Plywood for flooring

Skunked again

Active member
Joined
Dec 8, 2011
Messages
44
Reaction score
6
Location
Highland, Illinois
For your knowledge, the vinyl I bought was from cabelas.
Exact color and texture, for a boat that was already some 6 years old.

I’m feeling you with the budget!!! I’m down to $135.24 for this build. Luckily I’m pretty much done. Even the three new 14’ crappie rods came out of the budget.

I wish you the best!!
 

richg99

Well-known member
Joined
Nov 27, 2010
Messages
5,105
Reaction score
25
Location
Houston, TX & Crossville, TN
Use what you have (exterior plywood) and don't worry about it. The cost of marine plywood vs exterior will be prohibitive, and to no special value on a deck/floor.

I've done carpet; I've done vinyl. I preferred the vinyl, but, primarily because hooks didn't get stuck in it. Land a fish; spend ten minutes getting your lure back from the carpet monster.

Heck, some guys just paint the exterior plywood and sprinkle sand on it to make it non-skid. Have fun.
Keep Momma happy and go fishing.
 

Vol423

Member
Joined
Jul 27, 2011
Messages
21
Reaction score
4
I have a 20' boat with marine plywood flooring with vinyl surface. At 10 years old the plywood started rotting in places. I replaced it with 1/8" checker plate aluminum, scuffed it with a big coarse rotary cup brush to remove the shine. Best floor ever. It washes down with my on-board wash down system. If I get a stain I hit it with the cup brush. Instant fix! Material cost $700.
 

FuzzyGrub

Well-known member
Joined
Jun 7, 2010
Messages
709
Reaction score
37
Location
Rural NY
I will probably rebuild the '67 Starcraft floor this year. It will be exterior plywood, but hope to be able to get a 5' X 9' piece Otherwise it takes three sheets of 4' X 8 '.

I can't say I've ever seen marine plywood at any lumber yard/store. It is probably a special order only, and these days that probably means a long wait. Curious, if anyone has current pricing on a 1/2" X 4' X 8' sheet.
 

SAABologist

Member
Joined
Mar 28, 2022
Messages
16
Reaction score
3
Location
College Station, Texas
I recently redid my 16' Mirrocraft deck with new plywood. I kept it the same as factory floor plan so I could use the old rotten plywood as templates. I used 1/2" B/C exterior, not treated. (Marine ply was $200/sheet last year.) I coated the new plywood, including the edges, with epoxy resin diluted with acetone, applying 3 coats. I used 3/4" B/C plywood where it had been used before. Then I covered everything in marine vinyl flooring.

What I would change is to NOT use the epoxy resin. Why? Because then you have to use the very expensive and difficult to apply contact cement glue for marine vinyl ($60-$100/gallon). If I had just treated the plywood with linseed oil, I could use the easier and less expensive glue for installing the marine vinyl on plywood (like a pontoon boat).

I also now realize that this new plywood is going to last for years and years and years. Even if not treated with epoxy. And I do use it in salt water. But I keep the boat covered, rinsed in freshwater, and dry.

I think it's easy to go overboard (haha) worrying about how long the B/C plywood will last. If you do a good install and treat the wood with the good linseed mix, I think it would be fine for years to come.

Good luck!
 

jdsgrog

Well-known member
Joined
Nov 8, 2010
Messages
55
Reaction score
2
I really think it depends on a number of factors and your budget. The more water and humidity it's exposed to and the more frequent you are out will make a difference. Also, how it's stored - whether outdoors or indoors. And not to mention goals of how long you want it to last. Obviously, you get what you pay for - the better the plywood, the longer it will last when exposed to water.

1/2" plywood should suffice. I believe epoxy is more a luxury than necessity since it's pretty expensive. If the floor is not structural to the boat, I would even consider buying BCX or even a lower grade exterior plywood. But I would build it to make it easier to pull the floor out more easily if needed knowing that you probably will need to do so in a few years (or more).

