Pressure treating hardwood (or alternatives)

[imported_Daniel]

My next project requires a keel 2x4" x 20' long. The only wood I can find that is long and large enough is ash. I need to find a way to preserve this piece as it does not seem to have any natural rot resistance. Epoxy encapsulation kinda frightens me as the fasteners from the sheathing will penetrate the coating. I have been speaking with a gentleman who owns a pressure treating plant (the green stuff) and he has agreed to run the wood through his processing line, though he couldnt guarantee the treatment on ash. Any suggestions or alternatives? What about pressure treating AND encapsulating?

[ 09-21-2002, 09:02 AM: Message edited by: Daniel ]

[bugeye]

hi,
I've read that red oak is good for pressure treating because it is like a bundle of straws. I'd doubt that ash would work very well for the treatment. Keels rarely rot though, so I'd say if you've got a nice piece of ash, use it. It's very hard and stronger than oak. What knid of boat is it? Will you be using it in fresh or salt water?

[bud]

Wow! Guess if you hang out here you will come across anything in time. My understanding of pressure treating is that it destroys much of the strength of the wood. I would be very afraid of subjecting a valuable piece of wood to this process.
If Barry Bonds can hit a ball out of the park with a broken bat, then ash has got my respect in the world of wood. :D :eek:

[NormMessinger]

Set your fasteners in epoxy per Gougeon Bros method.

--Norm

[capt jake]

I second Norm's thoughts. smile.gif

[WFK]

pressure treated hard wood? Why? Dan, there has to be a scource where you can find what you need. How about laminating? Just a thought

Bill

[Bruce Hooke]

IIRC the Gougeon book says that encapsulation does not work well on thick pieces of wood because the wood moves to much (I think the recommend 1" as the max.) For thicker pieces I think they recommend laminating. So, laminating would be one way to go.

As far as the fasteners go I wouldn't worry to much about screwing into a laminated and ecapsulated member because the screwheads will presumably be puttied over and there will presumably be some sort of glue in the joint, so it will be hard for much water to get near the screw. Also, if water penetrating along the fasteners was a major issue then I'd expect to find rot around the threads of fasteners on traditionally constructed boats, whereas this is relatively uncommon in my experience unless there are other compounding factors that have allowed water into the area. However, if you are concerned you could dip the screws in epoxy before driving them. If you are using epoxy to glue the pieces together then this naturally happens as the screw gets run in through the epoxy that is squeezing out of the joint into the screw hole. The technique of drilling an oversize hole and filling it with epoxy and then drilling the screw pilot hole into the epoxy would, of course, also work; but it seems like way to time consuming. IIRC the Gougeon book mostly recommends this technique for very highly loaded fasteners such as those used to hold down winches.

[Frank Wentzel]

Daniel

I suggest that you try some "CopperTox" (Copper Napthenate), at least on the end grain. CN is a waxy compound that is dissolved in mineral spirits. The mixture penetrates wood fairly well (if the wood is dry - it won't penetrate worth a darn on wet wood). When the solvent evaporates the CN acts as a toxicant and, to a certain extent, a water repellant. I understand that it is paintable, and therefore epoxy-able after a few weeks drying. I have some 1" x 6" yellow pine edging that is about 7 years old around some flowerbeds and when I dug out a piece of it recently it still looked great. I live in Florida (the land of liquid sunshine) so the wood got a really good test.

/// Frank ///

[Scott Rosen]

Rot is not much of a problem for members that will be completely submerged all of the time. No air; no rot.

Pressure treating will probably interfere with the adhesion of epoxy or paint of any kind, and the chemicals used in the treatment will probably leach out of the wood pretty fast. So forget pressure treating a keel.

You could soak the keel in CPES and then follow it with a couple of coats of red lead. When you fasten, slather some CPES in each fastening hole and also dip the fastener in white lead.

[ 09-22-2002, 11:24 AM: Message edited by: Scott Rosen ]

[bugeye]

HI,
Geez, thank goodness for epoxy. Without it, wood would be totally unsuitable for boat construction. If you all are so distrustful of wood, why don't you just get a fiberglass boat and put that nice wood grained contact paper all over it.

