After building my first hollow cedar surfboard (See 9' Longboard - G1) and coming out with a completely flat deck, I realized the need to determine a better way to measure rocker from a board in hand. Although I am still working on it, I think I have a pretty solid method that I wanted to share. Refer to the following image series for a visual guideline to this project: Reverse Engineering Surfboard Rocker and Thickness That will either save me time explaining the setup or just make it a lot more complicated. I figured there was no way to determine the apex of an arc created by the bottom rocker on a board (I will leave deck rocker alone for now) for the reasons I have seen discussed in this Swaylocks Thread. Any point on an arc (bottom rocker for example) has a tangent. By PICKING a reference point "R" along this arc (bottom rocker), CREATING a parallel plane to the tangent of this point "T" and MEASURING vertical distances "TXn" from this plane "T" to points along the arc "Xn" I can DUPLICATE a rocker profile. As seen in the images, the reference point I chose was at the front end of the fin box. I did this for convenience, as it is a relatively flat surface and I can always know where the point is without marking the board in any way. I created my "relative" apex at this point using a spirit level and shimming the board to get this ref point horizontal to the ground. Now I have an invisible tangent plane "T" which runs parallel to the ground at the apex I chose as my ref point on the board: "R" The laser level I purchased comes with a tripod base mount which I modified to attach to the fin box using a fin nut and screw. I did not have to worry about getting this base plate level. The adjustment plate magnetically attaches to this base plate and has screw adjustment legs for precise leveling. The laser body has spirit levels and magnetically attaches to the adjustable plate. Put together, I can fine tune the laser plane "L" to be parallel to the ground, which is parallel to my invisible tangent plane, "T". Now I have a VISIBLE laser plane "L", which is parallel to the tangent plane "T" I created at the reference point "R" which is the apex of the bottom rocker. Using a right angle rule (to keep my rule vertical using its spirit level), I can measure the distance from my laser plane ""L" to my reference point "R" = "LR" Now I can measure the distance from "L" to specific points along my bottom rocker "Xn" to give me the distances LXn. These "heights" will always pass through T, which is my tangent plane at the apex R. (At R and only at R, LR=LT) Since LR is at the apex of the arc being measured it will always be less than LXn. By subtracting LR from LXn, we get TXn for any given point on the arc. To recap: L is the Laser Plane which is parallel to the tangent at the apex of the arc at R. T is the tangent plane of the apex of the arc at R Xn is any point on the arc other than at R, where n is your XY coordinates from R along T. TXn is the heights you want to determine relative to R. Your XY coordinates are variables, but are relatively logical to determine. I measured in 6" increments along T from R, to the tip and tail. I then measured perpendicular to this line from the centerline of the board to the rail in 1" increments. You only have to measure one half of the board, since the other half will be a mirror image. At the tip and tail, I added more perp lines since the rocker changed more dramatically. In the end, I had a set of numbers I can use to create my bottom rocker. Now for the deck rocker...this is easy. To determine the deck rocker, we need to determine the distance from Xn to Yn, where XnYn is the thickness of the board at n. Using a "boat caliper" or lathe caliper, we can easily determine the thickness of the board XnYn at n for all of our coordinate points. I am currently (First Week of January, 2006) at the point of having a full set of numbers to work with. I do not want to make any claims on how this process works until I have completed construction of another board using this technique.