As others have said, the answer is two anchors. Any boat is going to 'spin' around the single anchor no matter what kind of anchor it is.

I'm lucky in that sence as I have stumps with bushes/weeds growing out of them scattered all over the little swamp pond I usually fish in. I bought two bush/limb clamps that I have tied onto both sides of my little Basshunter pond-boat as I fear getting a Bass wrapped around an anchor line.

Dan