Nice rack @Gordon Nichols. You don't hear that very often from one guy to another.
I need to build one for my flotilla, two kayaks and a canoe. Though our canoe is hanging on the living room wall. It's a Mad River Explorer with ash gunnels and cane seats. It's too nice to keep outside.
In the Spring, I cover the cockpits of the kayaks with plastic bags to keep the birds from nesting in them.