Anchoring in large tides

[BruceK]

On my last outing, admittedly during one of the largest if not the largest spring tides of the year and near the southern mouth of the Menai straights where the current gets to about 4-5 knts, my claw anchor experienced it's first drag. As everybody was ashore at the time it gave me a bit of a scare with the boat dragging it's anchor at about 1.5 -2 knts at the time. Now I know these anchors in head to head tests have always performed poorly but mine has been absolutely reliable until now and that includes anchoring in some nasty weather up to storm force 9 this last August. http://www.youtube.com/watch?v=G5Y43EkTv5A
The issue that worries me most are the tide / current direction changes we get here of up to 8m. In this respect the Bruce / Claw has served me well so long as I avoid sea grass and caters to my shorter than ideal scope of all chain 3:1 (HW) and chain rode mix 6:1, the latter being rarely deployed.

I mostly anchor overnight and so what was different this time was an absence of an electronic anchor watch to give me warning and it was fortuitous that I noticed the boat drag as early as it did while ashore.

Based on the excellent reports I have read here I thought it would be a no brainer to go for a Rocna, or more specifically a Vulcan due to my boat's particular pulpit and bow roller configuration. (But then most reports were from the Med and my situation couldn't be more different) That's when I came across this video test which mimics my environment rather neatly. Fast current changes at 180 deg with shortish scopes in sand mud substrates. The Rocna did not perform so well. I seems the picking up of sand/mud on the blade upsets it's balance hampering resetting

Unfortunately further reading on what did survive these type of tests wont fit my setup. i.e. my second choice being a Spade (shank clearances) unless I attach it to the chain before each drop. Which leaves me with a Delta which I have even less confidence with having seen them drag more than set. What else is there that can fit my bow roller setup with that awful porpoise nose I have sticking out as shown below?

 

[CLB]

In mud, I have had excellent results with a delta. I always go one size up from recommended and have never dragged. I'm on east coast so maybe a different kind of mud.

Maybe you should try a fortress. https://m.youtube.com/watch?v=RmHxO8mbAyk

 

[BruceK]

..... so maybe a different kind of mud.

Possibly all I can say is a fellow boater in the group in a V40 has endless issues with his Delta here. Takes many drops to set and is quick to drag (plough?) in the soft mud here

 

[BruceK]

Maybe you should try a fortress. https://m.youtube.com/watch?v=RmHxO8mbAyk

The fortress wont fit my bow roller setup

 

[Deleted User YDKXO]

Not sure that the video was fair test given that the Rocna was about 5kg less in weight than the other anchors he mentioned. Whilst we do not get tidal changes in the Med we do often get big wind shifts which I guess puts the anchor to a similar test as a tidal change. When I use my anchor in the Med I always use the track feature on my plotter to observe how the boat is behaving and the anchor is performing. It is quite easy to see when an anchor has reset quickly when a wind shift happens because the boat track scribes a circle. If the anchor has started to drag before resetting then of course the boat track is not uniform. FWIW I've used Bruce, Delta and Rocna anchors in the Med and observed how each has performed. I have least faith in the Bruce because it just doesn't seem to cut through the weed we often get in the Med although it performs very well in mud. The Delta seems to perform well in all conditions but I have experienced a couple of drags with Deltas which dented my confidence. Whilst I've only had my Rocna since last winter, I have used it a lot this season and without doubt it outperforms the Bruce and the Delta IMHO even when the wind shifts. I experienced an example of this only 3 weeks ago. We anchored in a bay in a light westerly and went ashore for lunch. During lunch the wind changed 180deg and got up very suddenly to at least a F6 which had not been forecast. Frankly I was s***tting bricks because we hadn't put out an awful lot of chain and we left the restaurant in a big rush to get back to the boat. When we got back to the boat, there was that perfect circle on the plotter and the Rocna had not budged

Having said all this an anchor is only as strong as the seabed its trying to stick to. IMHO if the seabed is extremely soft or sugary, as it may be if you are in avery popular anchorage, then pretty much any anchor is going to have trouble setting and this might have been the case in that video. In these conditions, something like a Fortress anchor with wide flat surfaces might be the best choice. But I dont consider myself an expert in these matters. All I do know is that I'm pretty confident in my Rocna

 

[benjenbav]

Maybe look at increasing the scope and making it all chain?

