Where NOT to use ply on a boat?

[patrick.blanchard]

There are places were ply is not suitable on a wooden boat. The portlight is one example. Are there others?

[Bob Cleek]

Every boat is a collection of compromises and plywood is a compromise's compromise. You use it where you have to, preferably someplace where it won't have to be finished to look good and won't ever be exposed to moisture.

[Paul Pless]

You use it where you have to, preferably someplace where it won't have to be finished to look good and won't ever be exposed to moisture.or you can use it pretty much everywhere...;)

http://www.canoeyawl.com/images-boat/Picture036.jpg

http://i15.tinypic.com/2i03rwg.jpg

http://www.duckflatwoodenboats.com/designers/oughtred/eunmara4.jpg

[kc8pql]

Perfectly appropriate sometimes and not at all others. Depends on the design and construction technique, and what you want to end up with. as you can see from the photos above, size and intended use has little to do with it.

[patrick.blanchard]

Can marine Meranti be steam bent and still retain it's original performance?

[kc8pql]

Assuming you mean meranti ply, probably not. Steaming would be a severe test of the glue. If that kind of bending is required, the design isn't really suited for plywood. Ply hulls with a lot of compound curves can be done using cold molding techniques with several layers of thinner, and/or narrower strips though.

[patrick.blanchard]

if I ever get into blue water, the material has to be affordable and safe. So far ply seems to be the winner. Google for 'steam bent ply' got me thinking about using ply for joinery (and maybe bending it)

http://mocoloco.com/archives/morgan_cheetham_bent_one_may_04.jpg

I just had to get out of thinking that there was only one way to build a boat (thanks Paul).

[pcford]

There are places were ply is not suitable on a wooden boat. The portlight is one example. Are there others?

Plywood makes fine floorboards. Otherwise, don't use it.

[Tom Lathrop]

Some of the very best boats and aircraft are built with plywood as the main ingredient. Luddite opinions notwithstanding, this has been true for over 100 years. The great majority of boats that are home-built today are being built of plywood.

Plywood makes terrible rubrails and seat cushions.

[eastern270]

http://i250.photobucket.com/albums/gg280/eastern270/my%20boat/P1010209.jpg100% okuome ply from stem to stern. Meranti ply stringers bulkheads and motor beds.

[Lew Barrett]

There's very little plywood in my boat, (1938) but all of the interior bulkheads are ply, and they are original. They are in excellent condition after 70 years. I also laminated some ribbon cut teak veneers for use on some of the pilothouse interior surfaces when I rebuilt that cabin 13 years ago, and that mirrored the technique they employed at the time she was built. The rest of the boat is built from solid stock, including all the interiors and furniture. Why they did it as they did I can't say. Perhaps it was experimental in respect to the bulkheads, or perhaps they felt they wanted something special by way of surfaces in the pilot house. In any case, the bulkhead structural ply has held up perfectly, whereas the furniture veneers had to be replaced. Go figure!

[titanicslim]

if I ever get into blue water, the material has to be affordable and safe. So far ply seems to be the winner. Google for 'steam bent ply' got me thinking about using ply for joinery (and maybe bending it)

http://mocoloco.com/archives/morgan_cheetham_bent_one_may_04.jpg

I just had to get out of thinking that there was only one way to build a boat (thanks Paul).There are many ways to build boats, thank Goodness, but I don't know of any way to get marine plywood to take the sort of bends shown in that photo! You can boil good exterior ply for a long time and the glue will not soften enough to allow such curliques!

The fact is, there are really good arguments for and against just about anything. And sometimes you just have to try a thing before you can tell if it works for you. Now, plywood boats have been built and used by everyone from field marshals to dope-smoking teenagers clapping together a skiff for fishing the Fraser- and they (the boats) fulfill their purpose.

So the only way to answer the question is to put it to the test. My suggestion is that you try "traditional" plywood construction at first, like a light dory, say. Then, if you don't like it you can fiberglass it. And then you will know (almost) all you'll need to know.

Dave

[titanicslim]

Lew

Seeing as how that's the only stuff I've ever made a bulkhead of, I lean toward the opinion that our predecessors already had a pretty good idea of plywood's value in such applications. We steam and boil little pieces of the stuff- imagine how much experimentation went on when it was new technology! I imagine they had confidence that it would last.

Dave

[Lew Barrett]

Dave, the bulkheads are solid and make sense, give great strength to the boat and take and hold finish better than individual sticks. The veneers on the other hand de-laminated over time from leaky windows, leaky decks and so on. Those have all been repaired, and the new laminations look nice. However, the vast bulk of the boat is "stick built" as befits a traditional boat, and if I didn't point out the use of the non-traditional materials, they'd be hard to see to the casual observer. Still, an interesting transition and, I guess you'd say, "advanced application" in my late pre-war build. All of the plywood in my boat is "flat," no bends or curves, and the last, exterior bulkhead is planked, not plywood.

