« Clear as mud » !
|30 March 2012||Posted by Alex from Lagoon under Technical world|
One of the great advantages of a catamaran is her comfort at anchor: she is stable on her two hulls, offers several living spaces and a significant autonomy if the crew is thrifty enough! But before diving into crystal clear water and catching a crayfish you’ll have first to anchor. Recently, two owners of Lagoon, Thierry (Lagoon 450) and François (Lagoon 400) asked me some questions about anchoring. Here is the content of our exchanges:
Although anchoring sounds simple, it is a complex science in which some factors can influence the efficiency of the anchor, among which:
- The bottom: sand, mud or vegetation;
- The composition of the anchor set;
- The angle of the anchor pull;
- The adjustment of the bridle;
- The chain length;
- The tidal range.
The angle of pull is critical, and it must be as horizontal as possible for good performance. This depends greatly of the chain length. The rule is to release at least three times as much chain length as the water depth. Another more conservative rule is to use a coefficient related to the wind:
Current or anticipated Beaufort wind force X water depth = length of chain to drop.
If less than force 3 winds are expected, the principle of at least 3 times the water depth must be applied.
For your information here are the weights of anchors and chain lengths of the Lagoon range:
Lagoon 380: 75 m with a 10 mm link diameter – 20 kg
Lagoon 400: 75 m with a 10 mm link diameter – 20 kg
Lagoon 421: 75 m with a 10 mm link diameter – 20 kg
Lagoon 450: 85 m with a 12 mm link diameter – 25 kg
Lagoon 500: 100 m with a 12 mm link diameter – 45 kg
Lagoon 560: 100 m with a 12 mm link diameter – 55 kg
Lagoon 620: 100 m with a 14 mm link diameter – 55 kg
Too long has never been too much! And because all Lagoons are equipped with a windlass, do not hesitate to use it!
During these exchanges another question arose: the secondary anchor. This equipment may be necessary in certain anchorages or for safety reasons. In areas with currents or winds rotating or areas with limited space it can be helpful to add an anchor at the aft of the boat. It will keep your cat on a defined place without rotating, even if something changes. To this end, you may want to acquire a light anchor with 5 to 10 meters of chain and 30 to 50 meters of rope (for a Lagoon 400). The light anchor set is not as good as a normal anchor set but it is easy to manipulate. Different types exist: in aluminum, demountable … The best is to go in a ship chandler and see what they have to offer in consideration of the size of your storage area.
For sailors more accustomed to this type of anchoring, like our Scandinavian friends, it may help to have a real anchor roller and a dedicated windlass for this aft anchor (above on a Lagoon 380).