Here's a little tip that may be familiar to most of you, but I don't recall ever hearing:
Once tacked, you know if you are fetching or not by taking a bearing through the mark to the horizon or shoreline beyond.
If the point on the horizon is moving to windward, you are not fetching.
If it is moving to leeward, you are overstood.
From Steve Clark, sometime International Canoe world champion and C Class Cat Little Americas Cup holder.
Of course on our lake it may be going one way one second and the other way the next, but the principle holds.