We submit the photo above as a baseline for thinking about anchor size. We are ensconced in Vikingevagen, Norway. A tight, protected anchorage. Water depth is 40 feet (12m) and the barometer is plunging. It is gusting 40 knots, and the granite shore is 150 feet (45m) off our stern. This is not a situation in which you want to worry about anchor size.
So, how big an anchor is right?
This is a tough calculation. Typical tables published by anchor suppliers or organizations like NMMA are a joke. They assume good holding, and moderate, protected anchorages. Our basic rule has been to use a multiple of what would be considered a storm anchor.
This pays dividends in every day use allowing you to anchor with much shorter scope
At the risk of repeating ourselves (this topic is covered in great detail in our books), and using one of the new generation highly efficient hooks like the Rocna, Spade, or Bruegel, we would carry the following:
Sundeer 56/60 – 110lb/50kg
Sundeer 64/68 – 176lb/80kg
Beowulf 80 – 240lb/110kg
For yachts in the 40 to 50 foot range – 80lb/38kg
For yachts in the 30 to 40 foot range – 60lb/28kg
This assumes a chain rode.