[thechemist]

Pressure-treatment usually involves treating with a waterborne mixture of paraffin [an emulsion, for "water-repellent" qualities] and Chromium Copper Arsenate [otherwise known as CCA] which is soon to be banned because it is awful and might kill something, and much less effective materials substituted.]. You can go to one of the southeastern wood treatment places who pressure-treats wood and plywood for export and have them pressure-treat with CCA ONLY which will not interfere with gluing anything and is an excellent preservative, really the best thing. Exterior underwater paint of some sort , a "barrier-coat" if you will, ensures that prolonged water immersion does not leach out the virtually-insoluble-anyway CCA.

That'll do ya.

[paladin]

The other possibility is to find Bois D'Arc (Osage Orange) and laminate the pieces. It laminates well, is naturally rot resistant and available in some areas but not in long lengths.

[ken mcclure]

Try calling some of the smaller local sawmills. They may be able to find you alternatives that the lumber retailers just don't have.

There are also quite a number of tropical woods that are naturally rot resistant, and which come in big sizes (like purpleheart and angelique). Call some of the companies that specialize in boat lumber and see if you can get a piece shipped in.

[Bruce Hooke]

It just occurred to me that an easy solution might be to get two lengths of something more traditional for keels, like white oak, and simply scarf them together using resorcinol. It should be easy enough to get two 11-12' lengths of white oak this size and a properly made scarf should be as strong as the wood iteself.

[bugeye]

HI,
Osage is actually very difficult to glue sucessfully. It is so hard and dense that glues don't penetrate at all. I worked on the building of Sultana where quite alot of osage was used, and it's great stuff, remarkably similar to locust, but not for gluing. Anyway, a 20' piece of white oak is not hard to come by. If I were building the boat in question, and I had a nice piece of ash I think that's what I'd use. The care that the boat receives in use will have much more effect on the boat's longevity than anything else. In 1999, I replaced all the deckbeams, covering boards and deck on a very old skipjack with pressure treated high grade loblolly pine. The owner insisted on using the stuff, and I was skeptical at first, but it worked very well. The owner had had this lumber cut and treated two years before we used it, so it was nice and dry. I used some of the leftover lumber in my boat, laminating it into some rather curvy carlings and it glued as well as anything that I've ever tried. Alot of people looked at me like I was crazy for using PT wood on a boat, because they were thinking of what you buy at the Home Depot. But everyone who then saw the wood seemed to agree that it looked good. I'm surprized that more people havent experimented with treated woods in boatbuilding.

[imported_Daniel]

Thanks all. The boat in question is the Glen L Gypsy, not pretty but methinks it will be the perfect craft for exploring northern Ontario's many rivers and lakes. The keel fits into notches at the various framing members, so will not be underwater, but in the bilge of the boat. The boat will be living on a trailer for the most part, and used exclusively in fresh water.

[Andreas Jordahl Rhude]

To "bud": Pressure preservative treatment does NOT reduce the strength of the wood. This is a fallicy.

To "The Chemist": I don't undertsnad your statement that CCA is the worst thing on the planet and than in the next sentence you say it's the best. I must have missed something in your writing.

[thechemist]

Originally posted by Andreas Jordahl Rhude:
<snip>
To "The Chemist": I don't undertsnad your statement that CCA is the worst thing on the planet and than in the next sentence you say it's the best. I must have missed something in your writing.It's my sense of humor. One says something but actually means the opposite.

CCA is an excellent preservative, and used by itself does not interfere with glues or finishes.

I was speaking tongue-in-cheek, mimicing the bleeding-heart liberals who never got an education in any science but mushed their brains up with words not understood and are now afraid of those words because the word has become the object, and draft appropriately non-scientific legislation. An excellent example of this is California's Proposition 65, now a law legislating the toxicity of stuff. Before that, hazard diminished with concentration of the offending substance. Now, by law, any amount is as hazardous as any lesser amount down to the limit of detection, and if you can't see it any more, it is magically non-hazardous......Oooops...almost ranted. Gotta be more careful.

