The first step I would take is remove the lag bolt. The water needs to be removed. If there is water leaking from one bolt there is most likely water trapped in the stringer. Are all your limber holes cleared? Does water drain from the battery compartments? Does water drain properly from the forward section. Do you have any leaks in your fresh water system, hot water tank, fresh water tank, water lines that can be leaking and trapped because the limber holes are plugged? Unfortunately one of the issues with the stringer design is making sure water can get from one side of the stringer to the other (other being the engine compartment) where the bilge pumps are. The stringer design has tubes installed to drain water from outside the stringer system to the bilge area where the bilge pumps are. If water builds up in areas that need to drain through these limber holes or tubes because they are plugged the water sits. The stringer system is glued to the hull using resins. If there is a void in the glueing process which there probably is in any of these boats the water will seep into the void. It can then drain the water into the voids of the stringer which is filled with close cell foam. My guess is this is where the water is coming from. I would inspect all limber holes and comfirm they are draining properly I would remove the lag that the water is seeping from and use a small flexible tube ( engine oil suction tube) and see if you can abstract any water from the stringer. Remove a couple more lags from the side that the water is seeping from and inspect for moisture. This area needs to be dried out. The engine mounts are screwed to wood not aluminum plate. The wood in the compartments is not sealed on the bottom side so if water is sitting in those areas you will eventually be dealing with rot. These are the steps that I would take. If at that point you find that the compartments are dry, limber holes are clear and water is still coming up thru the stringer. Check the area around the transducer. I believe there is a hole cut in the I would lift the boat. First place I would look is the trim tab screws. There may be a couple tab mounting screws into the transom where the stringer is. These screws go al the way thru the transom. The next would be inspect the hull. My opinion is it its rain water that is trapped. Cleaning limber holes should be done at the factory before every boat leaves the building, then the limber holes should be on the preventative maintenance schedule every year to make sure the is no plug-age. Good luck in your inspections and removal of the moisture from the stringer.