I live up north, store my boat indoors, and only go out occasionally. I did use marine grade once, but it was overkill - but good stuff. But I've had success with ACX and BCX without needing to replace the floor or plywood components lasting years. I also used cheap indoor/outdoor carpet with good results. Dries quickly and UV resistant - but thinner than most marine grade carpets.
 

LDUBS

Well-known member
Joined
Aug 14, 2016
Messages
4,309
Reaction score
138
Location
Clayton California
Another ply treatment discussed on this forum is "old timers mix". The formula is one part spar varnish (or spar urethane), one part boiled linseed oil, and two parts mineral spirits. Put it on heavy until it is no longer absorbed then wipe off the excess. I've not used it but others have reported good results. Doing a forum search for "old timers formula" will yield a lot of info.
 

-CN-

Well-known member
Joined
Jun 2, 2015
Messages
336
Reaction score
6
Location
Mauston, WI
I’m getting ready to put the new floor in the jon boat I’ve been working on.
Its been many years since I’ve purchased any plywood so I’m kind of lumber dumb.
I ask my wife to pick up a sheet and make sure it’s not treated. She came home with RTD sheathing. Is this ok for aluminum? I’m going to glass both sides and edges.
Also I measured it and it’s 3/4” (I ask for 1/2”). She said they all where weird sizes. Lol
Im like do the math bless her heart.
What do you tin boaters say is thick enough to run across the ribs of a 16 footer?
Thanks everyone. Every time I have a question I can come here and it’s been a while because I had to put off the boat and do other things. Y’all have helped me with the trailer. Then the corrosion i found in the bottom which took me several hours of sanding. Now I’m ready to put a floor in and I’m excited to go fishing.
After I use it for a while I’m going to pull the motor and flip it to remove the bottom coating that’s starting to peel off and seal all seams and rivets then apply new coating. I’ll be asking about products then. While the motor is off I’ll probably go ahead and redo the transom then I’ll have a new 1983 16/52 boat.
All the advice is greatly appreciated.
A before picture of t
Hear me out on this one. I tested the following method extensively with my previous build. I've documented it here somewhere a long time ago. Been awhile since I've posted.

It's been mentioned to use foam between the ribs. For sure do this - it should be 1-1/2" thick to build up the floor to make it even with the ribs. This will provide all of the support for weight of humans and gear that you will need. After this you don't have to worry about what weatherproofing method you are going to use on plywood or what type of plywood to buy. Instead of plywood, go out and buy yourself a sheet of 3/4" foam insulation - the same stuff you just used between the ribs except in 3/4". The weight of this stuff is practically zero. This is what you are going to lay down as your finished floor. Cut this to fit your floor side to side and front to back. To make it look and feel nice and to protect it you can now use either marine carpet or vinyl. Cover the surface by gluing the carpet or vinyl down with flooring adhesive and wrap it around the sides to the back where you will again glue it and then staple it. Yes the staples will want to pull out but they are not there to hold it down - they will hold it laterally until the glue dries and that will glue the staples in place as well.

What I have just described is to use foam insulation board wrapped in carpet for your floor. It has no structural properties so that's why you need to have a flat supporting surface underneath it by filling in the voids between the ribs with foam. "The foam is light and will blow out of the boat going down the highway!" you say. All it takes is a panhead screw - I used exterior grade cabinet screws, and you screw through the carpet and foam and into the floor ribs - make sure they're not too long to protrude all the way out the bottom of the boat. A regular screw will pierce the aluminum rib all by itself, no need to predrill. A couple screws in each rib will keep this floor in place.

