Can anyone tell me where to get these cradles?:
I've seen a few car-top boat racks made from a long 2x6 or 2x8 with a
cradle bolted to each end. The cradles are made of a roughly U-shaped
aluminum frame with webbing slung between the tops of the U. I spoke at
the American Rowing Championships with a Canadian gentleman who makes the
cradles for sale. There may be other manufacturers as well.