1 inch plywood stringers vrs 2x4's laminated on top of one another as stringers

[bigbad4cyl]

well my stringers are made out of plywood ,,,when i up grade /recut new stringers ive been advised to epoxy some 2x4son top of 1 another then cut to size and use those instead ,,,any thoughts...my stringers are a maximum of 12 inches high...

 

[jshoes52]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

What kind of boat? Pictures? You can use versalam, preferably doug fir, instead of laminating 2x to make up the 12", or use a 2x12 and add a 3/4" cap to make up 12".

 

[alden135]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Use 3/4 plywood of an appropriate grade and make up the rest with fiberglass. That would probably be easier than edge gluing 2x4's (which you'll probabally need to square the edges to get it right). What ever you decide to do with the frame consider the weight you may be adding opposed to the original design.

 

[crab bait]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

can't glue 3-4 "2x4's" together stacked ON EGDE to make a 12 in high board..<br /><br />can't use framing lumber for boats anyhow..

 

[alden135]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Crab, you should consider substituting "shouldn't" for "can't". If you work in the building trades you know exactly what I'm talking about.

 

[bigbad4cyl]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

i asked this guy that and he said 3 2x4's would actualy be stronger glued togeather ,,due to the fact that there grains would all be running different ways most likely...............any way he said not to use plywood ,,,,,but im beggining to warm up to the idea of laminating 2 1/2 inch sheets together to make the 1 inch stringer .............

 

[bigbad4cyl]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

a 2 x12 inch stringer would be to dang heavy wouldnt it...

 

[Terry H]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

I definately wouldn't use any lumber that wasn't kiln dried to 6-7% moisture content for stringers, therefore your plywood idea will work just fine. You would be lucky to find 2x4 framing lumber less than 15% mc. Chief

 

[Realgun]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Laminate two 1/2 inch plywood sheets to get the 1x12 you need. It will be a lot stronger than an edgewise 2x12. or 3 2x4. Have you not seen the engineered i-beams made out of wood? <br />Then can go 24 ft where you would need a 4x12 beam to carry the load and these are 1x2 top and bottom with chipboard 3/4 x 10 right in the groves of the 1x2s. They use them because its as strong as steel and lighter and smaller than solid wood.<br /><br />I would think this would make an excellent stringer.

 

[Richard Petersen]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

If you live close to a marina. Work a deal for the Marine fir AB or AA 1" . One of them has to have some around from their jobs. I will give you a price.----------------Harbor products sell AA Marine Fir 1" for $114/ sheet, retail, Baltimore MD. They deliver free to NJ. 1-800-345-1712 That is all I can help you with.

 

[Mark42]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Yep, what Realgun said is the word. Plywood is many times stronger than dimensional lumber of the same size.<br /><br />Stop at the local lumber yard and ask about different grades of ply. Some are much better than others due to allowable voids, grade of wood, type of glue, etc. <br /><br />If you use pressure treated ply, be sure to let it dry well. It will shrink just like regular lumber. I just screwed 1/2" x 12" x 8ft lengths of pressure treated plywood to the parimeter of my basement wall. After a few weeks, there are 1/4" gaps between the ends of the ply. So let it dry. You might want to nail it down if possible so it doesn't look like a potato chip after drying.

 

[cc lancer]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

BB4C<br />I have been the 2X12 route and ...never again, I know I was in and out of the boat 20 times with a 2X14, plaining it down to get the right angle at the bow. If you are working from the bow to the stern/bilge area, I strongly recommend the plywood, and just remember to stagger the joints.<br /><br />I glassed it from the floor to the top, to stop any water from getting into it in the future. Gook Luck!!

 

[Paul Moir]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Realgun, study a wooden I-beam and tell me why it's stiff. I'll tell you now, it doesn't have much to do with the web material being made out of ply (or chipboard). A hint is that they use plain wood for the top & bottom rail. <br />Straight fibres running all in the correct direction is stiffer than ply in the direction it needs to be. The problem with natural lumber is going to be dimensional stability rather than stiffness, and the only real cure is going with a laminated stringer.

