Stringers.....Plywood or 1X6?

[waterwezl]

Going to get lumber tomorrow for stringers and bulkheads. The original stringers were made from 3/4 plywood cut about 6" high at it's tallest. Wouldn't 1X6 treated lumber be less prone to rot? I thought the ply was a little silly because when you put down the decking you'll be screwing into the edge of the ply and that doesn't seem real secure to me. I can't imagine the 1X6's being that much heavier than the ply.

 

[jcsercsa]

Re: Stringers.....Plywood or 1X6?

Going to get lumber tomorrow for stringers and bulkheads. The original stringers were made from 3/4 plywood cut about 6" high at it's tallest. Wouldn't 1X6 treated lumber be less prone to rot? I thought the ply was a little silly because when you put down the decking you'll be screwing into the edge of the ply and that doesn't seem real secure to me. I can't imagine the 1X6's being that much heavier than the ply.

Hi waterwezl

Well what i have learned , should i say read is the ply wood ext grade is better if your going to seal it !!! the plywood gas greater strenght and better flex to it !! the pressure treated has to be dried before use, and you have to use stainless screws in it !! or glue it !!!!

Now I went a different , on my two side stringer are like 5 inchs I went with the pvc decking, it says it wont rot and has about the same strength, my center stringer is 11 inchs i went with a 1x12 well it was a 2x12 planed it down to a 1x12 and am sealing it with poly. but frist died it out !!!

So that probley didnt help any , but i guess thats my .02 worth !! Ohh the pvc stuff was just a little more the the 1x6 !!! good luck , what ever you use will work perrty much !! keep us posted !! John

 

[tonyg11780]

Re: Stringers.....Plywood or 1X6?

John, how long does it take to dry treated lumber? Ive heard that it causes problems if you glass over treated...

Tony

 

[oops!]

Re: Stringers.....Plywood or 1X6?

dont know about lumber.... but my pt ply was over a month with a fan on it and a good wood stove at full throttle.....

as far as screwing into the edge of ply....the norm is to run struts across the top of the ply.......uasually 6 ins wide at four foot intervals... this will give the screws somthing to attatach to...add trememdous stregnth to the stringer.....and give more support to the hull.

you must incace the wood with resin for water intrusion prevention. py or not

 

[lundnisswa]

Re: Stringers.....Plywood or 1X6?

I normally would not offer advice since so new to boat building, but since I just did this I do have an opinion.

I convinced myself to use dimensional lumber, 2x's, since my stringers are 12' and 14', I thought it was a silly idea to use two pieces of ply joined together, I thought how could that be better/stronger than a 2x6?????/
So,
I used 2x10 // 2x6 high grade dimensional lumber, "no knots", planed to 13/16 thick, let dry for a month, the problem with dimensional lumber-espectially PT-is that it warps/cups/twists badly and is prone to grain length-wise cracking.
I was able to use mine but they indeed did warp, alot, I stop drilled the cracks and filled with epoxy filler-injected.

I would use Plywood next time, with the lap joint method, (Oops thread has a great picture of this) plywood is much-much stronger than any dimensional lumber could ever be.

And I also agree with you on the point of do not be drilling into it, use the cross supports as Ooops has said.

I encased my entire stringer with 8oz cloth first, then glassed it in the boat with thicker 1708, I will not drill any holes in it when installing floors/sole/deck, will use cross supports to screw into and PL the strings down.

Hope that opinion helps.
Dimensional lumber is pretty though-LOL.
Good luck
Lund

 

[tashasdaddy]

Re: Stringers.....Plywood or 1X6?

plywood is stronger than conventional lumber.

 

[jcsercsa]

Re: Stringers.....Plywood or 1X6?

Yep it takes a good while for it to dry ,I have a 500 watt lamp on mine and a fan going !! for the last week and a half and going to let it go for another week at least !! there right on the cross menbers thats what you drill into !! didnt dawn on me when I read it !! tired !! lol !! John

ps yes it does cause big problems if its not dry, it will rot from the inside out !!!

 

[Coors]

Re: Stringers.....Plywood or 1X6?

Use whatever is easier to use as a form. If you en-capsulate any wood or whatever with cloth/roven, etc and and seal any screws from the deck(over-drill, poly, and screw into that) the form can't get wet.

 

[Coors]

Re: Stringers.....Plywood or 1X6?

Add -on; cloth etc, and poly/epoxy, will build up the strength- 3/8" is a killer.
Almost like waterproof steel.

 

[waterwezl]

Re: Stringers.....Plywood or 1X6?

I stand corrected! Thanks fellas. If I get a quality plywood; does it need to be dried? If so; for how long and before or after it's cut to fit?

Since I'm NOT interested in doing this again any time soon, I want it right the first time. Although the building/restoration IS theraputic, I'm sure being on the lake would be more so.

 

[Robj]

Re: Stringers.....Plywood or 1X6?

If you get pressure treated plywood it will take about a month to dry. If you just use exterior grade ply that has already been kiln dried, then it is ready to go, but it does not have the rott protection of pressure treated. Douglas sfir is the best species of ply to use.

Have a great day,

Rob.