O.K have to put in my two bits here. If you are interested in making your own planes don't forget to refer to James Krenov in "The Impractical Cabinetmaker" and particularly "The Fine Art of Cabinet Making" this last one is very good. I haven't read the Woodenboat piece but I imagine these two texts are referenced at the end. It should be quite straightforward to make a series of planes that conform roughly to the hollows and curves for kayaks (maybe?).