Plywood - Type & what to watch out for.

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atlithor
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Plywood - Type & what to watch out for.

Post by atlithor »

Hi hi,

I am new to boat building but no less love for one well build. I am planing to build a "Sissy Do" this summer and pre-pair for "Jackknife" this winter.

My problem is what plywood to use? We (Here in Iceland) have some selection of plywood but I am not sure which one is being used? Plywood comes in different type, size, quality, colour etc etc. Reading about it here on Glen-L forum and elsewhere its only referred as "Plywood". So my questions is - "What plywood is being used?" and "What to watch out for when selecting plywood?"

All information will be greatly appreciated - Love to get started :)

Thanks in advance guys and girls.
Atli Thor's

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chugalug
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Re: Plywood - Type & what to watch out for.

Post by chugalug »

:D If you can get a marine ply,it would be nice,Either a fir marine ply or mahogany marine ply or equivalent I'm kinda a rebel I guess as I'm using an exterior ply(same glue as marine altho maybe more voidsthan marine .I went with 2 layers of 1/4 exterior ply everywhere for a total of 1/2 for sides and bottom of Bo-jest.(total of 6 plys) marine ply(fir or mahogany) would be much better.My boat will probably go about 6 mph so I'm not too worried about it .A jackknife will go much faster so would recommend a better ply(marine).My ply was still fir tho.Glen-l has some good books on subject.
Working on regular-sized Bo-Jest


"If it's not crooked,It's not mine

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mrintense
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Re: Plywood - Type & what to watch out for.

Post by mrintense »

Glen L has a book called "Boatbuilding With Plywood" (English text) that has all the information you would need. I would highly recommend you pick this up as it will answer almost any question you might come up with.

To answer your question specifically, there are two popular Marine Grade plywoods sold in the United States. There is Meranti and Okoume. Both are available from several different manufacturers. I have limited experience with Meranti but it is generally heavier and less expensive than Okoume. Okoume 1088 is the plywood of choice. If you can get the Joubert brand (made in France) it is of very high quality. It is however, rather expensive. I've not heard anything good of the Chinese brands of Okoume so I stayed away from them even though they are less expensive.

You can also use Exterior grade A plywood (this is a U.S. standard I believe), but this will be heavier than the Okoume. The difference in weight is significant, and on a medium size boat, could add up.

In the scheme of things, the cost of the wood for the boat is not a huge percentage of the overall cost. For my boat, I decided that I preferred the higher quality of Joubert Okoume 1088. The 1088 is actually BS 1088 and is a British Standard for Marine Grade plywood.

Perhaps other here on the forum can add some additional information, however, the forum has been suffering some problems with many members being locked out. This is a temporary problem which should be resolved soon if not already. So if no one speaks up right away, be patient because it may take a few days.

But as I mentioned, the book is a great resource and you would do well to buy it before starting your build. Good luck and please post pictures when you get started.
Carl

Crafting a classically styled Vera Cruise

Clipper Boating

atlithor
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Re: Plywood - Type & what to watch out for.

Post by atlithor »

Thanks a lot guys :)

The forum already been a grate help. Just called the local hardware store (Wood shop) and turns out they don't have "Marine" plywood anymore. Quit that long time ago. Guess not many where building boats in Iceland :)

From the look of it my best choice would be "birch plywood" as they have the most size / thickness available - anyone used this plywood building a boat?
Birch plywood
Birch plywood
images-2.jpeg (3.63 KiB) Viewed 4741 times
Thanks again - Will be fun :)
Atli Thor's

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Andy Garrett
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Re: Plywood - Type & what to watch out for.

Post by Andy Garrett »

Be aware of the weights of each sheet, no matter what you choose.

I had a product called Hydrotek (made in Asia--Philippines I think) shipped to me. I received some sheets at around 18lbs, with others (same size) at over 40lbs. They were all 1/4" sheets. The issue was well discussed in my build thread.

Weight each sheet when you get them and be sure to disperse the weight evenly from port to starboard as you build.
Andy Garrett

Perhaps the slowest Zip build in Glen-L history...

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kens
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Re: Plywood - Type & what to watch out for.

Post by kens »

The metric marine standard is BS1088. That is what you want.
There is a lesser grade, BS6566, but get the high grade BS1088 if you can get it.

I doubt you will see the American grade marine plywood over there, the metric grade plywood is higher quality anyway.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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chugalug
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Re: Plywood - Type & what to watch out for.

Post by chugalug »

:D That Birch ply- is it interior glue or exterior.you'll want exterior if that's all you can get.the glue is supposed to be same as marine however the exterior may have inferior woods for inner plys and more voids.hand picking might help some .the pics you show,show lots of plys,I used fir exterior ply on my hull;handpicked the sheets so no footballs and least amount of voids.and laminated the hull2 layers of 1/4 ply=1/2 everywhere.
Working on regular-sized Bo-Jest


"If it's not crooked,It's not mine

atlithor
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Re: Plywood - Type & what to watch out for.

Post by atlithor »

Hi hi,

After some more searching I might have some luck with a small company that advertise online having marine grade plywood - they have the following plywood on their website (Measurements in mm or millimetre)

Mahony (mahogany): 250 x 122 9mm & 13mm
Tekk (Teak): 250 x 122 9mm & 13mm

At this point my selection of marine grade plywood is very limited and so far this company my only choice.

As they only list two thickness available, the 9 & 13mm, my question is if that is enough for a boat like "Sissy Do" or Jacknife for that matter? My metric conversion says that 1/2' (inch) is equal to 12,7mm - I might be way off though :)

I will be calling them tomorrow to see is this is updated information that they have online - cross fingers that it is.

