The phrase "boat hulls" refers to the bottom part or outer structure of boats. It is the part that keeps the boat afloat in water and helps with navigation. Full definition
Around 1990, reports were all over the media about an inventor who was adding capsaicin to the paint used on boat hulls and intake valves on municipal water systems to prevent the growth of barnacles and zebra mussels. (fieryfoodscentral.com)
On view are abstracted photographs of boat hulls by Michele Dragonetti that highlight their symmetry and unique characteristics. (hamptonsarthub.com)
Scientists are continually looking to make waterproof materials that can coat boat hulls, car parts and medical devices. (businessinsider.com)