Welcome to the site! There are a TON of variables to your question. Water temp, and availability of food are two important factors. If there is a channel leading into the slough, or some type of cover around those boathouses, you may find them there. Trying different colors, or even live bait might help, but it sounds like that particular spot just hasn't filled up with fish yet. Just finding them there one time isn't enough to call it a "honey hole"