measuring rocker

Looking for a method for measuring nose and tail rocker. Apologies if this is a worn out topic (i did search the resources)

See photo of the “Rocker Stick” on page 31, in latest issue of The Surfer`s Journal, article by Chris Ahrens, “The Inventing Of Stanley Pleskunas”.

Put your board or blank on a set of racks or sawhorses so that the middle of the board is level (use a carpenter’s level). Find the midpoint and mark it with a dot. Find a long (longer than your board) straight thing (metal bar, pipe, angle, or wood) that is dead flat. Put in on the dot and measure from the bottom of your straight thing to the board at various points. Use a Stan P. (referenced by Dale) machine to reproduce the curve and you’ve got a rocker template…

Thanks Lee. I think i get it.

The most accurate way is to place the blank deck up on a level rocker shelf that is designed to measure rocker. In this way you can measure the “Balanced rocker” it will determine volume flow to rocker relation and how it all function together in the water. If you measuring with the bottom up and with a stick this is not accurate. I never understood this method, as you can shift the point around, and not know where exactly how the board sits in realtion to true level.

I don’t know about volume relations or the machine you are talking about but there is only one point on a curve where a line is tangent. Once you find the midpoint there is one and only one way a line will intersect that point on a bottom curve (Geometry 101). The only reason I mentioned leveling was that the straight thing will balance that way.

Sure, you can get the “straight thing” to balance on the board. But it will not be the same when measured with the “balance rocker”. The balance method will sit in relation to volume distribution. I find this method is the most accurate.

Most people use the “rocker stick” as you call it.Its not accurate but it is the way clark foam does it and has been a standard for years.If you want to get down to super tech stuff you will find that there is really no way of actually measuring rocker without a preset baseline.Then we would have to get out the laser level or water level to get numbers.Kind of interesting. R.B.

Lee V is correct . This is the standard way to measure rocker. You must also put your finger on the rocker stick at CL to hold it true to that point. You will always have an accurate point of reference with this method. The method of sitting the board deck up on a level surface is a great way to visually comprehend the way all the elements come together, but not the best way to measure rocker. aloha TW

Yes, you are correct this is the most common way how most shapers do it. My experience from doing this way is that it is not consistent depending on volume and bottom contours. Measuring balanced rocker is always consistant with the deck up and also gives you a solid baseline taking into considerations of volume. Just my 02. From over 30 years of taking and measuring rockers. I have seen so many guys measure with the stick for years, just to check it the balanced method and will be off from board to board. I would say measuring with the stick isn’t the correct way, it’s the easiest, but far from the most accurate, in terms of getting a good baseline taking into consideration all the factors in the shape. Just trying to share different methods.

I have tended to think in terms of the center method because that is how the blanks are measured and many shapers use this method. However, I agree that this method is not always satisfactory. As the wide point and thickest point move away from center as with guns, I find it more useful to measure at these points. I can better see where the elements are coming together. However, I still measure on the bottem with a balanced beam as opposed to a flat surface. The problem is when someone asks what the rocker is I have to explain my method or go back and measure at center. Can get confusing. Patrick

Just to make sure you aren’t misunderstanding the centerpoint method…it has nothing to do with level anything. Puting the blank or beam on level is only for convenience. The measurements from the beam to the stringer would be the same if things were tilted or if you were upsidedown. That said, if you were to make a template from the volume measurement method or the centerpoint method they would be identical. But, if you told someone that the nose had 5 inches of rocker it would make a difference which method you used. Its just a matter of baseline like you said.

There are a ton of ways to measure rocker. The important thing is can you do it consistantly and can you explain your method to your blank maker. For instance, Clark Foam can use any method for duplicating the rocker as long as you can translate how you measured the rocker to them.