Hollow wakesurf board bottom skin

In the last post we were readying all of the materials and preparing to attach the bottom skin to the core of this, eventual, hollow wakesurf board. We will be using epoxy to affix the skin to the bottom which may seem odd considering that we’ll merely be “melting” the core of the wakesurf board shortly. What we want to do is make sure the various layers of reinforcement are basically sealed to prevent water ingress into the core of the hollow wakesurf board. Now, epoxy and the underlying fiberglass and carbon fiber do have tiny microscoping holes, but they are much smaller than a molecule of water, so the water can’t penetrate merely through those holes. However, we want to make sure that we have completely covered all of the surface of the hollow wakesurf board with epoxy and some type of reinforcement material.

We are going to be working backwards with this part of the skin attachment. That is to say, we’ll start laying down the reinforcement material from the extreme outside layer and work our way back up towards the core of the wakesurf board. Just to be sure that we have everything cut correctly, we do a test fitting, laminate stack on the rocker bed and then the core. It looks good so we can proceed!

The surface of our rocker bed is covered in a thin sheet of Mylar. Mylar is very very shiny and uniform, but it’s also polyester and so epoxy will stick to it like there is no tomorrow. To prevent that sticking, we apply several layers of mold release wax, buffing between coats, typically about five on a fresh skin of Mylar and then one or two in between uses on a seasoned Mylar skin.

We didn’t get real good photos of the next few steps, but we’ll try and explain them clearly. The waxed Mylar is going to act like a mold surface. It has the shape of the bottom of the board and the Mylar will impart a smooth and shiny surface to the bottom of our hollow wakesurf board. What it will also do is create a shape on the bottom of the board that is smooth and uniform, an exact mirror image of the rocker bed, even if the components aren’t flush or even. Remember the honeycomb that was cut inward of the outline of the board? Logically we’d expect a step or some type of ridge where the honeycomb ends, instead the materials are compressed against the surface of the rocker bed and there is no ridge externally. Cool, huh? The internals are probably a jumbled mess, but we don’t really care, it’s the external surface that interacts with the water and we need that smooth and clean!

So the first layer down, the ourtermost fiberglass is laid down and is wet out with our epoxy.

Next layer up is some carbon fiber. Same process, we lay it down and sort of squeegee it into the epoxy from the first layer of fiberglass and then wet out any dry spots with more epoxy

There are two steps that are missing in this next picture, sorry for our lack of attention to detail! First the picture.

What we have already in teh picture above is applied a layer of carbon fiber against the foam core, as well as, the honeycomb. Both of those items were attached while being left “upside down” to cure. In this way we didn’t have excess epoxy flowing into the honeycomb due to gravity. So when we attached the foam core, in the picture above, there is actually a layer of cured carbon fiber and the honeycomb attached. The wet epoxy of the carbon fiber will then cure to the epoxed portions of the honeycomb and not fill the cell with epoxy.

So that’s all for that process. We should point out that the bottom of this hollow wakesurf board is in effect molded. The rocker table with Mylar is an open faced tool, and performs much of the same functions as a mold. The most important being repeatability.

Thanks so much for following along, we really appreciate you taking the time.

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