Marine grade plywood vs aluminum decks

[bassboy1]

Plywood is roughly 25 lbs per 1/4 inch of 4x8 sheet (dry!). 1/2 ply = 50 lbs. Alum is 165 lbs per cubic foot. 1/8 (.125) x4x8 is roughly 55 lbs. I'm in the same situation and thats what my research povided.

Now, saturate the plywood, and saturate the aluminum. Pull them from the water after a week, and see which is lighter.....

They key to using plywood is to have good drainage. Don't allow any place for water to accumulate. That means space up your supports from the hull, at least on top of the ribs, if not higher. Also, don't let mud and trash get underneath your decking, because they will retain water, and when in contact with plywood for a while, it will start wicking it up quite quickly.

I'm gonna go out on a limb here and say I think for most amatuer boat builders/modifiers like most of us are, plywood would be the material of choice.

Oooh, but aluminum is so much more fun. Not pushing one way or another, but you really don't need special tools to work it. Sheet can be cut on a table saw with a 60 or 80 tooth carbide blade, square and angle can be cut with a recipro. saw, with the stuff in a vise, or with a miter saw, again with a carbide blade. Odd shapes can be cut with a metal blade on a jig saw. To install rivets you just need a 20 dollar pop riveter, and a standard cordless drill and bits.

Now, the other stuff makes it a lot easier - vertical band saw, horizontal chopping band saw, drill press, pneumatic riveter (don't yet have one of those) bending brake (nor one of those) etc. But it is still quite possible with most wood tools.

 

[CWCW]

Thanks for the replies guys. I see that some people are giving weight specs on 1/4 and 1/2 inch plywood. Is this Marine Grade Plywood that you are talking about? I have had plenty of experience using plywood and pressure treated plywood, building in many different applications. Regular plywood wont last anytime in a wet enviroment but pressure treated plywood will last 10 plus years if stuck in the ground, being subject to bugs, dirt and water. Marine Grade Plywood is a grade above the pressure treated plywood. I would think this type of plywood would last 20yrs in a boat. I might be wrong but thats what i have been told by people in the lumber yard business.

 

[bassboy1]

Don't use PT in an aluminum boat don't you? The copper in the wood is a dissimilar metal with aluminum, and will soon react, corroding the aluminum, especially in a marine environment.

 

[CWCW]

Don't use PT in an aluminum boat don't you? The copper in the wood is a dissimilar metal with aluminum, and will soon react, corroding the aluminum, especially in a marine environment.

Oh no, im sorry bassboy1, my message was confusing. I didnt mean that anyone would want to use Pressure Treated plywood in a boat. I was just comparing the longivity of marine grade plywood to pressure treated plywood in defense that i dont see how marine grade wood would become damaged in less than 10 plus years or so, if pressure treated wood can last at least 10yrs sticking in the ground (being that pressure treated wood has a lower live span than marine grade when in a wet environment).