Seam on Centerline?

[jayhunt3]

Replacing floor in 16 ft. Starcraft. Will use 5/8 ply. with glass on top. It will be much easier to install the floor if I run the seam down the centerline stringer. Any problem? Thanks

 

[JasonJ]

Re: Seam on Centerline?

I think you probably could do it if the center stringer is wide enough to get a good bite with screws along each piece. Most people and boat builders (and myself) ran the seams crossways, cutting 4x8 sheets of ply to length (to the width of the boat) and laying them across the stringers. I would think if you lay the sheets in the way you propose that there could be a possibility that when weight is placed in the floor between the center stringer and the next stringer over that it could cause the edge to come up a bit. I personally recommend laying the sections crossways. I think it would also give you a more tortionally strong structure as well. Either way, good luck....

 

[jayhunt3]

Re: Seam on Centerline?

JasonJ - Thanks for the response. The center stringer is an encapsulated 2 by 6. My problem is that the way my hull is constructed it will be very difficult to lay in plywood that is the required width. If it is critical I can probably remove the side bolsters and shelf and get it to fit in. I am looking for suggestions. Thanks

 

[CCrew]

Re: Seam on Centerline?

Personally, I wouldn't do it. It puts a plywood seam with all the torsional stress on what is not a very "meaty" attachment point. Basically you're asking that one 2x6 stringer to take all the longitudinal and torsional stress. Even if you do get the attachment to hold, if load twists the hull you drive the stringer sideways. I can't imagine that that was the original design..<br /><br />I've looked at a lot of construction in starting mine, and haven't see the ply run longitudinally,<br /><br />-Roger

 

[hollowoods]

Re: Seam on Centerline?

I agree that the tortional stability of the hull is a very important factor and that the most stability will be gained by running the sheets across longitudinal stringers. The other important consideration is that the floor will be spongy feeling between the stringers if not run crosswise. Plywood is more rigid in one direction than the other. Almost always made with an odd # of plies. I would assume that the 5/8” you are dealing with is 7 ply. The Facing veneers run longwise on the sheet. Grain direction alternates with each ply. If 7 ply is used, 4 plies run longwise and only 3 crosswise. Even if you couldn’t remove one of the side bolsters, I think you would be better off with 4, 2’x4’ pieces than one 4’x 8’ piece. Remove the bolster. One thing I can tell you from long ago personal experience with this same project: Be VERY aware of where the hull is relative to the floor when cutting the old floor out. If you are working on a 1958 Dorsett Eldorado, the floor practically touches the outer hull at the sides. Set the saw blade only deep enough to cut through the floor and don’t cut all the way down both sides, before checking to see that you are not too deep.

 

[Hooty]

Re: Seam on Centerline?

Hollowoods,<br />That "check to see that you are not to deep" sounds like you had a bad experience. <br /><br />c/6<br />Hooty

 

[hollowoods]

Re: Seam on Centerline?

Hooty, oh yeah. My first boat, 15 years ago. Cut right through the hull on BOTH sides for 18-20 inches. Not a good day.

 

[jayhunt3]

Re: Seam on Centerline?

Hollowoods - Thanks for the advice. In certain areas my floor does rest directly on the hull and any slip on the cutting will go right through. Any advice on how to cut out the thick fiberglass around the edges of the floor? I am using an angle grinder with a masonry cutting wheel but it creates a ton of nasty dust. Based on the feedback I will not run the seam down the centerline. Thanks Duxman

 

[Knightgang]

Re: Seam on Centerline?

Got the right tool. Just remember, SHOP VAC, SHOP VAC, SHOP VAC. And keep that dust out of your grinder as best you can so that it does not burn up.

 

[hollowoods]

Re: Seam on Centerline?

Duxman, do you have access to an air chisel? 30-50 bucks @ Lowes or equal. Takes a good bit of CFM to run but that would be what I’d use for the bulk of the job. A flat blade on a pneumatic chisel can do a bunch with no dust. Again remember that the hull is there. Trying to take too much at once could result in the scrap material not flexing (peeling away) enough, whereby causing the chisel to dive. That could ruin a good day.