How measure rocker?

[NuclearFishin]

@$1

Exactly. You measure the flats then add the contours. Simple stuff really. Always do it the simplest method. Always think simplicity. Unless you have 7 elves

Okay, but say you want to copy or reference a board such as a 6’ 10 " …lost SD2 ( which i do actually heh heh , anyone got the numbers?), or any other modern design with a full length concave.Obviously , you want the rail rocker so you can cut the concave in later.

There’s the method our friend has shown above , or I thought perhaps (never tried it)-

Tape or clamp a 600 mm sheet of 5 mm MDF to the bottom of the board , nose to tail - hopefully it’ll span the concave and follow the rail rocker. Put your straghtedge on the mdf and measure all points as usual .

Whaddayareckon ?

[DMP]

@$1

@$1

Exactly. You measure the flats then add the contours. Simple stuff really. Always do it the simplest method. Always think simplicity. Unless you have 7 elves

Okay, but say you want to copy or reference a board such as a 6’ 10 " …lost SD2 ( which i do actually heh heh , anyone got the numbers?), or any other modern design with a full length concave.Obviously , you want the rail rocker so you can cut the concave in later.

There’s the method our friend has shown above , or I thought perhaps (never tried it)-

Tape or clamp a 600 mm sheet of 5 mm MDF to the bottom of the board , nose to tail - hopefully it’ll span the concave and follow the rail rocker. Put your straghtedge on the mdf and measure all points as usual .

Whaddayareckon ?

Sounds like a good idea. Measure the stinger rocker as well and you’ll have two good reference numbers. Hard part will be to duplicate it so it rides the same, so many variables besides bottom curve come into play.

[tommy]

i would measure along the stringer using the barnfield method at set intervals (3in, 6in or whatever you metric guys do…). at those same intervals, lay your measuring stick perpendicular to the stringer and measure the convave. you can also measure the concave at intervals from the stringer to the rail and create a contour map.

[TaylorO]

Bill B. method is a classic standard.

Bill T. had a post with the best way to do rocker an foil all at once.

I like to kook out and mention the “apex” of a curve is not the same as the center line of a surfboard, and building my own blanks based on my own stringers I’ve started from there… But that’s just my own trip, and, as was pointed out, I incorporate my vision of my finished board, which has to take into account convex and concave surfaces, foam foil distribution, etc.

I happy to tell you, I started out the same way you have, with the board perpendicular to a sheet of heavy paper… “measure twice, cut once.”

good luck

[lala]

Rocker sticks don’t work.Try measuring the board how it sits on the floo,Or turn the board deck down so a horizontal line is created from the deck nose and tail that is how a scan is done.this also helps find the apex.Rocker sticks can’t find apexes.With the deck down on a level floor find the highest point.mark it. That is te apex then go from there.Or i think that;s the way it goes.Any one who has had a real scan done knows that the horizontal line from the deck nose and deck tail is the curve.

[lala]

@$1

Rocker will always be relative to any method we chose to measure. Position of board on racks or measuring table or device / employing a lengthy straight edge / accuracy in taking measurements / and so many other variables. But, we get to develop a method and variables which ultimately leads to some sort of consistency in measuring rocker. Fundamentally, if you develop a logical and consistent method to measure rocker and stick with that method you will have a system of measure that will provide consistent useable data for design reference.

Develop a method and stick to it. Create a journal or notebook data base to keep records of your rockers. If through experience you want to adjust or modify your method make a note in your records that entries during certain time spans used a particular method to measure. As time goes by your journal will fill in and be a very valuable asset or tool to your shaping.

Well put dude.

[squalyboy]

Why not just lay the board on a flat surface deck up bottom down (fins off of course) and measure how far the nose and tail come up off of that surface?

 

Edit: Never mind I just realized what stupid question that was. (slinks away quietly hoping no one noticed....)

[tblank]

The whole point is to establish a reference mark or benchmark. From this all else follows. Choose either or the center or wide point and make it a constant.

[MarkW]

First post and apparently 7 years late to the party in this thread.

So as I understand it, the most important thing is to have a consistent method for measuring rocker. If your method is different from the industry standard mid point method it makes it harder for the industry and customers to compare to other brands. But for the one shaper they will be able to get consistent results and iterate from there.

But there’s also the factor of measuring rocker for shaping vs for the finished product. If you have an incomplete shape and your trying to get to a target rocker measurement it seems like the midpoint method would complicate things if a particular stage of the rocker doesn’t start at the midpoint. Not that rockers can’t be progressive but with the way I’ve been shaping it made sense to “start” both rockers (though they blend into eachother) at the wide point. (This is all for my shortboards and fish.) If, for arguments sake, the wide point is a few inches up from midpoint, measuring rocker from the midpoint seems like you’re artificially misrepresenting the actual nature of the tail rocker. The midpoint just seems like a natural point that the board would figuratively and literally pivot on. I guess the exceptions might be longboards or boards with staged rockers.

So my question I guess is, "what is the importance of wide points in surfboard dynamics? I understand there are countless other variables that go into surfboard performance but wide point seems to be a pretty crucial one. If that wide point defines the front and back of the board in terms of in-the-water performance to a surfer then it seems like a natural place to start the measurement from whether for shaping, industry standards or the consumer.

[surfteach]

Check your PM