If your candied sweet potatoes are watery, there are a few possible reasons. The first is that you didn't let the liquid boil long enough after removing the potatoes. It needs to cook down to thicken. The second reason is that you may have put too much liquid. While the recipe uses 1 cup of liquid to cook the potatoes, you may find that you need to use less depending upon the humidity or climate. I recommend decreasing by 1/4 cup, or alternately boiling the potatoes, draining them, then creating the sauce separately to coat them in after they cook.