i have a 10kg bruce, with 8 mm chain. the boat is a countess 28 ft, and a 7.5kg bruce with 8mm chain and anchorplait as a kedge, there is a web site which will give you the size of anchor and minimum size chain...
<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by colvic987 on 04/05/2004 21:32 (server time).</FONT></P>
When the anchor reaches the bottom and tries to cut the weed, it doesn't care what the size of your boat is. I have read somewhere that the minimum anchor weight is 16kg. And, believing that there is no oversized anchor (if you have an electric windlass that is), I got a Delta 16kg for my 6 ton Dufour and added 70 meters of 8mm chain. Sailing in Greek waters and mooring/anchoring in various conditions (from poor bottom holding to really strong gusts) I never regretted my choice.
You will most probably get every possible advice and they will all be correct...
I would humbly suggest that you need to get as much chain and nylon as possible. The chain legth will determin the breeze you can cope with. After that the anchor should be chosen to suit the bottom in which you wish to anchor.
There are lots of sources of more detailed advice.
can I suggest that you run a search on this forum against anchor for the last 3 months and you will get more info on the subject than you will get through before the season finishes!
Alternatively give much more details over the following -
Main usage - cruising, overnighting, lunch in nice sheltered anchorages............
Where geographically
Do you have or are you planning to fit a windlass and what is it?
How fit are you?
Will you be single handed often?
Are you concerned about restricting your boats movement in a small anchorage - but alone or do you expect to be with other craft in crowded spots? If the latter you will want to be consistent rather than 'efficient' with your set up.
How do you propose to stow (and rig) the anchor - do you have a stem head fitting?
All the above will enable you to tune your selection to suit your circumstances.
Most anchor manufacturers have websites with advice, and others like jimmygreen and westmarine etc give good general advice as well. Addresses will come up in your search.