Daryl Harris wrote:

Hello all

I own a 17ft half cabin boat which weighs around 800kg. I currently have a
traditional sand anchor (sized correctly for the boat) with around 2 meters
of light chain attached to it.
I anchor the boat on in an area of beach type sand, trying to always let out
about 5 times as much rope as the water is deep. On all but calm conditions
the anchor will drag, even after diving down and digging it in by hand. I am
considering buying a plough anchor in the hope of superior holding power. I
have been told the sand anchor should be as good as any in sand and perhaps
a heavier chain would help.
Any thoughts or experiences with different anchor types would be greatly
appreciated.

Not all "sand anchors" (maybe you mean a Danforth type?) are created equal. It
may be that the flukes are at the wrong angle, or not sharp enough, or it may
just be a piece of junk shaped like anchor.

I would recommend 1- more & heavier chain (this always helps) 2- letting out
more rope to get the anchor set, about 8 times as much as the water is deep. You
can always shorten it if needed, later, once the anchor has a good bite. 3- If
you want to buy a new anchor, get a Bruce. These are the best for all-around
ability to hold in various types of bottom, but they do not hold as well in sand
as a Danforth. They are also very easy to get a good set.

Fair Skies- Doug King