Anchoring, how much scope?

[longjohnsilver]

Sailing boats seem to be attracted not only to my trot mooring, see post below, but also to Eos itself! Spent a very pleasant few days in The Cove at St Agnes, all chain anchor rode, 3 x max depth with about 30m boats at anchor, no problems, even being a mobo we all swung the same way. But then along comes another sailing boat, about 35', finds a small space to drop his hook, but unlike everyone else he was on rope. Why anyone who goes to Scilly has only rope attached to their anchor I don't know, maybe they expect everyone else to move away from their swinging circle. So the inevitable happens, wind shift and before we know it they are within a few foot of our bow. This was late at night, they'd gone to bed and it was up to me to put out more chain to avoid them and then keep watch in case of another wind shift which then took me closer to other anchored yachts. No harm done but a disturbed night for me. Is it not reasonable to expect anyone anchoring anywhere in Scilly to use chain, particularly knowing the poor holding and close proximity of other boats?

Second incident in Falmouth on the anchorage just of the Town pontoons, dropped anchor well away from everyone, next day wind shifted to the NW and picked up. The nearest yacht that had been a good 20m or more away swung around and again was virtually on my bow. All chain rode this time. Chap came back to the boat and shouted across that no he wasn't dragging as I and another skipper had thought he was, then said he had a chain of rode! What said I, you've got 170m of chain out? He then changed it to 20 fathoms which for an anchorage with a depth of about 8m still seemed a bit excessive and explained why he'd moved closer to us. Again no harm done and I guess from his point of view better safe than sorry but in a sheltered anchorage with other boats around there's a limit to how much chain you should put down.

What do you think?

 

[RupertW]

Always a compromise if it's crowded

I tend to go for min 3 x in a tight anchorage , possibly 4 If less than 4m depth.

However when you find the smallest gap between boats, someone else seems to arrive and halve that gap.

Fenders on the stern and a rib tied alongside help my sleep a bit.

 

[Ex-SolentBoy]

Wake up the first guy and tell him to move. He arrived last and should anchor clear of the boats already there.

20 fathoms is I think about 36 metres. Doesnt sound excessive to me for 8 metres depth. Your turn to move.

 

[johnalison]

We seldom anchor except in shallow water and mud, so 3x depth with an oversized anchor is plenty, and sometimes a bit more for luck. "First come first served" is always the rule as far as I am concerned, though it didn't resolve a problem we has in Walton Creek years ago. Although I had been anchored overnight, someone who arrived for lunch though I should move, as he said "I always anchor here on Sunday".

 

[bluedragon]

Wake up the first guy and tell him to move. He arrived last and should anchor clear of the boats already there.

Easier said than done! I anchored in Cawsand Bay many years ago well clear of all other boats (I thought). In the night there was a knocking on the hull with an angry Frenchman telling me to move as we'd swung alongside of his cat (which I did). The following morning it transpired he had all rope rode and though I forget exactly it was hugely excessive and I'm surprised he didn't wipe out half the anchorage when we swung to the tide. I told him what I thought of his "bad manners" in not anchoring with a appropriate type and amount of rode. I still feel there was no way I could know what he had down and have taken reasonable avoiding action when anchoring. Though since then I try avoid cats / mobos / Frenchmen and anybody else that isn't a yacht with chain at the bow. Pity to tar all with the same brush, but there you go...

 

[RichardS]

Why all this distinction between chain and rope?

For the same scope, I can imagine that chain will take a bit longer to lie to the current or wind but is the ultimate circle going to be that much different?

If it is a really big difference, what is the "formula" : is 3:1 rope the same circle as 4:1 chain or whatever?

Richard

 

[rudolph_hart]

Why all this distinction between chain and rope?

For the same scope, I can imagine that chain will take a bit longer to lie to the current or wind but is the ultimate circle going to be that much different?

If it is a really big difference, what is the "formula" : is 3:1 rope the same circle as 4:1 chain or whatever?

Richard

Not as far as I can see. In a 24 footer with 2 fathoms of chain attached to the anchor then warp, I always allowed a minimum of 5x, and the same in a 34 footer with 10 metres of chain + warp + anchor chum weight. With all chain I use a minimum of 3x (prefer 5x).

