While Keith Paull was riding a wide tailed board, it was a roundtail. (The green board on the Combi Van.)
Hamilton and Martinson hadn't seen any roundtails up until that point, and it was a revelation.
You can see from this frame grab of Mark walking along the beach, his Harbour V was really radical. Too radical to be a good travel board, that's for sure.
Spin outs on big, full faced waves like La Barre were the norm.
In the smaller, tighter curls of Biarritz, it was more at home. (Top sequence.)
The Mac/Free crew ran into the Spencer/Young/Lynch contingent while in France, and the Americans were exposed to narrower roundtails that were even more advanced than Keith Paull's double-ender.
Predictably, a cross-pollination took place, and the pulled-in roundtail quickly displaced the wide square tails around the world.
Which is amazing, because in December of 1967, in the Islands, Young and McTavish essentially introduced the groundbreaking deep V to the outside world...
But by the time the World Contest in Puerto Rico came in December of 1968, the wide-backed Vs were gone.