I hail my canoe on my Yakima rack with no issues. I have the Pano roof. I tie the bow and stern down as well. The canoe barely budges. Mind you I also use the Yakima Keel Over canoe kit the essentially pinches the outside of the gunnels to the rack. My route takes me at speeds of 80-120km/hr. Blasts from transports are not noticeable and windy days just make a bit more noise.
Canoe pictured us about 50lbs. My other is about 80. Your kayak should slip through the air much better.
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