 

[Blueboatman]

LongJohn, I find the trick is to wrap the anchor round a rock, then the scope doesn't seem to matter so much. Of course if Jeff the fairygodmother and your goodself hadn't rowed over all suited up and ready to dive, I or at least my anchor would still be there, probably buoyed and a very effect future mooring for someone! Kind regards, Tim.
BTW Falmouth does seem to attract the bungee anchorers of a certain Gallic persuasion. Which with high topsides and skinny keels, I wonder should they show TWO anchor balls? ( = keep double yer normal distance away)

 

[bluedragon]

I wonder should they show TWO anchor balls? ( = keep double yer normal distance away)

What an EXCELLENT suggestion! A prize for that man...

 

[Blueboatman]

Tis Friday night,So thankyou kind sir! 

 

[Boomshanka]

How much scope do you reckon this is (takes a while to get going):

 

[hlb]

Thats nothing John. A boat came and anchored next to me in Salcolmbe and shouted for me to put fenders down in case they crashed.

 

[bluedragon]

How much scope do you reckon this is (takes a while to get going):

YES...this is obviously the French guy on the cat in Cawsand Bay! He clearly had some chain on the end of his 500m of rope. I couldn't see it in all the smoke

 

[longjohnsilver]

LongJohn, I find the trick is to wrap the anchor round a rock, then the scope doesn't seem to matter so much. Of course if Jeff the fairygodmother and your goodself hadn't rowed over all suited up and ready to dive, I or at least my anchor would still be there, probably buoyed and a very effect future mooring for someone! Kind regards, Tim.
BTW Falmouth does seem to attract the bungee anchorers of a certain Gallic persuasion. Which with high topsides and skinny keels, I wonder should they show TWO anchor balls? ( = keep double yer normal distance away)

Hi Tim, how's it going and where are you now? I'm currently at anchor in Babbacombe en route to Lyme Regis to watch the Red Arrows and do some diving. The last night in The Cove became a bit rolly but the trip back to Falmouth in the morning was fine. Just glad we weren't around in Scilly in the gales!

 

[jimbaerselman]

Brits are obviously not used to anchoring in places where there's a bit of wind, where the anchor need to do more than just lie on the ground.

If an anchor is going to be pulled with a force of some 500kg or more (and most anchors for a 12m LOA boat can hold that), whether you have a rope or a chain rode is almost irrelevant. Both will be pulled almost to a straight line, give or take a degree or two.

However, the certainty is that with x3 scope, the anchor will be pulled out, especially if the boat is yawing from side to side.

Most anchors need the rode to be pulling at less than 10 degrees elevation above the ground slope in order to develop their maximum holding. Modern anchors (spade, rocna etc) tolerate a steeper pull. Find the limits of your own anchor by (in a sail boat) motoring full astern. It should hold. At x3 it won't. At x4 it may, if you have an overweight modern anchor. At x5 a flat anchor, plough or claw anchor will probably pull out. At x6 (approximately 10 degrees) most flat anchors will dig deeper.

So most people who have experience of anchoring where it's routinely quite windy (25kts plus) will have a minimum of x5 scope, and x6 if they use a Britany or Fortress.

So, test you own holding before saying this is a load of old rubbish. See what scope is needed for your anchor to hold full astern in a sailboat. You'll then realise why so many boats drag when the breeze gets up at night. They were x3 scope people. Full of optimism, moaning about wide swinging circles.

No that sort of swingng, Charlie!

 

[Blueboatman]

Hi LongJohn,
I'm pottering around the Fal, watching the usual high calibre workboat racing( Flushing regatta) and in no partic hurry tho prob to Torbay and then CIs next week or so.
Red Arrows will be great, have you ever anchored off for the Eastbourne airshow?
I am still looking for 'that fish', but he's definitely in trouble now, I've invested heavily in Trago Mills finest quality feathers so reckon I'm at the top of me game now !
Enjoy the diving. I am slowly researching putting the kit together around a 7l bottle.
Is Jeff on here I wonder, perhaps a pm thx.

 

[longjohnsilver]

Scallops, lobster and mackerel on BBQ this evening, isn't life a bitch?!

Jeff definitely not on here but will see him in next few days for a dive. Will pass on your regards. We could well be in CIs in next week or so, hopefully catch up again soon.