Anchor wally

[aquaplane]

West Loch Tarbert Jura I picked my spot and hove to, dropped the anchor to the bottom and let more out as I drifted, I'm sad to say I only dug it in by backing the main when head to wind but I didn't budge. I was chuffed. Not bad for first time singlehanded.

 

[charles_reed]

An interesting thread - probably raises more questions than it answers:-

ie
1) the assumption that all anchoring is under power, 30% of the time I'll anchor from sail.
2) how do you decide the start point for your calculation of scope? where the anchor is in 4.5m of water and where the boat ends up in 9m of water. As one is trying to anchor under the lee of land, that's a common situation.
3) Is there really such a thing as a "standard" scope? No matter which arcane method you use for determining it? Does it all not depend on the composition of the bottom? And the anchor design.
i e a Brittany needs about 6:1 chain to set well - the almost identical Fortress will set effectively on 2:1 on rope.

Yes there is a difference between "new-age" anchors and old design ploughs, but is this not irrelevant when compared with the differences in anchoring techniques and competence between yotties?

I for one would hesitate to hold up to public scorn anyone who had problems with setting their anchor. It might be something as simple as a crew member who insisted on throwing a CQR in, upside down, because he insisted on handling it by the flukes.

I suppose that "in the kingdom of the blind, the one-eyed man is king".

 

[JumbleDuck]

2) how do you decide the start point for your calculation of scope? where the anchor is in 4.5m of water and where the boat ends up in 9m of water. As one is trying to anchor under the lee of land, that's a common situation.

It's the depth of water at the anchor that matters; whether the boat has moved into deeper or shallower water makes no difference. At the head of Loch Striven I dropped the anchor on a shelf which is about 3m deep, used my usual 3x chian and was in 10m myself. No problem.

 

[noelex]

How do you decide the start point for your calculation of scope? where the anchor is in 4.5m of water and where the boat ends up in 9m of water. As one is trying to anchor under the lee of land, that's a common situation.

Scope is a simple mathematical relationship. It is defined as the length of rode divided by the depth of water where the anchor is located + the bow roller hight (above the waterline). So the 9m in your example is irrelevant and does not come into the scope calculation.

However, the bottom slope where the anchor is located makes a very significant difference to the holding power of the anchor. This is much more important than most people realise. It is sometimes useful to calculate the "effective scope" which takes into account the slope of the seabed where the anchor is located. This slope is difficult to accurately estimate. You can get some idea by watching the depth sounder around the area where the anchor is dropped. In your example if the seabed was a uniform slope (which it rarely is) the anchor would be on a downslope (when the wind is blowing out of the bay) which will reduce the effective scope and the anchors holding ability.

 

[IanJackson]

I should made clear I was talking about anchoring under power which is what mostly happens here. What do people think about the latter "italian' , method drop anchor and drive over it?

 

[oldbilbo]

I should made clear I was talking about anchoring under power which is what mostly happens here. What do people think about the latter "italian' , method drop anchor and drive over it?

I'll make a start, while refering Good Posters to conside the OP...

If it works, that's fine. If it doesn't, try something different. Dogma is best confined to a church....

 

[ghostlymoron]

I would advise against 'driving' over your anchor as you risk fouling your prop. The 'handbrake turn' method is for anchoring under sail only. I'm surprised more sailors don't try this, it's quiet, environmentally friendly, and fun.

I should made clear I was talking about anchoring under power which is what mostly happens here. What do people think about the latter "italian' , method drop anchor and drive over it?

 

[Serin]

Quite a few years back, we had to beat up to Port Ellen ( south-east corner of Islay ) in a building gale and gathering dark. The engine on this Rival 34 - or at least, the hydraulic gearbox - had died on us and PE was the nearest haven. We had only the harbour diagram in Reed's....

It was a black night, blowing hard. We eventually felt our way up to the windward, NW corner, then beam-reached slowly back and forwards in about 3 metres of water under reefed main, while laying out 30 metres of chain on deck and snubbing it off on the solid Samson post. Making abut 2 knots, we dropped the hook. While letting the chain run out, I put the helm up, t'other half dropped the mainsail into the lazy-jacks, and the boat described a steady half-circle downwind - until the progressive pull on the chain brought her bows firmly around, head to wind, stopped.

Kettle on.

Anchor watch.

Very securely 'hooked'....

What a lovely, satisfying bit of seamanship.

 

[ghostlymoron]

I've just read that new generation anchors require more power for setting. This would mean modifying my 'engineless' technique by keeping more drive in the sail until the anchor is set. Should be easy as you are sailing downwind/tide.