This floor weighs nothing other than the weight of the carpet and it is completely weatherproof. It's a nice padded surface to stand on all day too. I did my whole boat - floor and decks in this fashion - I only substituted plywood of the same thickness anywhere that I knew I would need structure like for a trolling motor or a hatch lid. I even glued plywood and foam board together edge-to-edge and wrapped it in carpet all as one piece. The boat got used by me and a friend 2-3 times a week for 3 summers like this and the foam board has held up better than the plywood areas. No, it does not "crush" or flatten under weight. No, the screw heads do not pop through - the carpet prevents this. You simply have a small dimple where the screw is. That's it.

You want a light weight and maintenance free deck or floor - use foam board.
 

Stand Up

Well-known member
Joined
Jul 23, 2022
Messages
209
Reaction score
209
Location
Spruce Grove Alberta
Hear me out on this one. I tested the following method extensively with my previous build. I've documented it here somewhere a long time ago. Been awhile since I've posted.

It's been mentioned to use foam between the ribs. For sure do this - it should be 1-1/2" thick to build up the floor to make it even with the ribs. This will provide all of the support for weight of humans and gear that you will need. After this you don't have to worry about what weatherproofing method you are going to use on plywood or what type of plywood to buy. Instead of plywood, go out and buy yourself a sheet of 3/4" foam insulation - the same stuff you just used between the ribs except in 3/4". The weight of this stuff is practically zero. This is what you are going to lay down as your finished floor. Cut this to fit your floor side to side and front to back. To make it look and feel nice and to protect it you can now use either marine carpet or vinyl. Cover the surface by gluing the carpet or vinyl down with flooring adhesive and wrap it around the sides to the back where you will again glue it and then staple it. Yes the staples will want to pull out but they are not there to hold it down - they will hold it laterally until the glue dries and that will glue the staples in place as well.

What I have just described is to use foam insulation board wrapped in carpet for your floor. It has no structural properties so that's why you need to have a flat supporting surface underneath it by filling in the voids between the ribs with foam. "The foam is light and will blow out of the boat going down the highway!" you say. All it takes is a panhead screw - I used exterior grade cabinet screws, and you screw through the carpet and foam and into the floor ribs - make sure they're not too long to protrude all the way out the bottom of the boat. A regular screw will pierce the aluminum rib all by itself, no need to predrill. A couple screws in each rib will keep this floor in place.

This floor weighs nothing other than the weight of the carpet and it is completely weatherproof. It's a nice padded surface to stand on all day too. I did my whole boat - floor and decks in this fashion - I only substituted plywood of the same thickness anywhere that I knew I would need structure like for a trolling motor or a hatch lid. I even glued plywood and foam board together edge-to-edge and wrapped it in carpet all as one piece. The boat got used by me and a friend 2-3 times a week for 3 summers like this and the foam board has held up better than the plywood areas. No, it does not "crush" or flatten under weight. No, the screw heads do not pop through - the carpet prevents this. You simply have a small dimple where the screw is. That's it.

You want a light weight and maintenance free deck or floor - use foam board.
Thanks for the advice in your post. What a great solution.
 

Douglasdzaster

Well-known member
Joined
Sep 19, 2020
Messages
180
Reaction score
27
Location
Smithville,Texas
Hear me out on this one. I tested the following method extensively with my previous build. I've documented it here somewhere a long time ago. Been awhile since I've posted.

It's been mentioned to use foam between the ribs. For sure do this - it should be 1-1/2" thick to build up the floor to make it even with the ribs. This will provide all of the support for weight of humans and gear that you will need. After this you don't have to worry about what weatherproofing method you are going to use on plywood or what type of plywood to buy. Instead of plywood, go out and buy yourself a sheet of 3/4" foam insulation - the same stuff you just used between the ribs except in 3/4". The weight of this stuff is practically zero. This is what you are going to lay down as your finished floor. Cut this to fit your floor side to side and front to back. To make it look and feel nice and to protect it you can now use either marine carpet or vinyl. Cover the surface by gluing the carpet or vinyl down with flooring adhesive and wrap it around the sides to the back where you will again glue it and then staple it. Yes the staples will want to pull out but they are not there to hold it down - they will hold it laterally until the glue dries and that will glue the staples in place as well.

