up through the buoy and secure it with shackle, then add a swivel to the shackle (very important) otherwise you'll wind the mooring up and risk sinking the boat.

Finally, at sometime in the future you'll naturally want to inspect the mooring even if it's for your own peace of mind ~ just think about how you would go about that before you go lobbing tons of metal over the side?

Peter.

 

[afterpegassus]

Two lumps are plenty.
Remember where you are - you're surrounded by people with moorings and intimate local knowledge, so ask them.

 

[gandy]

Ditto the last point. Have a look at what others use for say Drascombes or other small boats. A lot depends on how much tidal rise, tidal stream, and how exposed the mooring is.

The harbour or other authority may have their own rules, for example our Fairway Committee tells us not to have the riser more than 1.4x water depth.