Luan reliability?

I will try WoodFinder first. Thanks Par.

 

Hey Par,
When was the last time you saw prices like that on sheet goods of any grade?
4 ply cdx is going for 26 dollars a sheet here in Maine. OSB 7/16 is 20. Is that why were paying so much? Sending it all down to hurricane ravaged Florida so you guys can give it away??

 

The reason you pay so much for the trees around you is that Florida is the worlds largest plywood consumer in the world. Quanity discounts.

 

Myself and several other folks around me have built kayaks and pirogues from luan with great success. We abuse our boats in shallow salt water, often grinding over oyster reefs, and after several years none have shown any signs of trouble, and one I know of is stored outside!. All are epoxy coated and painted, with glass cloth in critical areas (chines, bows, keels...).

 

Well Corpus, thank you for proving the old saying. "It is not what you buy, but how well you use it." Well done!

 

Light weight craft such as kayaks don't impose very high loads on the planking when being treated "roughly" on a rocky beach. A 30 pound boat being dragged across shards of broken glass will have reasonably light damage to it's sheathed surfaces. In most of these types of boats, the lauan ply planking is treated more like a core then a more typical plank in a larger vessel.

A 1/4" plywood topside plank on a light pulling boat, sheathed inside and out with 6 oz. cloth is a cored structure. The sheathing accounts for about ~ 30% of the hull thickness. This has a different set of principles applied then a 30' inshore cruiser with 1/2" planking and a 6 ounce sheathing on the outside only. The cruiser's sheathing amounts to only ~ 10% of the total planking thickness and requires a dissimilar scantling rule incorporated into the engineering of the structure.

In these small and light craft, lauan can be used with good success, but a wise eye should be passed over every sheet for construction flaws and other obvious defects. I still don't like the stuff, because it's so weak in comparison to the better grades of sheet goods, having more plys. I'd shy away from Douglas fur as kayak planking. I doesn't finish well at all and is heavier then necessary. Send me an email Jalexfolds. I'll tell you what is available in our state and where to get it.

 

We have an entire warehouse full of Mernti and Okoume (1088 and 6566) 1/4" 6566 Meranti is less than $28 a sheet - its 5 ply and a lot nicer than fir

 

JR
Are you a distributer? What are your prices for 3/4 marine ply? What would shipping costs be to Maine for a small order, say 10 -20 sheets?

 

I need to put in my two cents worth:

Several aspects I’ve noted:

1. Obviously, the only reason to consider it is cost! Cost being the same, it doesn’t take a rocket scientist to tell you which one to buy. … and not all of us are fortunate enough to live in Florida. In other places… here in Atlanta, for instance $95 a sheet or mail order and take your chances at $45 per sheet. Home Depot Lauan at $10.95 for 5.2 mm that I can inspect makes me pause.
2. It comes down to risk… how much are you willing to take? One might be an excellent boat smith, but know zilch about laminated plate theory, load paths and plywood chemistry. In this case, you buy the best and not worry.
3. Strength – unconditionally, marine will be more consistently the same strength. However, hardwood is stronger/stiffer than softwood. For a given ply thickness, hardwood Lauan will be stronger than fir. If the load path is predominately one direction (e.g. a beam cap, beach catamaran hull) and you can inspect the outer plies of the Lauan, you would have a stronger structure using the Lauan versus Fir plywood. If you have a mixed loading condition, you can’t count on it.
4. Water damage – Well, I’ve taken some Lauan, boiled it, dish-washer’d and held it under a pond for weeks. It didn’t delaminate. You are going to water proof it anyway! Marine plywood (to my understanding) does not add any preservatives or water proofing to the the wood… just the glue! Unprotected marine will rot just as fast as Lauan.
5. Plies – This relates back to consistency and strength – Marine is all that! The Lauan batch I bought at Home Depot for the SC20 project “happened” to have thick outer plies. (35%/30%/35%). The very next batch (from the same vendor) I measured at (15%/70%/15%). This would suck in any project!
6. Heavily warping – I’m warping the SC20 hulls pretty hard! I am noting that there are ripples out of my desired curves. This is no doubt associated with inner core gaps and knots. Marine would not have this problem. It will be far harder to get a true and fair boat with the Lauan!