What I have just described is to use foam insulation board wrapped in carpet for your floor. It has no structural properties so that's why you need to have a flat supporting surface underneath it by filling in the voids between the ribs with foam. "The foam is light and will blow out of the boat going down the highway!" you say. All it takes is a panhead screw - I used exterior grade cabinet screws, and you screw through the carpet and foam and into the floor ribs - make sure they're not too long to protrude all the way out the bottom of the boat. A regular screw will pierce the aluminum rib all by itself, no need to predrill. A couple screws in each rib will keep this floor in place.

This floor weighs nothing other than the weight of the carpet and it is completely weatherproof. It's a nice padded surface to stand on all day too. I did my whole boat - floor and decks in this fashion - I only substituted plywood of the same thickness anywhere that I knew I would need structure like for a trolling motor or a hatch lid. I even glued plywood and foam board together edge-to-edge and wrapped it in carpet all as one piece. The boat got used by me and a friend 2-3 times a week for 3 summers like this and the foam board has held up better than the plywood areas. No, it does not "crush" or flatten under weight. No, the screw heads do not pop through - the carpet prevents this. You simply have a small dimple where the screw is. That's it.

You want a light weight and maintenance free deck or floor - use foam board.
Thanks for the post. Awesome set up. My boat is a 16/52 and I believe I measured the ribs at 2”. I need to double check that. I have 12 grandkids and I tame them fishing when one or two come to visit. Last time my 7 year old grandson and I where on the crappie. He fought a nice one and while I was unhooking it with my back turned he stood up on the rear bench and jumped on to the floor. Made a loud boom when he hit the plywood and startled the you know what out of me. Needless to say that was it for the crappie. Would the foam hold up to my grandkids? I know it will be quieter.
Id love to build mine like yours. The less wait the better that 40 hp is going to push. I priced the 2” sheet of foam board and it’s almost twice as much as a 1/2” sheet of plywood. I’m on a tight budget with the admiral once she saw I was actually spending money on the build. Lol So I’m going to have to run the numbers. Let me know if you think it would hold up because I’ll bet it’s going to happen again.
 

Douglasdzaster

Well-known member
Joined
Sep 19, 2020
Messages
180
Reaction score
27
Location
Smithville,Texas
Does anyone know about rivnuts? I want to attach 1/2” plywood to the ribs in my boat and be able to remove it easily. I don’t know how thick the aluminum is that the ribs are made of and im not sure how to measure it.
If I used a caliper wher it curves out at the top of the rib would that be correct?
 

Douglasdzaster

Well-known member
Joined
Sep 19, 2020
Messages
180
Reaction score
27
Location
Smithville,Texas

Try above link. Look on YouTube also.
I put some in my boat, first time using them. Look up diy Rivnut tool. You do not need to buy a dedicated tool for this, especially if you’ll only be doing a few of them.
Metal shouldn’t be any thicker than .090.
Thank you for the help, Youre right I’m only going to put a few in the boat and that’s it.
 

-CN-

Well-known member
Joined
Jun 2, 2015
Messages
336
Reaction score
6
Location
Mauston, WI
Thanks for the post. Awesome set up. My boat is a 16/52 and I believe I measured the ribs at 2”. I need to double check that. I have 12 grandkids and I tame them fishing when one or two come to visit. Last time my 7 year old grandson and I where on the crappie. He fought a nice one and while I was unhooking it with my back turned he stood up on the rear bench and jumped on to the floor. Made a loud boom when he hit the plywood and startled the you know what out of me. Needless to say that was it for the crappie. Would the foam hold up to my grandkids? I know it will be quieter.
Id love to build mine like yours. The less wait the better that 40 hp is going to push. I priced the 2” sheet of foam board and it’s almost twice as much as a 1/2” sheet of plywood. I’m on a tight budget with the admiral once she saw I was actually spending money on the build. Lol So I’m going to have to run the numbers. Let me know if you think it would hold up because I’ll bet it’s going to happen again.
The 2" foam you are inquiring about should go between the ribs and the finished floor over the top. The noise the plywood made in your boat is because you didn't have foam underneath it. You'll want that foam there regardless of what your finished surface is. At my lumber yard, 3/4" foam board is $18 while 1/2" CDX plywood is $38.
 

