Graduation day: Note the load of sea grapes and other fouling on the line as one group of test panels emerges to wave in a fresh breeze.

With the final segment of a ban on tributyltin (TBT) paints, coating manufacturers have brought to market products to fight barnacles and other marine beasts on metal surfaces without using this toxic chemical. The change posed a particular challenge for paint manufacturers designing products for use on metals: how best to protect underwater metal structures from organic fouling while avoiding destructive galvanic interaction between the submerged metals and the most common copper-based replacements for TBT.

As boaters, we're concerned, or should be, about long-term environmental issues, but we also need to know what kind of performance we can expect for the coming season from the first post-TBT offerings of various manufacturers.…