1998 Nautique SS seat base

I have a 1998 Nautique Super Sport and the port side rear seat base has cracked. I have removed the upholstery and padding and now I need to make a new seat base. Does anyone know what this material is and where I can source this. It seams like a very heavy duty light weight Styrofoam type material. Any insight as to what this material is or what others have used to replace this would be appreciated. Thanks!

Andrew,
It's expanded PVC. Check your local HD to see if they stock it. We carry it at the Rhinelander Wi. HD but all stores don't have the same inventory. We have it in 1/4", 1/2" and 3/4" in 2'x4' sizes. Get one thickness heavier. It would be easier than trying to repair your old one plus, I would question the bond of the fiberglass resin to the PVC.

If you local HD doesn't stock it, it's available on HD's website. This is the 3/4" Shipping to your store would be free.

Also available on Amazon.
https://www.amazon.com/gp/aw/d/B00JPIBUGQ/ref=mp_s_a_1_fkmr2_2?ie=UTF8&qid=1514411592&sr=8-2-fkmr2&pi=AC_SX236_SY340_QL65&keywords=pvc+3%2F4%22+x+24%22+x+48%22

They make a PVC cement for expanded PVC but regular clear heavy duty PVC pipe cement will work if you apply it liberally on all surfaces and allow it to set at least 24 hours. It actually melts the pieces together and is a very strong repair by itself. If you replace it, keep in mind, if my memory serves me correctly, the board has a bend in it to fit the contour of the base.

Ok, so the heat gun was not effective. I could not get the PVC board hot enough to bend it. I almost started to burn the surface so I had to stop. I then propped up the one end and applied weight to it to get it to bend. In the picture below, I have 2 batteries and a 5 gallon bucket 3/4 filled with paint trying to bend the board. I have had it on there for over a week now and when I remove the weight the board flexes back some and won't keep the bend that I need it to. Does anyone have any other ideas on how to bend the PVC board?