Anchors and anchoring
Anchors are essential bits of kit but they can be a bit daunting and dangerous if used improperly. It’s extremely worthwhile training all crew to safely work with the anchor and windlass.
All too often sailors tend to bomb about marina hopping and never seem to use their anchor and if suddenly called upon to deploy one they get caught out due to inexperience. When you are in the way of using an anchor and have confidence in handling, it opens-up up many more options and many more attractive destinations. It is also a vital piece of safety kit and quick and efficient deployment is a major safeguard against running aground in the event of sudden engine failure.
There are many types of anchors which vary in cost and also suitability in different conditions. Most yachts have a bow anchor secured towards the bow positioned over a bow roller. The chain or warp is secured in a chain locker and may or may no be fitted with a windlass to help raise and lower the anchor and chain.
When at anchor during the day you must display a black sphere from a prominent position, usually from a spare halyard between the forestay and mast. At night you must display an all-round white light from a forward position or from the top of the mast. One all round white light us sufficient for a vessel up to 50 metres in length but may display more if feel inclined to do so.
How an anchor works
An anchor helps secure the vessel to the seabed but this is only part of the story.
The anchor cable is the chain or warp attached to the anchor. Sometimes it comprises chain only and other times a mixture of chain and warp. If using mostly warp you should always have at least 5-6m of chain attached to the anchor. The weight of the chain near the anchor stock is critical for helping ‘set’ the anchor into the seabed and it is this weight of chain tends to keep the stock horizontal with the seabed thus helping the flukes dig into the bottom.
When pulling an anchor out – breaking it free – you must pull all the slack chain in then, by pulling the horizontal stock upwards, you can break the flukes out of the seabed.
When anchoring you must assess the depth of water below your vessel and also compensate for expected tidal range. You don’t want to come back to your vessel and find it bumping on the seabed! If only using chain you should allow a scope of at least 4x the water depth but if using a mixture of warp and chain you should allow at least 6x depth.
For instance, if anchoring in 10m of water and using all chain you should pay-out 40m of anchor chain. If using warp and chain you would pay out 60 metres of warp. Remember from the Rope Section that we would want to use nylon warp because of its stretchability which prevents a lot of the snatching at anchor which can be generated by pitching and rolling.
4 x maximum death of water expected
Warp (usually nylon as it stretches and absorb the shock and prevents snatching)
6 x maximum death of water expected
If you are suing warp you should always have at least 5 metres of chain attached to the anchor before the warp starts. This helps set the anchor correctly and cuts down on the abrasion from rubbing on the seabed.
The main anchor is normally known as the bow or bower anchor but is normal for a vessel to carry a secondary lighter anchor which is known as the kedge anchor.
The grapnel anchor can be collapsed making it easy to stow. It works extremely well in weed as its narrow flukes and penetrate through the weed and get a grip on uneven bottoms.
It’s particularly useful for small vessels like RIBs and dinghies but it has poor holding-to-weight ratio and can be awkward to handle and lock into the open position.
It would be an almost useless system to rig as a permanent bow anchor.
This anchor works extremely well in weed because its narrow flukes can penetrate the weed. It has few moving parts and in some the stock can be dismantled making its easier to stow flat.
The flukes can work their way into and around rocks quite easily and, in this sense, can be a good choice when other anchor flukes would be too large to penetrate crevices and cracks.
The downside is that the small anchor spades can pull out of sand relatively easier than larger flukes on other anchor designs. But, all things considered, they have stood the test of time and are particularly useful in weedy or rocky situations.
Danforth/ Fortress Anchor
These are fantastic anchors and provide very reliable holding in soft ground with an excellent holding power to weight ratio. Often used as kedge anchors as they stow flat but can they be a bit of a handful man-handling them around a yacht’s stern.
They can be a little problematic when using in pebbly ground as stones often jam the joints which prevents the anchor ‘setting’ properly.
All said and done, if you are drifting onto a sandy beach and you throw one of these out it should stop you grounding. On the flip side, this type of anchor can be difficult to ‘break out’ when it’s well dug-in.
This is one of my favourite anchors because of its reliability and excellent power to weight ratio with no moving parts and comparatively easy to ‘break out’.
They aren’t meant to be very good on weedy ground but I’ve never had a problem with the one I use. Unless you’re in really soft ground it’s quite common for only one of the outside flukes to dig-in.
CQR anchors are meant to have an excellent holding power to weight ratio but in my experience, unless you are using a heavy one, they can be problematic. The design is built from forged steel which makes them very robust.
They can be difficult to stow on a bow roller and the crown can flop about a bit unless tied down. They do have a tendency to capsize and go over on their side quite easily unless properly set.
