Great shot.... Wonderful wave... The ocean did not cooperate with our surfers.
I did realize that I needed (wanted) just a bit of extra length than the 100-400mm on a 7D2 gave me. This was also true two weeks ago as I was shooting a polo match. However, I did not want to invest the cash in or carry the weight of a super telephoto lens. So after some soul searching and a bit of research on the Internet, I just purchased a used (in mint condition according to the eBay ad) Canon 1.4x Teleconverter Mark-iii. That will increase my 400mm to 560mm ( or an equivalent of 896mm) and retain auto focus using the center point. However, I have been told that in bright light I might be able to use the center point and the four surrounding points. We'll see about that.
I have always been a fan of long lenses, the longer the better. But at my age, the weight of a super telephoto lens is a bit too much for me to lug around. The teleconverter weighs very little and I could carry it in my shirt pocket...
The next time I shoot surfers, I an going to bring my 600EX RT hotshoe flash and a Flash-Xtender to possibly fill the shadows on the surfers a bit. That is, if I am shooting from the pier again and am close enough to the surfers. I would not use flash at a polo match because the flash might shy the ponies...