Testament to Douglas fir marine plywood and ?'s about.

[RonW]

On the last saturday of june 2003, I put 6 pieces of 3/4 inch 7 ply douglas fir marine plywood in a 2 gallon bucket of water. These pieces where from 1 to 2 inches wide and from 3 to 6 inches long, totally raw plwood. Just checked them again, which has been slightly over 6 months and they are as solid as the day I put them in, not one sign of delamination or splitting. I know the bucket of water, which is in a outside shed has frozen and thawed out at least 3 times over the last month. I am defintely impressed. Now some one should do the same with merranti and occume plywood. Time will tell. Might also be worth submerging m.d.o. and h.d.o. fir plywood to see what happens to the resin surfaces they put on them. I am also under the opinion that solid wood, probably wouldn't hold up as well or better, and might lead to a good argument that plywood is superior to solid wood at least for trailer boats that are in and out of the water.
With that being said, Question ? what is the opinion as to M.D.O. & H.D.O. plywood? Also seen on this board a few months back, where a gentleman from australia made the statement that down under thay have stopped the practice of laminating fiberglass cloth over plywood boats, but instead have started taking epoxy and thinning it down and coating the surface.It seems to me that saturating the outside veneer with thinned epoxy is now creating your own version of m.d.o. or h.d.o. plywood. I know that there are those that believe in cloth and those that think it might trap moisture. But what is the opinion to m.d.o. & h.d.o. as well as this thinned epoxy coating on marine douglas fir?

[Ron Williamson]

I boiled some little pieces of MDO in a microwave.
This MDO was a highway sign made in about 1990.It was removed in about 2000,after which it lay in the grass behind my shop until this past summer,when I cut it up to use for something else.This was one-sided material with the back side only primed,not even painted.
I boiled it twice for about five minutes each time,about five minutes apart.
It came through with flying colours.No delamination whatsoever,only a bit of swelling.
R

[Jack Heinlen]

Good Doug Fir plywood is fine stuff indeed. Getting good is not so easy anymore as much of it is from inferior trees. Look at the stuff made forty years ago, it's all from old growth, it still smells resinous even without cutting into it. It's been awhile, but the last time I looked at the recent stuff it couldn't hold a candle. And Ocumme and the Meranti are far superior in their workablility, but unencapsulated they don't hold up, in my experience.

Sidebar.

If you are ever looking for a power skiff, have a look at the Chris Sea Skiff built from the mid fifties through the early sixties. They are planked with old-growth Doug Fir ply, and their hulls are light, strong, and rot resistant. Same with Lymans.

[Domesticated_Mr. Know It All]

Almost all the marine Douglas Fir plywood in my 1961 Lyman hull is still good. The white oak and Mahogany ply pieces have rotted considerably over the last 43 years. Dunno why, just an observation.

[CaseyJones]

I built my first skiff in my garage on a rolling platform. To help with getting the roller wheels in & out of the garage, I laid some strips of 1/4 meranti at the opening. They stayed there, unprotected, for a year. I'm in Houston. They were subject to almost constant moisture. After I moved the boat out to the new barn, I picked up those scraps and there were no signs of delamination. Other than being moist, they looked like I had just set them down.

[Jack Heinlen]

I have the same experience Kevin.

I did some work on our Chris Craft Sea Skiff a few years back. It had some rot in the white oak framing and in the Phillipine Mahogany of the transom and aft deck, but the fir ply planking was as sound as the day it came from the factory, even where it had surface checked and been less that well protected. Good stuff!

Those Lymans and Chris' are fine boats, well worth a project if you find one that needs a new home, and you need a power skiff. And who doesn't?

But we shouldn't spread the word too loudly, it will drive up the prices. ;) Seriously though, a Chris Sea Skiff from about 1960 would be at the top of my list is I were in the market for such a boat. I believe it was 1959 that they made a transition in the hull form, giving the boat a lot more topside flair forward, and making it much dryer.

But this is starting to turn into a highjack. Sorry. redface.gif

[Jack Heinlen]

Casey,

I shouldn't have said anything about Meranti. My experience is with Ocume, which built into a skiff, not epoxy saturated, and stored outside under a tarp didn't hold up well. I don't know about Meranti at all.

[Jim Mathieson]

Jack ;We had the same experience with uncoated Okoume ply on a dingy, since then we have replaced the rot pieces and coated with epoxy -no more trouble for 2 years.
We got some half inch exterior grade spruce ply that I am impressed with. Very few voids at all, Some pieces left over have been wet outside for a year. I just brought a piece in ,boiled it and froze it again -no problems.For only $20. a sheet it's a bargain ,we'll probably use it for interior furniture,beds as it's stiff and light, on the R. Woods 32 ' Cat we're doing .

