Scotty_Tradewind
Well-Known Member
And I don't use 'all that chain' unless I need to. QUOTE]
I guess you've made my point
www.sailingscotty.com
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Anchor chain is 50m enough?
- Thread starter Seven Spades
- Start date
snowleopard
Well-Known Member
Looking at the alternatives we basically have 3 alternatives: Heavy chain, light chain and mostly rope (nylon). Assuming all three are stong enough not to break in any conditions short of the ultimate, we are concerned with the effect of heavy loads on the holding of the anchor.
Risks to the holding come in 2 forms: once the catenary is pulled nearly straight the pull on the anchor is above the horizontal so there is a tendency to lift the anchor out of the ground. A (nearly) straight chain has no elasticity so shock loads caused by the boat being thrust backwards by the waves are transmitted direct to the anchor.
A nylon warp will pull straight pretty easily so this set-up is most vulnerable to the upward pull problem. On the other hand nylon will always stretch so the shock load problem is not a factor.
Lighter chain will pull straight sooner than heavy so is more vulnerable on both counts than heavy chain.
From that analysis I would say the best options are either to go for rope with as much scope as possible to reduce the pull angle or, if you prefer all-chain, the heavier the better (and add a chum).
Risks to the holding come in 2 forms: once the catenary is pulled nearly straight the pull on the anchor is above the horizontal so there is a tendency to lift the anchor out of the ground. A (nearly) straight chain has no elasticity so shock loads caused by the boat being thrust backwards by the waves are transmitted direct to the anchor.
A nylon warp will pull straight pretty easily so this set-up is most vulnerable to the upward pull problem. On the other hand nylon will always stretch so the shock load problem is not a factor.
Lighter chain will pull straight sooner than heavy so is more vulnerable on both counts than heavy chain.
From that analysis I would say the best options are either to go for rope with as much scope as possible to reduce the pull angle or, if you prefer all-chain, the heavier the better (and add a chum).
Poignard
Well-Known Member
'...all that chain...', i.e. 65 metres of it
And I don't use 'all that chain' unless I need to. QUOTE]
I guess you've made my point
If your 'point' is that I carry too much chain, have a think about this:-
This year, as with most previous years, I plan to visit Normandy, the Channel Islands and Brittany.
Suppose it is June 17th, and I find myself wishing to anchor in one of the many bays near St Malo.
St Malo HW = 12.0m
LW = 2.0m
__________________
Range = 10.0m
I arrive at LW and anchor in 2.5m, which gives me 1.0m clearance
under the keel.
The depth at HW is going to be: 2.5 + 10.0m = 12.5m
I decide to let out 4 x depth at HW = 4 x 12.5m = 50m
This leaves me a couple of boat lengths in reserve, in case the wind gets up.
What is wrong with that?
ps and I have a 24lb chum, if needed!
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Scotty_Tradewind
Well-Known Member
You make an extremely good case for the chain in those areas where there is such a difference in HW/LW but why carry the chum?
I bought one when I had a CQR but in the last few years have taken to leaving it in the garage at home.
www.sailingscottydo.com
snowleopard
Well-Known Member
Poignard
Well-Known Member
Chum
You make an extremely good case for the chain in those areas where there is such a difference in HW/LW but why carry the chum?
I bought one when I had a CQR but in the last few years have taken to leaving it in the garage at home.
www.sailingscottydo.com
I can't add anything to Snowleopard's answer except to say that I also use it as a 'drudging' weight to hold the boat's head to wind when leaving an awkward berth.