If I was to take a standard performance shortboard, say 6’0" x 18" and brought it up to a 6’6" ,what would I bring the wide points out to? Including nose ,center, tail.Granted most shortboards around 6’ allready have a nose around 10 1/2 and tail around 13 1/2. Is there a mathmatical way of doing this keeping the dimensions of the shortboard and keeping them true in width along with the new length of the board? Im thinking around 19" for a center but am Just guessing.Is there a formula? I flunked Math… Too busy surfing! Ha Ha! Thanks!
With all due respect to the punk in SLO who insisted that “No way dude, you go longer, you have to go narrower” (and lost a sale) I’ll try and present this step by step. For proportionate width… first convert length to inches. 72" is to 78" as 18" is to “X”. (72/78=18/X) Cross multiply and divide. 78 X 18 = 1404. Divide by 18 = 19.5 For nose and tail, assuming nose = 10.5 and tail = 13.5 Nose: 72/78=10.5/X. Again, cross multiply and divide. 78 X 10.5 = 819. Divide by 72 = 11.375 Tail: 72/78=13.5/X. Cross multiply and divide. 78 X 13.5 = 1053. Divide by 72 = 14.625 Base board: 6’ X 10.5(N) X 18(W) X 13.5(T) New board: 6’6" X 11.375(N) X 19.5(W) X 14.625(T) OK? (Correct answer for surf punk to potential customer… “No problem! We’ll scale it up to any length you want!”)
Maybe this is a slightly long way of doing this but you’ll be able to scale your 6’0" to any size you want after this. Take measurments at regular intervals along your board anb measure from stringer to rail Centre(inches) 0 1 2 3 4 Width (inches) 3 5 7 6.5 you get the idea The more measurments the better and try and make em as accurate as possible especially at the tail. Fit the numbers into an excell spreadsheet and fit a curve to the numbers to make sure it looks liek the 6’0" You can now scale up on lenght and/or width. I’ve used this and it works really well when you get the hang of it. Brian
Thanks John, best tip in a long time - and don’t need a computer! - PK
I just recently did some scaling for a new board. I do it a little differently though. The math is the same I just do a different approach I find a bit easier. Scaling does not necessarily work through all sizes. As a board gets longer the wide point should not be xepanded the same scale. Some of the short er boards are proportionally wider for their length to make up for being so short. If you took those outlines up proportionally you might end up with a very wide board for it’s length. The size range being discussed is acceptable for direct scaling though. I divide 78 by 72 = 1.084 Then use 1.084 as your multiplier. 10.5 x 1.084 = 11.382 18 x 1.084 = 19.512 13.5 x 1.084 = 14.634 The multiplier can be used at any different points along the outline you choose. Hope this makes sense, MLC
I agree, scaling in true proprotions will get you some wierd dimensions as the board increases. What formula do you use for scaling rail, rocker, and volume? Basically the entire board?
In scaling it’s alright to scale everything, “straight scale,” except for the width. In John’s scale the rail to rail transition gets slower as the board gets longer. If you start with an 18" wide 6 footer, using straight scale you’ll end up with a 27" wide 9 footer. I wouldn’t want to ride that, would you? Instead use the traditional 22.5 inch for the top of the scale (9 footer) and use 18 for the bottom (the 6 footer). Take the 4.5 inches between and divide them by the 36 inches between 6 foot and 9 foot. You come out with .125 which is 1/8 of an inch. For every inch of length you adjust by 1/8 of an inch width. This will give you correct scale for different size guys.
Greg - I like your formula better. Thanks!
Greg, That is a great solution to the ever expanding ratio. I like it. Here on the Gulf Coast I tend to add an extra 1/4’ to 1/2" in width plus a bit of rail volume to make up for the slower waves we have. Shaped a 6’4" with a 13" nose 20" width and 14 3/4" tail. Little wide in the nose but works good for us older guys in sloppy surf. Your proportional range will work great for “real surf” power. great thread. Thanks to all. MLC http://img.villagephotos.com/p/2003-11/515178/UEXNT-firstboard.jpg