I've used this picture on a few posts and would like to add a little more about its story.
It's from way back in 1971 when I jumped into a small runabout and took pictures of Frank Bethwaite sailing with Julian at Northbridge Sailing Club. Most sailing pictures are boring because they're taken too far away, so my goal was to get some close-up shots.
The NS-14 (which stands for Northbridge Senior) is an amazing "development class" because, as you can see in the picture, they're planing upwind with no trapeze and the boat has just 100 square feet of sail. In fact, its DNA can be found in many other classes including Julian's 49er.
Frank commented at the time that the pictures were the best he had seen for NS-14s and he later used this picture on page 254 of High Performance Sailing.
Thirty years later told he how this picture changed his thinking about how rigs work.
So, who can tell us what Frank saw and why it changed his thinking?