plywood floor

From reading through some different threads on flooring, it seems that some have gone with a plywood floor instead of glass on foam. For those that went this route, what did you do to secure the floor?

Thanks,
Ryan

Ryan,
Ideally you should be able to get by without any fasteners. The ply should be set into a thickened epoxy on top of your stringers. Weights can be used to hold it in place while the epoxy sets up. The bond will far exceed anything you would get from screws. If you do want to screw it down, I even recommend using the screws temporarilly and then removing them after the epoxy sets. Then filling the holes.

If you want to leave the screws in place, here's some recommendations. Stainless if it does get wet and stays wet will rust!!! Brass isn't the best choice ether because although short term it will work, brass long term "zincifies" - the zinc in the copper leaches out and all the strengh is lost. Boat builders have learned from many years of experience that silicon bronze screws
are the best to use. If you do go with these screws, be carefull - the "frearson" head is NOT a "phillips" head. You need to use a frearson driver bit.

Use regular exterior ply with the CPES and epoxy. Do not use treated ply as any coating and the chemicals in the treated don't mix well! Many will contest to problems - With our members, I know Eric had some disasters!!!

If you have any gaps that need to be filled, stick with filled epoxy. We know it will stick whereas silicon caulking won't! If you do caulk, use 3M 5200.

Do not use silicon.
I believe I am quoting Pete here:

"Silicon won't even stick to itself"

ryanowen wrote: Hopefully this isn't too stupid of a question... but why not make a floor that's completely removable? Wouldn't that give things a chance to dry out each season?

Ryan,
If you follow the CPES, epoxy and care when you glass up the wood, water moisture won't get into the wood. Keeping it out is the key. Once it gets in, it doesn't like to dry out even after extended storage. The wood is like a sponge wrapped up in a plastic bag.

Edit: Any holes (like engine lags) drilled into the wood post stringer job need to be CPES'd and I recommend 5200'd when you run the fastener in.

Mike,
I'd say that those screws you removed in your 68 were silicon bronze and not brass! Aged it turns a slightly darker or browner color than brass. I'd also say they were Frearson heads. If you tried a phillips, I'll bet it didn't fit very well.

Here's an observation that got me thinking. Although I haven't pulled the floor up yet, I think it's safe to say the wood glassed beneath the drivers seat base is rotten. The 20 year old (untreated?) removable piece of plywood behind the motor is in remarkably good shape though. One of the back corners was starting to go, but I think that could have been prevented if the seat base had been removed every once in a while.

SNobsessed wrote: I am not a design engineer, but I have stayed at Holiday Inn Express lately. I would think you will lose some rigidity if you just screwed the ply floor down. Plus the screw holes in the stringers would be a water intrusion point. How do you attach it to the hull sides? Would you glass wood strips to screw into?

Me neither. I was wondering about rigidity too. I don't know what part the floor plays with the overall structure of the boat. The screw holes are definitely a consideration. I'm not sure if cpes in them would be sufficient or not. As far as atttaching the sides? Not sure. Again, just thinking out loud. Maybe glass pieces of wood or a long strip. Kind of like the way the swim platform backings are.

Pete, Funny you say that about the screws. Some came out with the phillips and some I ended up just drilling out after the head failed. I am guessing you are right about the material as the coloring you described is exactly right. I will look to see if there is an errant one left under the workbench of something. I would like to know.

Here is what I use when I re-floor inboards,
http://www.coosacomposites.com/
Check out the web site see for your self.
This stuff is a little more expensive than good marine ply.
I have had really great results with this material, Current Correct Crafts have this as floor boards behind the motor box.
Word of warning though Coosa does not hold screws well, needs to be thru bolted when ever fastening is required.

Jody

you forgot the good ole hammer and nail Pete

do you know who Hank Hill is?

8122pbrainard wrote: Using a Phillips driver on chromed Frearson deck hardware fasteners is quite damaging! Every once in awhile, I'll see the "newbee" mistake at shows on wood and some early glass.

And here I am just worried about my boat being able to float when I'm done with it!

Fl Inboards wrote: Here is what I use when I re-floor inboards, http://www.coosacomposites.com/ Check out the web site see for your self. This stuff is a little more expensive than good marine ply.

Jody,
Thanks for the link. Very cool material. Is it any harder to work with aside from having to through-bolt? I'll have to see if it's available here. I'm curious about the price.
Ryan

Pete, I am certain you are right about what screws were in the Mustang. Wish I could find one to be 100%, but just by looking I think they were Frearsons. Weird. Never heard of them.


Ryan, I looked at all my project pics and cannot find any of the little support blocks. They are just 3" x 3" or so pieces of 1x left over from my secondaries. Nothing special at all. Just fit them tight under the longitudinals or floorboard, or better yet, both.

Really, after you are done, you will look back and think it was a really cool undertaking, and will be surprised with how good it turned out. I was scared shi!tless beforehand. Afterwards, I was happy I did it, and can hardly wait to do another next winter.

But the grinding does suck. Bad.

Mike

JDiggs wrote: What did you guys do to seal the seams in the plywood or what should I do? Glue them together w/ epoxy sounds like the best option

JD, If you really want to get fancy, you could scarf them!

Don't forget the CPES

8122pbrainard wrote: JD, If you really want to get fancy, you could scarf them!

Geeze Pete?!!?   LOL

Mix some microballons in some epoxy and fill away.