P.s. Already ordered three books from Glen-L about building the boats - Need to wait up to 5 weeks for them to arrive. This is the life living on a small island in the middle of Atlantic ocean.

With regards,
Atli Thor's

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Locutus
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Re: Plywood - Type & what to watch out for.

Post by Locutus »

Sorry for the late response...I've been away from the forum for a while.

If you haven't already bought your plywood, here are a few tips:

If you're considering anything besides marine grade, make sure the glue is rated WBP (Water and boil proof). This is typically resorcinol, used in both marine and exterior grade plywoods. Do not use interior plywoods unless you can confirm that the glue is rated WBP.

I'm using both Merante and Okoume plywoods in my build, and do notice a significant difference in weigh between the two, with Okoume being lighter. Okoume is easier to work with than Merante, and less prone to splintering. But the Merante I have looks better with a clear finish coat than the Okoume I have. (Nicer woodgrain pattern). YMMV.

You can minimize (but not eliminate) voids in your selection of exterior grade plywood by closely examining the edges. Reject any sheets with voids along the edges.

Joubert brand BS 1088 seems to be the defacto benchmark standard, but my research indicates that Bruynzeel brand is even better, made from woods that are somewhat more rot-resistant than okoume. Okoume is rated as having poor rot resistance. This is okay as long as you can completely encapsulate the wood and keep it from getting wet. The Bruynzeel brand uses a similar species but which is reported to have better (but not great) rot resistance. Being closer to Europe than we Yankees, you may be able to special order Bruynzeel plywood. It won't come cheap though.

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gap998
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Re: Plywood - Type & what to watch out for.

Post by gap998 »

Hello Atli Thor,

Here in the UK Plywood is sold in metric sizes too but one usually finds that they often come out as imperial, i.e. over or under-size. As long as it's consistent though it doesn't really matter

Imperial to Metric equivalents:-
1/8" - 3mm (sometimes measures 3.2mm)
1/4" - 6mm (sometimes measures 6.4mm)
3/8" - 9mm (sometimes measures 9.5mm)
1/2" - 12mm or 13mm (usually 12.5mm in either case)

I haven't read the BS1088 standard but I suspect that the manufacturing tolerance allows for a single specification which serves both metric & imperial markets.

Also, in the UK you cannot get marine grade in general hardware stores and have to use specialist suppliers - these are usually much cheaper anyway.

Good luck!
Gary

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"Just when you think you've made something idiot-proof, someone builds a better idiot!"

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galamb
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Re: Plywood - Type & what to watch out for.

Post by galamb »

The Baltic Birch plywood's are a sound choice if you can confirm that they are made with waterproof glues, more specifically the Phenolic Resin glues.

Also with the Baltic plywood's the grading standard is considerably different than what you see here in the (West). While we have (APA grades) A, B, C and D grades, plus Marine grades (Mar A-B indicating that it's Marine rated with one face being A grade and the other side being B graded) plus the British standards BS1088, BS6566 (although now only used for historical sake - the BS standards are no longer "certified" by Lloyds) they do not equate to what you may see with these birch plywood's.

The Baltic grading system is typically the Russian GOST system. The plywood is made with two different types of glue. One is a phenolic glue, which is waterproof/boilproof - so what would be considered "marine rated" - it is identified on Baltic Birch with an "FSF" stamp. The second type of glue is melamine based, and while (technically) "waterproof", water "resistant" is more correct (on our side of the pond this would be classified as a sheet that can be used (structurally) if "protected" - like under shingles on a house roof etc. This second type of glue is identified with an "FK" stamp on the birch panels (and should be avoided on the hull/transom, but fine for interior stuff - bulkheads etc).

Also the grading system is typically with a double letter (single letters exist, but are not often seen on commercial panels), so you will see BB/BB or BB/CC. Just like over here the grade has to do with the quality of veneer layers, how well they are joined to form a single layer (higher grades = closer joins = less gaps etc) but the GOST ratings are actually a little more stringent than on our side so a BB rated birch panel has considerably better joins than a B grade in the APA rating system.

So while a Mar A-B would be a preferred structural marine panel and would roughly equate to a BS1088 panel (using the lloyds rating), a BB/CC FSF Baltic panel would be pretty close to the other two graded panels.

There is one other advantage to the birch and one detractor.

The advantage is that for any given thickness it will contain more plies than an APA panel, and usually "at least" equal to the BS marine ply, and considerably more plies as the thickness of the panel increases.

A 12mm (roughly 1/2") panel with an APA rating of Mar A/B would have (typically) 5 plies. A BS1088 panel and the Vost panel would have 9 plies.

On the downside, the BB and lower rated panels allow "patches" in the face plies. These are seen as very small football (not soccer) shaped "plugs" in the face veneer. These can "pop out" under extreme stress/flex and should be avoided for major structural panels. In the APA system you generally only see the patches (albeit about 2 1/2 times the size of those seen on VOST rated panels) on C grade faces and they are usually identified with a grade of "C-Plugged".

Now, for all my yapping here, this is my position on using Baltic Birch.

Given the "crap" that the APA rated stuff has turned into in the past 20 years, I consider the B.Birch "far superior" to anything on the market with an APA rating.

In the last 15 or so years even the (formerly) BS rated stuff has gone way down hill. So unless you are chucking big bucks for Joubert certified BS1088, the stuff that's being passed of as 1088 is barely better than 6566 Aquatek, so hardly worth the premium.

Because of that, if you can find some BB rated Baltic Birch with the waterproof glue, FSF, stamp, you will have a vastly superior panel both aesthetically and structurally to anything else on the market. The biggest issue in North America is sourcing full sized panels. It is typically imported here in 5'x5' panels only.

(my opinion here - worth what you paid for it) :)
Graham

Yes, Plywood is "real" wood :)

A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)

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