Composite sandwich multi-density wakesurf board core

Man that was a title! The concept that we are exploring is to glue up two layers of shaped foam as part of the core of the wakesurf board, that is the whole composite sandwich multi-density wakesurf board core in the title of this post.

If you’ve been following us for any time at all, you’ll have a solid working knowledge of a composite sandwich. A few of the principles include that the core is realatively weak compared to the skins. It’s not the same as monocoque construction, but conceptually the skins carry the loads and distribute forces across as wide a part of the skin as possible. Also the stiffness of the composite sandwich is exponentially related to the thickness. That is that if you double the thickness, the stiffness quadruples! Which sounds great, but obviously there are limits, we couldn’t surf a 4 foot thick wakesurf board…although it might be fun to try!

So what does that have to do with a composite sandwich multi-density wakesurf board core? And by the way, try saying that three times fast! There are compression forces, typically on the deck and tension forces on the bottom of a wakesurf board, with momentary switching when landing from any sort of aerial or lofted trick. However, when landing from an aerial there is this crazy point loading force under our boney heels! Right? You’ve seen it, you come down on the board and hit with your heels rather than the ball and heel of your feet. That point loading causes heel dents. It’s like repeatedly hitting your board with a bone’y ball-peen hammer. So we can effectively reduce that with a higher density foam skin on the deck, like all of the Flyboy Wakesurf boards.

We were thinking if one was good, then 4 has to be even better! Well, we aren’t sure, but we thought we’d try. The core of all Flyboy Wakesurf boards is a 1 pound density EPS foam, but we thought, what if we split that core in to two unique segments, a deck side that is maybe 3/8″ or 9 mm thick that is perhaps 3 pound density, so less than the deck skin, but more than the rest of the core? It would sort of act like a shock absorber, further abosorbing the points loads on the deck, but minimizing weight and MAYBE, just MAYBE enhancing the neutral axis transition from compression to tension forces. We’ll save the neutral axis discussion for another day, but just know that we are working hard at test, research and development and designing this concept. Not like in putting lipstick on a pig, like in doing the work and letting THAT speak for itself. Good or bad, you’ll know that we are doing the hard work, not trying to sell you a pile of crap.

We could use a higher density foam all the way through, and there are successful implementations of this like with the Lakewakes boards, but we take a different approach and we are wanting to maximize the transition at the neutral axis.  Plus, by changing the density of the foam, we can reduce weight, from a single density foam.

Ok, so off to the fine artwork!

Here is a side view of the concept. You can see the rocker, so this visualization would be looking at the side of the blank.

This picture is a little hard to make out at first glimpse, so imagine that we cut the wakesurf board in half width-wise, then sort of expanded the parts so that you could see the components. The rail of the board is on the left and the center of the board off to the right.

We will do the internal reinforcement with very lightweight fiberglass, probably 2 oz e-glass. The one point we wanted to bring up in that second picture is that we intend to lap the “rails” if you will internally. That is the joint at the outline will have a few layers of glass overlapping it and the laps themselfs will alternate, one going up, the next going down, etc. We believe that will not only provide perimeter weighting, but also will stiffen the rail line considerably, without the use of carbon fiber.

We know, that is hard to follow isn’t it? Hopefully as we start building the test blank in this multi-density foam composite sandwich blanks, it will become clearer. We really do appreciate you sticking through this explanation of our composite sandwich multi-density wakesurf board core and hopefully we’ll all be rewarded with the results!

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