Paul Worsteling breaks down the classic anchoring rule that catches a lot of boaties out: scope, the ratio of rope let out to water depth. Too little scope and the anchor won't set properly; too much and you're swinging further than you'd like in a crowded anchorage.
The 3-to-1 ratio is the starting point most experienced skippers work from, adjusted up in rough conditions or a soft bottom. Worth knowing before you're the one dragging at 2am.