 

[RobWales]

Not sure that the video was fair test given that the Rocna was about 5kg less in weight than the other anchors he mentioned. Whilst we do not get tidal changes in the Med we do often get big wind shifts which I guess puts the anchor to a similar test as a tidal change. When I use my anchor in the Med I always use the track feature on my plotter to observe how the boat is behaving and the anchor is performing. It is quite easy to see when an anchor has reset quickly when a wind shift happens because the boat track scribes a circle. If the anchor has started to drag before resetting then of course the boat track is not uniform. FWIW I've used Bruce, Delta and Rocna anchors in the Med and observed how each has performed. I have least faith in the Bruce because it just doesn't seem to cut through the weed we often get in the Med although it performs very well in mud. The Delta seems to perform well in all conditions but I have experienced a couple of drags with Deltas which dented my confidence. Whilst I've only had my Rocna since last winter, I have used it a lot this season and without doubt it outperforms the Bruce and the Delta IMHO even when the wind shifts. I experienced an example of this only 3 weeks ago. We anchored in a bay in a light westerly and went ashore for lunch. During lunch the wind changed 180deg and got up very suddenly to at least a F6 which had not been forecast. Frankly I was s***tting bricks because we hadn't put out an awful lot of chain and we left the restaurant in a big rush to get back to the boat. When we got back to the boat, there was that perfect circle on the plotter and the Rocna had not budged

Having said all this an anchor is only as strong as the seabed its trying to stick to. IMHO if the seabed is extremely soft or sugary, as it may be if you are in avery popular anchorage, then pretty much any anchor is going to have trouble setting and this might have been the case in that video. In these conditions, something like a Fortress anchor with wide flat surfaces might be the best choice. But I dont consider myself an expert in these matters. All I do know is that I'm pretty confident in my Rocna

Mike, looking at the material content, shapes of the pieces and assembley times and having just looked online at some sample prices I'm thinking.......someone is making a killing on these anchors!!
Maybe a sideline worth looking into I reckon....hmmmm

 

[BruceK]

Thanks for that Deleted User. I agree stories about the Rocna dragging on a wind shift is rare and the test also had rather a short scope out. It does however mimic what we have up here in Anglesey. Lots of soft mud and minimum scope. It's a confidence thing really. It's not possible for me to be up 72 hours over a long weekend trip out so I admit to sleeping while at anchor and during the days we are often ashore. Because of the tide range and because of available scope the net result is we drop our anchor on a fine line with the shore and often rocks not far off and a second anchor in Bermuda or stern kedge style would play havoc in the tight anchorages when other boats swing. When the Bruce / Claw dragged the boat had another 50 yards to go before it would have been swept down and out of Caernafon Bar. Luckily I was last in line with no one behind me. We only get 20 odd yards clearance between boats and often half that when it gets busy.

 

[BruceK]

Maybe look at increasing the scope and making it all chain?

Two issues. Weight up front but more particularly tight anchorages. I'd love to lay out 100 yards of chain. It would however in a tide shift cause me to hit all the other boats on a 3:1 scope. The favoured Anglesey coves and bays are small and tight.

 

[Mike k]

Bruce

I anchor in the Mersey with up to 10m of tide and up to 8knots of flow- I have a Delta 6kg on 8mm chain ( all chain) and go for 3:1- only dragged twice. Boat 24ft 3 tonnes.Must admit its not pleasant when it happened but its rare!

 

[doug748]

A few disjointed thoughts.

There is some talk that genuine Bruce anchors perform better than the copies. They are cheap enough now so might be worth getting a used one a size bigger, if it will fit. Although I admit yours looks a fair size right now.

Most anchor tests rely on the assumption that the higher the ultimate holding figure the better the anchor, can't see it myself. As RobWales has said it starts to looks like a PR/money making scheme.

