Hi everyone, I’ve searched and searched but cant seem to find a solid answer.
I have a little question on rocker scaling. If I have a specific design I really like at say 6’10", and I want to make a copy of the board for someone at say 6’4", is there a specific scaling for rocker dims? (under the assumption that all wave variables are the same).
I guess another way to ask this question: If I was making “stock” dims for a board, how would I scale the rocker dims per every inch change in length?
Depend of rocker type. For a constant curve rocker you have a radius from center to nose and one from center to tail so you can calculate new radius proportinaly and draw your new rocker. For stagered rocker you have to know how it’s draw, at least 3 radius (nose, center, tail), where they match, and then do the same as for constant curve.
I see, so with the staged rocker why wouldn’t the three radius decrease proportionally as well? wouldn’t it follow a specific ratio, and if so, is the calculation as follows:
Am I taking the current length, say 82 inches and finding the % of change to say 76 inches, and then applying that exact ratio to rocker dims, regardless of if staged or not?
so 76/84=90% of original length
then applying this percentage to the rocker dims?
I hope you know, im not rebutting because I think I know, just genuinely curious.
by rocker dims, I mean along the entire rocker line, not just at 0" nose and tail.
this is how i would do it, other people might use pen and paper or moon calendars. its just one option.
there is an option in shape 3dx called guideline measurements, its a table where you determine points and give values to this points, then it auto generates the drawing with your values.
example: open new board - open guidelines wizard- choose rocker profile - insert values of the original board - go back to design mode and choose constant porportions for resizing the board to the new lenght.
Important when asked tick the box measurements along the stringer unless you measure over straight line.
also in resizing you can adjust tail and nose rocker (but yeah like you said its only at point N1 and T1)
User JRANDY is very good with this stuff he might be able to help.
cheers and good waves.
@961
That is how I would do it.
Multiply length and rocker measurements at previous intervals (length and rocker height) by 0.927.
So for example, previous measurement that was 12” from tail with 1.5” rocker would now be 11.124” from tail with 1.391” rocker height.
This preserves original rocker slopes, regardless of rocker type.
Rocker slopes determine Lift and Coanda Effect.
The answer to your last question is that You wouldn’t scale per every inch. What blank did you make the 6’10 out of. Find a similar longer or shorter blank in the catalog and order the rocker overall and at nose and tail to match the rocker of the blank that you used to shape the 6’10 out of. If you made any adjustments (at the nose and tail usually) make the same adjustments. Otherwise the answer is to order rocker in the glue up at the factory. This is what smart hand shapers do. If you are a computer it makes little difference. If the blank is thick enough the machine will adjust the rocker. Smart hand shapers don’t overthink it…