[Dan Cavins]

Hi RonW. Funny you should ask. I have a piece of MDO that has been laying on my back slab for about two plus years now. That is by the way in Norwood, near the Smith/Edwards exit on 71. Howdy!
It has been rained on, frozen, thawed, sun baked, you name it. No degradation. Now the problem as I have stated before is that all MDO is not created equal. I've seen some that is just crap. Still called MDO. ? I found a good source. HDO seems similarly indestructable. Though I have not realy tested it. Thing to remember is that it is very stiff, no bending and the surface is made to be non-stick. So consider that as to fastening. It is also a bit heavy. I have used both and am quite happy with them. I have also used the doug fir ply. I believe the key is simply to use each where appropriate. As to the coating, the MDO surface is heat impregnated so I read. Don't know the science but in my test glueing the wood gives up before the outer layer. To me it seems tougher than a coat of epoxy would be. I state proudly that I am a mere backyard hacker, but that is what I have found. See ya', Dan.

[cmreaching]

I had a piece of 1 x 6 plowed facial fir left over from an eave job on the house a few years ago. Seems it was about 6ft long. This was the finger jointed stuff, as the solid boards were already hard to come by. This board got kicked around outside, used as a bike ramp, thrown in the mud...you name it. It turned grey from exposure from the Mississippi sun and elements but after almost 2 years it was still a good board. No rot and no delamination of the finger joints. That sold me on the durability of fir....

[imported_Conrad]

Fir is awesome- I prefer it over oak for durability, especially the old growth stuff. Meranti is good, comparable to true mahogany. Okume would never find its way into a boat- it is essentially junk wood like Hemlock, except that it comes in clear logs that allow for the manufacture of consistent plys for plywood. It has always seemed funny to me that 25 years ago no one would dream of using Okume in a boat, and now it's considered a good choice (with protection). The Okume hasn't changed, but the alternatives have become much harder to find and more expensive. As an aside, I have about 400 BF of clear, old growth hemlock, light and strong, that will eventually be used in a boat, probably along with some Okume, all well lathered with a lot of paint and epoxy!! ;)

[Bob Smalser]

http://pic3.picturetrail.com/VOL12/1104763/3019409/36929015.jpg

Much as I love tight-grained DF heartwood...and I mill a lot of it...the sapwood, which DF plywood is full of...isn't vary desireable...rots and checks pretty quick.

And DF also moves a lot and can be difficult to finish...uneven resin content and resin some finishing materials don't like.

Also suspect your effort tested mostly the glue, not so much the wood...I have sound old-growth DF logs that have been sunk in ponds for thousands of years...but the logs that floated are mere remnants of their former selves from the UV and critters that eat it.

http://pic3.picturetrail.com/VOL12/1104763/3223936/39972445.jpg

[Jack Heinlen]

Old growth DF ply has nothing in common with today's cousin. Another interesting topic.

And I just have to say that those skiffs were planked with really good stuff, in my limited experience. No voids, no sap. Were they rotary veneered out of really good, old logs? I suspect.

[Meerkat]

John Welsford, whose "other" job is as a timber specialist, says that occume and other tropical woods have the "rot resistance of wet toilet paper".

[RonW]

Occume and other tropical woods have the rot resistance of wet toilet paper.
Now there is some solid information you can sink your teeth ( or whatever into),
Never could understand why loyds would put there approval on a plywood that is intended for marine use, but made out of a non-durable wood.
It seems that for strong, tough and durable plywood, douglas fir marine is hard to beat. Just a shame it is so hard to get a nice finish on it without a lot of checks and grainy look.
I have heard that h.d.o. has paint adhesion problems due to the slick hard finish.And the resin paper on m.d.o. can turn gooey if exsposed to constant immersion, a major concern on boats that have floorboards.
My next boat is going to be a 20ft. garvey with floorboards. I am not a fan of the epoxy cloth method, has reservations as to whether it traps and hold moisture, besides, i want my wooden boat to look like a wooden boat, not a fiberglass boat.
Just would like a prettier finish while retaining all the roughness and durability of douglas fir marine plywood. That is where the question as to painting plywood with thinned epoxy, but no cloth came in at.Kinda like making your own m.d.o. but without the paper to possibly goo up later.
At this point i am leaning towards 1 or 2 coats of kirby's red lead primer followed by several coats of white primer sanded between, with a couple of finish coats of color.I have heard with proper paint jobs, you can make douglas fir look fine. Does anyone know the proper way to paint douglas fir????? Oil based obviously.
Hey Dan Cavins, I am in loveland, 20 minutes from you,feel free to e-mail, we have to get together sometime and trade info.
Oh yea on my extra big driftboat, i used a industrial grade epoxy paint. It is o.k. for the use it will be put through, but striving to improve on garvey. Thanks.