They can trip themselves relatively easily if the tide turns and your boat shifts around but they should reset themselves when tension comes back on the cable.
The Deltas are probably the best anchors on the market at the moment with an exceptional holding power to weight ratio. They can be launched quickly, set quickly and easily and dig themselves in deep if the ground allows.
This type of anchor is regarded as the best all-rounder except when anchoring in rock and weed when the Fisherman’s Anchor comes into its own.
Mushroom anchors are primarily used with semi-permeant moorings and not normally found aboard yachts. They are able to work there way into soft sands and mud and can be extremely difficult to recover.
When looking for an anchoring spot you should avoid busy channels where there is a risk of collision and where wake and swell may help to trip your anchor. You should always check your chart to ensure the ground is suitable for your type of anchor with no underwater obstructions like cable and pipes, old fish farm equipment or even wrecks … Indeed, anything which might create foul ground.
If the bottom is thick weed and stone its probably best to use a Fisherman’s Anchor but, if sandy, I would recommend a Danforth type. Usually you are limited to what the vessel carries but you should always be conscious of what the holding might be like with regard to your anchor type and ground conditions.
You should check the nature of the seabed on your chart and ascertain if it will be suitable to hold your vessel, using the anchor you have, in the current weather conditions.
Coarse gravel usually goes better holding than than fine gravel. Generally there is good holding in Gravel and depends how well the flukes can penetrate.
You may have a hard time breaking the anchor from mud, especially if t has been set for a long time but usually offers excellent holding.
More coarse sand is usually better for anchoring and offers good to medium holding
There is a rick of the anchor drag gin on rocky bottoms. You often get a false sense of security as the anchor seems to hold well until a rock moves. It is fairly common to get an anchor stuck in rocky ground and may tale some time to free it.
Holding on kelp and seaweed can be poor and can give a false sense of security until the kelp breaks and anchor starts dragging.
Choosing an Anchorage
- Always check the death of water at an anchorage, using the chart, tide tables and your death sounder. You should select an anchorage so that the vessel does not go aground as the tide falls or try to anchor in water that is too deep for the scope of anchor chain we intend using.
- Check that anchoring is allowed not eh chart and pilot books. Lots of areas have power and communications cables running along the seabed. Other areas have material on the seabed that will tangle your anchoring equipment and usually marked as ‘foul’ ground on your charts.
- Never anchor in a shipping lane or fairway except in an emergency.
- Avoid areas where there are strong tidal streams as increase the chance of anchor dragging or make it uncomfortable when the tide changes against the wind.
- It is unwise to leave your vessel unattended at an anchorage, particularly if there is any risk of the anchor dragging.
Preparing the Anchor
When operating and undertaking anchoring manoeuvres you should be primarily concerned about personal injury. The combination of heavy machinery, chain, and moving parts coupled with the close proximity of people on a tilting deck creates a potentially dangerous situation which can be heightened in bad weather conditions especially when vessel handling is severely restricted.
Yachts tend to have slightly different anchoring systems and no two boats anchor windlass’s behave the same. But what is of paramount importance to safe anchoring procedures is briefing the crew on safety and clear communication.
There should be no need to shout along the yacht unless through the noise of a wind. Whoever is operating the anchor must have shoes on, and keep fingers, loose clothing and hair away from any moving parts.
If the windlass is motorised then only the anchor operator should be controlling it. It is highly advisable to gain practical training in the safe operation and deployment of anchor systems and if you haven’t already done so I recommend that you undertake this training and be properly briefed when chartering a yacht. Pay attention to the location of trip and other switches for the anchor system.
- Approach the anchorage into the tide or wind whichever is stronger and observe other vessel to see how they are sitting to current or wind.
- Prepare the anchor for slipping.
- Slow vessel right down as you approach the chosen anchoring spot.
- Slip the anchor when the vessel is stopped in the water, and lower the anchor until it has reached the seabed.
- Let the vessel fall back with the wind or current until the required amount of chain/warp is paid out.
- You can put a small bit of astern with the engine to help the anchor bite.
- Use bearings or transits to confirm that you are maintaining the correct position.
Use a tripping line with your anchor if you think that there is any chance that it may get fouled. A tripping line is a line from an eye at the fluke of the anchor to a small pick-up buoy on the surface. You met make sure your tripping line is long enough to reach the water surface at the top of the tide. If the anchor become fouled it is possible to recover the anchor by pulling on this line.
When at anchor you must display the proper day signal which is a black ball hoisted on the forepart of your vessel in a prominent position. These black balls can be quite hard to spot on larger vessels and ships. At night you must put your anchor light on, which is an all-round white light at the top of the mast.
After you have set the anchor and the boat has settled down it ‘s important to check your vessel’s position so that you have a reference point to determine whether it’s dragging her anchor along the sea bottom.
All vessels at anchor should have some sort of anchor watch system in place to guard against dragging and this is especially important when the tide changes or the weather picks- up.
- Check GPS position
- Set the GPS anchor alarm
- Monitor a transit and bearing from the beam of the vessel
- Monitor the echo sounder and set depth alarms
- Monitor your position with respect to other vessels anchored nearby
If you monitor these things you’ll be able to determine if your anchor is dragging. You can also feel vibration from the anchor chain and hear a rumbling noise in the forepeak when dragging over a harder bottom. Sometimes you may have the sea room to drag and sometimes it may take a bite and hold. But more often than not you’ll need to reset your anchor.
The mantra is: If in doubt get more chain out! If you have the water depth and room to swing there’s no point having the anchor chain in the boat’s locker when it can be doing some good on the seabed.
When anchored you must make sure you have enough room to swing around in case of wind, current or tide changes. You must also take into consideration other boats and the fact they may have more or less chain out than you.
Different designs of vessel sit and behave differently at anchor and some heavy vessels might not swing as fast as your own vessel. In a busy anchorage it’s always a good idea to put some fenders out just in case you get a touch.
If a vessel has a deeper or longer keel it may be affected more by current and tide than by wind and will therefore have a different swinging circle.
A vessel affected more by the tide is called “tide rode” but will become more affected by the wind as the tide slackens or the wind picks up. You must consider these swinging circles when coming into an anchorage.
Always remember, it is good seamanship to leave enough space between you and the next vessel not only to guard against bumps but also to conserve privacy.
Restricting your Swinging Circle
You can lessen your swinging circle by using two anchors. Set your bow anchor into the strongest tidal flow then set the other kedge anchor in the opposite direction . This is a good method for anchoring in rivers and estuaries where there isn’t much space.
You can also deploy two anchors from the bow offset by 45 degrees. This helps anchor in heavier weather and also lessens the tendency for spade keel vessels to sail up and down their anchor cable in strong winds.
However, if the tide turns during the night you can end up with anchor cables twisted around each other that can cause delay and sometimes make anchor retrieval problematic.
Don’t Forget the Tide
The horizontal movement of water, currents or tidal streams can cause considerable boat movement and direction, time of turning, and speed must always be considered.
When anchoring in tidal waters you should consult your Tide Tables which are published tables detailing the times of high and low tide for your area (more about this in later module).
It may also be useful to have a look at a tidal stream atlas or tidal diamonds on a chart which helps give an impression of what direction the tidal current will change to.
You should check the tidal depth when you arrive at an anchorage and determine how far the tide will drop or rise. If the tide is dropping you must pay attention to the swinging circle of the vessel as it will increase and you’ll have to take some cable in. If it is rising then pay-out some more cable to compensate for the increased depth.
In my experience, from watching novice sailors anchoring, they tend never to put as much chain out as is needed and wonder why they don’t get a bite on the sea bed. They also tend not to set the anchor properly and lay it along the seabed – instead they just pile it up on the bottom and trust to luck.
Anchor in the Lee of the Land
When selecting an anchorage you must appreciate how it will be affected by wind and weather. Generally, the sea is more stable and predictable near a land mass although the wind may gust off the land in different directions. Offshore winds (blowing from the land towards the sea) don’t have much time and distance to greatly affect wave size. But, further offshore, the wind has time to take effect and it will have more influence on the condition and size of the waves.
When there is an onshore wind (blowing from the sea towards the land) the wind has had time and distance to affect the water surface and an anchorage previously suitable during offshore wind conditions can turn into a completely different kettle of fish.
The ‘fetch’ is the distance the wind has to blow and influence the sea state. With onshore wind conditions it would be foolhardy to anchor where the wind will blow you onto land so seek some shelter behind the land for a quieter night at anchor. However, you must monitor weather forecasts during your stay at anchor. Weather Forecasts are obtainable from various places and they will be discussed in later modules.
It is sufficient to say here that you must be certain that your anchorage won’t become untenable during the night because of the wind shifting around. If in doubt, head out! Preferably before it gets dark and the weather changes.
A good sailor always has at least one contingency plan up their sleeve. So, when you anchor in daylight have a good look round and familiarise yourself with the surroundings in case you have to move in the dark.
Always have an advance plan to make for another anchorage or port should the weather worsen so that if you have to move in a hurry you already know where you will head and how to get there.
When an anchorage is becoming untenable only experience tells you when is the correct time to leave. However, don’t allow inconvenience ‘factors’ to play a part in your decision which should based on the safety of those on-board. In my experience, as soon as you have any doubts about the situation, it’s best to haul the hook and head out from the anchorage!