In addition to her fiberglass laminates, it’s surprising how many different kinds of plastics you’ll find on board your boat. There’s a good chance, for example, that your rubrail is made of PVC or Polyvinyl Chloride. Some of your engine-room components (like pump housings, sea strainers, freshwater fittings, and even some hoses) are likely made of polypropylene or some kind of composite. And your water tanks? Well, if they’re plastic, there’s a chance said plastic is cross-linked poly.