Anybody ever see this?

[man5]

Cut the floor out of my Grady White and found this plywood. Have around 15 years in construction trades and never seen anything like it. I pried between the laminate and layed the floor up against the inside wall of the boat. Dont know boat construction terms that well looked for web sites on them can't find any.

[basstardo]

Wow. That's some weird looking material for a core.

Maybe it's a plywood quilt...HA!

[man5]

Okay now for some more odd stuff. Has anyone ever seen single 3/4" plywood stringers? I thought gradys were built alot better than that, or is it that there hulls could be tough enough to not need alot of support??? Any info is appreciated.

[SamSam]

Originally Posted by man5

Cut the floor out of my Grady White and found this plywood. Have around 15 years in construction trades and never seen anything like it. I pried between the laminate and layed the floor up against the inside wall of the boat. Dont know boat construction terms that well looked for web sites on them can't find any.

I worked at a place that did a lot of that in decks. 6" plywood squares. It was a pretty cheap way to core them, all the separate pieces allowed better contact between them and the laminate in the mold , with fewer voids. It also conformed somewhat when there was a slight crown in the deck. Sam

[basstardo]

Am I wrong by thinking that would cause more problems than a solid piece of plywood for a core? I would imagine the seams where the plywood meets would just be potential spot for the glass to crack and warp? I would think that you would have many seams there and once the glass got a little age and/or softened up by cracking a little bit, the core wouldn't be able to support the structure as well as a solid piece of wood?

[man5]

There is a slight crown in the deck (took lots of measurements). Hope the 1/2" replacement will bend to the contour. better get that bend in before I glass the bottom of the new deck. (didn't even think of that) . I will say that even though the wood was wet (years worth), not really rotten, the deck was soft but still felt strong. thanks.

[SamSam]

Originally Posted by basstardo

Am I wrong by thinking that would cause more problems than a solid piece of plywood for a core? I would imagine the seams where the plywood meets would just be potential spot for the glass to crack and warp? I would think that you would have many seams there and once the glass got a little age and/or softened up by cracking a little bit, the core wouldn't be able to support the structure as well as a solid piece of wood?

I really don't know. The problem with bigger pieces of ply is they are hardly ever flat and have to be weighted down plenty (we had a vast herd of crapped out car batteries with the built in carry straps for weights) whereas the small squares could just be mashed in by hand to a wet layer of mat and then the inner skin put on later or carefully put on immediatly. A big piece can warp whereas a bunch of little ones can't.I'm thinking that a cored laminate doesn't neccessarily get it's strength from the core itself (foam and balsa are fairly flimsy by themselves) but from the amount of separation between the inner and outer laminates and the layup of the two laminates themselves. The farther apart they are, the "stronger" it is. The cores job is mainly to tie the two laminates together, the more tenaciously it does that, the better. With the small squares they were able to get more tenaciously attached to the laminate in the mold and then there was also a resin tie between the two laminates in the spaces around the ply squares. It doesn't seem too much different than using a core of foam or balsa that has been cut into small squares and attached to a scrim, just larger squares. As I said before, it also was able to conform to a slight crown which in itself added strength. It sure wasn't pretty but it worked. Sam

[basstardo]

That makes more sense actually. Thanks.

[eyes]

Hi, I'm a new member here.
I was just reading about boat repair tips and stepped into your post.
The pics of the wood seems that its made from small ply squares.
I own a furniture manufacturing company here in the Dominican Republic, Caribbean, and i know that you can make this panels, and some do, and then cover them with vineer and nobody will know whats inside. The downpart of it, is that it doesnt have the strenght of a full layer of ply. The only reason of it is cost reduction, specially because it is made with left over.
I hope that wasn't a piece of your floor.

[buckknekkid]

Some Cubans do it for concave and convex curves, simple reason is that the bonding is easier without creating a jig to compress it. In the old? days the mixed they sawdust with the resin to create the fillers and then bonded the thing , held down with concrete blocks or whatever. It could be known as the Opa Locka core for all I know. I'll dig up some old pics sooner or later

[Russ]

Good answer SamSam, I was about to say about the same thing. Years ago I machined a 8 inch long roller with machined blades to penetrate foam core nearly thru. That could then be easily rolled over the core to relieve the concave mold condition. The core then lay tightly against the wet under layer. Today more boats are made under vacuum so voids are normally not a problem.
Incidently Buckknekkid, Squeezing the components together in your project would have been easy if you could have sealed the area off enough to use vacuum.
I just love you guys, Pretty damn smart!!!!!

[buckknekkid]

Bacuum, we dont need no steenking bacuum. Chit man it was invented back then

[Russ]

MAN5,,,,,
Yes I have seen 3/4 plywood in many smaller boats. It is easy to laminate in to make sort of box sections to support the floor. Mostly there will be heavier wood at the keel but not always.
The worst I have seen was a 65' commercial fishing boat. It came into the yard for rudder repairs and a new Cutlas Bearing. We lifted it and blocked all 60 tons of her. The keel showed water leaking out and when investigated I found the keel was a 3/4 inch box 6" x 6" filled with foam. Obviously it took a bit of repair to correct the leaks. Now THAT was a poorly built boat. I was told it was a cheap comercial boat that was expected to last only 10 to 15 years. God help them!!!!!!

[eyes]

Yes Russ you can machine a ply, core or any other material nearly thru and it will bend easily. actually some furniture is made that way.
No adays besides vacuum, we have many materials that will bend almost to any form and can be used as a template (in fiberglas construction).
you can see some at
http://www.marineply.com/stagflex.htm
http://vandykes.com/product/02013187/

[Russ]

I went to the sites you mentioned and was impressed. Looks like some really cool stuff. For use in boats I think I would have concerns about the possibility of rot and termites, similar to wood. Is it treated to prevent that?