Plenty of very practical rowing bikes around – take a look at this selection, especially from the Dutch.
Kontech design have one too made in the USA. Here the seat slides.
Although the action looks awfully like what you see from non-rowers on rowing machines in a gym
And, to round off the global tour, try this:
from in Australia, Boris Grigorievich Tarasov has improved the rowing bike action to get better speeds and leverage with his Row & Roll bike.
Although for a former champion sculler, on his bike he seems a bit of a bum-shover. I do like the kid’s trike.