 

[Realgun]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Paul your wrong completly. The top and bottom are to keep the wood straight and give you a nailing surface and thats it. That stuff is extremly strong in the up and down motion but not side to side.<br /> <br />Steel I beams are the same way. Thats why the top and bottom are so thin. Its like pywood panels they will bend in the middle but on edge they are extremly strong.

 

[Paul Moir]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Read the rules for cutting holes in them here:<br /> Look at 'Web Holes'<br /> <br />As you can see from rules 1 and 2, you are never supposed to damage the flanges but you can leave a grand total of 1/4" of web when cutting a hole. With that kind of hole in the web, could it be providing the strength?<br /><br />The cool thing about an Ibeam (as I understand it) is it puts the top flange in compression and the bottom flange in tension when it's carrying weight. The web simply connects the two together.

 

[Bondo]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Ayuh,..................Strength from Structure.........<br />Engineered Structures are Designed to turn All the loads to Push/Pull Loads......<br /><br />Real Gun,+ Paul are Both Right........<br />Real Gun is just much closer to Right....<br /><br />Paul, In your link it states that Atleast 1/8th" must be left at the Top, Or Bottom.......<br />It Doesn't say you can Remove 13 3/4" from a 14" beam........ <br />Big Difference............. I Think you're mis-reading them......

 

[BillP]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Plywood is used throughout the boat building world for stringers. High end ocean boats that jump off waves at 75mph use ply for stringers and bulkheads. Nothing wrong with ply stringers and I-beam construction isn't seen either. For stringer sizing you may want an example: Pursuit Boats uses 1/2 ply for stringer and bulkheads on their 24'CC.<br /><br />I used 3/4" ply in my 17' ob side stringers and 2x12 dimensional for the center stringer.

 

[Mark42]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

If I ever have to do stringers, I will use no wood at all. I plan on using a 1" or 2" thick styrofoam board and laminate glass around it. The foam board is just there to act as a form. After its all set, drill a few 1/2" holes in the tops of the stringers and 1/4" at the bottom sides and pour in acitone or the like to disolve the styrofoam leaving only air.<br /><br />The air gap is lighter than anything else you can think of, and it won't get water logged if soaked for long periods of time. If you build up the fiberglass to 1/4" or 3/8" thick those stringers should last forever.<br /><br />Just my 2¢.

 

[Paul Moir]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Bondo, you're right - I did misread that instruction. <br />But you're dead wrong about Real gun being anywhere near right. <br /><br />I stand by my post. If you look at that link a little further down you'll see a table that shows a 6.25" allowable hole through a 9.5" joist, as long as I cut it somewhere near the centre of the span. If you subtract the 3" of flange material (1.5" top and bottom) than that leaves you with a .25" remainder of web material. Although there's probably about 3/4" of web material embedded in each flange, I think you'll agree that 1.75" of plywood (or in this case, chipboard) total cannot be providing stiffness.<br />The reason why the hole must not be drilled near a support is that removing the web material does hurt the joist's shear strength. But we're discussing stiffness here.<br />I won't belabour this point. It really is just simple structural physics and if you don't believe me, look it up and prove me wrong. But please do me some justice and don't just say it ain't so.<br /><br />BillP - I wasn't arguing that plywood isn't a perfectly practical stringer material. What I'm saying is that it isn't as stiff as solid lumber in the axis we're concerned with. And that solid lumber is impractical for this purpose since it's not dimensionally stable and we can't tolerate any misshape in the intended use. And that ideally we would want to use laminated stringers (like in a paralam beam) but that they're far more expensive, and therefore also impractical. That's why I took issue with Real Gun's post, and not the handful of others recommending ply.

 

[Yacht Dr.]

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Re: 1 inch plywood stringers vrs 2x4's laminated on top of one another as string

Mark is half way correct..depends on the Stringer location. ( I would not use foam to mount my motor on ).<br /><br />Only thing is there is an Energy distrabution factor for stringers are the purpose of..transfering Energy ( which I wont get into here )<br /><br />putting a thin stringer made out of wood solid on the F/G hull will stress in points ( use a light putty about 1/4 " between them. )<br /><br />The strongest would be to laminate 4 1/4" sheets of ply... if your gonna go ply.<br /><br />YD<br /><br />PS. Bill..you worked for Pursuit ? have you ever worked at the Novarania plant then ?