For a specific wave if the shortboard is working well how should I approach the design of a step up board for when that wave is bigger? How is a board stretched out and how would this effect the rocker,foil,etc. Am I looking to keep the same overall rocker but have the apex in a different place? Do you keep the rails the same ? With boards being designed on computers I am assuming that the necessary changes to the curves are well known? Any rules of thumb?
Mark
Tail shapes normally, Make them rounded pins, Normally, rocker is the first thing I change, Reconfigure the volume a bit, I always put the volume further forward for paddling, Then Foil, I always make the nose a bit thicker, but keep the tail thin. Then, often, I put the fins a bit futher up the board for a longer turning diameter. I often go for chimed / pinched rails. Fins make a big difference too, aswell as the glassjob - your gonna want a stronger glassjob.
Hope Ive helped
Search the archives for scaling. There’s been some good threads about your very question.
A big question would be - How short is the board, and how long are you going to go?
The biggest “change” that come to my mind is, as the board gets long, it gets wider, but the tail should get narrower… That’s the tricky part, the rest can stay very similar - you’d probably go thicker too… But that comes with the scaling…
look this is not very informed, but it seems that the ‘best’ surfers are following the trend of wide points forward again like they used to be BUT they have hugely reduced length.
Therefore for step up, you need paddle power to get in to the wave and ‘relatively’ narrow tail for control. So, forget scaling for high performance and go almost fish like (wide point forward, nose wider than tail) but high perfomance dimensions. This it seems to me is the future from past lessons not just making a small board bigger because the waves are bigger. But what do I know ???
…until everything, you need to understand the concept of the design
for ex.: if somebody are scalling a fish platform…well, is not understand the idea and the concept of that design
a useful tip is if you have a 6 shortboard and want a 6 3
imagine that in your stance position the shape is the same, then modify the first 1/3 of the board for what will be intended
Thanks reverb that makes a lot of sense.
to quote Kirk Putnam “it all works”. So I think every approach mentioned on the thread could work as long as its a good design. I don’t know if there are any rules of thumb.
One approach that worked for my step-up was
scale rocker proportionally using (step up length/shortboard length x individual rocker measurements at intervals along the stringer)
keep the width exactly the same
narrow the tail a bit but not drastically narrower.
keep the same rear fin to front fin spread, but push the whole cluster up the board to match the longer length.
let the shaper choose wide point and nose width.
However since then my shortboard has changed drastically (became the 6’ 3" high rockered Bushman Pancho Sullivan). So I renamed my step-up a mini-gun instead as the length difference expanded to 7" which is I think a bit much to call the longer board a true step up.
Then further to that I got another shortboard 2" shorter which seems to have ended up as my regular ride (6’ 1" Byrne Macca)
So what I did then was rename my 6’ 3" Bushman the step-up. This conceptual renaming keeps me psychologically confident in my quiver.
Byrne do actually make a step-up Macca board - they kept exactly the same width, kept the same thickness. Stretched it 2" and narrowed the tail by just 3/8".
I believe your regular shortboard is comparable to my 6’ 3" Bushman - it is 6’ 3" with high tail rocker. I haven’t seen pics or full specs of your board, but I think the reason why your board would not keep me psychologically confident as a step-up board is because your board has a deep single concave and is quite thin (correct me if I am wrong on these details). Mine has a shallow single concave and is thick and domed (normal rails).
However I will admit to being a bit confused about board size and volume and wave catching so I’m not sure if extra thickness helps (although I think it does), its just that I’m starting to see the light about what others say about short boards catching waves more easily. However this is only the case if I vigorously kick my feet (which I always do now). I’m not sure about shortboards in big waves either - a few weeks ago I didn’t feel very good on the 6’ 3" and came in after just a few waves.
I can’t detect any difference in wave catching between my 6’ 1" and 6’ 3", however both these seem to catch waves better than my old 6’ 6" shortboard - but thats coz I can kick my feet a lot.
These pics of my 6’ 3" taken today
[img_assist|nid=1048752|title=Mr J, Feb 2010 on 2 and 7/8 of tail rocker|desc=|link=none|align=left|width=640|height=428]
[img_assist|nid=1048751|title=Mr J, Feb 2010 - on 6 foot 3|desc=|link=none|align=left|width=640|height=428]
I’m not the most experienced, but my limited experience can contribute 2 things.
You can simply scale a computer shape up about 3"., but if you want to go bigger, you should redesign because you’ll just end up with fat rails and a wide tail and nose.
Step up entry rocker can be 1/8 - 1/4" lower in the front third of the board from the rocker low point, but end point of the rocker may be a bit higher than your shorty. Funny thing is, after putting a lot of “proven” rocker templates into the computer, we’re finding they are really similar. A 6’6" rocker, say, can be put on a 6’1" (allowing for slight differences at each end).
I guess the overall questions you gotta ask is, “How much power do I want to shed?/ How tight do I want to turn?” - veed bottom, narrower tail, increased rocker all help to bleed off power.