No rats, but I did have a small bird make a nest in the exhaust vent (engine exhaust vent, thankfully not the fresh air inlet). You couldn't see the nest from the outlet, so it took me a while to figure out why this weird bird kept hanging around my boat while it was on the hard and why it followed my boat to the slip after splashing. By the time I heard baby birds chirping from the vent I figured out what happen. The baby birds lived and flew away, but not far as they hung around my boat all season long. The boat had the fewest spiders on it of the 7 years we've been at this marina. It was a pain to remove the nest, it was amazing how much stuff was in the vent.