where will mooring chains wear

[PabloPicasso]

Do mooring chains wear more rapidly at the top where they attach to float bouys and riser shackles, or at the bottom where they attach to sinkers?

My sinker is well buried in deep mud. Is this lkely to protect it or accelerate corrosion?

 

[lw395]

All depends on the location IMHO.
Some mud is a lubricant, some a very good abrasive.
Some harbours have a lot of metal dumped in them which can make the mud more corrosive according to some.
In my experience, there was significant wear where the buoy shackled on, possibly more movement here than the rest of the chain, and the shackle is wearing a smaller area of the chain. But the worst wear was the bottom of the riser, due to the fairly hard gritty mud.

 

[chewi]

Do mooring chains wear more rapidly at the top where they attach to float bouys and riser shackles, or at the bottom where they attach to sinkers?

My sinker is well buried in deep mud. Is this lkely to protect it or accelerate corrosion?

Either way the only way you'll know is to lift it, and continue to do so to keep it in service to a plan your insurers are content with.

nb another thread where several insurers have declined cover on DIY mooring maintenance.

 

[oldgit]

My risers always seemed to wear most and at the bottom near the sinker.

 

[ghostlymoron]

Either way the only way you'll know is to lift it, and continue to do so to keep it in service to a plan your insurers are content with.

nb another thread where several insurers have declined cover on DIY mooring maintenance.

I'm insured with GJW. They have never queried my self laid mooring.

 

[chewi]

I'm insured with GJW. They have never queried my self laid mooring.

from the thread insurance n self cert moorings.....http://www.ybw.com/forums/showthread.php?t=315599

Just heard back from GJW:


"we are unable to offer terms on this occasion as the mooring is self maintained.
Moorings must be professionally laid and maintained."

somebody here is playing games with the small print, so make sure you don't lose the game!

 

[markdj]

It wears the most at the shackle going from the buoy/riser to your boat and at the bottom of the chain for the height of the tide, so if your rise and fall is 4metres, the last 4 metres of the chain will be worn the most. Using anodes on the chain helps as does an annual dived inspection or a lift of the mooring if possible.

 

[Seajet]

My club maintains our own moorings, something I often take part in.

I'll mention at this point that my original galvanised mild steel keel corroded despite a lot of careful maintenance every winter; when I researched a little and got Portsmouth Uni' Marine Metallurgy Unit involved I discovered Chichester to Portsmouth has a known 'accelerated steel corrosion' problem, and a lot of effort is going into finding the cause and a cure.

Personally I can't help thinking a marinas' shore power and a large mains supply nearby are involved...

On our half tide moorings, the top chains definitely corrode much more quickly than the lower 'destroyer chain' very heavy stuff.

I'd expect about 3 years out of the riser / top chain, it's thought due to oxygen aiding the corrosion.

The weakest part of the whole mooring which demands good frequent inspections is the swivel.

 

[chewi]

I also do mooring maintenance at our club, where we have recently switched to replacing the risers every two years , rather than just when the inspector thinks it needs it. it makes it easier to plan materials and record them. Also there is less judgement required as if its not good for 2 seasons it doesn't stay there.

The much heavier groundchain is lifted and inspected between trots when th risers are checked , and the anchors lifted one end each year.


It is surprising how irregular the corrosion can be even in places where there is no extra load.

 

[greenalien]

The weakest part of the whole mooring which demands good frequent inspections is the swivel.

+1 - even a new swivel can sometimes last less than 2 seasons...