Anchoring, Equipment & Methods
revised December 2016
Link to Detail album – Anchoring, Equipment & Methods
Secure and sustainable anchoring even under sever conditions, starts with having reliable equipment.
Hard bottoms demand sharp, plough/digging anchors e.g. Delta, Manson, CQR while on soft bottoms you need bigger spade/claw like area, like e.g. Bruce, Spade, Roccna, Manson-Supreme, Bügle. The four latter are sharp enough to cope with most hard bottoms and are a very good choice as all around anchor.
Our Forgus 37 (9 ton) was equipped with a 23kg stainless Delta as our main anchor and a 20 kg Bruce at the bow, plus a 20 kg Manson Supreme at the stern.
Both anchors at the bow arranged to be able to launch either of the two (or together with five meters of chain in-between.)
Moon – our Koopmans 47 (15 ton) has a 40 kg stainless Delta, a FX-55 Fortress and a small aluminum 15 kg Spade. (The latter came with the boat together with a very tiny 20 kg stainless Spade which we sold because it was too small and not made of high strength stainless. The shank was bent to “prove” the need of high strength steel.)
Please observe that the manufactures size guide for anchors is related to anchoring in calm protected places. If you are eager to stay foot and sleep the whole night, choose at least two size bigger anchor.
Windlass and cabling
A windlass is more or less necessary when anchoring in deep waters. But, even with moderate depths it is a matter of safety. Without a windlass you are tempted not to re-anchor even if your holding seems not so good.
The windlass has to be designed to be able to carry the complete dead weight of the whole chain, the anchor (sometimes two when tandem anchoring) and a certain amount of kelp and other debris attached to the chain or anchor.
And this is for your whole journey, meaning the number of years x 150 anchorages.
On top of that the shaft and motor have to be protected from overload by a sliding clutch, otherwise the shaft, key or drum may brake if the anchor or chain gets stuck in the bottom. Most manuals calls for disassemble of the clutch every month for a full time cruiser, to check, sand and grease the mating surfaces in the clutch.
The boat have to be equipped with means to secure the chain when at anchor, and when the anchor is pulled out of the bottom (or into the bottom when anchoring), without transferring any load to the windlass.
The windlass should only be used to set and retrieve the chain and anchor. Never pull the boat with the windlass.
It’s important that the motor and relay are well protected and in a dry compartment. The chain locker is a really bad place for these electrical parts, even in short terms. At least the chain locker on our 37 footer sometimes got full of water when sailing in rough conditions!
Stray current and corroded chain/shackle is one risk, and another high risk is malfunction of the windlass.
Deep water and eventually double anchors sum up to great loads. Check your windlass when loaded.
The voltage drop with the motor running with full load should not be more than 0,5 v. If more, you have to enlarge the cabling area between the battery and windlass.
Check that the windlass uses its marked rating.
There is quite a difference between different brands, marked with the same rating!
Meaning that one brand’s 1000W windlass can be much more powerful (cope with more load) than another brands 1000W, in spite the chain speed being the same. If you are to by a new windlass, it’s a good idea to look into a bigger size than your first intention (but remember the cabling!).
Chain and shackle
Steel is strong when forces are gradually increased but compared with e.g. a rope, steel is brittle, and sensitive to rapid, jerking heavy loads. To avoid this damaging load on the chain, it should always be allowed to flex with the help of a rope or some similar flexing arrangement.
On Lindisfarne (about 9 ton) we chose an 8 mm high strength stainless chain with a breaking load of 5 ton. This is as strong as a normal galvanized 10 mm chain but much lighter. Shackle and eventually swivel has of course to match the chain both in size and strength.
On Moon (about 15 ton) we have a 10 mm Cromox chain. (See table below)
The anchor should always, whether you are using a swivel or not, be attached to the chain with a shackle, with the pin in the chain or swivel and the bow in the anchor. The obvious reason is to keep a straight line for the forces from the anchor onto the chain, without any additional bending forces in the shackle when the wind shifts or the boat is riding back and forth on the chain.
