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Aluminum is about 0.10 lbs/cubic inch
4x8 foot sheet of 1/4" fir plywood weighs 25 pounds. There are 32 square feet in a sheet, so a square foot of 1/4" fir plywood weighs about 0.78 pounds. Since 1/2" is twice as thick as 1/4", 1/2" fir plywood weighs twice as much, or 1.56 lbs, and 3/4" three times as much, or about 2.34 lbs.
There is to many variables with plywood, type of wood, glue, layers, treated and what nots. You can break the plywood down to cubic inch to get what your looking for.
But this should get you in the direction your looking for.
4x8 foot sheet of 1/4" fir plywood weighs 25 pounds. There are 32 square feet in a sheet, so a square foot of 1/4" fir plywood weighs about 0.78 pounds. Since 1/2" is twice as thick as 1/4", 1/2" fir plywood weighs twice as much, or 1.56 lbs, and 3/4" three times as much, or about 2.34 lbs.
There is to many variables with plywood, type of wood, glue, layers, treated and what nots. You can break the plywood down to cubic inch to get what your looking for.
But this should get you in the direction your looking for.
4 x 8 sheet of 5052 aluminum, .125 thick, is 52 pounds.
thanks guys, im trying to figure out how much weight i can keep from putting on my boat, i added a deck and floors and the bow rides way lower in the water and i do not likeit at all(didnt consider the weight,live and learn). i spent about 300-350 dollars on plywood,carpet,hardware etc...its not really about the money but the flat floors and deck+ the little bit of storage in the bow make a world of difference.oh and i did boot the transom mount for a bow mount that is pretty heavy..do you guys think swapping out the wood with aluminum will make that big of difference? i used 2 3/4 inch pine or fur(pressure treated)sheets of plywood 6-7 2x4x96inch boards a few 2x2's plus nuts bolts and screws
SVOMike86
Well-known member
Most common size aluminum for decking would probably be .125 (1/8"). What size boat do you have? Some of the smaller boats just aren't made to handle any more weight than a fisherman or 2 and gear. Doing any real mods at all to a small boat could easily push it over the weight limit especially if you weight more than 150 lbs, but on the other hand, if it doesn't go over capacity, a boat that sits deeper in the water is generally more stable, provided its not so low that it would take on water in any kind of small chop...
Just re-read your post, you have a lot of weight in 2X4's. I know that some people use them when building their framing, but most people get away with using 2X2's for it, that would cut down 1/2 the weight of just the framing. You may run into a problem down the road with using pressure treated wood, apparently some of the chemicals they use to treat it react with aluminum (your hull) and can cause corrosion, so keep an eye out for that. It will look like pitting. Going with aluminum for decking and bracing will definitely be lighter, but is more expensive. Probably the biggest advantage is you don't have to seal it at all and it will never rot. If you have any scrap metal yards in your area, you can usually buy scrap aluminum for about 1/2 price of buying new...
Just re-read your post, you have a lot of weight in 2X4's. I know that some people use them when building their framing, but most people get away with using 2X2's for it, that would cut down 1/2 the weight of just the framing. You may run into a problem down the road with using pressure treated wood, apparently some of the chemicals they use to treat it react with aluminum (your hull) and can cause corrosion, so keep an eye out for that. It will look like pitting. Going with aluminum for decking and bracing will definitely be lighter, but is more expensive. Probably the biggest advantage is you don't have to seal it at all and it will never rot. If you have any scrap metal yards in your area, you can usually buy scrap aluminum for about 1/2 price of buying new...
Sometimes this is how we learn, so dont feel to silly about it. I have done some pretty ignorant stuff, I have learned from those mistakes. LOL (This is no offense to you, trust me)
OK, pressure treated does weigh more, alot more. Your probably looking around 95 - 100 pounds a sheet. Sometimes when you buy pressure treated, it is still fairly wet. Did you by chance let it dry at all before doing your project?
No offense, I would redo the frame work with 2" x 2" and get regular 3/4" plywood. Dont fool yourself on this, if done right 2" x 2" can be just as strong as 2" x 4" and if done right in the layout you may not need that many. You can treat all the wood yourself.
Have you posted pics on here about your boat build? If you do, maybe some other members on here can help you figure out what to do to cut weight, different wood, placement of batteries, and such.
On another note, I know a guy that did this, almost same exact materials and he only had like 3" from top of boat before the water came in! SVOMike86 makes some very valid points as well.
OK, pressure treated does weigh more, alot more. Your probably looking around 95 - 100 pounds a sheet. Sometimes when you buy pressure treated, it is still fairly wet. Did you by chance let it dry at all before doing your project?
No offense, I would redo the frame work with 2" x 2" and get regular 3/4" plywood. Dont fool yourself on this, if done right 2" x 2" can be just as strong as 2" x 4" and if done right in the layout you may not need that many. You can treat all the wood yourself.
Have you posted pics on here about your boat build? If you do, maybe some other members on here can help you figure out what to do to cut weight, different wood, placement of batteries, and such.
On another note, I know a guy that did this, almost same exact materials and he only had like 3" from top of boat before the water came in! SVOMike86 makes some very valid points as well.
shawnfish said:
I use a lot of .090. When used correctly, and gaining rigidity by brake bends, as opposed to building a frame, it can be an excellent weight reduction method.
first, it is a 16ft loweline(now lowe owns them) and im 99% positive my uscg weight rating is 850 lbs occupancy and gear andim below that,the bow still sits about 2- 2 1/2 feet above the waterline with me on the deck(170lbs) and is more stable than before, im a boilermaker/welder and i can get all the scrap or new aluminum i want for free, just take a while for me to hoard the new stuff.SVOMike86 said:
linehand
Well-known member
Nice work by the way bassboy! I used .080 on my floor and deck backed the floor with dense foam level to the ribs and it works great. So I would say .080 + depending on the design. light and strong is always better than heavy and strong....don't forget the floor drain #-obassboy1 said:
