Marine Plywood.... How bad?

This weekend I purchased an 89 Bass Tracker Pro17. The previous owner recently replaced the decking and carpet. When he did, he used the marine grade plywood instead of using CDX. I am aware that aluminum ins a very reactive metal and will corrode at the drop of a hat.

Does anyone have any first hand experience to let me know the effects of using the marine plywood on the decking?

Additionally, does anyone have any pictures of the stern aluminum deck without carpet on it? The prior owner didn't remove the stern deck to replace the foam, although he replaced the foam in the main deck and under the bow casting deck. I would like to know if it is possible to pull up the stern deck by locating and drilling the rivets without removing the brand new, high quality carpet.

I'm a reasonably handy guy with two little kids and a limited amount of time available, so I want to get it right the first time with as little hassle as possible.

Thanks!

Marine plywood is great. I have used Ext AC, but marine is better. If you meant "treated" then that can be an issue with alum contact.

Is there a way to visually tell the difference between Marine grade and PT? Traditionally PT has a green cast to it, but I believe that some of the newer PT materials don't seem to be colored as much.

Are there any other ways?

Thanks!

What info is on the stamped MPA label?

Marine will have no voids.

I may be able to take a look under the bow for the label, but if I can't find it there, I'll be out of luck, as the rest of the plywood is covered with glued down carpet. I did find one small cutout piece from one of the casting seats, but I'll have to dig through the scrap bin for that.

Thanks for the info. I'll update with what I find.

Ok, so I was able to find the piece of plywood that the original owner cut out for the seat post. I've attached a couple of pictures here.

Based on my understanding, marine grade plywood only comes in A-A version, so the fact that the outside face of this piece has a knot in it means that it is likely that this is Pressure Treated instead of Marine grade. Can anyone confirm or deny that this is PT from these pictures??



So back to my original question: What can I expect for effects of the PT plywood to be on the AL and how quickly does this occur? I will have a very difficult time justifying the time and cost of a full floor replacement to the wife after I just bought the boat. If I put this off until next winter should I expect to see any severe damage?

Are there any quick fixes I can do to minimize the impact until then? If I pay particular attention to keeping it dry can I minimize the effects?

The carpeting on this thing is brand new this spring, and it has been on the water only three times since install and under a cover since. I am really not looking forward to tearing into it

That is not pressure treated wood.

Even if it was you would be fine to put it off as long as it hasn't been in for too long. I know plenty of people who have used it with aluminum and not had any issues a couple years later. The problem that happens I that copper is used in the treating of the wood, and that is what they call a dissimilar metal to aluminum...in other words they clash. The chemical reaction causes problems over time...

One way to prevent or delay this effect is to minimize contact between the pressure treated wood and the bare metal...painting the surfaces is one way to do that.

This kind of chemical reaction also takes place with galvanized fasteners coming in contact with aluminum. The original owner of my boat used a few bolts on my boat that we're galvanized. I know that these have been on the boat for many years, and the effect has been minimal to the boat...the nuts and bolts on the other hand were completely rusted out and hard to remove...some had to be drilled out.

Not pressure treated wood.
That is marine grade. Marine grade only means that there are not any voids in the wood. There can be knots in the wood. Marine grade is also known as cabinet grade. Much more expensive piece of wood.

Thanks for the information JDHolmes and Huntinfool. It certainly makes me feel better knowing that I don't have to pull up a brand new deck. I did check against some PT wood at Lowe's today and I noticed that typical PT has about half as many layers and they are not consistent in thickness.

So the only question remaining is to find out how difficult it is to get the stern aluminum deck off so I can replace the waterlogged foam underneath. Is it possible to locate the rivets under the carpet and only drill these to pull the deck off with the carpet attached?

I'll keep searching other peoples projects to see what I can find.

Thanks again for your help!

Post some pictures and it may get a little more helpful answers. Hard to say without being able to visualize it

Yea, that might be quite a trick to preserve the carpet. Spinning drill bits and carpet threads love to come together. I'd be interested in a technique that would leave the carpet presentable, as well.

PS: It didn't look like PT plywood to me, either.

kofkorn said:

Thanks for the information JDHolmes and Huntinfool. It certainly makes me feel better knowing that I don't have to pull up a brand new deck. I did check against some PT wood at Lowe's today and I noticed that typical PT has about half as many layers and they are not consistent in thickness.

So the only question remaining is to find out how difficult it is to get the stern aluminum deck off so I can replace the waterlogged foam underneath. Is it possible to locate the rivets under the carpet and only drill these to pull the deck off with the carpet attached?

I'll keep searching other peoples projects to see what I can find.

Thanks again for your help!

Click to expand...

I doubt seriously that you'll be able to find all the rivets through the carpet and drill them out and still be able to keep the carpet presentable. Some of the rivets will be dome head and you may be able to find them, but more than likely there will be some countersunk of large flange flat head rivets... and those will be pretty much impossible to find. They will all be blind (pop) rivets, and more than likely 3/16" diameter shank/hole.

Yeah, I've come to that conclusion as well. I've found some information that shows that the rear deck is not a simple covering anyway, and has to come out in a multitude of pieces. My best bet now is to try to gently peel off the carpeting, which should be possible, as it is nearly brand new.

I'll go through the whole process of drilling rivets and clear out the bad foam, put the deck back together and then re-lay the carpet back in the original location.

Putting the carpet back in the proper location is going to be a trick.

I've got about another week or two before I can get to it, I'll be sure to post progress as it happens.

Thanks!

You are correct, you will NOT be able to get the rear deck apart with the carpet on. Also if the PO used a quality glue you are probably going to have a tough time removing the carpet in a reusable piece. If recarpeting is not in the cards, the only thing I can suggest trying to remove as much as you can from inside the gas tank compartment. The rear most panel on each side should come out. It is not going to be fun and you will not be able to remove/replace much.
I see you are also in central Mass. Where are you? I am in Sterling.

Hi Derek,

I'm in Upton, near the intersection of Mass pike and 495.

Unfortunately, I don't think the panels on the Pro-17 are the same as the TX-17. I've done some looking, but it doesn't appear that I'll be able to remove any panels without removing the carpeting first.

I've started peeling a corner here and there, and it seems like I should be able to get it off. If not, I'm not adverse to replacing the carpeting on the rear deck, as long as I don't have to do the whole boat.

Thanks!

I see your other post now. They are different but I bet they go together similarly. One tip if you do replace the rear carpet. Butt to butt seams are more easily hidden on inside corners.