# advice needed: plywood captain's floor



## MT4Runner (Apr 6, 2012)

It's not an absolute "must" that you can't have a rigid floor, especially if you understand the pinch concern.
And the way your drop bars keep that ply floor off the raft floor by an inch or so also gives you more wiggle room.

Yeah, you'll like the stability of being able to stand on a floor solidly supported by the drop tubes.


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## climbdenali (Apr 2, 2006)

My floors all hang, but not because of the pinch-flat issue. I just don't have bars down there for them to attach directly to. The stability comes from strapping the boxes down tight to the floor from the frame. Hard for me to describe, but basically the boxes have to sit an inch or 3 higher than the frame so that there's space to create tension and downward force on the box, which in turn holds the floor down.

I know everybody loves running flat floors when it's low/shallow, but especially if you're running a rigid floor, I like running some decent air in the floors. The more pressure you have in the floors, the harder it is to punch holes. If you get stuck, you can always let out air then.

Some folks will run a layer of ethafoam in the bottom of bucket boats, in drop bags, under boxes, etc.

It looks to me like if you zip-tied your floor to those bars, that might give you a "breakaway" effect, but really if you hit something that hard underneath, you've probably got other problems than just some pinch-flats on the floor. I also don't think you need to cut it down much. I personally think that things (boxes, floors, etc) touching the inside of the boat isn't too big a deal as long as those edges aren't too sharp/rough.

As to the holes to tie down the boxes- as stated above, consider crossing straps- one running front to back across the top of the box, and the other running from the side frame bar, over the top of the box, to a loop of webbing/d-ring on the floor. Make sense? Should only need one or two holes per side for the box tie downs. If you try to tie your boxes down by the handles to the floor, you're always going to be cussing the box getting the straps fished through the floor standing on your head every morning.

You're going to love having the floor- I'll never go back.


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## timraphael (Mar 15, 2021)

climbdenali said:


> My floors all hang, but not because of the pinch-flat issue. I just don't have bars down there for them to attach directly to. The stability comes from strapping the boxes down tight to the floor from the frame. Hard for me to describe, but basically the boxes have to sit an inch or 3 higher than the frame so that there's space to create tension and downward force on the box, which in turn holds the floor down.
> 
> I know everybody loves running flat floors when it's low/shallow, but especially if you're running a rigid floor, I like running some decent air in the floors. The more pressure you have in the floors, the harder it is to punch holes. If you get stuck, you can always let out air then.
> 
> ...





climbdenali said:


> My floors all hang, but not because of the pinch-flat issue. I just don't have bars down there for them to attach directly to. The stability comes from strapping the boxes down tight to the floor from the frame. Hard for me to describe, but basically the boxes have to sit an inch or 3 higher than the frame so that there's space to create tension and downward force on the box, which in turn holds the floor down.
> 
> I know everybody loves running flat floors when it's low/shallow, but especially if you're running a rigid floor, I like running some decent air in the floors. The more pressure you have in the floors, the harder it is to punch holes. If you get stuck, you can always let out air then.
> 
> ...


Thanks, super helpful!


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## ElderStatesman (Jun 4, 2019)

climbdenali said:


> My floors all hang, but not because of the pinch-flat issue. I just don't have bars down there for them to attach directly to. The stability comes from strapping the boxes down tight to the floor from the frame. Hard for me to describe, but basically the boxes have to sit an inch or 3 higher than the frame so that there's space to create tension and downward force on the box, which in turn holds the floor down.
> 
> I know everybody loves running flat floors when it's low/shallow, but especially if you're running a rigid floor, I like running some decent air in the floors. The more pressure you have in the floors, the harder it is to punch holes. If you get stuck, you can always let out air then.
> 
> ...


Climbdenali's advice is solid. I've been running hanging floors in exactly the way he describes for decades on all kinds of rivers and conditions; high volume, low volume, big water, technical, super heavy loaded boats, lighter boats, you name it. The system works great. It was much less great in the days of bucket boats but we all moved on from that a long time ago, right?


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## climbdenali (Apr 2, 2006)

ElderStatesman said:


> It was much less great in the days of bucket boats but we all moved on from that a long time ago, right?


Bailing stinks, but they just track so damn well. . .

Not to hijack, because this is a whole other thread, but bucket boats do have some serious advantages in areas that most either discount or don't recognize:
-Amazing tracking
-Fast
-Keeps stuff dry if flatwater, and passengers don't get that damn ball-spray through the lacing with every little riffle.
-Light/Rolls tight
-Cheap cause none of y'all want them!


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## Bobthegreat (Mar 3, 2019)

Hey tim, are you able to weld some cross bars? If so you can then attach the floor to those and keep the floor off the sides.


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## timraphael (Mar 15, 2021)

Bobthegreat said:


> Hey tim, are you able to weld some cross bars? If so you can then attach the floor to those and keep the floor off the sides.


Unfortunately, not in my skill set. Good idea though...maybe I'll talk to my neighbor about doing that sometime.


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## Rightoarleft (Feb 5, 2021)

It looks like you are using cabinet grade plywood. While it looks pretty, the veneer doesn't get along with water. It ripples and delaminates. Exterior grade plywood used for siding is best but ordinary construction plywood works. 

I agree with having a rigid mounted hard deck. It does occasionally lead to floor damage but I hate standing on jello. Patch a hole in the floor every five years, so what. It's worth it.


