Tile underlay plywood

Ncsharker · Post by **Ncsharker** » Thu Feb 28, 2019 12:16 am

Hey guy.
So I looked up marine grade plywood. Then I looked up what makes it marine grade.

Well tile underlay plywood has the exact specs if not better and it’s only $13 a sheet.

Has anyone ever built a small boat with it??

fallguy1000 · Post by **fallguy1000** » Thu Feb 28, 2019 12:33 am

you can try anything you want, but a 30 minute boil test is advised

measure a small piece of plywood for thickness
boil for 30 minutes
remove from heat and measure thickness
if the glue is failing or the part is dimensionally changed or badly warping, etc. it is not boat quality

Fuzz · Post by **Fuzz** » Thu Feb 28, 2019 1:41 am

The FS-14 calls for 4 sheets of 1/4 and three sheets of 3/8 plywood. Total cost for plywood about $480 plus shipping. If you go with some other plywood it will cost you $100-150 so you MIGHT save $330. But will you have true marine grade plywood with no voids in it? I would bet not. By the time you add in all the other costs of building plus your time it just seems to me like it would be penny wise and dollar foolish to go with suspect wood. But as was already said it is your boat and you get to make the choices. Either way start a build thread and post lots of pictures

silentneko · Post by **silentneko** » Thu Feb 28, 2019 6:50 am

I built my first boat using underlaminate, 5mm if I recall. It did ok, but was not what I would consider quality. The only thing it has in common with marine ply is it uses waterproof glue. The plys are not really even thickness, with paper thin outer vaneers that make bonding an issue if your resin doesn't penetrate well. And the wood is pretty week stuff with plenty of voids. I'd be ok using it for a calm water rowing craft, but I wouldn't use it for a powered boat. For that I would stick with Merantti.

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