glue-lam beams?

[sr. jigaboni]

If a body were to build a sailboat with a real, by God keel and frames and whatnot, but wasn't so inclined to build a yacht -catch my drift - would glue- lam beams, such as are used in houses and such, suffice?

I reckon these things (the good ones) are what I would make anyway, resorcinol glued 2x whatever. I'm not talking more than 8x material here, 71/2 inches wide, by say 10 and 12. Certain family members are busily converting CA's breadbasket into yet another condo spread, and these things turn up frequently, often quite long.

If these would be suitable I just might build me a little Picaroon or some such. I got some old cedar boards gathering dust in "the pile" that would be nice for planking "ala Maryland".

Well, I hope someone posts an opinion.

peace
Rigo

ps I've been focused on building and flying kites for the short lived season. I am drawn to sticks tied together and covered in paper...on the water or in the air smile.gif

[Ron Williamson]

By 'the good ones', you don't mean those over-sized chunks of aspenite that look like giant granola bars?
R

[psk125]

The problem with glue-lam beams as a keel would probably be with the wood laminates absorbing water and swelling. This would tend to destroy the glue bonds holding the beam together, and all of a sudden you end up with boards attatched to shreds of wood like so much corrugated cardboard instead of the solid beam you dropped into the water three months before.

Most manufacturers stipulate that their beams be kept DRY in order to maintain their construction specs. A lot easier in a house than in a boat. For a boat the size you mention, a bunch of DF 2x12's glued and lagged together would probably be cheaper than an engineered beam, and provide a much more stable keel to sail on after it was launched.

[Bob Smalser]

Glulams are assembled with resorcinol under heat and pressure and won't come apart. Engineering specs require them to be kept dry only because wet wood has an entirely different set of strength specs...most of them much weaker...not because the Glulams will fall apart in water.

That said, there are other reasons why I wouldn't use one for a keel. The biggie is sapwood. No requirement not to have any in a Glulam, just like there isn't in interior plywood. That's no problem in your house, but a disaster in a keel. Plus, the boards are running in the wrong direction....I'd want them on edge in a bolted-up or glued-up keel....because that's where the stiffness is. Glulams are made from cheap, small, finger-jointed "studwood" face-lammed because 2X12's are too spendy. I suspect you could achieve more strength with less weight lamming 2X12's on edge.

Similar in a way to using plywood for beams, carlins and the like....sure, you can do it.....but every lam oriented in the wrong direction contributes little to the structure except excess weight.

[Gary Bergman]

I'd never use a glu-lam in a vessel, but..that said, 'standard' spec lams may be made from assorted wood, but I've custom ordered very high p.s.i. heartwood lams for steel column and post spans that are truely magnificent... for a really good example, check out the 'mammoth site' building in Hot Springs, S.D.

[Bruce Hooke]

It seems to me that since most of the structural parts of a boat, other than than keel and deadwood in some designs, are curved, glulams would not really be of much use*. I suppose on a boat with sawn frames you could theoretically use glulams but sawn frames are usually used only on big boats. The keel and deadwood are such a key part of the boat that it seems a shame to go "experimental" in that one area when the rest of the boat is going to be traditional.

It should maybe be noted that I believe custom laminated beams made by the kinds of places that make such things for construction purposes have been used for building LARGE wooden boats. These beams are basically custom glulams but I'm sure they are not cheap and furthermore it seems like this is really a big boat approach that would not really be of relevance to the matter at hand other than as evidence that glulam-like beams can successfully be used in boatbuilding under the right circumstances.

[ 03-30-2005, 01:27 AM: Message edited by: Bruce Hooke ]

[Bruce Hooke]

Originally posted by Bob Smalser:
Plus, the boards are running in the wrong direction....I'd want them on edge in a bolted-up or glued-up keel....because that's where the stiffness is. Glulams are made from cheap, small, finger-jointed "studwood" face-lammed because 2X12's are too spendy. I suspect you could achieve more strength with less weight lamming 2X12's on edge.Ummm...it seems to me that many keels have been laminated from boards laid on the flat, like a typical glulam. I believe the Gougeon Brother's book talks about doing it this way. I also think it is highly debateable that this method would be any less stiff than a keel laminated from boards set on edge.

