What to use for floor?

[msta999]

Hi all, I have a Hewes River Runner, 1994 18 ft and need recommendations on what to use to replace the plywood flooring? I replaced it once with treated plywood a couple years ago and read you shouldn’t use treated lumber on aluminum, so I need to replace it again!

[Daveinthebush]

Here is a post on the topic from a while ago.
composite decking - Alaska Outdoors Forums (outdoorsdirectory.com)

[JEH97LX]

The link has lots of ideas, but getting your hands on the exotic products seems challenging, but if you find a local source be sure to mention it. The simplest two options readily available are marine plywood and aluminum plate. I found marine plywood at SBS in Anchorage a few years ago. It's spendy and requires several coats of varnish for protection. I used marine plywood on my engine cover hatch with several coats of marine spar varnish and a traction product (essentially sand or nut shells sprinkled into the last coat). It looks great, but was a ton of work compared to aluminum.

I replaced my old plywood floor with 3/16" aluminum diamond plate 5086 alloy. I'd suggest marine-grade 5052 or 5086 aluminum diamond plate if you get into salt and you can source it (Greer Tank had it). 5086 is stiffer and stronger, but costs more and can be hard to get. The other common alloys are 3003 or 6061. 6061 is very strong, much more so than 3003, so if you are freshwater 6061 may do alright. I'd avoid 3003 for the floor as it has almost half the shear strength as 6061 and will probably bend or flex too much without going thicker. If it's a relatively light boat, the spans aren't too far apart, or you don't mind a bit of flex, 1/8" plate in 5086 or 6061 would probably work and cheaper. It may be worth handling a small sacrificial piece if you aren't sure (2' foot square plate and stand on it to see deflection).

It's easy to cut aluminum, similar to wood, I prefer carbide circular blades with a lot of teeth (40-60T) or a non-ferrous blade. I attached the plate using low-profile, pan head, stainless screws from an Anchorage fastener shop with a little TefGel to prevent thread corrosion. I also sealed the edges and seams using a product comparable to 3M's 5200 adhesive to protect closed-cell foam below the floor, but that's another project. Anyways, it's TMI, but some of the info may help figuring things out.

[mark knapp]

Hi all, I have a Hewes River Runner, 1994 18 ft and need recommendations on what to use to replace the plywood flooring? I replaced it once with treated plywood a couple years ago and read you shouldn’t use treated lumber on aluminum, so I need to replace it again!

I replaced the plyber-flywood floor in my Almar with 1/8" aluminum diamond deck. It's great.

[4merguide]

I replaced the plyber-flywood floor in my Almar with 1/8" aluminum diamond deck. It's great.

I did the same....lovin' it!

[mark knapp]

I did the same....lovin' it!

Yep, I also took out the 400 pounds (really) of waterlogged foam that was under the floor. Put in white dock foam. With the new engine, jet pump, helm and dash I now have more in my boat than I do in our two pick-up trucks. Sheesh. I hope to spend more time in the boat than I do in the trucks.

[msta999]

Did you put anything under the aluminum plate, also what did you secure it with? I was thinking about using nut inserts so I could remove it in the future if need be.

[mark knapp]

Did you put anything under the aluminum plate, also what did you secure it with? I was thinking about using nut inserts so I could remove it in the future if need be.

I put that two sided sticky stuff like weather stripping under the plate (on the ribs) so it would be quiet and I secured them with stainless, pan-head screws, No.10 I think. Works good. I can remove plates when I need to.

[spoiled one]

I put that two sided sticky stuff like weather stripping under the plate (on the ribs) so it would be quiet and I secured them with stainless, pan-head screws, No.10 I think. Works good. I can remove plates when I need to.

If you use stainless hardware, make sure you coat the SS screws with a product like Tefgel. This will prevent corrosion due to dissimilar metals.

[4merguide]

Did you put anything under the aluminum plate, also what did you secure it with? I was thinking about using nut inserts so I could remove it in the future if need be.

I put 1/4" neoprene between the plate and ribs, and used those hd large head 3/16" aluminum rivets installed via pneumatic rivet gun.

[mark knapp]

If you use stainless hardware, make sure you coat the SS screws with a product like Tefgel. This will prevent corrosion due to dissimilar metals.

I haven't had any trouble with corrosion. I think the salt water keeps it washed away

[spoiled one]

I haven't had any trouble with corrosion. I think the salt water keeps it washed away

It will happen. Keep on waiting or perhaps all the fish slime has created a protective barrier.

[mark knapp]

It will happen. Keep on waiting or perhaps all the fish slime has created a protective barrier.

I do keep the zincs in good condition.

[akgriz]

Marine plywood, glue-down vinyl marine flooring, stainless screws (use bees wax or grease on the screws!). JMHO.