What is the best way to join two pieces of plywood before screwing down the floor?

[bigesox11]

Just wondering what to use to join my two pieces of plywood that will be screwed down on the main/lower floor of my aluminum boat. Thanks

 

[jigngrub]

How big are the pieces and do they run fore to aft or port to starboard?

 

[phillyg]

I'm assuming you are asking about edge to edge joints. The proper way is to scarf the plywood at a 7 to 1 ratio or thereabouts and use waterproof glue and screws.

 

[sheboyganjohn]

You can also butt joint it with a full length butt block that is 15x or so in width the thickness of the plywood both glued and screwed. So for 1/2" plywood it would be another piece of plywood 1/2" or more that is at least 7 1/2" wide. That is how I did all the hull joints but one on the dory.

 

[lckstckn2smknbrls]

I did mine with biscuits with tite bond III glue and 1/8" thick 2" wide aluminum backer.

 

[lckstckn2smknbrls]

I used biscuits with tite bond III glue and 1/8"x2" aluminum backer.

 

[jbcurt00]

Wait, WHY would you want to make 1 LARGE 'sheet' of plywood BEFORE you put it in the boat? Esp on an aluminum boat??

If you are asking about fully supporting the butt joints between 2 sheets that are seperate, but adjoining, then a plywood or aluminum backer strip below the joint between the 2 sheets is sufficient.

Jig will be back to show a great system (similar but better then the factory original) of epoxy coating the individual deck panels, wrapping them w/ vinyl BEFORE putting them in the boat, then riveting the panels down THRU the vinyl. His butt joints/plywood seams are all well supported, and w/ the epoxy & vinyl wrapped decking, he's unlikely to have any problems for decades to come. If/when it becomes necessary to remove the deck, he can remove any 1 panel he needs to and reinstall it when any necessary work is completed.

 

[bigesox11]

Wait, WHY would you want to make 1 LARGE 'sheet' of plywood BEFORE you put it in the boat? Esp on an aluminum boat??

Because I need one piece of solid plywood flooring to adhere carpet and screw into place.

 

[bigesox11]

How big are the pieces and do they run fore to aft or port to starboard?

They run fore to aft. There was a flimsy aluminum strip with a thousand staples holding it together when I took it apart. I am asking if there is maybe a better way to join the plywood to ensure a smooth butt/seamless connection, especially since there will be carpeting on top.

 

[jigngrub]

Are you talking about the 2 large pieces on the front deck?



That was the only place I had a butt joint on my 17' Tracker, and the way my deep V was designed you couldn't get one large piece in place because of the gunwales and the side storage compartments.

Pics of your boat would help us help you better.

 

[bigesox11]

No. The bottom of boat where you would sit while driving, not the platforms. Wider than plywood comes so two pieces. I guess I'll use aluminum backer again. I added an additional cross member so that each piece will sit on its own. The plywood just needs to be one piece before being screwed down so the carpeting can be put on first.

 

[jigngrub]

Ok, mine was like that too. 49 5/8" wide I think.

The 1 5/8" rip was screwed through the edge of the plywood to the large sheet with 3" long screws.

This isn't a very good pic, but you can see some of the rip and the arrow points to the butt joint of the 2 pieces: