Wondering if you all have any recommendations for a good marine sealant/caulking to use for installing my Lowrance transducer? The owners manual is not specific at all as to which type I should use other than "high-grade". I did a little research, but not sure if I need something strong like 3M 5200 (polyurethane) which they say is pretty much permanent, or a polysulfide formula, or a weaker silicone based formula. If it helps, I do plan on replacing my sonar down the road. I also found a thread where a guy was saying you should fill the drill holes with epoxy first to help prevent transom rot, then install the screws and then apply sealant. Any merit to this method?