Authors: Flyboy Wakesurf
In the previous post we discussed the rough bottom shaping of the core of this wakesurf board project. As we’ve discussed previously, all Flyboy Wakesurf boards are a composite sandwich, sometimes called a stressed skin or even monocoque. The concept being that the Flyboy Wakesurf boards skin carry the loads, rather than an internal framework. So now we are going to add a layer of high density foam to form this composite sandwich. For this wakesurf board, we will be using Divinycell H-80. Divinycell is the tradename of a crosslinked PVC foam manufactured by the Diab group. In the construction of a composite sandwich, the skins carry the various loads and not an internal framework or higher density material, one of the main principles in this construction is that the distance between the skins or facings determines the stiffness of the underlying structure. More distance equals more stiffness.
Obviously there are some limits when designing a wakesurfer, a very stiff wakesurf board could be achieved by making it 2 feet thick, but it would almost be impossible to ride. The stiffness increase is exponential, so thinner boards can be achieved with the proper engineering.
We will be using Divinycell, sometimes called D-cell, H-80 for the exterior load bearing skins. The H-80 is a 5 pound density foam, significantly more dense thanthe 1 pound EPS core we use and the 2.5 pound EPS found in conventional wakesurf boards. We use a 3 mm thick skin, which helps add to the stiffness of the board, and is adequate for load bearing applications in this environment. In the following picture we have cut a piece of the D-cell and laid it out on top of the rocker jig, then place the shaped core on top of it to allow us to mark the outline on the skin. We will be saving the offcuts after we trim for other parts of this project.
In this picture you can see the grey D-cell skin that is underneath the white EPS core. D-cell in this density and thickness readily conforms to the rather minor curve of the concave in this wakesurfer, so we won’t thermoform or the like, instead merely using vacuum pressure to bend and fuse the various components of this composite sandwich together.Mail this post