I connect about a 5 foot length of hot dipped galvanised chain to the anchor with a safety wired shackel. The heavyer the chain, the faster the anchor will set. The chain also minimizes the wear on the anchor line (rode). Remember when anchoring in heavy wind or current, the rode should be up to 10 times the depth of the water.
Most anchors don't have a "trip" line to help release them from under a cable or large rock. A large heavy ring attached to a line can be useful for this purpose. When the anchor is stuck, pull the anchor rode through the ring. Keep the anchor rode as taught as you can, allowing the ring to slide down the rode and over the shank of the anchor. If a 2nd. boater is available, have them pull on the line that is attached to the ring in a direction that is opposite the anchor, backing the anchor from under the rock/cable. If no one is available to help, attach the anchor rode to a float leaving minimal slack in the rode while you operate the release ring.
Joleda, An 8 LB fluke anchor will hold up to about a 24' boat. Normally the anchor line is 3/8 twisted nylon, and 5-7 times longer than the depth of the water you expect to anchor in. The "anchor end" of the line should have a galvanized thimble to protect it from wear. The anchor line's thimble is connected to the anchor with a shackle. Chain is optional, if you anchor in sandy or other non-rock bottoms. if you anchor on rock bottoms, the chain will help protect the anchor line. In that case the anchor line thimble will be connected to the chain with a shackle and the opposite end of the chain will be connected tot he anchor with another thimble.
Agree with both and levittownnicks's notes on stuck anchors are very helpful.
On chain . . . My personal opinion is that chain is not "optional". This comes from my need to anchor at relatively short "scope" lengths from time to time. Scope is the length vs. depth ratio they have both noted. I like chain equal to the boats length if practical. This allows me to use shorter scope when I have to, and the pull along the bottom simulates a longer scope. An extreme example is a deep cove with steep sides. If the cove is only 200 feet across and it is 34 ft. deep, it is literally impossible to get over 3/1 scope and allow for 360 degrees of swing . . . My .02.
Torque gets you there. Horsepower gets you there in time for dinner.
I use a fluke anchor and agree with all that levittownnick and Chris1956 wrote. With one exception, I believe the 5 foot length of chain is mandatory with a fluke anchor. It is designed to be used with one. The function of the chain is to keep the line on the bottom and ensure the anchor is pulled sideways, not up. A fluke (AKA Danforth) anchor is designed to bite when pulled sideways (that is why they need long lines or "rode") and come right up when you pull them straight up.
Bottom line is it will perform 100% better with the length of chain, especially if the boat is anchored in choppy waters.
EDIT: Oops QC beat me to the post. Gee, does it really take me that long to post?
2 things I forgot to mention in my previous post: 1) Attach a length of floating type line to the end of an anchor line that is not permently secured to the boat. 2) Store the line as it is pulled in directly into a bucket or rope locker. The bucket should have drain holes in the bottom.
The floating line is to save me from myself, as I have had the end of the line quickly sink to the bottom this past summer. I was lucky enough to be in shallow water and was able to get it back. Now I have a 50 foot length of polyproplene line spliced to the end.
The line doesn't have to be placed in the bucket/locker in perfect circles, just so that it is put in in the order that it is pulled in. I have never had the line tangle using this method.