Trust your anchor

I just reviewed a book for the Ocean Cruising Club – Happy Hooking: The Art of Anchoring by Alex and Daria Blackwell. It’s over 350 pages long – and this is the third edition!

Clearly, if you want to grab a yachtie’s attention, just bring up the subject of anchoring.

Take a look at the sailing groups on Facebook – they’re full of arguments about anchors. Sometimes it seems the new generation of ground tackle causes more trouble than Trump or Brexit. It’s safer to bring up religion.

Certainly, I had no idea I was stepping into such contentious territory when I wrote about choosing a new anchor back in 2017 (August 19, if you’re looking for it).

Also, in those days, I had never heard of an anchor watch app. It turns out there are several of them. This summer I downloaded something called Anchor Lite. It nearly gave me a heart attack: At two O’clock in the morning, a police siren went off in my ear.

That was the alarm to tell me I had dragged 20metres already. Hadn’t I better do something about it? After all, weren’t the rocks less than 100 metres away? Quick, start the engine – would the windlass work? It takes at least a minute to get the chain hook off… Damn, stubbed my toe. Where’s a clothespeg to hold the companion lock open – I need both hands to slide the hatch…

And all this while the anchor was dragging…

Except, of course, it wasn’t. All that had happened was that the boat had shifted sideways as the wind changed. The rocks were now even more than 100 metres away. If the Anchor Lite thing had any sense, it should have played soothing music instead.

As I shuffled back into my sleeping bag, nursing my stubbed toe and banged head – yes, I managed to collide with the hatch in the rush to save the ship – it occurred that we never had all this trouble in the old days.

In the old days, you set your anchor (you didn’t just “drop” it, by the way) and then you relaxed, knowing that you were safe.

Of course, in those days when the CQR was the favourite, you did drag – but very, very slowly as the great lump of iron ploughed its way along the bottom as it was supposed to. When the wind got up, all the diligent skipper had to do was keep a track of his transits to see how fast he was going backwards. But he didn’t get any nasty surprises.

With the new generation of anchors, there’s no need to drag at all.

Of course, I could be tempting fate by writing that line – on the other hand, I do have a 20kg Rocna and 10mm chain on a 9.7metre boat.

Yes, it is massively over-sized but I have never used more than 3:! scope* and, used properly, it has never dragged – not once. Take a look at the screenshot of the Navionics app: This was Braye Harbour in Alderney, the UK Channel Islands, where the swell comes in like a freight train in anything from a North Westerly to Easterlies. The track shows a couple of days when the wind swung from SW to NW and puffed up to 40knots, throwing spray 20metres in the air as the waves hit the breakwater and setting Samsara bucking her chain enough to upend the coffee all over the bunk cushion.


But, although she pulled back and stretched the rubber snubber to more than twice its length, I don’t believe that anchor shifted more than half a metre (which it would have had to do as it dug itself deeper and deeper into the sand).

Compare that screenshot to the second one which I have just taken after two calm days in Poole Harbour, swinging to the tide in Blood Alley Lake between Brownsea Island and Furzey Island.

Blood Alley Lake, Poole

The point of this is to say that if you trust your anchor (and how well you set it) you should not need an app. All that an app will do is sow the seeds of doubt about what’s going on down there on the bottom. You will not sleep well – either because the police siren will shoot you bolt upright and crashing into the deckhead or because it hasn’t gone off at all and you have to check that it’s still set, that your phone hasn’t gone flat or, indeed, that you still have a GPS signal and the alarm for that didn’t go off.

OK, so I do sometimes wonder about the 10mm shackle between the chain and the anchor. It really ought to be one size up but it’s the biggest that will go through the bow-roller. Besides, it has a breaking strain of 10tonnes and the boat only weighs 5.3.

Anyway, there’s the snubber to take out the snatch loading and I’m getting a Dyneema strop to back it up.

If I didn’t have that to worry about, I’d only find something else.

