Building with plywood

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Steven r
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Building with plywood

Postby Steven r » Mon Jan 01, 2018 3:49 am

Hi all Happy New Year,
I am not a lover of plywood, but reading it seems a lot are! So maybe I am missing something. Frames in hardwood marine ply? Main bearers in ply lamanated so is it better than hardwood? For 1 easy to cut on a CNC machine.
Steve.

DSR
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Location: Allegan, Michigan

Re: Building with plywood

Postby DSR » Mon Jan 01, 2018 8:37 am

Happy New Year Steven,

The reason marine plywood seems to be the preferred choice for my build and many others here (along with many other non-Glen-L boat builds) are that the designs being built were created from the onset with plywood as the chosen building material, taking advantage of plywoods material properties, to build hulls that can be lighter, stronger, easier to construct and more economical than many other building materials and construction methods (especially in one-off non-production builds).

Taking my build as an example, the powertrain that I'm using for my TNT came out of an 8' long jet ski, built in GRP, that tipped the scales at 842 lbs dry weight, and going into a 12'6" plywood hull that will weight less than 600 lbs complete.

Plywood is not good for everything though. Frames are normally built in solid lumber because solid lumber has greater longitudinal strength than plywood and a lot of fastening into the frames is done into endgrain on the edges, where plywood has poor fastener holding capabilities. There are also times that "composite" structures, such as frames and engine stringers, are built using both solid lumber and plywood laminated together, to create members that are stronger, stiffer and more dimensionally stable than either material by themselves.

If you haven't picked up the Boatbuilding With Plywood book by Glen, I definitely recommend it. It explains a lot about the subject.

Thanks, :D
Dave
DSR Performance - Home of yet another jet TNT build :D
Codename "Just A Little....."
viewtopic.php?f=23&t=29753

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JoeM
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Re: Building with plywood

Postby JoeM » Mon Jan 01, 2018 12:11 pm

Happy New Years!

+1 for getting the Building with Plywood book from Glen-L.

Plywood is GENERALLY easier to use. In many ways plywood is stronger than lumber lb for lb. Plywood is more stable due to the multiple thin layers laid cross-grained to each other. Patterning out pieces is also a strong suit of plywood.

However, as Dave said, plywood doesn't have great fastener holding capability into the end-grain which limits it's use as a frame member. Dave pointed out that lumber is stronger longitudinally which also lends to frame members being made out of lumber instead of plywood.

Dave also correctly pointed out that having a lamination of both plywood and lumber makes for a stronger piece. That's why gussets are usually made out of ply.

If I recall, plywood usually has less waste and can be made from younger trees which greatly increases it's efficiency and thus reduces the cost. Also means it's a little more environmentally friendly.
Check out my project and blog! http://fv-escape-hatch.com/project

Steven r
Posts: 96
Joined: Sat Aug 12, 2017 12:41 am
Location: UK Dorset

Re: Building with plywood

Postby Steven r » Sat Jan 06, 2018 3:51 am

Hi,
When I build I am going to build in hard wood, frames and hull with epoxy. I don't want my hull made of plywood! Yes more time consuming and more expensive but it nearer how an old boat was made!
Steve.

DSR
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Re: Building with plywood

Postby DSR » Sat Jan 06, 2018 11:13 am

Hi Steven,

You can definitely do that too. Obviously a lot of really beautiful boats were built in solid lumber. Just make sure that whatever plans you're looking at building are from a design using solid lumber construction.

I may be wrong, but I believe that there will also be a little more involved with upkeep and maintenance of the hull after it's built?

Did you have a design picked out?

Thanks,
Dave
DSR Performance - Home of yet another jet TNT build :D
Codename "Just A Little....."
viewtopic.php?f=23&t=29753

Steven r
Posts: 96
Joined: Sat Aug 12, 2017 12:41 am
Location: UK Dorset

Re: Building with plywood

Postby Steven r » Sat Jan 06, 2018 2:59 pm

Hi Dave,
I am thinking of up scaling a Miss APBA like they have done in Canada. I will up scale to 1.2-1.25 and change the top! This could be a interesting build?
Steve.

