When rowing, remember, you are the engine. The amount of work you do is dependent on you, not on the machine.
The more work you do, the more resistance/drag you can overcome, and the faster you move.
The speed which you can maintain is dependent on the level of work you can maintain and, again, is limited only by you.
Row harder and you go faster, row easier and you go slower.
This is the self paced nature of the WaterRower and Rowing and allows Anyone to row regardless of age, sex, size of level of fitness.