More chain can't hurt, perhaps you could go up to 5:1 all chain? Maybe 75m so that would do you up to 15m at HW. This would mean you would be c90ft nearer the next boat but only when you need to be, on spring tides, and only when the wind is over 30kts at all other times you could be on less scope and/or the catenary of the chain would hold you much more tightly to your anchor. At the very worst, lots of chain will slow up the rate of drift!
I always feel chain has less drag than rope in a tidal flow.

I had a similar dragging episode to you. My thoughts are that sand holding is scoured from the anchor by a fierce tide. Salcombe springs to mind and parts of Brittany.

PS

The usual anchor suspects may overlook this forum so you might get some disinterested opinion! - Good Luck

 

[BruceK]

PS

The usual anchor suspects may overlook this forum so you might get some disinterested opinion! - Good Luck

The last thing I want is another anchor thread war. I'm just looking for a new age anchor with a rep that will fit by own particular setup and bow rollers. Preferably one that has a right angle in the shank rather than a curve. I loathe that porpoise nose affair but the marinas love it. A whole extra meter of nothing bloody useful and pig ugly too boot.

I could probably go to 200 foot (60m) of chain then rode but not much more. If I ever dropped off that much (accidentally) in deep water I have concerns about the windlass picking it up. I know when I have anchored in deep water (40m) briefly with half rode all chain the windlass starts to slip and stutter under the load trying to pick up all the chain and dislodge the anchor simultaneously whereas it will quite happily pull the boat against the wind and tide without engine assistance picking up chain at 15 foot depth. As I said previously total pickup weight is an issue and also for boat trim too as I have a large water tank under the V berth that is essential to fill before a cruise with my kids on board and already then starts to effect the boat. A larger anchor is a option. Mine is 15kg but I was under the impression Bruce no longer made these anchors. I'll need to double check that one.

 

[Deleted User YDKXO]

It would however in a tide shift cause me to hit all the other boats on a 3:1 scope.

Wow I'm not sure I could sleep at night on less 3:1 scope and I'm sure I wouldn't go ashore! You really do need the very best anchor you can get for the seabed conditions you are likely to meet. You say that at 3:1 you have enough chain on board to have an all chain rode? How about increasing the size of the chain? That is something I often do on my boats. I check the maximum chain size the windlass can handle, fit the appropriate gypsy and buy some bigger chain. Again I stress I'm no anchoring expert but IMHO the chain can make a big difference to the holding power of the anchor. If you have a heavier chain, firstly more of it lies on the seabed and there is less risk of an upward pull on the anchor, secondly the extra weight provides more catenary effect to dampen peak loads and thirdly the more chain you have on the seabed the greater the frictional resistance to movement between the chain and the seabed. Failing all that, there is always the option of an adding an anchor kellet (ie a weight which sits on the anchor chain) which IMHO provides some of the benefits of a heavier chain. I've never used one myself; it looks like a bit of a faff but if you've got no possibility of putting out more chain or increasing chain weight, it might be a bit of added security

 

[doug748]

No, as you say, they don't make them now but secondhand ones tend to be pretty cheap when they come up.

 

[benjenbav]

... I'm just looking for a new age anchor with a rep ...

Apologies: this won't help. I watched one of the old Pink Panther films again the other day and when I read that comment my first thought was: surely Bruce is just making it more difficult for himself if he insists on an anchor with 100% rope... Next thing, he'll be saying he doesn't have enough rheum to store it.

 

[BruceK]

You might enjoy 'allo 'allo curently being rerun on History channel Very Peter Seller-ish.

Back on topic my anchor locks against the underside of that pulpit affair. No bow roller ring job to hold the shank. The claw has a shape that incorporates two 90 degree angles whereas these new age anchors are C shaped over the shank with a blade that would then cut into the grp once pulled taught to secure it. This boat came with a claw from factory. It's almost as if it has been designed to be exclusively claw but the Vulcan or Delta might be made to fit with minimal modifications to the bow roller setup.

Edit History channel.