FOILING WITH A NON-FOILING FIN BOX
I am mounting my foil on a non-reinforced fin box and I'm a little worry that the forces on the foil will make the screws go right through the relatively thin layer of glass of the board's deck (about only 3mm thick!). So I decided to build a small carbon layup part to distribute the load over a larger area and to provide a stronger surface on which the screws can push down. This is my first time laying up a carbon fiber and S-Glass sandwich.
This might be either unnecessary, overkill or just not helping at all but, I don't want to take a chance, especially because I just got a new 90cm mast that will likely put more leverage over the setup. With the PowerPlate underneath and this additional carbon reinforcement on the deck, let's hope I keep this board intact!
Here are a few pics of the build.
It looks like there's a chance for me to test this out on the water today. I'll post for first impression!

The finished product (Small racetrack black part below the fin screws)




With the PowerPlate underneath, this should be bullet-proof!




Next post will show a few pics of the build steps.

THE BUILD

First, a layer of polypropylene plastic film (Home Center stuff) stretched over the deck to offer easy-part release (no release agent needed)
Cut and ready Carbon and S-Glass pieces.


Wetting the layers with epoxy resin with disposable brush. I squeegee between each layers to make sure the fabric is well saturated with no excess resin that could weaken the part


Last "cosmetic" layer of an 8-layer build. Using a roller to push away any air bubble and squeeze out any excess resin.


18 hours later, un-molding of the part and pulling the plastic layer (comes right-off)


Building the layout on the board for centering the part and locating the screw holes


Drilling the screw holes with brad point bit (from both sides to avoid tear-up)


Rough-cutting the excess material and leaving a few millimeters to bring the part to size and shape


Sanding the part to the outline and rounding off the edges all the way to 400 dry/wet (Edges only)


And the finished product just before a couple of coats of clear automotive varnish to protect the carbon layer

Great break down of how you did that. Looks awesome. I was wondering if you did, or going to, put some rubber material on the underside of your part like the PowerPlate has?

Thanks Reid.
And yes, great observation; I was thinking like you. I need to find a very thin (~1-1.5mm) sheet/membrane of rubber to pad the connection. I need to go research what I can find that would do the trick. Roofers often use rubbery membrane on flat roof weatherproofing that can be glued well with contact cement.

you can use cork gasket material from the auto supply store... i think it's a mix of nitrile rubber and cork... flexible, compliant, and relatively thin (about 1.25mm)

I was going to make myself a carbon winging boom out of a super light mast tip (broken)... and I need to fabricate the front boom end connection... was going to use this to go between the boom and the LE for some reason I'm not sure is even necessary. Also works as boom grip (thin and tacky, but also a bit heavy).

When and if I ever get up to foiling, I was considering the same type of part for a Bic Nova, that has a deep tuttle, but a fully padded deck including where the fin screws are. Was going to fashion a metal plate, bend it a bit, drill some holes, and put it on top of the padded deck.

I am curious whether the power plate is necessary for a board that already has a deep tuttle if the mast has a flange at the base. Do you think the adjustment that the power plate offers is useful? Does the added base area of the power plate make you feel better about the strength?

Thanks for the tip Kevin. I’ll have to check that out.

David,
A standard deep tuttle fin box has high density PU foam around while a “foil-ready” DT box has usually twice as much of that very rigid foam. It provides a bit more structural rigidity and integrity for foiling. Also, foil-ready boards are likely to have added reinforcement patches of carbon or glass above and below. The PowerPlate distributes the load over a larger surface than the flange that comes with some foils, so I have to assume it does a better job at preventing material fatigue around the box. The P-Plate foil adjustment capability might be useful depending on your board straps and mast track position. This is useful for me to adjusted the position of the front wing right between the front and back strap. This is suppose to help distribute your weight between front and back foot and making leveling the foil easier and more comfortable while sailing.

One last thing regarding your setup with the bic nova: If the padded surface is thicker than 2mm, I would recommend you remove a small area of that pad around the fin box screws to make sure your metal plate makes a tight connection to the board. You don’t want a loose-fitted foil! Just a thought.

Hello Greg,
Nice work on the carbon deck plate ! Where do you sail?
What size front wing are you running?
I am a Slingshot demo rep located on the North Shore of Chicago.
If anyone is interested in giving foiling a go, please contact me.
I will have free demo`s all summer long at greenwood beach in Evanston.
I currently have the 150 Levitator and Infinity 76 foil available.
Slingwing 4.2 hand held wing is also ready to fly on a sup.
Please be at least a solid intermediate windsurfer.
Text - Bob 847.477.3578

Thanks Bob.
Front wing: Infinity 76