airshot

Well-known member
Joined
Feb 18, 2009
Messages
237
Reaction score
67
Have used rivnuts many times with great sucess...you might have some issues with the radius on top of the rib when drawing the rivnuts down tight but I think they will work fine. If you can find fine threaded rivnuts go that route..under vibration fine threads are much less prone to vibrating loose. As mentioned make your own tool for setting the rivnuts, far cheaper!! When drilling the hole for the rivnut, be sure to make it as snug as possible, sloppy fit in the hole lessens the grip of the rivnuts!! Good luck...we need some pics when your done...
 

Douglasdzaster

Well-known member
Joined
Sep 19, 2020
Messages
180
Reaction score
27
Location
Smithville,Texas
The 2" foam you are inquiring about should go between the ribs and the finished floor over the top. The noise the plywood made in your boat is because you didn't have foam underneath it. You'll want that foam there regardless of what your finished surface is. At my lumber yard, 3/4" foam board is $18 while 1/2" CDX plywood is $38.
I’m getting 1/2” plywood for $26 and 2” foam is $40 hear. I was just committed on prices of things lately. Especially when on a budget.
I’m sticking with plywood. The middle seat is removed creating a 26 3/4” gap between those ribs. The boat is a 1983 and a plywood floor will help brace things. I’ve looked for aluminum hat channel I could notch over the ribs but the biggest I can find is 1 3/4”.
 

Douglasdzaster

Well-known member
Joined
Sep 19, 2020
Messages
180
Reaction score
27
Location
Smithville,Texas
Have used rivnuts many times with great sucess...you might have some issues with the radius on top of the rib when drawing the rivnuts down tight but I think they will work fine. If you can find fine threaded rivnuts go that route..under vibration fine threads are much less prone to vibrating loose. As mentioned make your own tool for setting the rivnuts, far cheaper!! When drilling the hole for the rivnut, be sure to make it as snug as possible, sloppy fit in the hole lessens the grip of the rivnuts!! Good luck...we need some pics when your done...
Thanks for the information I appreciate it. I’m going to have 3 seams in the floor. It’s 52” wide so have to cat the plywood differently only laying 48” at the time. I’ll definitely post picture. I have my material list except I was thinking about tying the seems together with something. That ides may go out the window since I’ll have riv nuts in place.
 

thill

Well-known member
Joined
Feb 25, 2011
Messages
331
Reaction score
36
Location
Virginia, USA
For what it's worth, I have had extremely good success with cutting my plywood, and they spraying it with Thompson's Wood Preserver. It has lasted for years and years for me, so far.

I am about to add a floor to a 1648 Tracker I just picked up. I find that cut pile marine carpet doesn't grab hooks like the closed-loop stuff. Just a suggestion. I like it more than the vinyl flooring because it is quieter in the back coves, and more comfortable underfoot, especially if you like to go barefoot in the summer.
 

Douglasdzaster

Well-known member
Joined
Sep 19, 2020
Messages
180
Reaction score
27
Location
Smithville,Texas
Has anyone ever used Total Boat penetrating epoxy? I have ordered a half gallon. I’m doing new Plywood flooring 52” wide 10’ long. The product can be diluted for better penetration.
Do I have enough? I’d like to have some left to do the front deck which is about 3’.
EDIT: Please excuse the post. I couldn’t find coverage information anywhere until I made this post. Then I tried a different search and found a chart. Looks like I should be good and hopefully have enough left for doing the front deck which is next. After some fishing though. Lol
 
Last edited:
Top