We want to talk a little about the concept of thermoforming a wakesurf deck skin. For those that have followed along with us, you’ll remember that we started these composite sandwich wakesurf builds with a high density rail material. It was almost a perimeter frame, that was built up and glued into place. For wood skinned boards that’s still needed, bacause bending 3 mm sheets of balsa of basswood is almost impossible without splitting the sheets on the grain. We have been using high density foam sheets for the skins of our wake surf board for awhile now for a few reasons. The high density foams are readily available, in fact they are easier to acquire than balsawood in quantity. In comparison to other materials commonly used as skins, they are more uniform. Balsawood for example is not uniform throughout, nor from piece to piece. That lack of uniformity while not a huge problem, does tend to create strtuctures that aren’t balanced.

The high density foam is the same over it’s length, width and thickness. Now wood, when done well, can make a board feel alive, but sometimes depending upon the lack of uniformity, it can just make it feel weirdly alive. High density foam can also be acquired in sheets large enough to cover the entire top of bottom with a signle piece, thereby eliminating seams and glue lines. Although we have seen some amazing combinations of wood and foam that results in stellar good looks.

Principally we have been using the high density foam for skins with the basica purpose of creating stiffness with low weight. We do not use a center stringer, so that the Flyboy Wakesurf Boards have great strength, flex and light weight. Further they don’t exhibit rail twist off as is common with center stringed conventional construction.

When we acquire our high density foam skins, they are typically 4′ x 8′ x 3 mm flat sheets. That requires that we cut them to the basic outline of the wakesurf and then for the deck skin, heat and bend them to shape. We can’t just bend them to shape as the rather tight curves along the rails will cause the foam to split. Larger diameter curves, like the bottom concave or the deck roll aren’t a problem and do not require thermoforming. The rails, however, do. We’ve become quite practiced at it, and we’ll show you the finished results in an upcoming post.

So the first thing we do is trace the basic outline of the shape we need. We use a simple marker for the task.

Next, using heat, we soften the high density form so we can mold it to the desired shape. We use a female open faced tool for this process and once the high density form has been molded to shape we trim any excess. We intentionally use a slight bit of excess because we aren’t quite that accurate while handling hot melted foam and pressing it in place! The extra gives us some leeway.

Once the high density foam is thermoformed we wet out our reinforcement layer fabric and apply it to the core. Next we lay the thermoformed skin on top of the wet out reinforcement layer. From there we apply 7,000 miles of blue painters tape. OK, OK, OK, not that much, but enough to hold the skin in place and the edges down to the core while sliding it all into the vacuum bag. Here you can see the tape, but also the thermoformed area around the wings of the wakesurf board.

In that area around the wings, you can get a good idea of how intricate the thermoforming can be. The hardest areas to thermoform are these tight compound curves.

In this picture, you can see the right hand rail of the board pulled tight and unifromly curved for the length of the board in the picture.

We leave the wakesurf deck skin in the bag overnight to cure and did you notice? The board is right side up, so what will happen with the epoxy and sandwich layer? You got, it! It will flow downward towards the core EPS foam, just as we did with the bottom. We are balancing the two cycles to achieve the same level of resin penetration.

Thanks for following along!

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