There's rowing and there's rowing. Rowing freely, for speed, indeed it is rather hard to sing. However, I'd posit that it's a different thing entirely if you're dragging a dead whale back to the ship.

The mate of the boat would cut the tendons in the whale's flippers so that the whale could be towed, backwards. Nonetheless, you were probably good for about a knot. At such slow speeds, the rowing is not stroke----stroke but rather pull..............pull................. and the speed suits something like 'Go to Sea No More.'

You're not going to get yourself into a state of winded because you have too long to row and too far to go to do so. Slow and steady, that's the way.

Similar for rowing a piece in a skiff. You don't make like it's Harvard vs. Yale. About the speed of 'Yeah Ho, Little Fishies' suits just fine, and you can be happy after five miles at that rate.

One would guess that in such a situation, the boat-steerer would take on role of chanteyman.

A rowing/singing scene I found touching was when Antony Hopkins as Lt. Cmdr. Bligh rowed off from the Bounty, with the lads singing 'The Water is Wide.'