On Thu, 01 Nov 2007 18:34:51 +0100, Marc Heusser
d wrote:

Most trouble for not setting with my current anchor stem from the fact
that as soon as it drags, it will fill up with sea grass and not hold at
all.

Yes, you need an anchor that quickly penetrates through the grass into
the underlying bottom. The longer that it takes to set, the worse it
becomes.