Considering the recent thread: What came first ? heavy concave or heavy rocker ? brings a question to mind.
What constitutes heavy concave and what constitutes heavy rocker ?
For sake of discussion (and since there are so many relevant designs out there) in the context of just a few boards, where do we draw the line between shallow concave & low tail rocker; moderate concave & moderate tail rocker; and heavy concave & heavy tail rocker ? (I’ve suggested these boards as they are designs where concaves are most common.)
(1) “glass slipper,” something like 6’ 2" x 18 1/2" x 2 1/4" Squash or Thumb tail
(2) “extended short board,” something like 6’ 6" x 19 1/4" x 2 1/2" Squash or Thumb tail
(3) “small semi gun,” something like 6’ 10" x 18 3/4" x 2 3/8" Round Pin tail
Anyone care to throw some numbers out there regarding actual depth of “heavy” concave & measurements of “heavy” tail rocker in the context of these designs ?
Anyone want to take a further step and discuss how much rocker may be required to accommodate certain depths of concave in the context of these designs ?
Tossed this one out there Saturday evening - What constitutes heavy concave and what constitutes heavy rocker ? To my surprise, no replies. Just thought I’d bring it back in case anyone wanted to comment.
Another question: when designing a board for a particular surfer and the conditions they normally encounter when surfing, when are concave bottom contours more relevant and when are convex bottom contours more relevant ?
I thought these topics might be more interesting to wrestle with (and on point with regard to “surf board design”) than China, Surftech, and User Profiles.
Craftee, I tend to agree with you on moderation. I get good results by incorporating “radical” ideas into shapes yet using those ideas in moderation. I tend to use deeper concaves in shorter / narrower boards and shallower concaves in longer / wider boards. In the lower volume boards I believe we can add more concave and appropriate rocker and outline curves to release water flow out of the concaves thus eliminating drag and that sticky feeling. Higher volume boards don’t require as much lift to generate and maintain speed as the volume itself will generate and sustain speed.
I’ve got a couple of primary rocker profiles I like to incorporate in boards for smaller waves - flat to a foot or two overhead. One is a “lower or relaxed” entry rocker with more tail rocker: 4 3/4" in the nose and entry with 2 3/8 to 2 1/2" in the tail. The other is a “natural” rocker that has more lift in the nose and flatter in the tail: 5 1/8 - 5 1/4" in the nose and entry with 2 1/4 to 2 3/8" in the tail. (I’ll put up to 5/16" concave in both rocker profiles about 18" up from the tail, which is pretty deep.) These boards would be from 6’ 0" to 6’ 4" in length. The rocker numbers grow proportionately with longer boards and the depth of concave decreases.
The relaxed entry rocker is more than simply dropping the rocker from the natural rocker profile. When I drop the nose I’ll actually add a little rocker between the entry and the widepoint to keep the rails from getting caught up in tight transitions. That little bit of extra lift near the front foot can be very forgiving with the lower numbers in the nose. Here’s something I think is pretty cool. The lower entry boards seem to perform better for surfers who are more front footed in their technique and the natural rockers seem to perform better for surfers who are more back foot oriented with their technique.
A surfer can make critical take offs and really drive hard through all their maneuvers with either rocker profile and fit into those tight transition areas of a wave without fear of digging a rail.
Screwfoot, you’re so right. The variables of custom shaping are endless. The cool thing is we can get the variables working in harmony (as Craftee was referring to.) Keeping records is very important. CNC shaping is quite good at that. You can’t imagine how many variations with comments and feedback I’ve got in my data base after only 3 years of cyber shaping.
I still believe surfboard design begins with and is constantly fueled by our intuition. Keeping good records based on a consistent “measuring” system accelerates the evolution of everybody’s shapes. Matthew Barker, formerly of Clark Foam, once offered this analysis of the evolution of surfboard design. He identified two types of progress: quantum and incremental. As I see it “quantum” was usually the result of intuition. George Greenough watching tuna and sea mammals or Simon Anderson visualizing a combination of fins. “Incremental” was usually the result of tweaking the variables and keeping good records.
Screwfoot, No I don’t soften the rails in the entry with the lower or relaxed rocker, although my rails in the entry are very neutral / soft to to begin with. I pay a lot of attention to the foil or thickness flow of the rails from nose to tail - thin enough to penetrate the water in front of the surfers front foot yet full enough to support their displacement factor (size and technique of the surfer as they initiate and push their rails through any maneuver) through the wide point. There’s certainly some give and take required getting the rocker and rails to work in harmony with each other based on shaper / surfer preferences. But I do believe you can chose to work that out around your own preferences.
The HF with low rocker and down rails is a good example of getting all the variables working together. The low rail nose to tail is probably accompanied by a real mellow continuous rocker throughout. That continuous rocker helps keep a lower rail from getting stuck or caught in the tighter areas of a wave.
In contrast you should have a look at some of Taylor Knox’s Merricks. They have a machined edge from the tail all the way past his front foot. Very radical indeed. Those would be very difficult for the average surfer to ride. But TKnox is not your average surfer. I’m sure he’s been working with Merrick for quite some time to get such radical features to work in harmony with each other. Most of his peers have very neutral rails from entry through the wide point with the machined edge developing a few inches in front of the fins.
NJ_Surfer, Yeah. Anything 1/16" or less would be so subtle it may not have much if any affect at all. You could probably end up with a “shallow” 1/8" of concave just in the glassing process. The lap from the deck lamination would yield 1/16" concave by itself.
In contrast you should have a look at some of Taylor Knox’s Merricks. They have a machined edge from the tail all the way past his front foot. Very radical indeed. Those would be very difficult for the average surfer to ride. But TKnox is not your average surfer. I’m sure he’s been working with Merrick for quite some time to get such radical features to work in harmony with each other. Most of his peers have very neutral rails from entry through the wide point with the machined edge developing a few inches in front of the fins.
How much concave is TK using?
I think sharp edges can be combined with more neutral bottoms.
Sharps with deep concaves are harder to surf, it tends to get squirrely, unless you use lower volumes. Been struggling a bit with this lately, so I moded my latest using a circular saw.
Craftee, I never had a chance to measure the depth of concave in TKnox’s boards. The concave in the boards I’ve seen run from nose to tail and appear pretty deep. I’d say from observation alone certainly 1/4" - maybe a little more. That’s pretty brave taking the circular saw to your finished board. Sounds like you take after your dad !!!
Reverb, Just had a glance at some of your work. The quad fish look beautiful. Do you incorporate the tucked edge nose rails in the fish more than in your other shapes ?
…I had been positive feedback about those nose rails (most of these boards were/are made for steeper waves or beach breaks toobs)
but in some point about 10 years ago or so too much people did the softed ones that I started to think that I was wrong trying to make nose rails with bottom edge
then a few years ago I started again…in an old thread I discussed that point with B Burger and I get more “confidence” (due to the positive feedback that him obtained with his boards in several conditions)
In my opinion are very good for late take off in steeper waves
in the fish I do the bottom part of the nose rails rounded with an edge
in other shapes I “stretch” the tucked edge and make it not so rounded
all the boards have moderate entry rocker and most have heavy tail rocker or only a tail kick
