It’s the day of the Inis Spraoi boat race. The kids have made their own boats to race in the waterbasin, but some of them won’t float. They sink to the bottom, and the kids can’t figure out why. Conor suggests a trip down to the dock to see if Skipper Seamus can give them the answer. It turns out that Hermie Crabnik has damaged Skipper Seamus’s own dingy, there’s a big hole in it which he has to fix to get it seaworthy again. Through a lively song, he teaches them why some boats are able to float while others sink. The group work on their boats together, and soon they’ve got them back on the water.