Yes we know that some anchors do not provide a slotted hole, but that doesn’t change the fact that forces don’t want to run around corners without adding forces!
And on top of this, you want to be able to use as big shackle as possible, and that’s the thickness of the pin into the chain – not the bow which need more space, giving you a smaller and weaker shackle.
The latter means that you have weaken the whole system with a smaller shackle exposed to fatigue due to bending at the anchor, VERY BAD!
A chain is very strong when forces are gradually increased, but chains break under strong and rapid jerks, especially if it has already been exposed to fatigue load.
– If the breaking load of your snubber chain hook is below the working load of your chain, you can keep track of the load effect on your chain, minimizing fatigue.
Then you can use your chain “forever”, at least if it is as ours – a stainless high strength – ( no re galvanizing either!)
Most boats have narrow bow rollers and to prevent the shackle to hit the steel on any side of the roller, use plastic washers to center the shackle onto the chain. Se photos in the Anchoring album.
Table – Example of working load and breaking load
X = equipment we were using on Lindisfarne 9 ton, 37 feet
Y = what we now use on Moon 15 ton, 47 feet
|Wichard products (HR = High resistant)||Ø||WL (kg)||kg/m||BL (kg)|
|Chain hook||10||720||2 400||X+Y|
|Swivel HR||10||3 200||5 500||X|
|Shackle||10||1 520||4 300|
|Shackle||12||2 080||6 000||X+Y|
|Shackle||16||3 200||10 000|
|Shackle HR||10||2 640||6 000||X|
|Shackle HR||12||3 600||10 000|
|Shackle HR||14||5 120||12 000|
|Shackle HR||16||6 800||19 000||Y|
|Galv Chain (normal shortlink)||8||800||1,4||3 600|
|Galv Chain (normal shortlink)||10||1 200||2,2||5 000|
|Stainless Chain (normal shortlink)||8||no safe WL||1,4||2 800|
|Classified Stainless Chain 8-5||8||1 250||1,4||5 000||X|
|Cromox G6 ASI 318 NL, 1.4462 (Stainless)||10||5 000||2,25||10 000||Y|
|Classified Stainless Chain 10-5||10||2 000||2,2||8 000|
When it comes to the anchoring maneuver, there are a number of things we try to live up to in every occasion, even if it’s “dead calm”.
– Round up the entire area you will use because of the scope you need, checking the depth.
An even bottom is of course favorable. Avoid steep angled bottoms if you can’t put a rope ashore.
– Now you have a nice round track on your plotter and can put the boat in the middle and use the clutch to release the anchor to get it on that spot near the center of the round up just as the boat start reversing, not to have the chain on top of the anchor.
– When minimum 3 x depth + 10 m have been let out, secure the chain with the secure chain hook (without any tension on the clutch) and carefully continue reversing.
– When the chain comes out of the water in a straight line to the anchor, increase the revs on the engine to about 70% of full power to dig down the anchor.
If the depth is greater than your chain (three times…) lengthen your chain with a rope, see below.
– When the anchor is set, gently tension the clutch and release the secure chain hook.
– Then attached the little chain hook with its flexing ropes (snubber) to the chain and fasten the rope to the bow cleat.
– Then the chain is let out so the boat rests on the cleat, connected to the chain via the snubber hook.
– Finally we attach the securing chain hook on the deck again and release the clutch.
– Put the locking pin above the roller in place to prevent the chain from “jumping” out of the roller if the snubber breaks in swell or similar conditions.
– Finally switch of the power to the relay to avoid the relay if shorted due to eg. Oxidation engage the windlass.
If the bottom is very soft and we still “have to” anchor on that spot, we use two anchors in tandem.
Two anchor in series with 5-10 m chain in between.
– We start the procedure by shackle a 5-10 m chain in the front of the main anchor to the shank on the extra anchor.
– Then a 10 m rope is attached to the chain half way between the anchors.