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## timraphael (Mar 15, 2021)

Rightoarleft said:


> It looks like you are using cabinet grade plywood. While it looks pretty, the veneer doesn't get along with water. It ripples and delaminates. Exterior grade plywood used for siding is best but ordinary construction plywood works.
> 
> I agree with having a rigid mounted hard deck. It does occasionally lead to floor damage but I hate standing on jello. Patch a hole in the floor every five years, so what. It's worth it.


Thanks Rightoarleft, even if I varnish everything thoroughly??


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## Rightoarleft (Feb 5, 2021)

timraphael said:


> Thanks Rightoarleft, even if I varnish everything thoroughly??


Varnish just prolongs the inevitable, which for a boat floor, isn't very long. It's going to soak up water. I would use what you have until it falls apart, then use it as pattern to improve the next deck. 

With plywood, most of the water damage comes through the endgrain. I haven't found anything that seals engrain short of coating with urethane sealant, like what you would use to caulk around windows. It's messy but once its dry, it's pretty bomber. 

I did see a guy online seal endgrain with cyanoacrylate (super glue). This seems easy and smart. I'm going to give it a try on my side decks. Home improvement stores sell it in bigger bottles.


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## timraphael (Mar 15, 2021)

Rightoarleft said:


> Varnish just prolongs the inevitable, which for a boat floor, isn't very long. It's going to soak up water. I would use what you have until it falls apart, then use it as pattern to improve the next deck.
> 
> With plywood, most of the water damage comes through the endgrain. I haven't found anything that seals engrain short of coating with urethane sealant, like what you would use to caulk around windows. It's messy but once its dry, it's pretty bomber.
> 
> I did see a guy online seal endgrain with cyanoacrylate (super glue). This seems easy and smart. I'm going to give it a try on my side decks. Home improvement stores sell it in bigger bottles.


Very helpful. Really appreciate it!


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## wdeutsch (Apr 27, 2020)

Rightoarleft said:


> Varnish just prolongs the inevitable, which for a boat floor, isn't very long. It's going to soak up water. I would use what you have until it falls apart, then use it as pattern to improve the next deck.
> 
> With plywood, most of the water damage comes through the endgrain. I haven't found anything that seals engrain short of coating with urethane sealant, like what you would use to caulk around windows. It's messy but once its dry, it's pretty bomber.
> 
> I did see a guy online seal endgrain with cyanoacrylate (super glue). This seems easy and smart. I'm going to give it a try on my side decks. Home improvement stores sell it in bigger bottles.


I got my hands on a bunch of Penetrating Epoxy Sealer for a song. Normally it's not cheap -- but you don't need much. That stuff is amazing for wood preservation. Made a set of decks for my raft out Baltic birch and sealed 'em with EPS. They look like new after their first year - even with two dogs scratching all over 'em. I did some top rails for garden boxes in my back yard last fall. After a full winter of exposure, they have a few places that have surface issues, but no cracks and no apparent water penetration. I only did 2 coats on the garden box rails. The three on my boat decks seem to be the ticket. The key is that the first coat soaks into the wood and then cures. So, it's not a coating - it truly seals your wood. You can also paint or varnish over it if you don't like the look of clear coat. Amazing stuff.


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## climbdenali (Apr 2, 2006)

Rightoarleft gives good advise on the wood. CDX is what I use for most of my boating plywood, and for the price, it does a great job. I paint my ply with oil-based Kilz, and either touch up, or recoat every season or two. Even if you have to replace your floor every other year (which you won't), a sheet of CDX is so cheap that it's not a big deal.

I've had floors and decks built that way last 5 years before it was really time for new plywood on the framework.


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## B4otter (Apr 20, 2009)

MDO...


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## cupido76 (May 22, 2009)

Don't overthink it.

Maybe I'm in the minority but I change things up with my frames enough that if I only get a few years out of a floor I'm ok with that.

I've made a seat and side decks out of OSB covered in Deck Cote (sp?) And they're going strong after 3 years with no signs of failing.

Epoxy on the end grain is probably fine but most epoxy is not UV stable.... but if it fails, redo it with something else.

All that said, I'm trying MDO for the first time on a cat floor. It honestly doesn't look or feel any better or different than normal ply (maybe I have crap product near me?), but I'm not going to treat it.

I'll see how it goes and if I need to make a new one, so be it.


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## Rightoarleft (Feb 5, 2021)

climbdenali said:


> Rightoarleft gives good advise on the wood. CDX is what I use for most of my boating plywood, and for the price, it does a great job. I paint my ply with oil-based Kilz, and either touch up, or recoat every season or two. Even if you have to replace your floor every other year (which you won't), a sheet of CDX is so cheap that it's not a big deal.
> 
> I've had floors and decks built that way last 5 years before it was really time for new plywood on the framework.


CDX and T1-11 is all I've ever used. I've see guys get fancy with marine grade sheeting and I get a little jealous but with all the frames I've built, I've never had to purchase materials. There is always enough laying around the shop to get the job done. 

My friend was finishing some CDX frame decks and had several old cans of stain. Or at least he thought it was stain, some of the cans had lost labels so who knows but he mixed it all and added solvent for penetration. It got hot. I mean smoking hot. It was fuming out the bucket like a chimney. He decided to apply it anyway. I told him he was going to end up with a gooey mess that would ruin his decks. I was wrong. 

What he got was a midnight brown super-coating. It smelled funny but he never had to finish his decks again. This guy unlocked the secrets of the universe and I have no idea how he did it. Your results may vary.


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