Re: the "PLUG' why do you....
Yep. What jay and erwinner said.
There are several invasive species of mussels and weeds, and most states ask/recommend/or legally force you to drain and dry your boat before putting it back in the water. Some states say it has to be dry 72 hours before launching again, to make sure all is dead and not ready to be introduced to new waters.
Zebra Mussels. Do a google search. Nasty critters that can kill a boat in a couple weeks.
Personally, my ice chest drains into the bilge under the engine. So does any water brought in from wet wake boards, swimsuits, or just wet bodies jumping into the boat. After a day on the water, I usually have at least 8 gallons of water (melted bag of ice) plus whatever else was brought in by people. On the ramp, I pull the plug first thing, and let it drain while I tie everything else down and prepare for dragging it back home.
I keep it out, even though it is in covered storage, just in case it rains. I had a jet boat that with plug OUT killed the battery during a rain because it filled up faster than the bilge pump could keep up, and the pump drained the battery, and boat just had to drain by gravity through the drain plugs. If it was plugged up, there would have been a mess to clean up.
My routine is to pull the plug first thing on the trailer, and put the plug in first thing when backing up to the ramp.
Get a routine, and stick to it, and don't let bitchy wives and gabby boaters distract you from it.