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John Di Dio
05-10-2002, 04:05 PM
Has anyone ever built, or considered building a mast using LVL or Microlam "engineered" lumber?

I need to make a pair of 6" daimeter X 28' long masts for a gaff schooner. Have been considering using the LVL to make relatively thick walled (about 1.75") hollow spars. The material is about 1/3 the cost of spar grade douglas fir, and I can get perfectly straight 30' long planks of the stuff at a local lumberyard. I made a 3' long mast section out of some scraps a friend of mine had left from a construction project. Used the birdsmouth technique. Worked out good. The stuff seems plenty stiff. It weighs about .024 lb/cubic inch, which is about 15% heavier than some fir I weighed for comparison, but the hollow spar winds up being lighter than a solid fir spar, which is what the plans show. I believe the LVL was made from yellow pine, but believe some of the mills in the Northwest make it from Fir which should be lighter. I plan to seal the spars with epoxy and paint them.

cs
05-10-2002, 04:16 PM
John, I have considered using LVLs for different projects cause I could get it for next to nothing and to be honest with you I don't believe you want as a mast. I ended up using mine as a strong back to build on. If I'm correct a LVL is glued up lumber, now do we know what type of glue they used? I don't belive that is shoud be exposed to the elements. Most LVLs are used as interior load bearing beams. If it is exposed to the elements you either use rough sawn lumber or steel.

With that said I don't believe I would use an LVL as a mast.

Chad

ptpost
05-10-2002, 06:08 PM
Without a doubt there are engineered lumber products made to reist weather. Checkout the website for (no link sorry) Truss joist Macmillan and Boise Cascade. Between them have many options. It also occurs to me that engineered lumber would perform a number of tasks better than solid wood. ie: ribs and other below deck structural members.

ptpost
05-10-2002, 06:12 PM
Without a doubt there are engineered lumber products made to reist weather. Checkout the website for (no link sorry) Truss joist Macmillan and Boise Cascade. Between them have many options. It also occurs to me that engineered lumber would perform a number of tasks better than solid wood. ie: ribs and other below deck structural members.

Dwight
05-10-2002, 06:43 PM
Look at the places where a layer is made out of two pieces joined end to end. I'm thinking you are going to see butt joints or rather high angle scarf joints where you'd like to see 8 to 1 or better scarf joints. This is not too important if you have a lot of layers, but if you may only have a few layers if you are building a hollow spar.

imported_Ola Sylwan
05-10-2002, 07:35 PM
Microlam is probably not very good as a boatbuilding material.
Read on and do a web-search for microlam before building your mast.
______________

Outdoor use of microlam

My builder used microlam as a support beam on my deck, Now the building
inspector says it all has to be changed. The deck is beautiful and solid
(cost $13,000) Is there something he can do to weatherproof the microlam? Or
is it OK as is? Thank-you.
Barbara

Regarding the microlam, the inspector is correct, but I'd like to suggest a solution that might be less painful. If the microlam supporting the deck has been nailed through the decking, you could Sawzall the nails between the top of the microlam and the bottom of the the decking. Then I would slip copper flashing over the microlam, in between it and the bottom of the decking. You could bend the copper down on an angle, creating a miniature roof that would shed water away from the microlam. I would then coat the microlam with a high-quality epoxy paint that would weather-proof it. Perhaps the inspector will allow this. You could also call the company that supplied the microlam and ask them to suggest an alternative, or explain my idea to them, asking their opinion.

Wasn't a drawing of the deck submitted to the building department, showing the structural details? If it showed this microlam, then somebody was asleep at the wheel. Unfortunately, that doesn't change the fact that you still need weatherproofing. Good luck! Bob November 6, 2000.
____________

http://peckbuilders.com/questions.html

Bill Perkins
05-10-2002, 08:33 PM
John the LVL I see in the SE is Southern Yellow Pine , generally kind of heavy .I did get some in Tulip Poplar once ,which is lighter , out of Jacksonville I think ( ends painted Yellow rather than the typical blue ).

The main point of LVL is to produce beams deeper, longer ,and clearer than now available as solid sawn lumber .You don't need particularly wide pieces , and you can scarf for length ( and to avoid knots ) , so a good grade of solid sawn lumber may be a better buy . Why pay for the sawing into veneers and glue up you don't need ?

I would at least price Clear ( C) Yellow Pine in the thickness you need to see if the LVL is really even cheaper in the dimensions you need . Thicknesses of 3/4 in. , 1 in. , and 1 1/2 in. true dimensions are commonly available in good yards . So is a Finish ( clear ) grade of Douglas Fir .

