Light, water resistant sheet stock

[RPE1]

I need some material to rebuild a winter cover for my boat.  I used luan underlayment last time and it worked well for a few years, but the wet finally got it and it delaminated and fell apart.  Anyone have a suggestion for another material that would be light, weather resistant and not cost an arm and a leg?  The luan was fastened to 1X2 "rafters" butted against a 2x4 strong back running the length of the boat's cockpit creating a low A-frame shaped structure..  I covered that with a plastic tarp and lashed it all down.  It shed snow well and kept the inside of the boat reasonably dry.  I wandered around the big box yesterday, but didn't see anything that I thought would work well and wouldn't be so heavy that I'd have to tear it apart to get it off the boat..  Any help?

Phil

I'd get the corrugated plastic 4'x8' sheets.  It's light and easy to work with.  It'll last for ever.  Then, get some Zip tape for the seams.  That stuff will never come off.  It'll take your finger prints off if your're not careful.  Zip tape is expensive.  Shop around.  It's wide so you can only use half width to double the capacity.  You can cut small pieces to cover screw holes.  Everything would be water tight.
RP

[photobug]

CDX at menards

They also make green treated plywood. 

Treated plywood

I am two hours from any big box store.  When I went into my local lumberyard they said they no longer stock CDX.  They must have sold me treated plywood instead.

[Lynden]

HDO or MDO plywood would last a long time. The minimum thickness available is 3/8", but you could reduce the weight of the cover by using fewer ribs and 1x4s or 2x2s around the perimeter instead of 2x4s. You could also build it in two halves held together with bolts at the ridge.

https://www.apawood.org/overlaid