[Canoeyawl]

This boat is all plywood (Spars, framing, and rubrails excepted!) and it is all bent - there are no flat surfaces anywhere except a few watertight bulkheads.
Planking and decks are 12 mm Sapele, the interior is oiled the decks are canvas covered and the hull is painted with oil-based enamel.
No fiberglass anywhere, None.
http://www.gunkholing.org/images/sallybot2.jpg (http://www.canoeyawl.com/building-sally.htm)

[Paul Pless]

Jake, how did fasten the laps on Sally?

[Canoeyawl]

West system epoxy with Cu rivets.
The thickener for the glue was chopped cotton fibers.
Planking detail (note the garage sails!)
http://www.gunkholing.org/Images/345 050crop.jpg

[gregleeber]

The window frames and the bottom of the boat on my 1956 Sedan were of ply. The bottom is incredibly strong. Just a few days ago I bumped into a tree while backing the boat into the barn. It was the window frame that hit the tree and in broke into dozens of pieces. It appeared to be very dry. The tempered glass that I put in the window held up just fine...

[John B]

This old plywood thing has done pretty well for nineteen sixty frozen stiff too.

http://i227.photobucket.com/albums/dd48/Waione_photos/coastal%20classic%2008/100_1648_1.jpg

I don't know how many transpacs, a just completed Tahiti race, the NZ Coastal Classic and entered for the Sydney Hobart on boxing day this year.

[Jay Greer]

This old plywood thing has done pretty well for nineteen sixty frozen stiff too.

http://i227.photobucket.com/albums/dd48/Waione_photos/coastal%20classic%2008/100_1648_1.jpg

I don't know how many transpacs, a just completed Tahiti race, the NZ Coastal Classic and entered for the Sydney Hobart on boxing day this year.
Yes, but it has been rebuilt many times at great expense!
Jay

[Jay Greer]

After some fifty odd years of repairing rotten and delaminated ply wood in various asundry boats, I must confess that I tend to agree with L. F. Herreshoff that the only place it is suitable might be as a seat for the wooden bucket; as long as it doesn't get wet.
Jay

[John B]

I respect that Jay ,but I could argue that the Infidel/ Ragtime rebuilds are more to do with bringing the boat up to a higher performance standard rather than rot or delamination. Not that I know about that specific boat , she's spent her life after 1970 in the US and its been a hard racing life too.
But there are a lot of ply boats here of the same age and if they've had a maintained life they're often good. There are the disasters as well of course.

[Jay Greer]

I respect that Jay ,but I could argue that the Infidel/ Ragtime rebuilds are more to do with bringing the boat up to a higher performance standard rather than rot or delamination. Not that I know about that specific boat , she's spent her life after 1970 in the US and its been a hard racing life too.
But there are a lot of ply boats here of the same age and if they've had a maintained life they're often good. There are the disasters as well of course.
While the boat has undergone an evolution of improvments over the years, still there were some structural problems involving failure of the plywood that needed correction. Cecile Maley would be able to give you more input on that than I.
Jay

[pcford]

Some of the very best boats and aircraft are built with plywood as the main ingredient. Luddite opinions notwithstanding, this has been true for over 100 years. The great majority of boats that are home-built today are being built of plywood.



My dislike for plywood has little to do with "Luddite opinions."

Plywood has definite problems in terms of longevity. And it is a pain to repair.

Solid wood is far more pleasant to work. For amateur builders I would think that this would be an attraction. Unfortunately many designers for the hobbyists would have you believe that building in solid wood is beyond the ability of most. Not true.

[Thad Van Gilder]

I agree. Having taught wood boat construction, I personally feel that solid planked lapstrake is the easiest way for a beginner. Not that one can't built a boat of plywood. You can. I just feel that its much easier for the beginner to hang a cedar plank than a plywood strake. Then there is a cost issue. decent plywood costs tons of cash... planking cedar is still quite cheap. The 9 foot cedar on teak garvey I planked up recently cost about 60 cent a square foot for 1/2 inch cedar planking. If I planked her up out of, say, 3/8 inch khaya ply it wood cost what? 4 or 5 bucks a square foot before epoxy and whatnot...

-Thad

[Bob Cleek]

I started this "luddite" thing about plywood and feel the need to chime in again. Plywood just is NOT the right thing to build boats out of. Now, I know, some decent looking boats have been built out of it, but on balance, as the "experts" in here have said, it costs more, it lasts less, and it's a bitch to work with, compared to wood off the tree like God made it. You can build a boxy little skiff out of plywood, or something designed without compound curves intended for plywood, but a plywood boat will never, ever, be worth anything near the same boat built traditionally of real wood. Never. Ever. Back when I was working in the brokerage years ago, we'd cringe when a plywood boat came in for sale. They always sold to a first time boat buyer. The smart money had no interest in them. Plywood has its place in FLAT surfaces to some extent. High quality plywood is fine for cabinet work and bulkheads, so long as you seal the hell out of it. Beyond that, unless you are just thinking about building a junky boat for fun as a goof, your labor and time are worth so much more than the materials, it makes no sense to skimp on materials. Too often, the plywood manufacturers' propaganda entices beginners to look to a plywood boat because they think it is "easy." It isn't at all. Natural wood is much easier to work. Building a boat may be a daunting enterprise, since there is so much to learn. Anything worth doing is worth doing well. There aren't any shortcuts. And, if you are thinking of building a boat for any purpose other than sheltered waters, a shortcut in boatbuilding may be the last one you take.