[mark ward]

Daniel, I think I read about this in Pardey's book, though I haven't tried it and it may evoke some stimulating conversation: I'm assuming that your going to steam bend the keel prior to further framing and such. After it's bent, leave 4-5 inches extending above the deck. At the ends, drill a 2" deep by 1" diameter hole in the end grain. From time to time, during construction, fill that hole with a wood preservative of choice, the more liquid-like the better. By the time you're done with the construction, several ounces of the preservative will, by force of capillary action, be distributed throughout your keel, and you won't have to deal with the negatives of pressure treating.

Just a thought......

[Bob Cleek]

God... somebody recently asked in another post what they meant by "old timers" in this forum. This thread is really illustrative of how bad things can get. Obviously, half the posters above (and I am sure your mothers love you...) admittedly have no frigging idea what they are talking about, but find that no inhibition whatsoever. Bad advice gets heaped on top of bad advice and then more bad advice gets added to that.

Hey, Daniel... assuming you are an earnest fellow as you seem to be, I'll give you the straight answer to your question. If you can't find a 20 foot long 8/4 in anything other than ash, you don't have what you need to build your boat. Simple as that.

The answer is not a bunch of BS about pressure treating or any number of other schemes to make a silk purse out of a sow's ear. Ash is simply not suitable for your keel. Particularly since as you describe it, it has cut-outs for the frames in the bilge, which is where it is going to rot in a hot minute. Pressure treating works for fence posts, not boats. You want a keel that is covered with those perforations that permit the poison to get into the wood? Obviously not. Ash has exceptional strength, but it is not even remotely rot resistant. It's good for oars and on rare occasions in racing boats which aren't intended for long life, it is used for deck and cabin beams because of its lighter weight. It also makes a decent cleat and nice belaying pins. Otherwise, there isn't any place for it in the structure of a boat particularly because it rots so readily. Moreover, the bigger a piece of wood in a boat, the more likely it is to rot. Pieces don't come much bigger than a keel, so it ought to be the most rot resistant wood you can find.

There are many, many woods suitable for your keel. It is simply not true that you can't find them. You may not be able to find them in your local construction grade lumberyard, and you sure won't find them at Home Depot or Lowe's, but there's plenty of good wood out there. You may have to pay a little more to order it from someplace far away if you live someplace where there aren't any trees, but Ontario? Hey, they had lots of trees up there last time I heard.

Check out a good specialty lumberyard and find out what they can order for you. You have lots of options. White oak is the best, but perhaps too pricey for you. Then use Douglas fir. (Not "white wood" or "hemfir," real Douglas fir.) You can go also with any of the really decent pines, although they are not as desireable as oak or doug firm. OR... you can go to your local recycler and find some big old well seasoned beams without a lot of nails in it and cut one of those up for your purposes. (Just saw a beautiful rudder built out of old growth fir, maybe 12 rings to the inch, completely clear and straight grained... came out of a 100 year old bridge timber.) For the size you are describing, lamination is far more costly, given the wood and glue and time, than an honest hunk of wood which will never delaminate. Coat all the wood that goes into your boat with CPES and red lead. That's about as much as anyone is entitled to expect in terms of rot resistance.

For the umpteenth time, the only thing that really helps prevents rot is decent tried and true construction methods, lots of ventilation, good paint and maintenance. They haven't invented anything that makes wood rot proof. All they've ever done is a lot of advertising that fools people who don't know any better. Wooden boats aren't meant to last forever, unless you keep replacing bits and pieces of them. Good construction and maintenance will 1) slow down the rate of decomposition and 2) make repair easier. Wooden boats are inherently biodegradable. Quit making yourselves crazy trying to build a wooden boat that won't rot. Your time would be better spent trying to turn lead into gold or designing a perpetual motion machine.

Oh, and Daniel... When you've got that good wood... enjoy building your boat knowing your time and skill is being applied to materials that deserve it. Remember, Michaelangelo didn't do the ceiling of the Sistine Chapel in magic markers.