Stringer Wood

[vandy21]

Sorry guys, I know this is a popular post, and a little research will turn up a lot of results, but I am wondering exactly what type of wood is best for stringer wood. I know people say things like "Douglas fir" and "cedar" or whatever, but exactly what kind of wood? If I were to walk into Lowes or Home Depot or something and pick up some wood, what would it be? I know some people say Plywood works fine since the wood is not what provides the strength, it is the fiberglass around it. Is dry pressure treated the best, or non PT or what? Also, The stringers are approx. 12'x3/4"x7" is it better to use a single board? I think it would be nice to be able to use a 12' board so I wouldn't have to attach two pieces of wood together, but a finding a piece of wood that long is hard. If I did use two pieces of wood, I would probably attach them in the way I showed in the diagram below. Is that a good idea or not? Thanks guys

 

[tashasdaddy]

Re: Stringer Wood

that splice has no strength. but the ends together the apply atleast a 4 ft piece to each side, called sistering. glue and screw them together. i realize it makes a wide joint. don't know who told you the wood does not have strength in a boat. but that is false.

 

[vandy21]

Re: Stringer Wood

thanks, that will be much easier anyway. So do you agree plywood is the route to go then? (as for the wood not providing the support, thats just what I read when searching through other threads).

 

[iwombat]

Re: Stringer Wood

Actually if laminated properly that joint has more strength than a solid piece of wood. Joining two different grains of wood together is much stronger than a single piece. The problem is, not many people laminate it properly and it can crack just behind the lap. The key to a joint like that is to laminate the ends of lap joint so that the vertical surfaces are part of the joint - not just the horizontal ones. I use biz-kits and whatever glue/epoxy/whatever you're using elsewhere on the ends on a joint like that. In this case, I'd recommend marine epoxy. Better yet, if you can manage a finger joint, or even a back-diagonal cut to maximize the surface area on the end it'd be better.

EDIT: ^^^ is true for solid pieces of wood. I don't think it's necessarily true for ply since your essentially compromising the laminate with the cut. However, the common mode of failure - cracks behind the joint - isn't so much of a concern either. Hrm . . .

All that being said, the sister method is still stronger.

 

[oops!]

Re: Stringer Wood

pt ply is great ...IF you have time to dry it....(a month or two)....(beware of the chemical reaction with screws and metal...read up)

if not....ac grade plywood is fine.......as td says....once it is encapsulated with glass.....what does it matter.......

done propperly.....its 20 plus years from both kinds

cheers
oops

 

[vandy21]

Re: Stringer Wood

yeah, I guess if water gets into my stringers I'm SOL anyway so the type of plywood really shouldn't matter. Esp. since I do not want to wait a month or two for the would to dry, I'd like to be back in the water by that point haha. Thanks all, and again, sorry for asking such a newbie question, but I guess there are no dumb questions. esp. when it comes to not having to ever replace the floor in this boat again.

 

[vintageglastron]

Re: Stringer Wood

Hey,
I'm going with composite to replace the stringers. I can buy them in 16 foot lengths and cut them down . On my V156 Glastron, once I grind out the old glass covering the old stringers the will fit perfectly into the slot. I plan to glue them down with resin. Glassing them to the transom and housing them in glass should make things as good as new.

Just an idea

 

[vandy21]

Re: Stringer Wood

I like that idea. I'll look into it more. I though about going with SEACAST, but it really wasn't practical and I don't know enough about it. But a composite wood would be just like real wood, but longer lengths and would never go bad.

 

[iwombat]

Re: Stringer Wood

I mentioned that idea on here a couple of years ago. Seemed like a natural to me. They don't bend, twist or cup, they're strong as hell and they make outdoor versions too. Spendy though, and I wonder how glass bonds to the resins.

 

[vandy21]

Re: Stringer Wood

oh good call. If I go that direction, I will try to buy or cut a small piece and see how it works with glass. it is somewhat expensive, but I only have two stringers to do (plus cross members) so it shouldn't be outrageous.

 

[jcsercsa]

Re: Stringer Wood

Hi and welcome , I am useing comopite wood on my two outer stringers , I just got my epoxy today , I am going to epoxy two peices together tomarrow and see how the composite wood likes it !! It shouldnt really matter though It the glass that does give it strenght so it wont ever rot or worp !! I just cant use it on my center stringer , can get a piece wide enough !! so I will let you guys know how it goes !! And agian welcome this place is great !! John

 

[jcsercsa]

Re: Stringer Wood

well , I got the epoxy on two peice of the composite and it really seams to be holding, its not dry so will let you know tomarrow !! John

 

[vandy21]

Re: Stringer Wood

thanks, I checked out some composite deck wood at Lowes today and it seemed pretty cool. So I'll wait and see how it goes for ya, and maybe I'll give it a try. would be nice if there was no wood down there to ever go bad.

 

[jcsercsa]

Re: Stringer Wood

yep thats what i was thinking also , but my center stringer is 14 inchs tall so I am out of luck there , but my two outer stringer are compsite , i will let yea know , John

 

[jcsercsa]

Re: Stringer Wood

Its a go !!! couldnt get them apart !!! lost the pic but i will take it again tomarrow . I put a pipe wrench on the one peice and it wouldnt move so i say it a go with epoxy , I dont kno how it will wor with poly !!! Jhn

 

[vandy21]

Re: Stringer Wood

Awesome! thanks for testing that for us. I'll think about using a composite wood now.

 

[Ezrider_92356]

Re: Stringer Wood

if you use demetional lumber make sure you get wood with NO knot's in it period. I learned this the hard way the other day, i got good quality stuff for the keel and then two side stringers i picked out a couple lower grade peices of lumber and picked out the cream puffs of that stuff. my side stringer in a couple spots are quite thin well 1 knot hole fell in one of these thin spots with no way around it and it broke just handling it at the knot. so today i went out and bought some more quality stuff and going to re cut both side stringers out of the good stuff tomorrow. so save yourself the time/ money and get the right stuff the first time even with the sticker shock. of $30+ a board. for me dementional lumber made sense as on my 15 ft boat my longest stringer was just under 12 foot and my side stringers just under 10. also that is what it was originally constructed with and it lasted 50 years and that way i wouldent have any splices and i figured it would hold strength longer once it starts to rot than ply.

 

[jcsercsa]

Re: Stringer Wood

here yea go I still couldnt get them apart !!

john

 

[tysonnathan]

Re: Stringer Wood

hey john,
is that composite wood in the picture???
it looks like pine or something... im thinking of the trex decking stuff... (made of recycled plactic or something)

 

[jcsercsa]

Re: Stringer Wood

hey john,
is that composite wood in the picture???
it looks like pine or something... im thinking of the trex decking stuff... (made of recycled plactic or something)

yep its composite , the one side has a wood grain to it !!! never sposed to rot or warp !! john