Good alternative to plywood?

PunkR0ckz · Nov 18, 2024

Hey everyone, I am still on the market for a good material to use for my floors.

At first, I thought I wanted sealed plywood + fiberglass, but then I found aluminum composite panels, but they are priced pretty high.

Today, I found someone selling some styrofoam-like material that is covered on both sides with aluminum sheets (similar to aluminum composite panels, but instead of a composite, its foam).

The seller says its good for walls & ceilings, it is 48" x 64" x 11/16" in thickness. I would double them up to make a 1 3/8" thick floor and thus doubling the floatability.

Would it be a good alternative, or should I resist the "want" ? I would like to have something durable, that wouldn't need to be replaced over the years and that would add floatability in case of "emergency" to prevent it from sinking.

Obviously, I would seal the edges somehow (I will most likely glue/epoxy some aluminum from the 18' aluminum pool I was given to cover up the seams, and all of the exposed edges)

Note; Weight isn't an issue, my boat can hold 1900 lbs of weight; I would be alone in it 99% of the time, with a 70hp 4stroke Evinrude and a gas tank, that's pretty much it; so less than half of that weight capacity.

Stand Up · Nov 19, 2024

I believe this material will dent easily when you walk on it or set something down on it with a bit of force. They look like left over cut out material from manufacturing.
The foam used in them is not meant to be exposed. My thought is that the foam will deteriorate over time.
Keep looking for an alternative. I'll keep my eyes open for ideas as well.

flatheadsteve · Nov 19, 2024

Open cell foam on a boat is a bad idea. Even sealing the ends that foam will absorb moisture over the years. I have some very similar panels on our farm we used to insulate cat houses and calf hutches and a very old case 580d with a busted heater. They don't hold up very well and like stated above dent very easily.

thill · Nov 20, 2024

That doesn't look like a good idea. Any fasteners going through it would ream out the holes in the material and pull through over time, besides what's mentioned above.

Bantou · Nov 20, 2024

I would not recommend using those panels as a boat deck. They look like insulation or decorative panels. The aluminum is paper thin and will provide little to no structural support. It will dent at the drop of a hat and puncture nearly as easily. They will also be slick as ice the moment they even consider being wet unless you cover them with something textured.

One of my crews works with ACM on a daily basis. I wouldn't trust it for a boat deck either. They would be a little more resistant to denting (I've seen them take 1/2" hail strikes without a dent) and penetration, but they are not intended to be load bearing in any capacity. Even doubled up, they are likely to sag significantly unless heavily braced underneath.

If you are wanting an alternative to wood, you might consider something like 1/2" HDPE panels. They are going to be significantly more expensive than plywood, but should last a long time if properly protected from the sun.

thill · Nov 21, 2024

There are fiberglass panels that are supposed to work well. I remember someone doubled up 1/4" FG panels with construction adhesive between the layers, and they said they were nice and rigid once set. It was either here or on another forum, but if I recall, they got them free from their job, and it worked out really well for them, and the weight was similar to plywood.

airshot · Nov 22, 2024

Why the worry about plywood ? My boat is a 1992 and floor still very solid all out of plywood. After 32 years, you probably won't even own this boat any longer. If your boat is properly stored, a plywood floor will outlast you !!

Buster · Nov 23, 2024

airshot said:
Why the worry about plywood ? My boat is a 1992 and floor still very solid all out of plywood. After 32 years, you probably won't even own this boat any longer. If your boat is properly stored, a plywood floor will outlast you !!

That proper storage is a biggie. A day or two fishing in the rain isn't going to harm marine or exterior ply or saturate floatation foam or any of the things we worry about. But sitting uncovered along the tree line through rain and especially snow with freeze thaw cycles and not enough sun and airflow to dry it out and bow down so it doesn't drain is killer.
My old girl spent its idle time upside down on the beach for 50 Minnesota summers and winters and the ply was fine until it spent two summers uncovered on a lift, after which the seats became splinter generating menaces.
On the other hand, I think that plywood was saturated with chemicals that are probably now banned and considered weapons of mass destruction so wouldn't be shocked if the new stuff struggles more.

thill · Nov 23, 2024

airshot said:
Why the worry about plywood ? My boat is a 1992 and floor still very solid all out of plywood. After 32 years, you probably won't even own this boat any longer. If your boat is properly stored, a plywood floor will outlast you !!

There are alternatives, but for MY boats, I always go with plywood. Light, strong, economical, durable, stiff, comfortable, not hot, not loud, not reflective, easy to work with, cut and form, etc, etc, etc. All I do with mine is spray every piece in Thompson's Wood Preserver/Waterproofer until it won't absorb any more, especially edges and cutouts for excellent, long-lasting results.

I did my Princecraft probably 10 years ago, and I used good plywood and good carpet, and the guy who bought it thought it had been a recent rebuild.

As far as storage, all I did was keep it covered with a silver tarp. It doesn't have to be a special garage or carport. I like silver tarps better than most boat covers because they are cheap from Harbor Freight, are truly waterproof, and keep everything out. I used an 11x19 tarp, and it fit my 16 footer perfectly, including motor.

You will need to figure out a system to shed water. I put a big cooler on the front deck and ran a 16 foot 2x4 from the cooler to the top of my outboard, threw the tarp over, then tied it down tight. It was the best boat cover I've ever had. I have the same system on my Spectrum, and it's the same. Perfect coverage, regardless of the weather.

No matter what the cover, wet snow is your enemy, so go knock the snow off before it stacks up too high.

