Ripping Douglas Fir 2"x6"

Thanks for all the help guys! They are called stringers in the woods design plans, not sure what other word would be appropriate for them. From the plans verbatim: "stringers are 1 1/2" x 3/4" on edge".

 

That looks like regular home construction lumber, which is on the low quality end for boatbuilding. Any Home Depot will carry 1x2 size. Otherwise, you can get a 1x4 or 1x6 and rip it. It is easier to cut a 1x board to size.

 

Great advice.

 

Hey guys, this is really bad news for me since I already ripped a ton of the lumber that I bought which they claimed was Douglas Fir. I'm hoping that it might have just been the latest purchase that was bad. I already glued the 1"x3" timbers that I bought previously (that look to be better quality) that was labeled Douglas Fir to the bulkheads! Do I have to throw those away?? Please tell me what you think of this timber, can I keep it or is it too low quality?? Any advice is greatly appreciated!!!

 

Hi Gonzo, thank you for your advice! Are you saying that this looks like regular home construction douglas fir, or a different type of lumber that they mislabeled as douglas fir?

 

It's regular low quality Doug fir.

Don't use any knot in any structural application.
Scarfing is structurally accepted.
8-1 scarfs are easily calculated. Measure thickness by 1/8 inches. Then make scarf that many inches long. 3/4 is 6/8 so it requires a six inch scarf joint.

 

Thanks so much for the reply Blueknarr I really appreciate it. There are a few knots in the 1"x3" timbers around the bulkheads, should I redo those? Would the timbers around the bulkheads that are knot free be ok to keep or should I redo those too? How structurally important are the 1"x3" timbers around the bulkheads? Is there a way to better reinforce the low quality douglas fir rather than completely redo-ing the bulkheads like maybe adding a strip of fiberglass/epoxy or something along those lines?

Thanks for any advice!

 

No knots should be on your bulkhead stringers/timbers. None!

use what you have made

the reason the wood is not great is the number of grains per inch

more grains per inch is better

flat grain lumber is less stable

store all the lumber flat and wrap them to keep them from moving

if you go shop for more lumber; take Gonzo's advice and look for 3/4" lumber, closer grains per inch, select for knots

 

Thanks guys I went to San Diego and checked out Home Depot and Dixie Line. Home Depot only had construction grade 2 douglas fir (with knots) while Dixie line had furniture grade douglas grade c or better with no knots. The specialist I spoke to at Dixie Line told me that my grade 2 douglas fir I had previously bought in Mexico would be fine for my application, especially since it will be enclosed in fiberglass/epoxy. I'm not sure how much boat building experience he has though (I don't think any to be honest haha). He said the grade C or better (furniture grade) was mainly for cosmetics and that it wasn't that much structurally better (especially if enclosed in epoxy). Would you guys agree/disagree with that statement?

 

All depends on grains per inch.

Lumber that grows super fast is not as strong as slower grown timber.

There are several subspecies of Douglas fir, but looks for more versus less grains per inch.

For semantics, I offer a couple pictures. These are different woods, but compare within the selections of fir.

The top board is ash and 7 grains per inch vertical grains.

Bottom board is old growth redwood and over 25 grains per inch.

when you compare douglas fir count the grains for a truer understanding of which board is better; just must be done with vertical, not flat grains when counted and of course comparing ash and redwood is not useful; but easier to teach than comparing say a 5 grains per inch fir to an 11 grains per inch..plus I would have to spend some time looking for same species compares

what I can tell you is your flat grain pieces are not as stable or strong as the vertical grains

 

You can see here the way these are cut. Two are rift or vertical and one is flat.

the one under your thumb is about 8 grains per inch; the others cannot be counted because they are not clearly vertical grained; the middle board is flat cut

 

fallguy, you are so amazing, that was an awesome explanation!

I will definitely take that into account looks like I will have to just export it from the US since I don't think they sell the good quality douglas fir in mexico. I know you said in an earlier post that I should just keep the ones I did, which are bulkheads 1, 4, 5 and the transom. Should I reinforce the timber with extra fiberglass/epoxy if I decide to keep them? Or should I throw it out and redo it? I'm tempted to just throw it out and redo it with the higher quality grade C or better douglas fir, it's not that much work I'm losing and better to do it now than to have to go back and fix it later.

I found this Douglas fir grade C or better at Dixieline (see photo), which is furniture grade and knot free and have a higher number of grain/inch. I plan to buy this to use from now on, this would work right? It's definitely a higher grain/inch than my other ones.

Also what is the worst case scenario if I keep the work I've already done...could there be issues with leaks or major cracks in the future? And with epoxy/fiberglass, it should be strong enough and leak proof, I would hope- but please correct me if I'm wrong. If a leak were to be revealed later, I could simply reinforce those areas with more epoxy/fiberglass right?

Thanks for all the input guys it's super valuable!!

 

I would replace some of your knotty pieces.

Some of the pieces are too short to have serious structural application. I think what you have shown so far are thickening pieces too have a larger target for nailing into. I saw at least one large knot that would be difficult to nail/screw into.

Most Home Depot do stock " vertical clear grain fir" it is on the"trim" isle not in the framing section.

This is the wood you should be using. Or the furniture grade from the other store.

Common #2 stud wood is cheaper but one must careful select only the best of the lot.

 

I would redo them, not so much for the wood quality but because of your piecemeal construction. The joints between the individual futtocks (the frame pieces) should be half lapped, the way you have done it glues endgrain to endgrain and is only acceptable with plywood knees both sides of the joint. Google images for "ply on frame boat building" to see how it's done.
Ideally no knots should be present in installed structural wood, high ring count and vertical or rift sawn is to be preferred. You either buy a better grade or look at wider planks to select from.
There are exceptions to high ring count like ash (fallguy's example is actually almost wagoneer quality) but it's not relevant to you.
Mexico has some nice wood available, but it's a big country and location matters.

 

Thanks for your input Rumars! When I asked the designer he said that I can lay out the timber like that without any issues. I thought Tijuana would have plenty of good quality wood but everyone I've called either don't have it or they only have poor quality Douglas fir. Do you know any places specifically with good quality wood in Tijuana? It's a pain to import wood from San Diego so I would prefer to buy it in tijuana.

Thanks everyone for all your input!