Anchor not holding- advice please?

Elessar said:
Suggest posting on the scuttlebutt. They have a lot of knowledge about anchors and I'm sure it will be forthcoming. :)
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Yes but every thread on anchors and anchoring only ever ends in a fight over there. At least this thread will be conducted in a civilised manner;)
 
Some great advice as usual- can anyone take a view as to the possibility of the tide swivelling the anchor so it lay on its back and thus caused the problem in the first place ? Sorry to repeat this as some have suggested swivel not a problem but surely it must be if it lands on its back and with the tidal pull I could easily see that could happen.
 
search for Rocna anchors they have a very interesting video showing anchor behaviour and for some balance look up Manta anchors as well. Obviously they favour their own products but still worth a look. I have had problems with various anchor types and some do land on their backs and struggle to flip over/dig in. (Delta, CQR, Bruce) particularly if the boat is moving too quick relative to the bottom.
 
kennyh said:
I had a few anchoring mishaps in the early days, and as I was using my anchor mostly for overnights on the hook, it was pretty important to get it right!

So I bought a book that helped in understanding the techniques and science behind anchoring. Since then, I've had no problems.

Have a look on Amazon for a book called "Staying Put: The Art of Anchoring".
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I agree an excellent book. Should be on every sailors book shelf.

http://www.amazon.co.uk/s/ref=nb_sb...keywords=+"Staying+Put:+The+Art+of+Anchoring".
 
Mike k said:
Some great advice as usual- can anyone take a view as to the possibility of the tide swivelling the anchor so it lay on its back and thus caused the problem in the first place ? Sorry to repeat this as some have suggested swivel not a problem but surely it must be if it lands on its back and with the tidal pull I could easily see that could happen.
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Firstly when a tide turns, it is not instant and the boat tends to rotate around the anchor, gradually turning it in the opposite direction. Secondly, anchors are designed to turn themselves the right way up when pulled so even if the anchor was pulled out of the seabed and was somehow laid on it's side when the tide turned, it is very likely that it righted itself when the boat started to pull it. IMHO your problem as I said before is due to having an anchor which is too small for the fierce tidal conditions you were trying to anchor in and with unsuitable characteristics for the soft seabed you were trying to set it in
 
Monique said:
I love anchor threads; almost as good as porn.... Repetitive but always fun to watch. :-)

I'll get my coat. MWARFFF
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More than likely its been said a lot of times before, but in most cases its not the anchor but the length of chain, and the amount of rope that's been let out that causes it slipping.. And mine
 
Deleted User said:
Firstly when a tide turns, it is not instant and the boat tends to rotate around the anchor, gradually turning it in the opposite direction. Secondly, anchors are designed to turn themselves the right way up when pulled so even if the anchor was pulled out of the seabed and was somehow laid on it's side when the tide turned, it is very likely that it righted itself when the boat started to pull it. IMHO your problem as I said before is due to having an anchor which is too small for the fierce tidal conditions you were trying to anchor in and with unsuitable characteristics for the soft seabed you were trying to set it in
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thanks Deleted User- I was meaning the force of the tide against the decent of the anchor ( starting out facing right way then getting swivelled) when originally lowering the anchor rather than when the tide turns the boat around 180 deg. But you have answered my question by saying that no matter how it falls it should right itself. Thanks again
 
I suspect that either the anchor is moving too fast over the seabed when it makes contact, so tends to skip along rather than digging in, or it is digging in but just can't arrest the momentum of a 3 tonne boat doing 7-8 knots. Either way, the answer would be a bit of forward gear when anchoring to slow the boats SOG to give the anchor a chance to set properly.

I also agree with others that a bigger anchor is needed, and maybe even more scope than the 5 times the OP currently uses. 7-8 knots of tide must be equivalent to a howling gale above sea level in terms of anchor load, due to the much higher friction of water on the hull.
 
Nick_H said:
I suspect that either the anchor is moving too fast over the seabed when it makes contact, so tends to skip along rather than digging in, or it is digging in but just can't arrest the momentum of a 3 tonne boat doing 7-8 knots. Either way, the answer would be a bit of forward gear when anchoring to slow the boats SOG to give the anchor a chance to set properly.

I also agree with others that a bigger anchor is needed, and maybe even more scope than the 5 times the OP currently uses. 7-8 knots of tide must be equivalent to a howling gale above sea level in terms of anchor load, due to the much higher friction of water on the hull.
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thanks Nick- sounds spot on. Combo of Bigger anchor and forward gear then. We did give it forward gear yesterday but its so hard to judge how much for how long so with more experimenting with a 10kg should help.
 
What is size chain do you have? I've found that going up helps significantly and regularly anchor a 27ft 3.5 tonnes boat with a 6kg delta in the Bristol Channel, but I am using 8mm chain not the usual 6mm that I seem to see on other similar sized boats.
 
wakeup said:
What is size chain do you have? I've found that going up helps significantly and regularly anchor a 27ft 3.5 tonnes boat with a 6kg delta in the Bristol Channel, but I am using 8mm chain not the usual 6mm that I seem to see on other similar sized boats.
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thanks Wakeup but its 8mm
 
My rig is a 20 kilo CQR on 10 mm chain for a 17 tonne boat. This year I've been playing with attaching 20m of loose chain to the lead of the shank on the anchor before I drop. The logic being that the chain holds the anchor on the bottom and counteracts the tendency of the cattinery to lift the anchor up. When I've done it the anchor hasn't moved and sets immediately. Haven't tried it in extreme conditions yet, so if someone else tries it please publish
 
Mike k said:
thanks Nick- sounds spot on. Combo of Bigger anchor and forward gear then. We did give it forward gear yesterday but its so hard to judge how much for how long so with more experimenting with a 10kg should help.
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Mike k there was an interesting anchor test in this month's Passagemaker magazine in which they tested various anchors in soft mud conditions and the Fortress/Danforth type performed better than any other type of anchor in these conditions. Intuitively this sounds right because the Fortress/Danforth anchor has large flat flukes which present a large flat surface area to resist pulling through the seabed. Maybe worth a try if you are considering upgrading anyway. Also you should talk to other boaters in your area about which anchors work best for them
 
Deleted User said:
Mike k there was an interesting anchor test in this month's Passagemaker magazine in which they tested various anchors in soft mud conditions and the Fortress/Danforth type performed better than any other type of anchor in these conditions. Intuitively this sounds right because the Fortress/Danforth anchor has large flat flukes which present a large flat surface area to resist pulling through the seabed. Maybe worth a try if you are considering upgrading anyway. Also you should talk to other boaters in your area about which anchors work best for them
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Thanks Deleted User= I found the article and it was an interesting read ''Anchor Math and Management Part 2''. Going to talk to otherlocals too. Thanks again for your helpful posts;
 
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