Presumably, Nazca's insight concerning boating has come in handy - Balthier knows the basics, and is genre savvy enough to get by, but there are gaps; he's used to flying, and he'll have said so.

He joins her at the close of her second round, amiable but quiet. No use overdoing it right away. A nod in hello. This all sort of sucks, doesn't it? Hm.