Weight, size and type of mooring are all variable, depending upon the bottom you''re mooring in and the waves you''re likely to get in that much breeze. Our mooring, designed to withstand up to 70 knts, must weigh about fifteen pounds; its a helical screw, fastened into a muddy/silt bottom. Our harbor is in a narrow, winding river, so there is no fetch for waves to build. Before the new setup, everyone here used mushrooms; up to 200 pounds for 50'' boats. I''ve heard of other types of anchors - including old car engines and big poured blocks of concrete being used as well. The best idea may be to see what people in your harbor use, and if it seems to work, go with that.
Paulk (I think) is talking about the Helix Mooring System which does not depend on weight to hold your boat; it is a different creature from the typical mushroom or dor-mor type anchors. Personally I have a 34'' sailboat. The harbormaster requires a 350lb mushroom type mooring. I have a 500lb dor-mor which buries itseld into the sea floor and gives alot more resistance that a typical 500lb mooring. Let it suffice to say that Paul is mistaken in his mooring weight estimate; a 200lb mooring will get dragged all over the place by the weight and windage of a 50'' boat. Check your local regulations and then go one or more sizes up on the mooring itself, the chain, and the penants.
West or Defender have guides within their catalogs but I would get the advice of a professional in your area. Also, if you are going for a mushroom type anchor, I would recommend that you spend a few more bucks and go for the dor-mor as it gives alot more holding power for its weight. (www.dormor.com) Good luck.
Contrary to what you read here a mushroom anchor is designed to work upright and buried. If not it will "walk " back and forth and you will find your boat high and dry in a big blow. That is how so many boats ended up on shore after "BOB" here on Cape Cod. Have it put down and set to start out. Then it will work itself in over time. How much time depends on the movement of wind and tide.Also have it checked every season to ensure that it is set and the gear is up to spec.
Do not rely on weight alone to hold your boat!