Anyway,

airshot · Nov 23, 2024

My boat sits in a barn when not in use, so that helps the plywood to last longer, much longer !! Another thing to do is when I get home with wet carpet/ floors and decks is to put a fan on the boat to quickly dry everything. A fellow that works for a restoration company told me that the plywood looses its quality when it sits in moisture for a long period of time, if dried quickly, it won't be damaged.. All I can say is after 32 years and being taken care of it is still like new except for some thread bare carpet from use...

fltbtm · Nov 23, 2024

walls and ceiling is correct. they look like cooler and freezer panels they put in stores.

Buster · Nov 24, 2024

The cover/tarp thing also huge. Bad covers or tarps do a better job keeping moisture in than they do keeping it out. A couple quarts of water under a cover in the sun make a 100% humidity environment that saturates wood and carpet and helps all sorts of nasties grow.
if I didn't have a spare garage stall I think I'd make a PVC shelter frame and lace one of those silver tarps to it. Keep the rain out and allow for lots of good airflow.

FuzzyGrub · Nov 24, 2024

During winter, tarps are closed. On the G3, during the summer, back is open along with the bow for ventilation.

Buster · Nov 25, 2024

FuzzyGrub said:
During winter, tarps are closed. On the G3, during the summer, back is open along with the bow for ventilation.

That's the stuff.

thill · Dec 6, 2024

AlanT · Dec 7, 2024

Buster said:
The cover/tarp thing also huge. Bad covers or tarps do a better job keeping moisture in than they do keeping it out. A couple quarts of water under a cover in the sun make a 100% humidity environment that saturates wood and carpet and helps all sorts of nasties grow.
if I didn't have a spare garage stall I think I'd make a PVC shelter frame and lace one of those silver tarps to it. Keep the rain out and allow for lots of good airflow.

I agree. It really depends on the environment. I live in the deep south and have seen boats covered in mildew from a waterproof tarp. I used a "waterproof" canvas tarp to cover my boat that allowed airflow. It was not perfectly waterproof, but allowed some airflow. Thankfully my boat is now stored in a garage. I would think a waterproof tarp would work well in northern less humid climates.

908Boater · Dec 7, 2024

thill said:
View attachment 123683

Hi - I just acquired my first boat, a StarCraft 14, with the purchase of a trailer. Not knowing anything about boats I'm curios about the three holes shown on the bottom of the transom. I have the same arrangement and no idea what two of them are for. I know one is a drain as I have the plug. TIA

boaterB12 · Dec 7, 2024

airshot said:
Why the worry about plywood ? My boat is a 1992 and floor still very solid all out of plywood. After 32 years, you probably won't even own this boat any longer. If your boat is properly stored, a plywood floor will outlast you !!

I know right. If “Weight isn't an issue.” -And just like anything else, take good care if it. I still have mine on my 1992 aluminum.

Now if money is no object and you want to throw other criterias/considerations, I recommend those coosa boards. They are strong, lightweight, etc.. A buddy of mine rebuilt his entire transom. I used it as a platform between a set of outriggers I purchased for my canoe. I was tired of sitting, wanted to stand and stretch. (see images)

Some helpful links below. Good luck!

Replacing Deck by Nick:
https://www.boatoutfitters.com/replacing-a-rotten-wood-core-deck-with-coosa-learn-content

Comparisons:
https://coosacomposites.com/the-coosa-board-advantage/

Technical Data & Specs:
https://coosacomposites.com/technical-data/

Coosa FAQs:

https://coosacomposites.com/coosa-composites-faq-what-were-asked-most-about-our-panels/

https://coosacomposites.com/wp-content/uploads/2023/07/Frequently-Asked-Questions-6.30.21.pdf

Other:
https://www.cruisersforum.com/forums/f55/tips-for-working-with-coosa-board-264163.html

PunkR0ckz · Dec 7, 2024

Sorry about the huge delay guys.
I had quite a big plate on the table that needed addressing.
I live in Canada, where it rains, snows, hails, and is humid.
The boat would be either sitting outside (90% of the time) or in a garage during winter.
I do have access to some used shrink wrap that fits my boat.
I will, no matter what the material ends up being for my floor, put EVA foam on top of it. I already have the roll for it (had purchased for a boat I sold).
If I end up using plywood, what would be the best way to seal it ?
My uncle swears with used car oils with his lumber, but I highly doubt that would soak up well in plywood.

Ray Clark · Sunday at 7:53 AM

PunkR0ckz said:
Sorry about the huge delay guys.
I had quite a big plate on the table that needed addressing.
I live in Canada, where it rains, snows, hails, and is humid.
The boat would be either sitting outside (90% of the time) or in a garage during winter.
I do have access to some used shrink wrap that fits my boat.
I will, no matter what the material ends up being for my floor, put EVA foam on top of it. I already have the roll for it (had purchased for a boat I sold).
If I end up using plywood, what would be the best way to seal it ?
My uncle swears with used car oils with his lumber, but I highly doubt that would soak up well in plywood.

Some people do put used motor oil on lumber that will sit out in the rain, for example, something like a wood deck on a utility trailer. It's not something I would do on a boat. While I think it would soak up well on plywood, I think the oil will negatively affect the performance of whatever adhesive you use for the covering foam.

Edit to add: Old motor oil will never cure hard and will not adequately stop water penetration into the plywood.

I have a fair amount of plywood in use on my boat. All of it is sealed with fiberglass resin that was mixed and then painted on and allowed to cure before installation. I paid particular attention to coating the edges of the plywood very well. Once cured, the resin will accept adhesives on the surface. Scuffing of that surface is recommended.

Good alternative to plywood?

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