Anchoring your yacht or motorboat
Anchoring is one of the most important boat handling skills. If you can set an anchor correctly with confidence and know your boat will be safe in a secure anchorage, then you can rest in comfort and will not need to rely on moorings and marinas when cruising. You can also leave your boat at anchor and go ashore safe in the knowledge that the anchor will not drag.
If you do not know how to anchor correctly then you risk endangering your boat and also others who might be anchored nearby. And if your anchor is unsuitable for the type of seabed beneath your keel then there is a high chance of the anchor dragging. For some boat owners, the fear of the anchor dragging means they stay awake all night, as a result getting little or no sleep and most likely stressing out their crew into the bargain!
Getting anchoring right is not always straightforward. It can be confusing with the many types of anchor available and there will always be conflicting opinions on which anchors would be best suited for your boat and your chosen cruising ground. Anchors and chain weigh considerable amounts, so loading up with excessive amounts of chain and anchors can affect a vessel’s performance and only really be necessary if planning a long distance voyage along a variety of potentially exposed stretches of coastline.
Types of anchor
Choosing the type and size of anchors and cable to carry aboard will depend on the type and size of your vessel and the sea area it is being used in. Most importantly, choose anchors that are big enough for your vessel and those which are recommended by the manufacturers. Cruising yachts normally carry at least two types of anchor, plus suitable lengths of chain and rope cables. Types of anchor include:
Bruce – good power to weight, easy to handle, holds well in mud, sand and rock
CQR or plough – good power to weight, stows well on bow roller, though awkward on deck. Holds well in mud and sand. Very popular and reliable
Delta – good power to weight, also plough shaped. Stows well on bow roller
Danforth – stows flat, good kedge anchor, hard to break out of mud. Excellent back up anchor. Prone to pull out if the wind or current reverses
Fisherman’s – the traditional anchor. Good for rocky and heavily weeded seabeds, but heavy and awkward and not so good in sand and mud.
Chain and warp
Anchor cables can be either chain or rope, or both. For an anchor to work effectively, the vessel’s pull on its cable must be parallel with the sea bed, otherwise the anchor will break out from the sea bed and drag. The weight of chain prevents this from happening, providing there is sufficient length of chain lying on the sea bed. A further factor that helps is the effect of the catenary curve of the cable between the boat and the anchor. This acts as a shock absorber between the boat and the anchor, so if the boat is hit by a sudden gust of wind the cable will straighten and tighten before it pulls hard on the anchor.
Hauling in an anchor and chain can be very heavy work if your vessel lacks an anchor winch, but chain is much stronger and will not chafe on the sea bed, unlike rope. A workable solution is to have the anchor cable consist of part chain, which lies on the sea bed and part rope, to make it more manageable. An all rope cable is much lighter and easier to manage, but less secure and prone to chafe. All rope cables are normally used with kedge anchors.
How much cable should you use? The amount, or scope, depends on the type of cable, the depth of water beneath the keel, plus the weather conditions and the height of tide. If anchoring in calm conditions with little or no tide, then the absolute minimum scope for chain is considered to be 3:1 and 5:1 for rope. In light to moderate conditions a ratio of 5:1 for chain and 8:1 for rope is generally accepted and in worsening conditions a ratio of 8:1 for chain and 10:1 for rope. In tidal areas, the rise and fall of the tide needs to be allowed for and if necessary adjustments will need to be made if at anchor for several hours or over night.
Most anchors have a small hole for attaching a trip line, for use if there is risk of the anchor becoming fouled. The line is either brought back onboard and cleated or connected to a small buoy which floats above the anchor.
All of this advice and more is available in our easy-to-use, quick to access app for iPhone and Android. Go to SafeSkipper.com for more.