floor supported by insulation foam in a v hull?

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answer3

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I am working on a Lowe 1467 v hull boat and planning to add a floor with carpet to improve comfort in the boat. I saw many guys here adding aluminum structures to support the floor, but I am wondering what happens if you put the floor on some insulation foam (like the pink or green sheets from home depot / lowes)? is it strong enough to support the weight of 1 or 2 people on the floor? did anyone of you guys do it in your boat?
 
Are talking about filling the entire space under the floor with foam or building stringers and ribs out of the foam?
 
if every surface of your flooring will be in contact with the foam (totally flat floor, no bowing in the middle) then you can even use FRP sheeting instead of wood and apply it directly to the foam because yes - with a tough skin layer on top the foam will support the weight.

Make sure you use extruded foam not expanded foam - they look similar but only extruded is closed cell so it shouldn't take on water over time. Do not spill gas in the boat or it will eat the foam right quick.
 
onthewater102 said:
if every surface of your flooring will be in contact with the foam (totally flat floor, no bowing in the middle) then you can even use FRP sheeting instead of wood and apply it directly to the foam because yes - with a tough skin layer on top the foam will support the weight.

Make sure you use extruded foam not expanded foam - they look similar but only extruded is closed cell so it shouldn't take on water over time. Do not spill gas in the boat or it will eat the foam right quick.

what is frp sheeting?
 
Fiber reinforced panel(plastic). Probably about 1/8" thick and can be had at Home Depot. I don't know if I would recommend this though. Seems like it would be slick. To each their own though.
 
I think it would be too slick too, but a piece of Nautolex marine vinyl over it (from Defender Marine) would solve that easily enough without adding any appreciable weight.
 
The floor is not flat as this is a v hull, but not too deep either. Maybe 3" in the middle compared to the levels on the sides. So if I add foam it will not be uniformly flat this is why I was thinking of adding plywood on top of it because it is strong and I will have a flat surface. So if the plywood floor does not touch the foam on all it's surface do you think it is fine or do I have to add some structure underneath using aluminum tubes/angles?
 
You can have an idea of the floor shape on this picture. I filled the boat with water and you see the depth in the center compare to the sides more easily.
 

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how much do you really want to get into? if you don't support the plywood with anything but foam down the middle eventually it will sag on the edges if they see enough traffic over time - then again, if you're using plywood you're not looking for a permanent setup anyway, and by the time the floor would be sagging it would be time to replace the plywood anyway.
 
I want to make something solid and clean but don't want to spend the whole spring working on the boat instead of fishing :)
You are saying that the plywood is not a permanent solution, is this also true even if I figerglass it or seal it with epoxy?
 
It looks more like a semi-V boat. 1/2" or 5/8" plywood might be all you need with a little foam.
 
not as permanent as a .100" sheet of aluminum...it all depends on how much of an unsupported span you have and how much load is applied to it.

3" in the center sounds a bit much - even still you can have a pile of foam in the middle at that rate with a pair of thinner strips flanking it down the sides which will just about support your plywood everywhere. The foam will not crush under the plywood with you standing on it, that's for sure. If you're using 1/2" plywood with unsupported spans (areas where there is no foam behind the plywood) kept under 10" you should be fine.

Someone mentioned a 4'x8'x2" foam board floating 362lbs...their math is a bit off, water weighs 62.5lbs per cu. ft. not 67.88...but you do not add flotation capacity to your boat by adding foam. The weight of your plywood pound for pound reduces the capacity listed on the USCG sticker in the boat. Foam only comes into play if you've swamped your boat, and at that it has to be secured to the boat in order to matter. Foam beneath a removable deck is irrelevant - swamp the boat and it will float the deck to the surface and leave the boat behind...so you want to make sure to secure the plywood to your boats ribs if you care about the extra emergency flotation it offers.
 
I mentioned the 362 pound figure. I wasn't saying the foam would increase the weight carrying capacity of the boat.
 
I installed a .062" aluminum floor in my jet boat, using 1 1/2" foam board panels between all ribs. It's very sturdy and has been holding up through 10 years of use with no signs of sagging or warping.
 
How much would it cost to make a floor of 0.100 or 0.62" aluminum? When I see the price of just regular angle aluminum or tubes I am worries it will be very costly...
Did you cover the aluminum floor with carpet?
 
answer3 said:
How much would it cost to make a floor of 0.100 or 0.62" aluminum? When I see the price of just regular angle aluminum or tubes I am worries it will be very costly...
Did you cover the aluminum floor with carpet?

you might try scrap yards. you should be able to find tubbing and maybe even some diamond plate for scrap prices.
 
answer3 said:
How much would it cost to make a floor of 0.100 or 0.62" aluminum? When I see the price of just regular angle aluminum or tubes I am worries it will be very costly...
Did you cover the aluminum floor with carpet?
Discount Steel is about the cheapest place I could find online.

https://www.discountsteel.com/items/5052_Aluminum_Sheet.cfm?item_id=126&size_no=0&pieceLength=cut&wid_ft=0&wid_in=0&wid_fraction=0&len_ft=0&len_in=0&len_fraction=0&itemComments=&qty=1
 

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