[Lucky Luke]

BS 1088 does not concern the rot resistance of the wood, but gluing and voids mainly. It does not mean that this is a proper "marine" grade ply. Neither does French CTBX.
Okoume ("occume"?) has a really BAD resistance to rot, miles away from "Sipo" or "grand bassam" (African dark mahoganies), and Douglas Fir of course, which are wood that allow "marine" grade ply.

Oh , I'm so JEEAAAAAAALOUS :mad: when I see the timber Bob has got ;)

[JimD]

Only three types of people should attempt to build in DF plywood:

1) Lousy woodworkers, so when the boat turns out all crooked they can blame the DF
2) Lousy fiberglassers, so when they botch the sheathing and fairing they can blame the DF
3) Lousy skippers, so when the boat goes to the bottom first time out they can rightfully proclaim "That boat would still be afloat if it wasn't for that blasted douglas fir!"
:eek:

[High C]

Originally posted by JimD:
Only three types of people should attempt to build in DF plywood:

1) Lousy woodworkers, so when the boat turns out all crooked they can blame the DF
2) Lousy fiberglassers, so when they botch the sheathing and fairing they can blame the DF
3) Lousy skippers, so when the boat goes to the bottom first time out they can rightfully proclaim "That boat would still be afloat if it wasn't for that blasted douglas fir!"
:eek: Eat me! tongue.gif

[JimD]

Eat me! Now HC, you never would have said that if it wasn't for the douglas fir :D

[Venchka]

Ya'll play nice or we'll send you to the bilge without your grog, Ya'hear? :D

[High C]

Sorry fellers, it was lumber lung that made me do it! :D Plus it's unnaturally cold here in the swamp today, got me all atwitter. :eek:

[Venchka]

Ah yes, frozen grey matter. :D
You're excused. I like to froze today with the wind coming off the ICW.

Shhhhhhhhhhhhh!!!!!! Don't tell the Northern Folk what the actual temperature is or they will think we are sissies.

[ 01-07-2004, 06:25 PM: Message edited by: Venchka ]

[Jack Heinlen]

Doug Fir plywood was a tremendous planking material until the plethora of trees ran out. Always a bit more difficult to work than the modern 'tissue paper' woods, it remains an incredible material, in some boats from its ERA.

[Nicholas Carey]

Originally posted by Lucky Luke:
BS 1088 does not concern the rot resistance of the wood, but gluing and voids mainly. It does not mean that this is a proper "marine" grade ply.Actually, BS 1088 is specifically a marine plywood standard. And I believe it does specify which species are acceptable.

From the abstract for BS 1088-1:2003...
This part of BS 1088 specifies requirements for marine plywood for use in the manufacture of marine craft and in other marine and waterway applications. It also applies to marine plywood that has been selected for use in building construction, in extreme climates and in such applications as vehicle bodies and general building work where a high standard of durability is required or where the cost of replacement in the event of failure might be high.I believe you're thinking of BS 6566, "Plywood. Specification for construction of panels and characteristics of plies including marking". BS 6566 specifies a standard for exterior-grade plywood, not marine-grade plywood. BS 6566 is no longer a current standard. It has been withdrawn and has not been superceded.

BS 1088 has recently been updated (there was a kerfuffel about 3-4 years back about whether BS 1088 would be updated or not. Manufactuers weren't willing to pony up the funds required to bring the standard up-to-date and BSI was threatening to withdraw the standard. Evidently the problem was resolved in the right direction :D ) So BS 1088:1966 and BS 4079:1966 have been withdrawn and are superceded by BS 1088-1:2003 and BS 1088-2:2003.

You can order yourselves a copy of BS 1088 from the BSI at

http://www.bsi-global.com/Transport/Standards+Publications/Sea/index.xalter

Each part of the standard is £27 for members of BSI and £54 for non-members.

And remember...if it's not stamped with the BSI kitemark:

http://www.speakeasy.org/~ncarey/images/kitemark.gif

and the standard number(s) to which it conforms, it's not, strictly speaking, BS 1088 marine ply.

Claiming compliance doesn't mean actual compliance. The BSI kitemark does.

