I made a SUP surf foil board and a wing foil board a couple years ago and here is the status update after using these boards regularly for 2 years. Boards are still working, no delamination, nor structural break down. They have been great boards, very durable and functional, there has never been a day where I felt my performance or ability to foil was held back by the board being to heavy or some other material failure. The plant flax or linen cloth on the wing board has held up great with no signs of failure, I have been very rough with that board setting it on pavement and concrete and in the back of vehicles and drilled a big hole for a camera pole.
Here is a YouTube video where I talk a about the boards and foam:
The SUP surf foil board was my first build and the tracks lifted from the expanding glue, I have since found a solution and used it on my third board build, I share what I did below for members.