Getting out of routine is a sure bet on a problem.  Several years ago, I was going to meet a friend at a camp ground on the lake, this is a 77,000 acre lake.  So, I had just come in from fishing when he called and it was 13 miles by water and close to 50 by highway, and the ramp was only five miles.  In a hurry, I just jumped back in the truck, dropped the boat in the water and was there in no time.  Visited about an hour, and then back to the ramp.  When I pulled the boat out, I went back to take the drain plug out, just to find I had never put it in.  Where it sat at his camp site was about 40 feet deep and I was not paying attention to the boat. 

My saving grace was the drain plug is one of the screw in kind and on a tether through the hole.  The tether kept in in the hole and the water pressure must have kept it pushed up against it so it didn't get much water in the boat.  Which on the drive back to the ramp it would have pulled any water out so I'm not sure how much, if any actually got in the boat while sitting at the camp site.  Had it not been for the tether, I'm sure the boat would have been at the bottom in about 40'.  

If your boat doesn't leak just put a mooring boat cover on it. It would also help to keep it clean/protected.