Second test sample. A lot better! I degassed the epoxy mixture in a vacuum chamber for 30 minutes. I then applied it to the poplar wood together with the fiberglass. I rolled out any air bublles and applied the vacuum:
Simple and cheap vacuum chamber. I used a thick glas jar and a thick sheet of plastic as a lid. I applied some rubber from a car tire to the plastic using tacky tape.
This time using the bag (with a simple diy vacuumconnector)
No air bubbles can be seen with the naked eye. I am not able to get a nice flat finish, the bag pulls in between the fiber yarns showing dents and revealing the treads connecting the fiber yarns. I need a rough surface since I will be doing the glassing in multiple stages. Sanding is not an option since I will damage the fiberglas yarns. Peelply will be the solution here.
I ordered some peelply, bleeder and breather fabric which I will use for the third test sample. It seems that I am able to pull a pretty even vacuum on the test samples. But I feel that the board will need a breather fabric to acchieve an even vacuum distribution since it has a much larger surface area.
The air pressure will most certainly be enough to from the rocker Zob; surface area is around 0.5 m^2. Assuming a 90% vacuum gives an air pressure of 90000 N/m^2. This gives a force of 45000 Newton on the board which is equivalent to a mass of 4500 kg. But, I am using a bag! So I need to get creative with some clamps.
I don't really understand the thing about the waterline and the need for a strong topsheet downunder. Could you please explain?
I have a nylon topsheet which I will probably use.
Do you guys have any tips/recommendations for the edges? I feel like the fiberglass+epoxy layer will be exposed to the water since it is laying on top of the sidewall...
How to prevent delaminations. My current wakeboard somehow sealed the edge all the way from the base to the topsheet.