Weight alone has little to do with an anchor’s efficiency. That the design is important is apparent when it’s realized that a concrete block will hold little more than its own weight. A mushroom-type anchor will hold only about twice its weight, while the modern lightweight patent anchor with pivoting flukes can hold up to 1000 times its weight. A small outboard utility of under 15 feet can be anchored safely under most circumstances with a four-pound patent anchor. A 15- to 20-foot outboard will require an 8- to 12-pounder. The heavier the boat the heavier the anchor.
A lightweight 25-foot cruiser, either outboard or inboard, should be safe from straying with a 12- to 15-pound anchor, while a 30- to 35-footer will ride out a heavy blow with a patent hook of 20 to 25 pounds.
The anchor line should be long enough and heavy enough so that it will cushion sudden shock loads due to wave action. It should lead nearly horizontally away from the anchor, that is, parallel to the bottom, even when it is under strain.
As a general rule of thumb, the anchor line should be about seven times as long as the depth of the water. If you’ve ever had a power failure in bad weather, and had nothing to hold you off a lee shore but your ground tackle, you’ll