What’s up RDM,
a lot of the design approach depends upon the specific wave type. For example, DOH with really rough conditions (like typical Sunset w/trades) is a different approach than DOH sheet glass Hollow Trees. I would say there are advantages to going smaller in a given situation once the surfer is “up and running”
This advantage is weighed against catching the wave. A lot of fit surfers seem who seem to be going smaller are compensating for wave catching with different (aka: ‘Ballsy’/risky) techniques. For example seeing guys taking off more critical on smaller boards seems to be the trend. CJ or Cory at 'Chopes on 6’3" round tails is almost a proven approach. Critical skills allow an increased quality of ride such as more movement in the tube thus a better chance of making a deep-positioned ride.
It seems that this envelope has not fully been tested until recently. I am doing many more “step up” boards rather than full-blown guns. Almost all surfers are coming back from their trips with positive feedback. I should note that the travelling surfer I am talking about is expected to have decent skills as they are becoming more comfortable in the critical zones of the surf breaks they seek. I would never send a novice out to DOH HT’s on a step-up board, (I wouldn’t send them out there on any board, a big easy-paddling gun may even get them in trouble!)
The biggest gun I own is 9’3" but this winter I used smallish boards. The longest I used was 8’2" but the surface conditions dictated the length, I still wished it was smaller once the face stood up and became clean. I was stoked at how many days I got on my 6’5" round tail (usually surf a 6’1" shorty, I was 170 lbs at the time).
With That Said, this winter I witnessed guys surfing absolutely flawlessly and beautifully on large guns, getting in clean, early, and even doing a drop-in-fade (try that on a 6’3" at Teahupoo) setting 8 feet of rail for sustained powerful bottom turns. So I guess it depends upon what you are feeling on that day.
The design of the step-up boards are usually a rounded/closed tail, about the same width as a shortboard, and the tail about 1/2 to 3/4 inch narrower than normal. Thickness might be a little more (like 1/8) but sometimes it is the same. Length is about 2 to 4 inches longer than your daily shortboard.
Here’s a shot of at the end of winter riding a 5’7" x 19-1/4 x 2-1/8",twinnie.
I’m 5’10’ tall.
The surf was fast but NOT critical, the board has a displacement v-hull with
doubles and rode very smoothly given the texture.
Just some food for reflection…