Ground tackle is the term for the entire package - the anchor plus the anchor rode (the line and chain that attach the anchor to your boat)... The anchor rode must be strong and long enough to absorb the shocks of the boat jerking in waves and wind without breaking or dislodging the anchor and must orient the force pulling on the anchor to be as nearly parallel to the bottom (horizontal) as possible.

Anchoring with all chain

D = Maximum depth at high tide L = Length of chain Scope = Ratio of chain out to depth of water... minimum of 4:1 Rode = The anchor line between the attachment on the vessel and the anchor.

Almost all cruising 'bareboats' have all-chain anchor rodes and an electric anchor windlass. Obviously, these rodes are much heavier than rope, but chain is also stronger and more durable than nylon rope. An all chain anchor rode enables you to use less scope (see the next topic 'Figuring scope') for given conditions. Although chain doesn't stretch, it can provide some shock absorption if the rode has enough scope that it curves...sags down to the anchor... called a 'catenary curve'.

A pulse of wind or wave on the boat simply pulls some of this sag out of the rode, absorbing some of the wind or wave energy.

Figuring scope - the chain to depth ratio
The length of the anchor line depends upon the depth of the water where you're anchoring but doesn't equal it...You determine the maximum depth of the water you're anchoring in (at high tide) from your tide tables book (see later)...The basic rule is to use a minimum 4:1 scope (four time the depth of the water at high tide) for average conditions. For example, if the anchorage is 8 meters deep at high tide, then you let out 32 meters of anchor rope... You can see this calculation in the discussion below... 'Anchoring depth of water'.

More scope means better holding power

This effect of scope, or the ratio between the amount of anchor rode you let out and the water's depth, is an important concept to understand when anchoring, the more scope (that is, the more chain you let out), the more chain you have out between the boat and the anchor, the flatter the pull is on the anchor will be, and your anchor remains firmly dug-in on the bottom, which means better holding power, as you see in the diagram.

Too little scope is dangerous - A short scope will tend to lift the stock of the anchor and cause it to break out of the bottom at a high tide...In fact that's exactly how an anchor is retrieved, you reduce the scope by pulling in the anchor to make it break out.

To tell how many feet or meters of chain you have out charter boats often paint or attach plastic markers into your anchor chain at set 5 to 10 metre intervals... check this at your boat brief.

The anchor rode
It is the anchor rode more than the anchor itself that makes for secure anchoring. Correct anchoring practice employs a long length of rode that acts as a shock absorber reducing the weight on the anchor itself to virtually nothing. The rode is in effect the anchor, the anchor itself being merely a hook to hold the rode in position.

The longer and heavier the anchor rode the better the anchor will hold - that's also why as boats get bigger, the anchor chain gets heavier.

Anchoring depth of water
When anchoring anywhere along the Queensland coast your most important consideration must be for the tide/height variations (and this is particularly true in the Whitsundays... during spring tides, the tidal range in the Whitsunday's can be as much as 4.3 meters between high and low water).

The height of the tide (taken from your tide tables) must be added to the depth obtained from the depth sounder to give you the total depth of water.

As the sea level of the sea is constantly rising and falling, the depth shown on charts must have a common level from which they are measured. This level is the lowest predictable level to which the tide is likely to fall. It is known as chart datum (low tide level). This is the level above the seabed below which the sea seldom if ever falls.

Never anchor in less than 4 meters depth of water at low tide...or above 11 meters depth at high tide.

It is important that you allow for the state of the tide, when deciding how much scope to use. For example, if you anchor at low tide and use a minimum scope, your scope will decrease to a dangerous level as the tide rises. It is not uncommon for a vessel to break ground and become adrift in such circumstances... A good rule is, "when in doubt, let it out!" Letting chain out allows the chain to form a catenary (sag) and will cause the anchor to dig into the bottom rather than being lifted out... However, common courtesy in a crowded anchorage dictates that you still don't let out more chain than you sensibly need.

