Rocker – Just lines

Well progression has been slow but finally after many reworks I have developed a continuous low profile rocker that I believe should be quite functional for a nose riding Longboard. One element that I would like to have included is a nose concave. Being unhappy with the way in which it integrated with the bottom roll and my inexperience in building HWS, I have decided to remove it from the current design but may reapply it for the next board.

I kept it rather simple concentrating on three primary rocker profiles, Bottom, Rail and Deck that have been developed with reference to each other. The Deck Rocker has approximately 50% of the lift of the Bottom Rocker ie. If the bottom rises 2” the deck raises 1”. This has created two independent profiles that are relatively parallel with respect to any two points of close proximity and results in overall cord thicknesses over the 114.5” (plainer length not curvilinear length) in the range of:

• 1.5” from the nose = 1.53”
• 45” to 50”mark from the tail (Wide point ) = 3”
• 1.5” from the tail = 1.65”

This was done in an attempt to encourage a more equilateral flex ratio through out the centre of the board with further restriction on bending placed on the nose and tail flex through rib placement. My idea behind doing so is that when one is on the nose bending will be permitted or limited to the centre of the board further flattening the bottom profile and in turn aiding nose ridding. The bending in the tail region has also been restricted to enable the structure to cope with the coaxial forces that may be produced by pressure from the D Fin whilst undertaking such things as turning.

Nose lift is approximately 4” whilst the tail lift is around the 4 3/8”; Noting that these values are for maximum rocker at point 0 (tail) and 114.5 (nose) and including an addition of lift resulting from the rail profile. Through my research I have identified that tail lift is extremely important for boards designed for nose riding, even more so then such things as nose concaves and the like. It is hoped that the functional ability of the design as a nose riding board will be enhanced by keeping a flat rocker profile with the wide point and apex of rocker shift behind the centroid of length.

Naturally the Bottom Rocker was the first to be developed with points on the nose side of the apex obtained simple by adding a linier deviation of 3/8” in the Y-direction (Y0 = 0 @ 50”). The Tail side of the Bottom rocker in the Y-direction was obtained using the following limiting equations:

Y0 = 0 @ 45.5”
Yn = (Yn-1 + 0.25) + [0.025 x (n - 1)] …(where, n > 0)

Positions in the X-direction (from the nose) where determined through the use of the separate limiting equation; refer to the Excel plot for results. The Rail Rocker was initially set to enable the development of 50/50 rails through the centre with a modification in the nose and tail that enable it to taper into 60/40 down rails at the nose and 40/60 up rails at the tail.

As any designer knows, actual values will undoubtedly deviate from the desired values and the reality is that it’s just a plan or grouping of ideas; as one of my high school teachers always said: “failure to plan is planning to fail”. This first board may just be a dog, but having the data to reflect back on will definitely be beneficial next time around.