I found this interesting web page that calculates the maximum speed for a rower.
http://www.sciencebits.com/rowers

It's a bit disconcerting that the page discusses 'rower boats',
I don't understand all of the math, but the sum of it is that over 2000 meters the minimum time is 400 seconds which is 5 m/s or 9.7 knots.

I believe I calculated the winners of the kayaking (not rowing) events at the Beijing Olympics 2008, was about 12 knots.

Why I thought it worth sharing is that a lot of it is different from most of the analysis of hull speeds, etc... that I've seen.

always,
Will N