Now we are ready to deploy. This time not using free fall, and only to let the main anchor hang vertical under the bow roller.
– Next step is to deploy the extra anchor using the rope. When it hangs straight down and loading the chain to the main anchor, fasten the rope to the chain between the main anchor and the windlass.
Now you are ready to anchor.
Using this method, retrieving the two anchors is fast and easy.
– Retrieve until the rope is up on deck and the main anchor hangs just under the bow roller.
– Detach the rope from the chain and pull the extra anchor using the rope and the windlass capstan.
This means that you first have to secure the main anchor and free the windlass.
– As soon as the extra anchor is up, tension the clutch on the windlass and pull the main anchor up over the bow roller.
Without the rope attached in between the two anchors – it is impossible to get the main anchor “around” the bow roller with the extra weight hanging in its front end and you will have to deal with a situation where you have one anchor under the bow roller and another anchor five to ten meters down, eventually still in the bottom.
Not a situation you easily can cope with, especially if the weather is bad.
For this operation it’s almost necessary to have two bow rollers.
Secure the chain and take the load off the windlass
The boat have to be equipped with some items to secure the chain when at anchor, or when the anchor is pulled out of the bottom (or into the bottom when anchoring), without transferring any load to the windlass.
And once again, never allow the chain to jerk without a snubber.
You need two chain hooks. One that is weaker than the working load of the chain and is fixed to the boat via a flexing rope, a snubber, that prevents the chain from jerking directly on to the windlass when at anchor.
The other chain hook should have similar braking load as the chain, because this is your last securing hook.
The windlass should never be allowed to take these loads because the risk of breaking the key and/or the shaft in a jerk, well before the chain breaks. This is of course not valid for big windlasses with separate brakes, not affecting the key and shaft but the chain.
The deck securing chain hook has to be fastened to the boat at a very strong cleat, and still be elastic enough to relieve the chain from any jerk. A non elastic rope with a rubber damper will work fine.
Remember to loosen the clutch after securing the “deck rope”. There has to be a loop on the chain between the snubber and the deck securing hook to allow for the flexing in the shock preventing snubber, without any force transferred over to the deck securing point. This loop of chain between the hooks also prevent noise from the chain to enter the boat.
– If the breaking load of your snubber chain hook is below the working load of your chain, you can keep track of the load effect on your chain, minimizing fatigue.
Fixing the chain in the chain locker
Never use a shackle to fasten your chain in the chain locker directly without a strong thin line in between!
– First it’s dangerous when you are in a hurry getting rid of the chain in an emergency situation.
– Second it’s not good for the windlass (or chain) if it will stop instantly when the chain comes to its end and the windlass is still pulling out by the motor. The rotating forces will most certainly kill the key, the shaft and/or the line.
– Third – sometimes you need to get the chain up on deck to be able to free the chain even in “normal” circumstances when you have to attach a rope at the end of the chain, while anchoring in deep water.
All these three occasions are easily solved with having a strong, thin and long enough rope/line tied to the end of the chain and then fastened down in the locker.
Long enough so the chain can pass the gipsy before the rope stretches and slide in the gipsy without any forces onto the windlass, chain or line, even if the windlass motor is still running.
If the rope is to short, there is a risk that either the rope or the windlass breaks if the chain still is in the gipsy when the rope stretches.
How to lengthen the chain with a rope
– Stop the windlass when there is a meter of chain left in the locker.
– Attach the securing chain hook in front of the windlass and bring up the rest of the chain by hand with the chain still on the gipsy.
– Untie the locker rope from the chain and connect your prepared strong anchor rope to the chain. (We use 18mm rope with a timble and a shackle big enough for the timble).
– Release the deck securing chain hook and start to put out the chain again with the anchor rope on the capstan or on a winch.
Pulling the anchor rope up, use the capstan or a winch until the chain is well up on the deck, secure with the chain hook before disconnecting the anchor rope.
Tie the locker rope onto the end of the chain and lead it by hand down into the locker and when the chain is completely around the gipsy, release the securing chain hook and continue pulling the chain and anchor as normal.