My decision process would go something like this:

• Make the boat for someone else – use marine pass the cost on!
• Ever think of selling it – use marine!
• Sailing in the ocean – use marine!
• Showcasing your perfect curves or wood working – marine!

For myself, in my cost/risk I obviously decided to give it a try. Here is why – It is my first boat design and build. I expect to make mistakes in both the design and build! It will only go out on a lake in nice sunny weather. It will have sealed buoyancy so it will be of the unsinkable variety. I and anyone else on it will have protection (it’s the law). I want to try some oddball things so it’s a test bed, not a showcase! It’ll likely last longer structurally than I have the desire to sail it… I will be moving on to grander projects! All other hardware (besides the hulls) will likely move on also. So far I have $70 invested in wood. I’ll probably have another $100 in fiberglass and epoxy. If I used marine, I be adding another $600. When I move on, I can toss $170 far easier than $770.

 

You don't have to justify yourself for the fact that you take scrapwood for basic boatbuilding material.
The reasoning process is your own - we are marine professionals and as such we have our own thoughts about material - I am am not a "Boat's Smith" and I don't think that according to the value of materials I have to be educated.

 

If I have offended you or anyone else, it was not my intent. New to this field, I didn’t know that Boat Smith was a bad term. I personally considered it to be an artisan and some thing I would like to aspire. I happen to agree with most of the comments on this thread (on both sides).

Your bias is from your considerable experience and worth referencing. However, unless you have actually done extensive testing with other materials, or have access to such results of that testing then by the simple definition… it is just a bias… and not facts. Boats of either material have broken up… it is impossible to label Lauan as the culprit. If designed correctly, it will work just as well as marine grade plywood. With all the various material used in boat hulls… steel, aluminum, fiberglass, concrete, reeds, hay… it should be obvious to any casual observer, that it’s the proper design using the given material that makes for a safe boat.

Good engineering ALWAYS includes cost factors. We all can’t live in a world of Lexus and Rolex. Using proper design methodologies, “scrap” materials can be effectively used. Noting that near every post on this thread is based on opinion, I merely wanted to add mine and I believe my opinion is as worthy of this site as anyone else’s. I have no accurate test results, so I tried to address the characteristics on a more segregated basis with logic instead of opinion.

You will note that except for my one (current) project, I will be using marine grade plywood myself. The main point I wanted to add (that had not been discussed) was the workability of the material. Some other people (more cost conscious than yourself) might want to factor that in.

I am here on this site to learn as much as I can and sometimes experts come-off with a lot of attitude! That being, “I know everything there is to know about this subject… trust me… don’t use that ****!” Some do not substantiate any of their statements. Either they don’t really know or are unwilling to share it. On the flip side, there are many experts that are exceptional teachers… They not only know their craft, but they’re willing to teach it. In my short time here, I have noted several exceptional ones: brian eiland, tspeer and eric sponberg. I believe there are a lot of people on this site (me included) wanting to learn and have more reasoning (or at least, curiosity) ability than you give them credit. If you had pointed us to some extensive testing data, I am sure your summation would have been taken as gospel! I wouldn’t mind you telling me my opinions smell like crap as long as you tell me what kind of crap and where it is and substantiate it!

 

In your own right, you are correct - the word "boat smith" has indeed a negative sound in my language - even degrading!

When I concipiate a boat - I am a composer that has the orchestra to perform and together we make the symphony. Neither a conductor is a "music smith" I am not a "boat smith" - according to your luauan - what do you know exactly about this sort of wood, its manufacture, the used glues, the used intermediate laminates etc.?

I apologise for being cynical, but you are so advanced in other materials that I was real surprised that you went to utterly unusuable materials like this Luauan product in order to make your cat.

Of course you can and may use any material, provided that you will tell also the grave disadvantages of the material you use.