To determine the anchoring depth of water, check the tide tables and add the height of the tide to your depth at the time of anchoring... then multiply the sum by 4 to indicate the minimum length of anchor chain you should put out.

In Practice

Be familiar with this calculation before approaching your first anchorage. But regardless of the calculations, it is good practice (particularly in the Whitsunday's ) never to put out less than 35-40 metres of chain.

Several different types of anchors are in common use. Various anchors perform differently, depending on such factors as the type of bottom (sand, mud, grass, or rock). Each anchor has its own strengths and weaknesses. The two you will encounter most often on bareboats are the Danforth and CQR anchors.

Danforth anchor
A common sailing anchor, the Danforth anchor, is also called the lightweight anchor; because the large flukes bury so well. The Danforth needs a soft sand or mud bottom to grip properly and is in popular use on bareboat tenders because of its light weight and low profile when folded 'flat.'

CQR anchor
This anchor is generally referred to by it's trade name 'CQR'...but as it also looks like a farm plough, it is also called a 'plough anchor.' The plough is secure on most bottoms and is arguably the best all-around anchor for larger boats (over 30 feet or 9 m)... Although heavier than a Danforth with the equivalent holding power, the plough can get the job done in most conditions. The plough is often kept secured up forward on a roller with the fluke hanging over the bow...this is a common anchor and is used on most bareboats.

These two anchor types are the most suitable for general use on a mud or sand bottom, since they dig in well and are relatively easily extracted when you wish to move on.

However, while cruising you will still run across rocky patches and in particular anchorages where there is rocks...in these conditions the plough anchor can be difficult or impossible to dislodge. If you anticipate the problem you can rig your anchor accordingly, particularly if you are going to anchor where there is a good possibility you could snag... You can see a good rig for this in the diagram below... remember that when cruising in a marine park you are not allowed to anchor over coral.

Alternatively you could use a Rock anchor or Grapnel - this anchor can foul but with 'extreme' vertical pull at short stay, the round steel rods tend to straighten releasing the hold...This anchor is not commonly available as a primary anchor on bareboats, and is not carried on the tender as the steel rods can puncture a rubber inflatable.

Anchor rigged for 'rock' when there is a definite danger of snagging

This is not an anchoring method to be used by a 'bareboat' skipper unless the experience is there to do it correctly...and under no circumstances would you do this if anchoring overnight...But would be permissible for a day anchorage.

Shackle the chain to the anchor crown (called 'scowing') - then run the chain along the shank and seize it to the anchor ring with rope yarn. Should the anchor foul, on weighing, the surging will part the rope yarn under vertical strain, and the anchor can be heaved out crown first.

Scowing should only be used when someone will be on board the boat in constant attendance...and should never be used if the anchorage is rough, the tugging on the anchor may break the binding causing the anchor to 'break out' and the boat to drift.

There are many types of anchor winch in use, the one particular to your boat will be explained in detail by your briefer. The diagram shows a deck mounted windlass, a type in common use, particularly on motor cruisers.

The anchor winch is designed simply to recover your anchor and chain from the bottom. It is not designed to pull your boat bodily up to its anchor... which can damage the electric winch motor and break the shear pin in the winch gearbox. And while on the subject of damaging your winch gear - you never use your windlass as a mooring bollard.

Any winch repair is expensive, and will cause you considerable inconvenience and expense if you damage it during your charter.

• Most windlasses operate on an interlock and will not operate unless your engine is running. This is a safety precaution designed to minimise the drain on your 'domestic' batteries and if your boat is fitted with foot controls it will prevent the unintentional pressing of the 'up/down' foot switches while your boat swings at it's mooring
  
• A circuit breaker automatically cuts off power to the windlass to protect the electrical system if an overload develops... If the winch ceases to operate during anchor recovery, check this breaker has not tripped because of an overload...if it has, simply switch it on again and the anchor winch should work... make certain you know where this breaker is located during your boat brief.