: Risto,
: How did you do a hollow loom? Run it over a half-round bit before laminating?
: Or did you use the birds-mouth style?

...I just cut away a 1,5cm x 90cm part from the middle of the blank, clean thru and then epoxied a thin (1,0cm) strip on both sides to cover the hollow. From then on I just sawed and planed and carved like Chuck Holst desribes, keeping in mind where exactly the hollow was (some bother required to mark it again after each pass with saw or plane).

The resulting hollow is rectangular and oriented at 90 degrees to the plane of the blades, that is, the thick sides are the top and bottom of the loom when held for paddling. The front and back are just thin rounded covers. The greater stiffness (theoretical) thus resists the bending from the stroke.

So no router, no birds-mouth technique, just simple and dirty. Since you apparently are going to use laminated blanks, you would get the same hollow by simply leaving out one or more of the central strips in the loom area, and placing them only in the blade area, where the thinness of the end result requires the presence of material.

Hmmm,... I guess one could say that I looked at the final shape to see where it was thick enough so that wood in the inner could be left out, and then figured the stresses to determine what shape the hollow could be to maximize the gains in lightness. I also wanted to laminate anyway, to reduce warping later on as the paddle would get wet and then dry again. So it was just putting the inevitable (laminating) to more use, getting two extra bonuses: the stiffness and the lightness (well, relatively speaking).