In addition to the eaves of houses and under bridges, there are a few nautical nesting spots that these birds especially like. If you have a sailboat, these are some of the areas you should inspect regularly:
Sail covers with an opening at the end of a boom are very popular spots. Of course, any gap in a sail cover is just too tempting for these critters.
If you have a powerboat, you are subject to the same abuse – they don’t play favorites. Your aft cockpit with an awning or cover is a favorite. Also, any other damaged or poorly-fitted cover (anchor windlass or outboard motor) begs to serve as a nesting site: