Another possibility. If you had fish in the well and it was full of water. A fish tail was covering the overflow. If your live wells are not sealed to the bottom of the deck, your fill pump was filling up the boat. Had this happen to me and had to install the fill pump screen that is on the transom (step area) of the boat. Look at a bass boat transom, you will see the screens covers next to the drain plug. It took a while to figure out what was going on.