Line a shore
In many places around the world we have been forced to use shore lines to be able to have a safe anchoring. It’s not always one line we are talking about, rather up to four when circumstances are like in Chile Patagonia.
But even in those places we have been sleeping very well.
Using one 100m floating line most problems are solved.
– First, as always, have a surrounding check of the bottom and put your anchor at the right distance from shore.
– When good holding is achieved, use the dinghy to get one end of the floating line ashore and secure it using lots of chafing protections.
It helps to have one crew attending the helm and engine, to keep the boat into the wind and near the shore until you can load the shore line using a winch.
– Now it’s time to consider whether you need more shore lines, and if so you now have plenty of time to arrange those. We are usually equipped with one 100 m and two to three 40-60 m lines for this purpose. Floating, not covered dyneemas don’t take up much space, only be sure to use lots of chafe protection.
Depth to be able to deal with
You have to be able to deal with at least 25 m depth with reasonable chain angle. This means 3 x depth + 10 m, minimum 85 m chain.
– This is the best role that we have found out and can be applied both on shallow and deep waters under “normal” circumstances.
Eventually 40-60 m chain + rope (the rope should never, because the risk of chafe, be allowed to reach the bottom). If a shorter chain + rope is used, make sure to buoy the connection between the chain and the rope and the part of the rope that eventually can reach the bottom.
Remember it’s your safety and your undisturbed sleeping we are planning for. Don’t use floating rope for your main anchor. There is always a risk of chafing at the surface too – beside propellers…
Where there is no tidal current we use an anchor sail on the back stay to prevent the boat from sailing on and off on anchor.
The sail prevent the boat from jerking the chain when it “tacks”, stretching the chain in both ends. It reduces the load on the chain because it keeps the bow and not the beam towards the anchor and less swinging saves a lot of space, important in crowded anchorages.
Anchoring among corals
Corals are nice to look at, but a big challenge when it comes to anchoring.
If you use “normal” procedures, tide or wind shifts will make you snag corals with your chain and you are not anymore swinging around your anchor, but around one or several coral heads. You no longer have the scoop you put out when anchored.
Another problem, if boats around, is that you may hit boats that haven’t snagged any corals, or the other way around.
No wonder a sudden wind shift in popular coral anchorage makes havoc among boats…
What to do – Put buoys on the chain
One way to avoid to get snagged and keep swinging around your anchor as if there were no corals, is to use buoys on the chain, preventing the chain from trawling the bottom for corals.
It’s even good for preventing damage to the corals, an escalating problem due to increased cruising and bigger boats.
Hitting other boats is unfortunately not solved because there will still be boats snagged by corals.
But there is another most important advantage.
By avoiding getting snagged you avoid diving, trying to loosen a snagged chain, which of course happens in darkness and increasing wind. Don’t forget the sharks – they are more dangerous when you can’t see them!
We use a technique with one hard buoy 10-15 m from the anchor (depending on the depth) and then big round fenders attached every two times the depth minus 5 meters along the chain behind the previous buoy..
In very shallow waters you need many buoys to get the right scoop.
It’s important that the chain closest to the boat are free from buoys enough to let the boat swing around above the chain not to get caught by the hanging chain around the keel. The latter is common in very shallow waters.
This method works best when there is a constant breeze over the anchorage.
Same technique can of course be used avoiding other obstacles on the bottom, big branches, logs and so on.
We once got snagged around a big root stump in Canada BC and could only with very little margin free us.
Never use this method combined with an anchor buddy.!
Diagram Buoys on chain and how to use a chum.
In NZ we found an Anchor Buddy, a 12 kg zinc/aluminum weight that runs down on the chain to just above the bottom using an inbuilt block.
Increasing the weight of the chain, reducing the swinging circle in protected an crowded anchorages.
However if when the wind exceed 25-30 knots your chain is stretched even with a chum, the only solution keeping a descent angle between the anchor and the bottom is to increase the scoop.