DSR
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Location: Allegan, Michigan

Re: Building with plywood

Postby DSR » Sat Jan 06, 2018 4:32 pm

Hi Steven,

Miss APBA is definitely a beautiful design and it sounds VERY interesting.
I'm not familiar with the construction. Is that design a plank or cold-molded?
DSR Performance - Home of yet another jet TNT build :D
Codename "Just A Little....."
viewtopic.php?f=23&t=29753

DSR
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Location: Allegan, Michigan

Re: Building with plywood

Postby DSR » Sat Jan 06, 2018 5:06 pm

Just took a look at the Great Lakes Boat Building website and it looks like a combination of the two, with plank sides and cold-molded layers for the bottom. Very interesting indeed.....
DSR Performance - Home of yet another jet TNT build :D
Codename "Just A Little....."
viewtopic.php?f=23&t=29753

Steven r
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Joined: Sat Aug 12, 2017 12:41 am
Location: UK Dorset

Re: Building with plywood

Postby Steven r » Sat Jan 06, 2018 7:59 pm

Hi Dave,
Had a look at that web sight nice work!! I would cold mould it with epoxy diagonaly and plank the last layer again beaded with epoxy so not a lot different except no ply wood? Hope this makes sense. I looked at Neals Palm Beach build and saw lots of extra frames, so up scaling say 25% would be doable as plan comes in PDF. I think this could be very interesting build :lol: in lots of ways!
Steve.

DSR
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Joined: Mon Mar 21, 2016 8:11 pm
Location: Allegan, Michigan

Re: Building with plywood

Postby DSR » Sun Jan 07, 2018 5:34 am

Hi Steven,

125% upscale. That will be a good size boat at 32.5'.
Not sure if you've checked yet, but I would verify that the upscale doesn't create too much open space between batters and frames for fasteners when applying the first layer of planking. Has that size upscale been done on this design before?

Hopefully just upscaling will be more straight forward for you than it has been for my TNT. Of course I had to throw some other mods into the mix and moving the frames around, so it got to the point of completely reengineering the hull (I'm thinking at this point it would almost have been easier to start with a blank sheet of paper on mine...... :lol: )
DSR Performance - Home of yet another jet TNT build :D
Codename "Just A Little....."
viewtopic.php?f=23&t=29753

Steven r
Posts: 96
Joined: Sat Aug 12, 2017 12:41 am
Location: UK Dorset

Re: Building with plywood

Postby Steven r » Sun Jan 07, 2018 9:22 am

Hi Dave,
It is being built at 1.50 in Canada! It looks amazing! I am sure there will be lots of issues along the way.
Steve.

MattCox
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Re: Building with plywood

Postby MattCox » Wed Jul 04, 2018 12:17 pm

Hi Everybody, about the material you are talking about, well... plywood is an assemblage of wood veneers bonded together to produce a flat sheet..it's great for many uses but, I don't think is durable enough for a boat

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hoodman
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Re: Building with plywood

Postby hoodman » Wed Jul 04, 2018 7:34 pm

MattCox wrote:Hi Everybody, about the material you are talking about, well... plywood is an assemblage of wood veneers bonded together to produce a flat sheet..it's great for many uses but, I don't think is durable enough for a boat


I'm so glad that you came along to let us know. Who would have thought that plywood is made of plies?!

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JoeM
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Re: Building with plywood

Postby JoeM » Wed Jul 04, 2018 7:55 pm

MattCox wrote:Hi Everybody, about the material you are talking about, well... plywood is an assemblage of wood veneers bonded together to produce a flat sheet..it's great for many uses but, I don't think is durable enough for a boat


Welcome to the forums Matt! Why don't you think plywood is durable enough for a boat? I'm not trying to argue, but there is a lot of information on Glen-L site alone, and all of the books on the subject that refute your opinion. Not to mention the boats out there that are doing just fine with plywood used in it. I am planning on using lumber for my framing but use plywood and fiberglass to complete it. But if you don't feel like plywood is durable enough for you there are other options you can take. Have you built a boat before or are you contemplating a build?
Check out my project and blog! http://fv-escape-hatch.com/project

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hoodman
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Re: Building with plywood

Postby hoodman » Thu Jul 05, 2018 9:45 am

I suspect this is someone trolling or a bot or something. As it is their first post.


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