FRP over foam floor

[JNG]

I've noticed a few posts concerning FRP for boat floors. I have experience with FRP here at work. This peaked my curiosity. On a lark the other day I took a scrap piece roughly 2'x4' .090" thick and layed it on a scrap sheet of 2" thick styrofoam. I don't know the density of this particular foam but if I had to guess it would be 25 psi. I stood on it ( 230#). I jumped on it. I had another guy (300#) jump on it with me. It was like standing on the concrete floor. No bending, no cracking, no nothing. Over 530# total JUMPING up and down on it! Somewhat surprised me. Guess what I'll be using in my new boat for a floor? It does have advantages over wood. Won't rot, no extra cost/time sealing it, can be cheaper, every homecenter sells it, very light. A 4x8 sheet weighs roughly 19-21#. Advantages over aluminum are much much cheaper, won't dent, and likely will be lighter. Overall disadvantages are, must be covered with something. It's not UV stabilized. While it is tough and won't dent, a heavy sharp object falling can crack it or punch a hole. It must be backed by something like foam. If a guy layed this over 25 or 60 psi extruded polystyrene like blue/pink board and riveted the whole mess down to the ribs, he would have a maintenance free and affordable floor for his jon boat. Cover it with carpet or hydroturf and be good to go. I don't think vinyl would be a good choice for frp but could be wrong.

 

[DaleH]

I don't think vinyl would be a good choice for frp but could be wrong.

I was thinking marine vinyl would be an excellent choice, glued down to the frp floor that is.

My new boat's floor, stringers and transom (less the inner core) layup are all composite, frp honeycomb material and divinycell, which is frp covered foam core. My 1st experience with it. Seems every bit as tough as the 3/4" plywood decked offshore boats I've owned, yet far lighter - and rot free.

I also believe it (well, the foam anyway) to absorb the vibrations and hull noise, as it is the smoothest and quietest hull I've ever run to boot, belying the deadrise.

 

[JNG]

It's my understanding that vinyl must secured at the edges or it will lift. How wood one go about doing so? FRP won't accept staples for example.

 

[DaleH]

You leave a few inches wider than floor and tuck down between hull and floor. On some hulls, you can remove the front superstructure screws a bit (like on a front bow deck) and tuck it under, then re-secure. Clearly depends on the layout of the hull.

Sorry , am admittedly showing my bias against carpet. That said, people here on this site do some amazing transformations using carpet - it just doesn't work for my tastes and boats. From boating in saltwater and heading down to the beaches (my favorite beach shown) ... sandy carpet is just HORRIBLE to clean up ...

 

[onthewater102]

I used FRP over foam in my boat and it's excellent - though I painted it with TuffCoat, so I can't speak to how you could cleanly apply vinyl over it.

Being so thin I don't think you'd be able to wrap the vinyl around the 1/8" thickness of the FRP. Perhaps you could attach the vinyl to the FRP first, then finish the edges with Trim-Lok Edge Trim or something similar? You would have to use construction adhesive to attach the FRP to your stringers/foam, but that shouldn't be an issue.

This is the stuff I'm talking about:

https://www.amazon.com/gp/product/B00NL3ZSE6/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

[wmk0002]

I'm not familiar with FRP. Can you tell me what exactly it is and where it is sold?

 

[onthewater102]

Fiber Reinforced Plastic

It's sold in 4x8 sheets at just about every big box home improvement store. Typically used in bathrooms/washrooms as a waterproof wall covering.

 

[jethro]

Yep, if you've ever used the restroom in a Wal-Mart you have seen it. The most common is the textured "white pebble".

 

[surfman]

I would just glue the vinyl down with contact cement.

I am not a fan of using foam under the floor, I use my boat in salt water and I would prefer it to be air space to vent out and dry completely, I worry about salt water under the foam and not being able to rinse it out thoroughly. What are thought on this?

 

[onthewater102]

You cannot use FRP without foam to support it.

You can line the areas you'll be pouring the foam with painters plastic so that you can still rinse out any salt water if that's an issue. See my '85 tracker III rebuild link in my signature for pics on what I'm talking about.

 

[JNG]

No, FRP cannot be used without something firm behind it. It does not need 100% contact with a foam, plywood, aluminum, etc backer but it does need at least 85-90% contact though.

 

[onthewater102]

If you don't have support behind it and point load the unsupported area it will likely crack. I stupidly kneeled down on the small area I had (<25 sq in) and it gave out. Fortunately it's easy to patch with fiberglass.

 

[Tinny Fleet]

If you don't have support behind it and point load the unsupported area it will likely crack. I stupidly kneeled down on the small area I had (<25 sq in) and it gave out. Fortunately it's easy to patch with fiberglass.

Hmmmm. The power of this board to generate ideas!!!! Not to hijack the thread or anything, but I wonder how FRP would do to cover a "soft" plywood floor so that a person could have a restored floor without having to do the complete gutting and replacement of the plywood.....

 

[JNG]

I really don't know. FRP is incredibly durable but does not like impacts from sharp objects and the sheets are very flexible. If your soft floor flexes, adding FRP will likely add NO stiffness.

 

[LDUBS]

My thinking is covering the problem isn't going to make it go away. YMMV. (Impressive net speak for your mileage my vary - haha)