ANCHORS and TIPS FOR ANCHORING

 

Anchor recovery - Alderney Anchor Rig

By courtesy of Crayside Marine and Anchor Yanka

 

The modern method of anchor recovery used by an ever-increasing number of dinghies and charter boats is with the aid of a buoy.
The size of the buoy is selected to provide sufficient buoyancy to float the anchor and chain and will probably be in the 20.-24 inch diameter range. The buoy is fixed (usually by, splicing) to a 3ft length of 10 - 12 mm rope and is then clipped to a large diameter ring that slides on the anchor warp.
When the anchor is lowered, the warp is allowed to slide through the ring, which is temporarily retained in the boat. When the anchor reaches the seabed and the warp starts to pay out, the buoy is clipped to the ring and dropped over the side. (note some skippers prefer to put the buoy over the side before the anchor touches the bottom) When sufficient warp is out, it is created off and the buoy then slides on the warp via the ring. The buoy will remain close to the bow of the boat by tide action and will be out of view. It is preferable to have the buoy in view to indicate clearly that the boat is at anchor so just prior to cleating off, a stop can be attached onto the warp to stop the ring. By releasing additional rope and then cleating off, the buoy will float a distance from the boat.


Typical Alderney Set-Up

To recover the anchor, the boat is steered forward at an approximately 30-degree angle to the warp to provide a safety clearance for the boat and warp. As the buoy clears the stern, the crew takes the warp inside a stern cleat. (This step of the operation is not always done but it is probably safer to do it.) Under no circumstances secure to the stern cleat as this is potentially dangerous, the anchor load MUST always be taken on the bow.

By motoring uptide (or in the direction of the anchor if there is no tide), the angle of pull releases the anchor and the warp flows through the ring.

Eventually the chain passes through the ring leaving the anchor and chain suspended by the ring and supported near the surface by the buoy.

The manoeuvre is completed by the crew pulling the warp back into the boat, with just the weight of the floating gear to contend with. The recovery of the gear can either be from the bow or amidships, the latter is ideal for boats with no safe access to the foredeck, i.e. cabin boats with no fore hatch.

It is obviously necessary to take great care when manoeuvring to ensure that the warp is kept clear of the hull and prop at all times but with sensible care this method of recovery is safe, reliable and far less strenuous.
Suitable buoys can be purchased from chandlers at about 25 each but a 5-gallon polythene drum makes a suitable substitute. To ensure that the chain passes easily through the ring, it needs to be of sufficient diameter (approximately 6 - 8 inches is ideal).

 

The basic rules of a good anchoring system

The selection of the anchor is critical, as it is obviously playing a major part in your anchoring system. Don't skimp on such on essential safety gear: use the products of an experienced manufacturer for your peace of mind.

Do not overlook the importance of every element in your anchoring system: it is only by selecting quality gear and assembling them correctly that gets reliable anchoring. - The chain diameter must be generous (see table), and its length at least 5 times the boat's length. -The rope rode: opt for polyamide/nylon, which provides good abrasion and tension resistance, and has a good stretching capacity (18 to 25 %) to absorb the surges that waves impart on the anchor.

The scope (length of anchor line) should be determined according to the water depth below your keel and the wind conditions -
less 10m : 3 times the water depth, up to Force 3;
5 times the water depth, up to Force 6;
7 times the water depth, up to Force 9.
- More than 10 m : no more than 5 times the water depth.

Recommended Anchor Sizes

Boat
Size
Anchor
Weight
Chain
Size
Rope
Dia Min
4m 4kg 6mm 8mm
5.5m 6kg 6mm 10mm
6.5m 8kg 6mm 10mm
7.5m 10kg 8mm 14mm
10.5m 14kg 8mm 14mm

 

Some Common Anchors Available - Each anchor performs differently in different sea beds


Grapnel Type

Folding anchors are not intended for use as main anchors on larger boats.
They are widely used on speedboats and dinghies, where space is premium. Due to its small fluke area and shaft, it is not that powerful but could be used for a 'quick stop' in a larger craft.


Plough Type

The plough anchor gives good performance in most sea beds.
As a general rule of thumb the size of anchor required, in lbs, is equal to the length of the boat, in feet. For example, a 25ft boat would require a 25lb anchor.


Danforth Type

Danforth anchors are very good for muddy or sandy beds. Their flat design allows them to dig in and come out easily.
The Danforth's power is similar to the plough and the same rule can be applied when sizing. That is, that a pound in anchor weight for every foot length of the boat will be needed. For example, a 25ft boat would require a 25lb Danforth anchor. Obviously, for vessels with higher than average displacement, a larger anchor will be required.


Bruce Type

Bruce anchors are regarded by many people as the best all-round anchor.
They are more powerful than normal anchors, so a smaller Bruce anchor can be used instead of a Plough or Danforth anchor.


Fishermans Type

Fisherman anchors are generally regarded as a typical anchor.
They are becoming used less, with the introduction of newer anchors, but they are still a very good anchor.

 


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Disclaimer: Everything written in these reports are based on personal experience and the individual's opinion only. I have tried my best to present the facts correctly, but I/we take no responsibility for any mistakes or omissions.