BSI doesn't allow the use of the kitemark w/o licence and you have to jump through hoops to get it. Those hoops include BSI conducting ongoing product testing, QA audits and site visits as long as you maintain your licence.

Here's the flowchart for getting kitemark approval for your producten: http://www.bsi-global.com/Kitemark/Apply/flowchart2.xalter

And BSI actively prosecutes (copyright violation) concerns using the kitemark w/o license. If your kitemarked plywood is delaminating on you and you suspect you've been taken, let BSI know.

You can search for current BSI licensees at http://webserv.bsi-global.com/client_directory/ (Supposedly, though I haven't had any luck getting it to work).

Similarly, you can search for manufacturers of products with a current type approval certificate from Lloyds Register at http://www.lr.org/rules_and_standards/Approval_services/approved_manufacturers.htm

Under 'Useful Links', click on 'Approval database on ClassDirect Live'.

On the resulting popup window, Click on 'Approvals' in the tree control on the left-hand side of the window. Then click on 'Type-Approved Products List'. Finally click on 'Search Engine' and fill in the search form (specifying 'plywood' in the product field will give you the list of manufacturers holding a current certificate of type approval for Lloyds Register.

Alternatively, under the 'Type-Approved Products List' mentioned above, click on 'All Products' and then scroll down to the product in which you're interested in. Clicking on 'Plywood and Other Wood Boards (Part 1A) (17)' will give you the same list as above.

[imported_Conrad]

Originally posted by JimD:
Only three types of people should attempt to build in DF plywood:

1) Lousy woodworkers, so when the boat turns out all crooked they can blame the DF
2) Lousy fiberglassers, so when they botch the sheathing and fairing they can blame the DF
3) Lousy skippers, so when the boat goes to the bottom first time out they can rightfully proclaim "That boat would still be afloat if it wasn't for that blasted douglas fir!"
:eek: Your third point is wrong- a doug fir boat would never sink. That suff's too tuff! :D

[Todd Bradshaw]

But, if we have plywood scraps made with waterproof glue and toss them into a bucket of water and just leave them there, it seems to me that they are actually in a much more stable environment than that which many boats are subjected to. If the glue doesn't fail and the stuff doesn't delaminate after a couple weeks of soaking, it could probably stay there for years with little change. I'm not saying that the ply isn't good stuff, but it would be interesting to try the same test but take the ply out of the bucket and let it dry out every other week.

[imported_Steven Bauer]

I like the dishwasher test. Who was it that told us about that trick? I can't remember. :(

Steven

[J. Dillon]

The last boat I built in 97 was of DF. I'm still using it. Sound as the day she was launched. At that time there was a product around called "Firzite" or something like that. It claimed to "tame the wild grain" It did and very well. In fact I like the color it gave the wood and used it as a stain for my oak thwarts.

Unfortunately I don't think they make it any more. I'd like to use it to stain any new oak wood work that I might make. I cannot duplicate the effect with any tried combination of store bought stains.

http://www.imagestation.com/picture/sraid97/p1bb2f8026fa5970c31a8e614ec70d246/fa12a3f3.jpg

JD

[JimD]

JD, niiiice boat! I know you've told us before, but tell us again - what's the design?

[J. Dillon]

Jim,

I designed the boat myself on paper, made a 1" to a 1' scale model but tweeked it a bit after I started building it. After launching and a few sails, cut off some of the skeg. Some more sailing, re stepped the mast and changed the rake.

A couple of seasons later added the jib.

This season a top mast and sail.( will have to buzz Todd B. about that ) I continue to improve it a bit here and there but nothing major.

JD

[Keith Wilson]

I built my first boat in 1989, a Bolger Gypsy, out of ACX fir from the lumberyard and (gasp!) polyester resin. 15 years later she's still sailing, despite pretty hard use, outside storage, and indifferent care. She's sheathed in glass cloth outside, but the inside was just sealed with polyester resin thinned with acetone, and checking has been very minimal under oil-based house paint. One more data point.

I don't build boats that way anymore - I know more now, have a little more disposable cash, and really, the smell of the polyester is just too horrible, but still . . .

[fishing fool]

Well I am convinced that fir ply will be the way to go when I build my drift boat. It might be a little heavier than the original design but not incredibly so. As someone had already mentioned west coast wood for a west coast boat ;)

[High C]

Originally posted by Keith Wilson:
I built my first boat.....out of ACX fir from the lumberyard and (gasp!) polyester resin. 15 years later she's still sailing....Ahh, it's just a matter of time, now. :eek: ;)

[Keith Wilson]

Ahh, it's just a matter of time, now. Hey, eventually even the continents drift! :D

[Lucky Luke]

Nicholas Carey: thank you very much for the points and for the links.
I had in mind, without having checked, that BS 1088 was the equivalent of CTB (French) "X" grade.
Then, I am a little disappointed that okoume ply can be accepted as "marine ply": it rots! and it rots fast!

