Just know that not all composites are the same. Many companies have lawsuits filed against them for not honoring their warranty after the boards deteriorate. I have seen more than a few brands (including the most notorious Trex) deteriorate and crumble into pieces. There have been major advancements in the generations of composite lumber. The only really good ones now are the boards encapsulated in PVC.
If you don't want to use wood then Azek or similar material will probably hold up better. Azek is a PVC board and can be found at many local lumber yards. Home Depot and Lowes usually also stocks PVC trim bade by different manufactures. Any should be sufficient for your application but I still wouldn't trust the fasteners to hold in a boating situation. A good PVC will hold the pieces just as well as fasteners though. Combine the two and you should be O.K.
FWIW I may pull the foam out of my boat when I re-do my floor but I will keep the foam around the tank and I have tons of composite drops laying around. There is just not a better support for the tank than foam.
|