Hi Jack,

With the PVC being white and as thick as it is (Schedule 40) I don't think there is any heat buildup. When I have removed them on a sunny day they are nice and cool. Also the notches I cut in the pipe go all the way through so the rack on my cap is flush with the inside of the pipe, so the inside of the pipe is vented. I use a screw on cap on the end. If I could have found a bigger pipe I would have made it a little larger. 3 paddles (two standard length and one storm paddle just fit inside.