With so much investment literally riding on your anchor, your boats anchoring system is no place to cut corners. Your choice of anchor depends on the size and type of your boat and the weather and anchoring conditions you generally encounter. It is recommended that you carry one anchor of sufficient size and strength to hold your boat for an extended period, like overnight or in an emergency situation (like, for example, if you run out of fuel).
When you are thinking of buying an anchor – bigger is better! Also, there is safety in numbers. No anchor will work for you in every situation, so if you have space then it's recommended to carry two anchors, preferably different types.
Generally, it is recommended to have either one foot of chain for each foot of boat length, or to have a pound of chain for each pound of anchor length. Whichever method you choose, having more chain than necessary is never a bad idea. A Rough Guide: 1lb a foot or 1.5kg per metre is a starting point and not too bad a one, but only a guide. From there you adjust for the varying factors.
Never, ever anchor a small boat by the stern! Your engine and the bulk of the boat's weight rests there. Stern anchoring is likely to result in swamping and flooding.
If you're unsure as to what you'd need we have a Bayside Basics guide that tells you everything you need to know.
Bayside Basics - Anchoring Guide and Anchor Types