At least it doesn’t wake me up in the middle of the night with a siren in my ear…

*Scope: When my father taught me about anchoring back in the 1950’s, we never used more than 3:1 (and I don’t recall adding the freeboard – but then, in a Folkboat there wasn’t much). So, it came as a surprise that the Rocna manual recommended a minimum 4:1 and 5:1 in anything of a blow.

Admittedly I do “round up” the calculations so a depth of 3.1metres becomes 3.5 … and 3.6 becomes 4.0. This makes more difference in shallow water which is where you need more scope – so it seems to make sense.

11 Responses to Trust your anchor

  • I had the same experience with the anchor alarm as you BUT if you learn to use it properly then it is great to use. The alarm sound can be changed to a soothing song. You must learn to set the swing properly on the app and you will stay inside the circumference not triggering the alarm. Once I learned to use it correctly, it never goes off unless I have truly dragged more than 20 meters. This has only happened once in the last year and I am glad it did as a strong wind came up and I was below. I was dragging toward the marina channel with heavy traffic. I reset the anchor and all was good.
    I have an oversized Rocner (for 50′ on my 40′) and it was set 7:1 because at the time I only had 20′ of chain with rode. I sleep better knowing my anchor app is there “just in case” because I learned to use it properly.
    Another huge concern we have here in Mexico waters now are anchor pirates. Many boats are having their anchors stolen while anchored and the the bastards let the boats drift away while people are sleeping. I haven’t heard of any victims ending up on rocks yet but another good reason to have an anchor alarm and learn to use it properly.

  • Yes, anchors seem to be the one topic that many sailors argue about. We have Alex and Daria a Knox anchor to try out and mention in their new book. Its now the only UK made anchor. I use a 13kg on my Rival Contender, but a 9kg would be adequate. Your 20kg Rocna seems overkill. On snubbers or shock loading absorbers. Dyneema won’t be very good, it has little stretch and springiness, you need nylon. And what many forget is to use enough length. I make mine off at the cockpit,. allowing nearly 10m of nylon snubber to absorb any shock loading on the anchor. I use a chain hook onto the rode, over the bow.

    • Hi Geoff. The Dyneema will be wrapped around the rubber snubber so that will provide the stretch (nylon is chafing)

      • With my nylon rope snubber, (about the length of the boat), I get 1m of stretch at the bow. This is why I think it so much better than those short rubber types. I use a 1m length of hose round it to stop chafe.

        • Don’t you find the chain gets wrapped round the rope?

          • No, no chain / rope wrapping. Most of the rop is on the deck, runs over one of the two bow slots (no roller on Contender), with hose to give chafe protection. Then over the bow there’s perhaps 1=1.5m of rope under tension as it’s taking the load of the anchor rode. There’s also a loose loop of chain. The chain is under tension from the snubber hook just above the water, and all the way to the anchor. The chain on the boat side of the snubber hook is a loose loop from hook, hanging down and up to the bow slot. (The other one to the rope). This is made off at the Sampson post, but loose between SP and chain hook.
            There is the possibility for that loop to wrap around the tensioned rope, but it’s never happened to me, even under gale force winds.

          • Sorry, Geoff, Confused: You say the snubber is the length of the boat – about 10m. But if the hook is just above the water (about 1.5m) and the chain above it is not under tension, presumably there is only about another metre of rope between the bow and the cleat/Sampson post. So why the need for so much rope? If you’re only going to let out the rest if you need it, the set-up will not look after itself – you may be too late.l After all, 2.5metres of nylon rope won’t have much give.

          • Rope runs over bow, and back to cockpit where it’s made off on cleat. That gives length for extension. I get about 1m stretch in strong winds about F7-8. Hope clearer now, should have explained.

          • Ah, that makes sense but it would chafe on the side of my coachroof. Happy with my arrangement. In a blow or if I’m leaving the boat, I take the chain off the windlass and have a second hook and nylon line on the slack (to absorb the enormous shock if the snubber and its line should part and the whole weight of the boat suddenly comes on the chain and bow cleat). I think we both have our belt and braces well secured!

          • Mine does touch the coachroof, but not really any chafe. There would be chafe over the bow, but protected by hose. Could be many ways to absorb shock loading on anchor.