hi guys i want to start making a few surfboard blanks so i can keep the cost down of making my own boards. I was given a huge block of what I think is eps foam and can't work out if I was clearing out someone's garbage or the guy was actually being nice! It has been left outside for ages, does eps take on water? Also the beads of foam look too big to be able to sand I think and achieve a good finish. please let me know if you think it will be ok to use or if i am wasting my time. thanks!

looks like L grade you would need to dry it for a long time
try and find a hot room around 50 degrees ?
maybe ask the bikram yoga place

Can you shape boards from it?

Yes you can shape from it
Try and find a hot wire cutter and get a basic rocker cut
It will dry heaps faster then