As you prepare for another season on the water, you’ll face a bewildering number of choices—some of them complicated, some costly, some even philosophical. The need to kill, prevent, or clean marine fouling has been with us since the dawn of navigation. In the warm Mediterranean, Phoenicians tried pitch, tar, wax, and lead to prevent slime, worms, and barnacles. Copper emerged in Roman times as sheathing tacked to wood hulls, and it’s credited with giving Nelson a 20-percent speed advantage at the Battle of Trafalgar in 1805. The first paints containing copper and other heavy metals, including nasty mercury and arsenic, appeared in 1860. Mercury paint was still being used in Connecticut a century later.