Mike stands to answer you better in your manner of thinking. He does a lot of computer whereas I make full size lines because I can ‘feel’ them better that way.
But as far as flat water and you’re diagram… when are you EVER on flat water? Means zip to me in what I do.
Moving the points back and forth like CAD is fine, but (here we go) back to the lines in space, I look at the CURVE more than the dim. I say this a lot to guys ordering customs from me that are locked in on a bunch of numbers (which sometimes I liken to them trying to put a strait jacket on me)… “IT’S MORE ABOUT THE CURVE THAN IT IS THE DIMS”. Yes, dims are important, but as a guideline beginning point to have a beginning reference point.
Just as you can assign numbers to points forward of center say at 0, 12, 24, and 36" forward of center… the curve can vary within those measurements… of course if you increase the number of increments you measure at, the closer and finer you can determine a given curve… 6" increments than 3" increments… how defined do you want to go? It depends on how knowledgeable, demanding or exacting you want to be.Heck, you can extend those measurements so fine that it is a connect the dots that are almost touching each other!
Same thing is possible with the deck… decks are NOT just a by product of bottom rocker transposed to the deck! Even if you had a thickness of 1.25" @ 12" on the nose, a max thickness of 2.25", and 1.5" thickness @ 12" up from the tail…not only the curve, but the thickness flow can vary siginificantly while still havng those same dims. The “lowly designer” guy that posted earlier stated this, and he is absolutely right.
To illustrate that point in words (I should get my Sharpie out and draw it, but I’ll try describing it first)… picture a board with a curve on the deck that looks harmonious with the bottom rocker within the numbers I cited. Now picture a board with a super straight deck line thru most the board from the center but step decking abruptly at each end to the 1.25 and 1.5" dims at 12" up from tail and 12" back from nose…
WILL THOSE BOARDS RIDE EXACTLY THE SAME BECAUSE OF THE SAME BOTTOM ROCKER & DIMS AS NOTED?
No way.
Set up two posts at each end of the board on shaping racks to create a level line like a bottom rocker stick ala Barnfield.
Place a vertical sheet of masonite or similar above the board sitting deck up, attach a marker to a can or cylinder that will allow you to scribe the deck line onto the material. You now have a deck rockerline relative to level.Even then, you can screw this up if the board is fudged forward more on the shaping rack from one time to another. You would have to try to register each board so it sits on the rack centered longitudinally or joing the scribed deck and bottom lines might not meet up accurately. I know, I know, how much do you want to pay attention to detail?
If you do the same for the bottom, you will have a physical (hard copy) of both and how the relate to a LEVEL line.
Now, how do they relate to each other? If you scale some of your models you offer to people but use different blanks due to desired lengths for each customer… how do the deck rockers differ from each other? P-I-T-C-H-?
The guys that don’t hand shape say… doesn’t matter, the file cuts the blank, whatever blank, to the curves created from the scanned master. So they tell me that the file creates an absolute. But when Surfding and I talk, he says he endeavors to have arranged deck rockers per the file he makes so machining results in 1/16" removal of foam from the decks thereby netting a strong board. I believe that practice is more an ideal, than a common practice within the industry. I think over machining is probably pretty common as is over shaping. Even if it is primarily on the bottom of the blank.
I have no doubt that guys wanting flat decks flip out that the blank manufacturers have chosen not to supply cross section illustrations of their blanks as Clark did. In fact I know this to be the case because I have already brought this to their attention nearly a year ago.
If you only want to shape status quo domed deck pinched railed HPSB’s you needn’t concern yourself. However, if you actually have ideas that you want to create a design for yourself within blanks being offered, you should be able to have enough information on that blank to actually choose which one will work, and how you have to reconfigure it without having a ridiculously weak rail crown that crushes when you duck dive, or have the deck or bottom dent from normal use.
There were a lot of claims by many blank manufacturers (including a fair share of MDI based guys) that their foam cell structure and hardness is consistent thru the entire blank.(Yeah and the rail configs and dims are symmetrical too- not).
THAT IS TOTAL BULLSHIT. If you know what you are shaping, you can feel the foam changing as you remove 1/4" of it and more… if you can’t tell, then mow or machine away in blissful ignorance.When the decks cave in for your customers, you might remember this post. DON’T BLAME THE GLASSER.
That’s probably a good argument why MD and others just said, screw it…quality EPS is much more uniform than PU.
Believe me, there’s enough room for improvment to go around for everybody,
