I wouldn't.  I doubt there are any contact points between the two boats that would be structural enough for that kind of crushing force.

I respectfully disagree with the captain's assessment. Here's why:

A Kaholo 14, according to the ad copy, is rated to handle a 280-lb paddler. Assuming size 12 or so feet, that works out to around 300 lbs/sq.ft or 2 lbs/sq in (double that for when they're staning on one leg).

The Duckling is 22 lbs total weight (again according to the ad copy).  So as long as its weight is distributed over at least 11 square inches, the load on the Kaholo is completely within the design limit, not even into the safety margins.

Based on what I've seen of Wood Ducks, I'd estimate that there's a bit over 21 square inches of bearing area along the Duckling's keel. So as long as the cam straps are tightened to less than 20-some pounds, everything should be quite safely within the design loads for both boats.

As a real world observation, I have been tightening my WD12 to a ladder rack atop my truck with ratchet straps, not cam straps, for over 10 years. I put the straps just in front of the coaming, where the deck arch is the most pronounced and is reinforced by the stiffness that the coaming provides to the deck. Never had any trouble.

Sp whatever else may be going on in terms of air resistance and so on, mechanically it should not trouble the boats.

Good luck,

Laszlo

Ha!  Sometimes I think my role on this forum is to state an opinion, thereby goading Laszlo to respond with much better contradicting info. ;)

Come on, I never said anything about the gunter rig for the Passagemaker, did I? :-)

 Three years since this post and I'm happy to report thousands of miles of Duckling riding atop kaholo 12'6" and there's no damage. Sooooo...what's the consensus of a WD 12 hybrid cruising the Colorado/Wyoming highways and by-ways atop the same kaholo 12'6"? I simply can't figure a way to transport a Chesapeake 17LT, Kaholo, and WD 12 with the rooftop real estate I have without the stack.