That said, I am not advocating using glulams in a boat.

[L.W. Baxter]

Considering that the glue lines in a laminated beam should be stronger than the bonds within the wood fibers themselves, I would think that the orientation of the laminates would be of no consequence.

A beam that is merely bolted or nailed, however, would be much stiffer with the laminates oriented vertically, as the laminates would tend to slip.

Edit to add: of course, this is assuming that the greater stiffness is desired vertically. In a boat, horizontal stiffness might be just as important or more so, no?

[ 03-30-2005, 01:50 AM: Message edited by: L.W. Baxter ]

[pipefitter]

Lams are great. For one..you can build them with prestress in them and they can be designed to accurately carry a designed load. Also,marine plywood is the first Lam the water comes in contact with anyways on plywood boats. So after all that considered,would mainly depend on the marine capabilities of the wood itself.If a guy can build his own boat he can surely build an accurate Lam.
Lams also have alot less end grain exposed than if you were to cut a curve in a straight timber.Can also build in rabbets nicely.

[ 03-30-2005, 03:18 AM: Message edited by: pipefitter ]

[wolfietuk]

I would agree about standard gluelams not being suitable because of sapwood. I too have used large gluelams that were exposed (in a church) that were made of a good grade of wood. And these were custom bent. They were also horrendously expensive. Remembered there are 4 common types of engineered beams.
Rimboards or timberstrand - These have little structural strength. They are used in conjuction with wooden I-beams.
PSL - paralel stranded lumber, these are the most common type. They look like osb plywood. and are available in a treated variety.
LVL - or microlam These look like plywood. 1/8 inch strips laminated together, very strong. and more expensive.
Glue lams- srtongest and most expensive. made from 1x material. availabe in custom (read horrendously expensive)sizes and shapes.

The first three are made from fast growing aspen and poplar. Trees that are harvested young and the entire tree is used. I have changed out rotten ones in two year old houses. All are very expensive and only become cost effective when going over long spans.
I hope this answers your questions.

Rick

[Bob Smalser]

Originally posted by Bruce Hooke:
</font><blockquote>quote:</font><hr />Originally posted by Bob Smalser:
Plus, the boards are running in the wrong direction....I'd want them on edge in a bolted-up or glued-up keel....because that's where the stiffness is. ...it seems to me that many keels have been laminated from boards laid on the flat, like a typical glulam. I believe the Gougeon Brother's book talks about doing it this way. I also think it is highly debateable that this method would be any less stiff than a keel laminated from boards set on edge.

</font>[/QUOTE]They also use plywood for beams.

Given two or three solutions to a problem, they strangely always pick the one that sells the most glue.

What makes a face-lammed Glulam stiff is mostly the glue. Common sense in a submersed timber says it should be mostly the wood. Sure you can do it....but why when you don't have to? The only reason Glulams are made that way is so they can use junk studwood.

Glulams are also very expensive for what they are. Solid FOHC DF beams are much cheaper per foot in many places...especially bought green.

Airdried 2X12's from a local sawyer would be cheaper still, with the advantage of inspecting all the faces of the wood for the junk hearts and sap the commercial laminators like to hide from you in the center.

[ 03-30-2005, 09:18 AM: Message edited by: Bob Smalser ]

[Bruce Hooke]

It seems like lots of people besides the Gougeon Brothers use glued up keels with the laminates running horizontal. From an engineer's perspective such a beam is likely to be stronger than a solid beam. However, whether you think glued up beams are a good idea does to a significant degree come down to home much you trust glue. They probably make the most sense in boats that are largely put together with glue, such as cold-molded boats. For a traditionally planked boat solid timbers for the keel and deadwood are certainly a perfectly reasonable and likely cheaper solution, especially in parts of the country where large solid timbers of suitable woods are readily available. For someone who does not like knowing that the integrity of their boat depends on some chemical poly-glop, traditional construction is probably a better way to go anyway.

