Joined Plywood?

[linxlvr]

Hello all.
I have a Starcraft 16' Utility (essentially an overgrown rowboat) that I need to put a new floor in. After removing the main floor plywood, I have found it is a "sheet" of plywood that is wider than 48". What is typically done about this?

Thanks
--
dw

 

[robert graham]

Re: Joined Plywood?

Assuming a standard 4'X8' sheet of plywood, can you run the length(8') of plywood for the width(48"+) of the floor, or run 2 plywood sections joined on the centerline of the boat? There's an "H" section channel aluminum strip at Home Depot for butt-joining 2 pieces of plywood. Good Luck!

 

[duke33]

Re: Joined Plywood?

Assuming a standard 4'X8' sheet of plywood, can you run the length(8') of plywood for the width(48"+) of the floor, or run 2 plywood sections joined on the centerline of the boat? There's an "H" section channel aluminum strip at Home Depot for butt-joining 2 pieces of plywood. Good Luck!

I'm new to boats but am a carpenter. Makes sense to me.

 

[jigngrub]

Re: Joined Plywood?

Break your joints on a stringer or rib.

How much wider does your plywood need to be? What does the below deck framing look like (we need a pic)?

The main deck in my boat is like 49" wide, I cut two 1/2" rippings and attached one to each side with PL and 1 1/2" stainless steel screws. I predrilled the screw holes in the rippings and main deck so as not to split the ply.

 

[linxlvr]

Re: Joined Plywood?

OK, as for Pics.
First is the overall length, with the tape measure set for 8'
With the tape measure at the same location throughout, here is the bow view,,
the 48" mark if I was to put a seam there,
and the stern end
Here is a shot of the original ply floor, with a "seam" af the exterior sheet at 48" width. The plywood at the largest section is 54". I am considering adding a "crossbeam" at the 48" mark and creating a new seam there, but I had intended to keep it all original.
Any ideas appreciated. Thanks
--
dw

 

[Woodonglass]

Re: Joined Plywood?

I think all you need is to use 8" 3/8" plywwod cleats (4" on each side). Epoxied and leave a space for the center stringer and the sides.

 

[jigngrub]

Re: Joined Plywood?

I know that boat design, the decking was supported mainly by expanding urethane foam. It's a poor design because it traps water in the bilge and the foam becomes saturated over time because there isn't any drainage.

If it was my boat I'd install additional framing to support the deck instead of relying on the foam. I'd blind rivet 1 1/2" angle on each side of the center stringer continuous forward to aft and the install cross members of the same 1 1/2" angle on 16" centers... attaching the crossmembers to the center stringer angle and perimeter angle with blind rivets as well. After that, your plywood will break on a crossmember on 4' or 8' centers and be supported too.

If you try to deck your boat as is without the support of urethane foam or additional framing it will be springy/flimsy and you'll wish you'd done something else.

This is how another member solved a similar deck problem with my suggestion:
http://forums.iboats.com/showthread.php?t=535347

 

[linxlvr]

Re: Joined Plywood?

Thanks all for the ideas and suggestions. Still not sure what I am going to do, but I'll probably add a crossmember at the 48" mark, and use two sheets across.

Thanks again.
--
dw

 

[jigngrub]

Re: Joined Plywood?

If you go with crossmembers on 4' centers and run the grain of the ply from side to side and not front to back it might be ok if you use 3/4" decking.

Do you plan on installing any floatation foam?

 

[linxlvr]

Re: Joined Plywood?

If you go with crossmembers on 4' centers and run the grain of the ply from side to side and not front to back it might be ok if you use 3/4" decking.

Do you plan on installing any floatation foam?

The two "rowboat" type seats have the Starcraft factory Styrofoam in them.

The very small (24"?) in the tip of the bow that is made easily removable I had removed sometime ago for room had the Styrofoam in it also (At most 2 cu ft ). I thought of throwing a few pool noodles under the deck to make up for that. There wasn't pour in foam under the deck, but it certainly did become flimsy once there was edge rot in the Ply deck. I actually had straight ply screwed onto the deck just to get me through last fishing season. I was quite surprised how "minimalist" everything under the floor was.
--
dw

 

[jigngrub]

Re: Joined Plywood?

Ok, I didn't realize you had a bench boat. I see it now when I look at the pics.

There isn't any support at the plywood joints because the joints are covered by the benches.

I'd still frame it up if it was mine.

More floatation won't hurt a thing, pool noodles under the deck is a good idea. Foam floatation will float about 60 lbs. per cubic foot.

 

[linxlvr]

Re: Joined Plywood?

Ok, I didn't realize you had a bench boat. I see it now when I look at the pics.

There isn't any support at the plywood joints because the joints are covered by the benches.

I'd still frame it up if it was mine.

More floatation won't hurt a thing, pool noodles under the deck is a good idea. Foam floatation will float about 60 lbs. per cubic foot.

An oversight on my part in explaining the earlier photos.

The seams that are 96" apart are "under the benches". The center "48 in." mark is not, if I were to lay two sheets sideways. Although in the photo I realize now the dark area in the "48 in mark" area makes it look like another bench goes there, it doesn't. These get a small storage bin/stiffner/seat as seen here:
The old sheet is indeed 96" x 54" for this reason.

This is of course meant only as a point of information, leading us back to your recommendations.

Thank you for your time on this, and your many replies to others as well, which I am using to know what to do with the new plywood and covering.

--
dw

 

[fishrdan]

Re: Joined Plywood?

If you want the 96x54 one peice of plywood, I'd use a finger joint router bit to joint the plywood together, or use a biscuit router bit to route fingers into the edges of the sheets. The biscuit bit would take more setup, but the bit is cheaper. I picked up a biscuit router bit on sale a couple years ago for $5-10. Glue the sheets together with Gorilla glue; wet the joint, brush glue into the joints, clamp and the glue will expand and foam as it cures overnight.

 

[fngboater]

Re: Joined Plywood?

i work construction and noticed the cabinet guys had 5x8 sheets of particle board. i wouldnt use that but they might be able to get bigger sheets of ply from their supplier. Maybe try some cabinet or millwork companies...you never know

 

[linxlvr]

Re: Joined Plywood?

Thank you all of you for your various insights. I am going to go with the adding more support and putting a seam on one, as jigngrub suggested. The added benefit I see to that would be would be sturdier than OEM and if I need to replace rivets or get under main floor for some other reason, I will need to remove only the center "small storage bin/stiffner/seats" and leave the fore and aft "full benches" in place.

Thank you again, all of you. I must say this place is amazing to learn boating ideas at.

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dw