What are the Fastest Sit-On-Top Kayaks?

RTM Tempo
is really the current incarnation of the Scupper Pro:


I am a fan of the scupper pro, having two currently that I use for fishing and kayak camping out in the boston harbor islands. Works for me, as a 150 lb paddler. I find it plenty stable and fast enough for what I do (easy to maintain a 3 MPH pace).