[ssor]

I believe that the reason for making Glu-lam timbers is because large clear sections of the best grades of timber are no longer available. Visit old churches or farm barns or factories and you will see massive timbers. But a visit to a modern church will reveal graceful laminated timbers. I suspect that reconstruction of an old church with traditional timber sizes and species would be far more costly than rebuilding with Glulam. We have squandered our forests and will not, in the lifetimes of anyone alive today, have access to timber such as was cut a hundred years ago. :(

[pipefitter]

A good glulam or microlam could be a good thing if you wanted to make it that way.Yes in a glued boat. I wouldnt want to use one in a traditional boat. It is a way a person could make a large timber from wood he could carry in his truck as opposed to having a log brought in on a flatbed semi.They strip build boats to make it easier to follow complex curves and such instead of carving it out of a solid timber.Lams are definitely more stable from warping or twisting.I couldn't see ever buying one premade of construction grade but i think it would be good for some things like a stem or curved knees just for the non end grain exposure.Look at the way they have to build up a stem in traditional construction to keep as much linear grain in the right direction. then you have to have stopwaters and bracing and staggered joints and there is still end grains throughout even the slightest curve unless you happen to find a natural crook. Also,a natural knee or crook with the sides cut flat is indeed a Lam.

[George Roberts]

Gluelams have higher allowable strengths than solid wood.

I expect that using the proper specie and glue will provide a superior product.

[Bruce Hooke]

The other reason why glulams are popular is because the fact that they are laminated of multiple pieces means that a defect in one of the laminates is likely to be isolated to that laminate rather than continuing all the way through the timber. This means that from an engineering perspective glulams are rated as being A LOT stronger than solid wood beams. Now, I said "rated as" intentionally. The assumption the engineer has to make is that the solid wood beam will have the worst defect allowed by the lumber's grade in the worst possible location. A smart builder (of boats or anything else) can, of course, circumvent this to some degree by knowing what sort of defects cause problems and making sure there are not any in his beam. There is still the possibility of a hidden defect inside the beam where it cannot be seen so a glulam should still, I think, be considered stronger than a prime solid wood beam. BUT, lots of good boats have been built using solid wood timbers so I see no reason to stop now if the stock is available. On the other side of the coin, laminated timbers also clearly can be used to build good boats if it is done right, and if you think anything made with lots of glue is "good"! :D

[westinghouse]

But Bruce you're missing Bob S's point that glulam boards are made from finger jointed short stock. Nobody, not even Gougeon, advocates that for structural keel members (and if they ever did, well they also put ash stringers into the Golden Dazy: live and learn, I guess)

In fact, studs made with the same process are stamped 'verticle use only', which is exactly not what a bent glulam keel would be.

So I'm back to Bob's point that the only way to use a glulam for a keel should be on edge, and man that's gonna be pricey - unless it just turns up, as srjigaboni has mentioned it might.

Eli

[ 03-30-2005, 02:30 PM: Message edited by: westinghouse ]

[Bruce Hooke]

Maybe I didn't make it clear enough, but my point was that a custom glulam of the proper stock is the first essential step in using a glulam for boatbuilding. My guess is that proper stock would mean no finger joints, but I am not positive about that.

With that out of the way, I disagree that a bent glulam is "vertical" in any sense. In the context of studs "vertical" presumably means carrying a compression (column) load without bracing to keep the stud from folding at the finger joints. True, the top or bottom of a glulam can be under compression depending on the way the load is applied (like any beam) but there are other layers adjacent to each finger joint that prevent the beam from folding at a given joint. This is why finger-jointed layers work in gluelams used for more usual purposes.

[westinghouse]

Sorry Bruce, that was some nasty editing. I meant 'verticle use only'. That changes my meaning entirely, but not your argument. I see what you mean and it makes sense to me.

Cheers,
Eli

[George Roberts]

The "National Design Standard for Wood Construction" provides the stength numbers fo standard sized gluelams.

And finger joints in studs come in two forms. One form is suitable for compression loads only. The other for all loadings.

