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This is NOT a wood vs composite as a material thread, we all know they both have their benefits and drawbacks. So please don't tell me wood rots, because as most builder's here know if you use good epoxy resin then the boat will out live you. This thread is only to try and compare the actual weight of flat panels, and to see if it is worth going with composites. I have been told by several builders/designers that on a small boat their is virtually no weight savings, but I wanted to see the math.

I've been trying to work out the math for the weight difference. I am using 1/2" plywood and 1" composite for my figures.

For Plywood:

½” Okoume BS1088 is roughly 40lbs, and Meranti BS1088 is about 50lbs

4’ x 8’ = 32 sq ft / 9 sq ft = 3.556 sq yds of surface area per sheet side.

If I cover each side with a layer of 6oz cloth, as I have in the past, that will be 42.672oz per side assuming a 50/50 ratio of glass and resin.

85.344oz / 16oz = 5.334lbs

So the weight of a 4’ x 8’ sheet would be roughly 45.3lbs for Okoume, and 55.3lbs for Meranti.

For 5lbs per cu ft composite:

1” thick works out to 2.667 cu ft x 5lbs = 13.335 per sheet.

If I cover each side with a layer of 1708 and 6oz cloth (this is what was suggested) that is 31oz x 3.556 sq yards = 110.236. Assuming a 50/50 mix of glass and resin then it is 220.472oz per side.

So a 4’ x 8’ finished sheet would roughly weigh 40.9lbs

Does this all sound close? So using composites would only save me about 5lbs per 32 sq ft of material used over okoume?