We were a bit concerned with attaching the deck skin, because of the various curves in different directions. There is a curve with teh rocker and then the curves with the concave deck and finally the curves back down towards the rails. We are using a 3mm divinycell skin on the deck of this concave deck wakesurf board, because it tends to wrap these curves much better than the corecell we used on the bottom. Both materials are a good solid choice for composite sandwich construction, but the divinycell formulations allows for a tighter radius curve. But, the first thing we do is cut the sandwich layer reinforcement, again this is carbon fiber.
Ok final shape! No, the divinycell will bend to match the curves of the deck on this concave deck wakesurf board, but it will take the force from the vacuum to do that. We are merely taping it in place here so we can handle it and slide it into the vacuum bag.
Vacuum bagging is sort of a fine art, we don’t just slide the project in the bag and pull a vacuum, the bag itself will want to stretch and bridge gaps, so we have to fill the gaps with the bag. Not really a pleat, but we pull excess material INTO those areas where the bag will tend to stretch and leave a void. In the picture below we pull excess material into the deck concave using a fire extenguisher! That weight will hold the bag up against the concave as the bag is being pulled tight.
This picture gives you an idea of how the divinycell forms to the compound curve. We did have one issue on the left side rail, where the divinycell broke, but it was beyond the rail material so will be discarded. We just cut that area of the deck skin a little too wide and so without anything to support it, it cracked when the vacuum was applied. You can see that the skin formed the curves well so we didn’t need to worry!
One last picture, showing the deck side concave.
That picture should also make you students of wakesurf board and composite sandwich theory perk up. Can you guess what that concave deck will do? That’s right, it’s going to stiffen the deck side of the board pretty substantially. Remember our discussions about curves and folds in flat panels like your car doors? Those stiffen those panels so that they hold their shape without requiring extral metal to support them. That concept applies here also, those peaks and the concave will add stiffness to the length of the board without having to add other exotic fibers. This is going to be an unknown for us. We want this concave deck wakesurf board to be really agile and manage turning and such quickly in the smaller pocket that is available in the MOW boat wakes. This added stiffness, maybe a benefit!
Thanks so much for following along, we appreciate it.