[NormMessinger]

All the glulam esoterica is interesting but don't forget the question sr. jigaboni asked was about left overs from what they use in cheap (or not) tract houses.

[Bill Perkins]

Hi Norm . Now on a construction site if the piece left over is more than 12 in. long ,somebody's screwed up ( I've got a 5 foot piece I use as a coffee table ). I think the original poster was considering buying new stock gluelam .

The beams I've used were to be stored as well as used dry. Part of the elegance of the vertical stack for land use is that high grade lumber can be used at the top and bottom where bending stresses are greatest, and lesser lumber used to carry the shear loads in the center .I suspect this non homogenous construction tends to make them dimensionally unstable in the presence of moisture .It's probably not a question of the glue line failing .There's sapwood and other defects in the inner pieces , and no doubt it will rot in a boat first , but it's not being hidden; it's being placed where less strength is needed . I've seen some magnificent pressure treated glue lam for exterior use . As near as I could tell the same grade of lumber was used throughout .

I think we should be laminating our backbones athwartship : not because this makes a stronger keel , it doesn't , but because it allows piecing together the keel , stem , and stem knee by spacing out the joints in the laminates , which can be way thicker than those required to laminate the curve fore and aft .This may allow the use of stock 1 by , as opposed to laboriously resawing stock to produce thin laminations for bending .The stem knee would cease to exist as a seperate member .

[ 03-30-2005, 10:34 PM: Message edited by: Bill Perkins ]

[JimConlin]

I'd worry about the decay resistance of the species used in the member.

[pipefitter]

Seems the natural glue holding the wood together fails before the synthetic glue joints fail even with alphatic resin glue. I imagine epoxy or the gorilla stuff has to be stronger yet. I once made a lam out of thin layers of veneer for a special stair part and the epoxy was making the wood nearly transparent as it soaked it up. Especially near the end grain. Sure this isnt traditional boat building but either is not hauling the log out of the forest with all the neighbors and their oxen. I feel that in 2005 we can do just about any designation with wood if need be.The traditional part I feel is making it by hand however you do it. I would sure feel better about a member made with select heartwood over what nature decides.
One example. The ridge pole in houses used to be made with a large 2x edgeways. Now it is 2 with a ply core sandwiched in. You dont see swayback roofs anymore. Same with load bearing headers,etc.
Also,all the original,traditional boatbuilders used all the good wood. smile.gif

[ 03-31-2005, 12:08 AM: Message edited by: pipefitter ]

[sr. jigaboni]

man, oh, man!

I don't even know where to begin responding:

Firstly, I usually don't pay for wood. Consequently, I don't always get good stuff, but I always manage. A lot of the stuff I aquire is from construction work; both cull wood and over bought. One of my uncles is a foreman, so when wood needs to be "used fast", I get first right of refusal.

I don't need to repeat that there are some good sticks in the construction pile. I have pulled some 2x6s out of their stacks that would make you cry. Then again, most of it is crap.

The commonly available solid timbers for sale around here tend to be boxed heart and maybe 8 grains/inch, or real ugly flat sawn stuff that I wouldn't put in a keel. The other factor is that this size wood is (really) expensive, especially from the "friendly" local sawyer(s).

I ain't after a yacht. I'm talking about a single chine, beefy framed, outside ballasted boat. The floors would be bolted through this keel with, say 3/8 in bolts and the ballast (full length of the keel) would be through bolted with, say 1/2 in bolts. I don't think the finger joints should be a factor.

I guess if I picked carefully enough, it would be cool. Some of my family remodels, and that is where I saw the chunk that made me think of these things. It was only about 18in long, but every piece of wood was nice; 8 nearly flawless 2x12s glued up.

Yeah, if anyone has any old oak 6x10s they want to send my way, I'll use them. Meantime, I will keep considering these free chunks... if I find a good one.

ps thanks for all the change ($.02 worth)

[wolfietuk]

If you have construction conections try talking to the guys doing the clearing. You may find some nice oaks or other local trees ( even virgin growth pines) that you can have sawn up by someone with a portable sawmill. I had a guy do some walnut trees for about .15 cents per board foot. Think about it.

Rick