Some of the best boatbuilding wood grow in your own country and still you continue to use the **** (excusez le mot) from overseas.

In your case I would make a study of traditional boatbuilding before you start to make somethinmg in real. Or, look at the threads of you fellow member PAR who is a fine craftsman and who has a good source of knowledge.

It took me a year to bring a new product to Fokker Aircraft. So, if you build a boat, take a bit the same line and check a building material carefully before you start. There are also other cost-efficient materials that are better suited to build a cat-hull than Luaun!

Check for yourself!

 

He's got a website here....Sam
http://www.boatbuildercentral.com/

 

My ironworking friends proudly call themselves blacksmiths and do incredibly complex and highly engineered work for museums, cathedrals and government buildings . They would find it curious that someone would think "smith" a derogatory term. Same for goldsmiths and silversmiths.

As for luan. I really like the stuff, but it will delaminate when exposed to frequent moisture. Doorskins are made of the stuff and they regularly delaminate (even when painted) if exposed to the rain. The very fine grained wood is actually quite splintery and tends to open fine cracks in weatherproof coatings. To use it on a boat hull you might want to soak it in diluted epoxy to get absorption deep within the wood. It is quite absorbant. Maybe better to use 1/8 inch with more layers for more effective epoxy bonding.

 

Truck shipments from Florida aren't that costly. Hell, I'm not very far from Atlanta, I can drop off some panels for a case of Bud. Tell you what, I'll met you have way on the price for my efforts. You'll get $90 dollar sheets (Atlanta prices) for 45 bucks and I'll make a bundle. Give JR a yell and see what his shipping costs look like.

Inquisitor, you are under a false impression that luaun is a hardwood. It's a confer (a pine) that looks like mahogany (to some) and is sometimes called Philippine mahogany, but it's not really close. You also seem to think luaun and marine grades of lumbers will rot at the same rate, under similar conditions. The species used in marine grades are known for their rot resistance and only those species are used within the panel. This isn't the case with luaun. You have know idea what's under the very thin outer veneer. It may be luaun (likely not) or it may be junk. It's cost is a reasonable indicator of it's quality, construction and rot resistance. This is why we must rely on a grading system (which is only voluntary in the USA) The BS system or a Lloyds rating are good indications of a panels qualities. Most of the sheet goods in the USA are coming out of the far east (south east Asia) and their quality, construction and assembly practices should be questioned at all times.

None of this is speculation, but well known by the folks who deal with these problems daily. The testing that has been done is why we have grading systems. The bad panels coming out of the far east isn't imagined, but coped with by every wood butcher requiring their products.I personally have conducted tests on ply of all the major species that I thought had a chance at surviving immersed exposure in Florida. Luaun was discounted right from the start. More information regarding spices properties can be had from the FDA and the forestry service (local or federal) All the manufactures can supply product testing data. I've also conducted test on adhesives, fabrics (abrasion resistance testing), joints, construction methods, fasteners and many other elements of tasks in this industry.

In defense of luaun, there are two types found in the Lowes/Depot type stores. One is an exterior grade (water proof glue, but still lousy construction) the other isn't and does delaminate quickly. In Inquisitor's case, building a test bed he didn't need a long term solution to his planking. Typically the planking is some of the best, if not the best stock available and this is based in sound engineering principles. In small boats particularly, the planking bears the majority of the longitudinal loading and this shouldn't be done with inferior material. In a knock down type of test bed where tossing new ideas and concepts into the mix every so often is the desire, in can make sense. You must understand, we like to build things that are handed down to our grandkids. The thought of using a less then desirable material makes most of us shudder. I've built a cardboard boat once. It didn't last long, but I did come in second place on the race course.

Lastly, there's no such thing as water proofing wood or a wood product (like ply). The only true water proofing that can be performed, is to embalm the boat in goo, then park it in a climate controlled museum. Water will get in, it's just a mater of time and use.

I kind of like the Boat Smith thing, though much prefer his majesty. So, Inquisitor and Brien, kiss and make up. It's likely you've both mistaken comments out of their intended context.