We're ready to start the rebuild. Flooring question!

[Bhard]

We've been off line for a bit, getting ready for this project.  The motor is now off and stored  the console is ready to come off (I'm just trying to cut through the "glue" he put down without destroying the console itself; it's in good shape and I'd like to keep it) and the boat fits perfectly into the barn.  As soon as the console is off we're ready to start ripping the floor and transom off.

I'm writing to ask you opinions on materials to use for the flooring.  I believe everyone will say that marine grade is the best, but it also comes at a huge cost.  Any comment between using AC grade (I believe it averages 5-7 ply, it generally very dry and my wood guy recommends it) verses pressure treated (I believe it averages 4 ply and generally comes very moist..).

Thanks,  Betsy & Brien

[slippery73]

Depends on what you want your floor to look like. Are you getting ply from big box store or a lumber yard? You will find a lot of the ply from box stores isn't the highest quality stuff in the world, even the A-C ply tends to be import ply from china. They use very low quality adhesives, and even worse veneer layers, lots of gaps, fill etc. The A-C is good ply meaning you will have one good face A rated and one C rated face. You could get an A-A rated ply which would be the same quality as the marine ply but isn't laminated with the marine glues. That would save you some money as the marine glue doesn't help a whole lot unless you plan on your new deck to be wet under all that glass.

Whatever you get go to your supplier and make sure you get domestic ply, not imported. Pull a sheet off and make sure each veneer layer looks consistent and even throughout the sheet. Also stand the plywood on edge and make sure its straight, no waves, flops, curves, etc.

Now that I gave insight to that..... check out nidacore. Its lighter, never rots, easy to use etc. Thats a whole other can of worms though.

[Bhard]

Thanks for the input!  I'm getting my wood from a lumber store, not a box store..family owned business and well trusted.

[Mad Dog]

The biggest difference between marine grade and A-C is the glue used between the vaneers and the size and number of voids in the inner layers.  With marine grade you should have almost no voids, that leads to more structural strength and no chance of hitting an empty pocket with a fastener.

As for treated wood, forget it.  Yes they used exterior glue and wood resists rot but it is also quite wet.  As it dries it will warp.  Warped wood is very hard to lay flat as a sole.  And, it is unlikely you will get good adhesion between the wood and resin.  Here is a link with the pros & cons of marine ply.  

http://en.wikipedia.org/wiki/Marine_plywood

My humble opinion is, if I am going to put as much work into a rebuild as these boats require I do not want to scrimp on materials.  I want to give myself the best chance at the longest lasting result I can get.  If you have decided to use plywood for the rebuild then use marine grade.  For a sole replacement domestic marine grade is fine and not as expensive as the imported meranti or okoume.  It will last longer and be stronger than the alternative of A-C.  Treated wood sounds good but is not really a workable alternative.

Like I said before this is my opinion and the path I took.  Its your boat, you decide.

MD  

[MarshMarlowe196]

I would say a good quality wood to use that's not as expensive as marine grade plywood would be oak.  That's what I used to replace the floor in my old SeaCraft and I also used it rebuilding the transom on my 19-6 (Dad's advice).  It's pricey, but it's one thing you shouldn't skimp on, as MD mentioned earlier...

[aqua70]

Most will disagree. We used exterior plywood. NOT SHEATHING. Hot coated it twice. Each coat was applied before the first coat cured, totally sealing it.
If it is sealed properly it shoud last 25 years. This comes from a guy that has been restoring and fixing boats for 50 years here on the harbor.  Pressure treated ply will not work. Resin wil NOT adhere to it and it is unfinishable.
You can not go wrong with "Marine Grade" Plywood and have piece of mind as well. If my sole lasts 25 years I will be happy. The boat is already 39 years old. Another 25 will make it a Classic"classic". Pictures ae posted under Aqua 70 in the photo gallery.

[Ken G]

The wiki article is not completely accurate.  Marine plywood uses the same exterior grade glue as all other American made exterior plywood products.  The difference is mostly in the grade of veneer plys and the lack of voids.  I found this information at a website for the organization formally known as "The American Plywood Association" found at:  http://www.apawood.org/

When I did a search I found two interesting articles at:  http://www.apawood.org/perf_panels/inde ... %20plywood    and also:  http://www.apawood.org/level_b.cfm?cont ... %20plywood


The first article makes treated plywood worth looking at but most of what I've seen locally is soaking wet and warped badly.

The Oak plywood that I've seen looks great but I believe it is made with interior grade glues.  This may not be a terrible problem if the plywood is encapsulated well and remains completely sealed.

I also think along the same lines as aqua70 that since my '77  19-6 lasted thirty years before needing the transom replaced I'll be 78 years old in 2038 so the next rebuild will be someone else's problem.