Wayne Jeffers
05-10-2002, 10:50 PM
As much as I like SYP (which isn't really available around here :( ), I would go with Doug fir. The SYP is heavier (extra weight aloft, which you don't want) and doesn't glue as well as the Doug fir.

Wayne

wolfietuk
05-11-2002, 05:54 AM
I think there is a really big point that everyone is missing here. Engineered lumber is just that ENGINEERED for a specific purpose. Lets start off with the fact that it is designed to take loads from a specific direction. Masts and spars may have to takd loads from different directions. Also there are very specific ways you can cut them before you greatly change their properties. If Macmillian-Blodel could market their product for boats trust me they would. As it is there are engineered masts and spars. They are made of aluminum and carbon fiber, and for good reasons.

Rick

Andreas Jordahl Rhude
05-13-2002, 09:01 AM
Do NOT use laminated veneer lumber (LVL) for a mast. First off, it will not be all heartwood of a durable species. If it is Douglas fir/larch species you are getting, belive me, the finsihed billet will be chock full of sapwood. And as we all know, sapwood of any species is NOT decay resistant. There also will be voids in the interior of the member.

There are no glued end joits in LVL such as a scarf or finger joint. Just butt joints.

Second, LVL is designed as a bending member for a roof or floor loadings. It is used as columns as well. But can you take a chuck off the shelf at your local home center and successfully use it as a boat mast? I doubt it.

The adhesive utilized is a waterproof phenol resourcinol or straight resourcinol, which are waterproof. It is possible that some manufacturers use other adhesives, which may not be waterproof. Consult the manufacturer's specifications.

Wayne Jeffers: You said that Southern Pine does not glue as well as Douglas fir. That's not true. The company for whom I work has been gluing on Southern Pine since 1934 with great success!

If you want an "engineered" timber, have a custom made piece of structural glued laminated timber made. Have a piece made specifically for your needs, of a species that you desire, etc... Contact the American Instituite of Timber Construction (AITC www.aitc-glulam.org) (http://www.aitc-glulam.org)) for a list of manufacturers.

Structural glued laminated timber has been used successfully to make masts for ships such as the USS Constitution and the repica of Captain Cook's Endeavor.

Wayne Jeffers
05-13-2002, 12:06 PM
Originally posted by Andreas Jordahl Rhude:
Wayne Jeffers: You said that Southern Pine does not glue as well as Douglas fir. That's not true. The company for whom I work has been gluing on Southern Pine since 1934 with great success!
Andreas,

Tons of SYP plywood in lumberyards all over the country speak to the ability of SYP to accept glue under controlled conditions. No question.

As to the ability of SYP to accept a variety of glues in not-so-carefully controlled conditions in the average home workshop? It can be glued successfully, but not as reliably in this environment as Douglas fir. I am pursuaded by both my reading and my experience that the failure rate will be lower if Douglas fir were used instead.

The only glue failure I've ever experienced in boatbuilding was with clear SYP stock glued with epoxy.

Wayne

centroid
05-14-2002, 04:49 PM
this might be a silly question but what if you can make the entire backbone construction using lvl. i'm talking about using resorcinol glue, finger joints, and make the entire stem, foregripe, keel, backbone, hone timber, etc. all one continuous piece.

Andreas Jordahl Rhude
05-14-2002, 09:44 PM
Centroid: That's the beauty of structural glued laminated timber (not LVL). It can be made to almost unlimted shapes and sizes, basically restricted only to shipping clearances.

Keith Wilson
05-16-2002, 08:55 AM
I won't venture an opinion on LVL, but a simple test for the adhesive would be to throw a piece in a pot on the stove and simmer as long as you can stand. If it holds together, the adhesive (if not the wood) will be OK for your mast.

OTOH, if you're making a birdsmouth spar, why pay for spar-grade stock? Reasonably good construction lumber can be made into an excellent mast if you're willing to do a bit of scarfing and throw away the bad parts. Nominal 2x stock would give you about the wall thickness you mentioned (seems a little thick to me, but that's just a guess). This is, BTW, a similar process to making microlam (good wood out of bad through the Wonders of Chemistry), but if you make it yourself, you'll be absolutely sure about the materials used.

flyon
05-16-2002, 09:33 AM
I picked up some microlam off my jobsite a few weeks ago. I cut it ino 3" X 3" X 1 7/8"cubes and boiled it hard for two hours and then simmered it in a coffee warmer for the rest of the day. There was no delamination what so ever and when I broke it into slabs with a chisel it split at the center of the wood not at any glue line. In one case about a 1" square section of the glue was showing. It seemed like there was a small void in the wood as there was no glue on the oppsite side. I do not see why it could not be used in a cold molded or strip build boat if well coverd with epoxy

[ 05-16-2002, 10:34 AM: Message edited by: flyon ]