[ 01-09-2004, 12:21 AM: Message edited by: Lucky Luke ]

[stevenj]

since we're talking DF ply and checking.... has anyone tried using penetrating epoxy and NO fiberglass on DF ply to stop the checking? If so, how did it work?

I was thinking, take your panel, warm with electric blanket, then soak panel with penetrating epoxy. The cooling wood would draw in the penetrating epoxy that much more.. what do ya think?

regards,
stevenj

[ 01-09-2004, 09:39 AM: Message edited by: stevenj ]

[Ken Hutchins]

When looking for plywood, look for the purple (resorcinol) glue lines which is far more important than the type of wood. A basic problem is the tendency is to shop based on price which is a mistake. Resorcinol glued plywood costs more to produce. Pay em now or pay em later.

[Frank E. Price]

One thing to keep in mind when shopping for plywood is that the stamp does not guarantee that the sheet in hand meets the standard, only that the manufacturer has been approved. There was an article in the Polynesian Catamaran Association's magazine last year by a Wharram builder who related his experience with a tropical ply stamped BS 1088. In short, he was well along in hull construction when he noticed some suspicious spots, investigated, and found many and large areas of glue starved plies. He chainsawed the boat and started over. Inspect each sheet before purchase is the caveat, regardless of the stamp.

Frank

[Keith Wilson]

The only time I used douglas fir plywood without glass/resin sheathing and it didn't check was when I sealed it with polyester resin diluted about 20% with acetone. It may just have been a lucky aberration.

[whb]

JD

It sounds like your firzite is what we used to call a neutral blender. It was a penetrating material that penetrated the dense grain less than the softgrain. After it dried you gave it a light sanding. This had the effect of taking it off of the top of the denser grain and leaving it in the softgrain. Thus the two grain densities were brought closer together and finished more similarly.

I think you should be able to achieve the same effect by using a thinned version of whatever you are going to use to finish the wood.

I would test the compatibility of the stain with the finish first before I did anything radical.

Howard

[brian.cunningham]

I'm about to find out.

I picked up the wood for my crossbeams. The panels that require a lot of bend to them will be okumme (sp?) but the rest of it is douglas fir ply and solid wood for stringers. This will be made into an I beam, so it should be tested pretty good!

[imported_Conrad]

Sadly, even the "stamp" from a well known brand doesn't mean you've got the good stuff. I've read of off-shore secondary manufacturers forging the stamps of other agencies/manufacturers on non-complying product. Plywood piracy, if you will! Buy from a reputable dealer!

[Spenie]

You really have to know plywood to answer your questions. There's some big differences and you should get an expert to help in large purchases of plywood for boatbuilding. Find out who uses plywood for purposes similiar to yours, then buy exactly what they buy. There's so many different types with different plys and glue's used.
But, I will say that I have used some fir plywood-3/4 inch for floor boards. These have been exposed to sun light, rain, snow, ice, mud, and heavy traffic for 5 years. No bubbles or delamination noted. I did, however, coat and fill the edges of the ply with a homemade epoxy putty twice. I also covered the boards with a couple of coats of thined epoxy as well. That said, I made a hatch cover for a small boat. 1/4 inch sheet that I bent (stressed) slightly for runoff. Covered it in one coat of polyester resin, and the panel bubbled and began to delaminate in weeks.
I think if I was to build a small ply boat today, say a 12 to 25 footer, I might go with fir ply, but I'd epoxy putty all edges and coat and glass exterior sides. More plys the better. Probably epoxy coat all insides too. Cost is the big thing and all those epoxy coats take a lot of work and time. Why buy fir if I'm gonna pay hundreds to epoxy coat. Could just buy good marine grade and then just polyester glass outside and cuprinol inside. Poly will go bad in 5 to 7 years, but so what, just tear it off and put another layer on. Just about the time you can't get anymore paint on anyway. New poly's, or even vinylester, are supposed to be good.
Here's one piece of advice, and I've owned a few ply boats, do not build a sailboat out of plywood. To many twisting stresses for the ply. Fasteners will come lose and stress will create places for the water to go. There will be those who say I'm wrong, but the only ply sailboats that work are overbuilt and horribly heavy. And another thing, big plyboats over 25 feet, are generally very ugly.