[Tom Lathrop]

I build boats for the water and furniture for the home. Rarely use plywood in furniture except for drawer bottoms and the occasional panel where its stability is the main attraction. I mainly use plywood in boats because I like its good qualities. I use solid timber in boats where I think it best meets the intended use. Many fine boats have been built from both materials. I recently finished a lapstrake boat where the strakes are glued plywood and the deck and seats are solid Honduras mahogany and the masts are aluminum. I think that was the best comonly available material for each use.

I don't mind if others build their boats from any material, even some that I may privately think are poor choices.

What is puzzling is the crusade against plywood. Get over it. It's been here since the ancient Egyptians and is not going away. It's just wood assembled in another way. If past experience is a good indicator, I expect many of my boats to still be giving pleasure to their owners long after I and many detractors here are long gone.

[pcford]

What is puzzling is the crusade against plywood. Get over it. It's been here since the ancient Egyptians and is not going away. It's just wood assembled in another way. If past experience is a good indicator, I expect many of my boats to still be giving pleasure to their owners long after I and many detractors here are long gone.

Those that have built their boat with plywood and are satisfied with the results...well, fine.

(You soon learn when a prospective client brings a boat in, you don't say anything about his dog, wife or boat.)

My remarks were more for prospective builders. I think they are often brainwashed into thinking that plywood is the only prudent path to take.

Bottom line...for me...solid wood is more pleasant to work with.

[MiddleAgesMan]

Try building a 15' 6" high performance skiff (like the Goat Island Skiff) out of solid lumber, keeping the designed hull weight at or under 130lb. If you go much beyond that weight you'll have a nice looking sailing skiff that needs a 1 mile head start in a 2 mile race.

You'll need 1/4" cedar or balsa planking but you can't use lapstrake 'cause it'll be slowed by the eddies, so it's carvel with 1/4" planking...

How's that work for you traditionalists? ;)

[Ray Frechette Jr]

Different horse for different courses.

both materials and methods have theri benefits and downsides.

Arguing that only one is the only proper way to build a boat and the only acceptable and prudent way is childish, arrogant and ignorant.

This forum seems to be rather full of such viewpoints

[Tom Lathrop]

Well said, Ray.:)

[patrick.blanchard]

Solid wood is aesthetically better than ply for me. However, cruising in blue water is aesthetically better of the three for me.

[Krunch]

Well said, Ray.:)

What he said. :rolleyes:

[Krunch]

Steaming would be a severe test of the glue.

Is that true? Somewhere on the Intardwebs I read that to be considered "waterproof," the test for plywood was to boil it, submerged, for 4 hours, then dry it in a 140°F oven for 20 hours, then boil it for 4 more hours, allow it to cool in the water, and then sheer-test it wet.

You mean to tell me that steaming it would be a more severe test of the glue than that?

I'm not trying to argue with you -- I'm just trying to understand.

[Sven Heesterman]

Ply only for flat surfaces?
http://houtenbootjes.nl/files/images/P9170375.preview.JPG

This hull is all ply. It is less work to maintain than any lumber built boat I know. A boat builder once said to me that it is still the cheapest way to build a lightweight, strong and stiff hull.

[AndreasJordahlRhude]

Plywood hull planking. Plywood transom. Plywood deck. Been around and in use since our family got her in the spring of 1965.

Andreas

http://i232.photobucket.com/albums/ee189/ThompsonBoat/rhude44-R3-041-19-1.jpg


Here's me on the same boat circa 1966. I'm the littlest one!
http://i232.photobucket.com/albums/ee189/ThompsonBoat/Andreas01-1.jpg

[kc8pql]

Is that true? Somewhere on the Intardwebs I read that to be considered "waterproof," the test for plywood was to boil it, submerged, for 4 hours, then dry it in a 140°F oven for 20 hours, then boil it for 4 more hours, allow it to cool in the water, and then sheer-test it wet.

You mean to tell me that steaming it would be a more severe test of the glue than that?

I'm not trying to argue with you -- I'm just trying to understand.

Yes, that is the test. If it survives it's good stuff, but do you want to build your boat out of ply that's been through a process designed to induce maximum stress and make it come apart if there is the least flaw? I wouldn't. :eek: