CJW said...Never understood why surfers measure the wave from the back? What the f@# is the point...you never look at a wave from the back when you have any scale reference to judge its size from, IE a person, so what the hell? Weirdos ^_^
As an example, it's stated above the wave is ~ 10-12 foot - sufer scale...so that's 2 average people tall. If you asked anyone, who isn't a sufer, whether that wave was 2 people tall I expect the average response would be "you taking the piss?".
/rant

I think it stems from Hawaii, and perhaps some machismo understatement thrown in.
surfer 1: man that looks like a solid 8 ft
surfer 2: nah, 4-6 max. You should have been here last week, now that was 8ft

The thing with waves is that the face height can vary for a given wave depending on the break. Shallower breaks tend to jack the face more, but have a thinner wall. The wave itself still has the same power as a similar wave on a deeper break with a smaller face, thicker wall. Whereas the back of the wave before it breaks tends to be more consistant wrt power.
I have surfed the north shore and certainly my experience was that waves that had a similar height face to say queensland beach breaks used to absolute trash me comparatively. One day I was there I surfed 4 ft and got pretty worked on a few occasions. Locals were calling it flat and didn't even go out.....