Wood species and type for stringers

[Wildey]

Hey all. I see all kinds and types of wood used for stringer replacement.
What is the basis for choosing ? Most common ? Does it matter much ?
My little 92 Bayliner looks to have regular ol 1" pine stringers with ply bulkheads.
The SlickCraft has 2 main mahogany stringers, then ply stringers / bulkheads.
Good southern yellow pine is stronger than regular mill SPorF framing.
Just wondering,
Thanks

 

[Scott Danforth]

Arauco ACX lumber

why:

• its cheap
• its plentiful
• its made with water-proof glue

Marine ply uses the same glue, however is 3x the cost

 

[Wildey]

Thanks, that's good info for the ply, but a 1"x4"x 8' board stringer would be better of solid wood ... would it not ?
THAT is the wood I'm interested in using.

 

[Scott Danforth]

Thanks, that's good info for the ply, but a 1"x4"x 8' board stringer would be better of solid wood ... would it not ?
THAT is the wood I'm interested in using.

No, plywood on edge is significantly stronger than dimensional lumbar

that is why dimensional lumber is not used

 

[Chris1956]

Use dry pressure dimensional treated lumber. It is so much more rot resistant and lamination resistant than plywood and has good enough enough strength.

 

[Wildey]

When in doubt, go with OEM.
That would be straight grained, clear solid wood for primary stringers, plywood for secondary stringers, boxing and horizontal panels/flooring.

 

[kcassells]

Use dry pressure dimensional treated lumber. It is so much more rot resistant and lamination resistant than plywood and has good enough enough strength.

The wood to use is described as exterior grade ply not pressure treated lumber.
They come as mentioned acx, bcx and cdx, something like the. acx being the best with less voids.

 

[mickyryan]

i used dimensional lumber in my trophy for stringers because that is what they used, also i have a issue with plywood as in most of it is junk and you are only gluing to the outside ply at best where as dimensional lumber well you get the point, also dimensional lumber gets wet it don't fall apart like thin veneer's do large areas and bulk heads kinda got no choice

 

[JASinIL2006]

The nice thing about Arauco plywood is that it not only is made with waterproof glue (as all exterior plywood is), but it has more plies and almost no voids compared to many other types of ACX plywood. That makes it much closer to marine plywood than most regular exterior plywood. Even better, it costs about the same as normal exterior plywood (at least it did when I restored my boat).

I also believe a laminated board like plywood will be stronger than a similar sized piece of dimensional lumber.

 

[zool]

If you do an extensive glass laminate schedule, the core becomes less important. Thats why some OEM builds cored with foam, or just hollow boxed stringers. I use whats available to me and glass it all in nice and beefy.

 

[kcassells]

If you do an extensive glass laminate schedule, the core becomes less important. Thats why some OEM builds cored with foam, or just hollow boxed stringers. I use whats available to me and glass it all in nice and beefy.

But people don't understand the concept of add'l glass over dimensional lumber. They just go "This looks good, 2 laminates will do." "Oh my the bubbles"
I agree 100 with your suggestion.
The other issue is the dimensional woods available seem to gas off alot. I've used them and they are a pia.
If I'm putting down 5 to 6 layers of glass over dimensional, I don't care at this point about gassing off. Cause its not getting done in one application unless you own a fab shop.

 

[JASinIL2006]

The fiberglass that makes up my foam-cored stringers is at least 3/8” thick. That a lot of layers if you want to skip the wood.

 

[76SeaRay]

I find it almost impossible in my area to find high quality dimensional lumber that is straight and without cracks or checks. A lot of it wants to split as well. It is hard enough putting in new stringers without having to fight bent wood. I went with 3/4 inch marine grade plywood for the stringers which was much easier to get here.

 

[chevymaher]

But people don't understand the concept of add'l glass over dimensional lumber. They just go "This looks good, 2 laminates will do." "Oh my the bubbles"
I agree 100 with your suggestion.
The other issue is the dimensional woods available seem to gas off alot. I've used them and they are a pia.
If I'm putting down 5 to 6 layers of glass over dimensional, I don't care at this point about gassing off. Cause its not getting done in one application unless you own a fab shop.

I went with hundreds of extra lbs of wood and glass LOL Tank.

 

[Wildey]

No, plywood on edge is significantly stronger than dimensional lumbar

that is why dimensional lumber is not used

Well, actually, the FRP aside .... as a stringer (or wing spar) the bidirectional grain of the plies of wood in plywood make it far inferior to a clear, straight grained stick of solid wood. A laminated stringer, or spar would be acceptable if the grain of each ply is oriented in the same direction. Plywood has its place, for sure. Boats are cheaply built, plywood is (was) relatively cheap, easy to configure and is engineered to be satisfactory in conjunction with the FRP.
Compare a typical wooden broom handle to one the same size cut out of a sheet of plywood. I notice 2 the main structural stringers in this SlickCraft are solid mahogany. The intermediate stringers and associated bulkhead and boxing are all plywood.
Just my opinion .... ( and the FAA and EAA )
Thanks

 

[88 Capri (2022 SOTY)]

The nice thing about Arauco plywood is that it not only is made with waterproof glue (as all exterior plywood is), but it has more plies and almost no voids compared to many other types of ACX plywood. That makes it much closer to marine plywood than most regular exterior plywood. Even better, it costs about the same as normal exterior plywood (at least it did when I restored my boat).

I also believe a laminated board like plywood will be stronger than a similar sized piece of dimensional lumber.

I look at it this way...although the manufacturing process is a bit different LVL's are made with multiple layers glued together like plywood and are structurely super strong compared to dimensional lumber.

 

[Wildey]

I look at it this way...although the manufacturing process is a bit different LVL's are made with multiple layers glued together like plywood and are structurely super strong compared to dimensional lumber.

LVL stands for Laminated Veneer Lumber and is similar to plywood in appearance. The difference is that plywood changes the grain’s direction with each layer, and LVL keeps the grain direction the same.
A drawback of LVL (and plywood) is it is more susceptible to water damage and rot if it gets wet than traditional lumber. The adhesive on many LVL beams (and plywood) is waterproof, but that glue will start to delaminate with repeated water infiltration, weakening the LVL beam. LVL work for interior and dry location applications. Same with plywood.

 

[88 Capri (2022 SOTY)]

LVL stands for Laminated Veneer Lumber and is similar to plywood in appearance. The difference is that plywood changes the grain’s direction with each layer, and LVL keeps the grain direction the same.
A drawback of LVL (and plywood) is it is more susceptible to water damage and rot if it gets wet than traditional lumber. The adhesive on many LVL beams (and plywood) is waterproof, but that glue will start to delaminate with repeated water infiltration, weakening the LVL beam. LVL work for interior and dry location applications. Same with plywood.

I agree but when encapsulated in fiberglass correctly you get the strength just like indoors without delamination.Not trying to start an argument but whatever kind of wood you use it has to be encapsulated correctly where water exposure has the highest probability.

 

[Wildey]

Yes, I agree on that, no problem there.
I just wanted to point out the difference in the grain directions. LVL's are superior to solid lumber for several reasons. Plywood is far inferior to clear, close, straight grained lumber. As I said earlier, all FRP aside, just the wood.
Thanks

 

[kcassells]

This is a "beat the dead horse" story. Easily researchable.