The Fluke or Danforth style anchor is the most popular style anchor for use with a power boat. Using this type of anchor depends on the anchors ability to bury it's flukes into the bottom rather than by the weight of the anchor.
To achieve this, a near horizontal pull on the anchor is required while setting it. Two requirements are needed to assure this. First a length of chain between the anchor and rode (anchor rope), and releasing 7 ft of line per foot of water that your anchoring in.
Experts suggest using a length of chain equal to the length of you boat, but for powerboats over 20 foot we found that a heavy 5 foot length of chain will do the trick combined with the proper length of anchor rode. For smaller boats, 16 foot and less a 3 foot chain will make a difference in helping to set the anchor. For boats 17 to 20 foot a 4 foot chain will help greatly.
For example, if your anchoring in 10 feet of water, you will need to let out 70 feet of rode to help the anchor get a good set.
For a light
hold with no current or wind, you can reduce the length of rode to 5 ft of line per foot of water
that your anchoring in. And of course always anchor off the center of the bow of the boat for best results.