For a kayak from lauan ply to have a hope of structural integrity and a long
life, a full glass sheathing is needed. If quality plywood such as bs1088
okoume or even marine fir is used, taped seams are fine. For two sheets of 1/4"
ply, you'll save maybe $90 by using the lauan, but the added cost of glass and
epoxy for sheathing will eat up most of those savings.
When you consider also the greater weight of the sheathed lauan boat, the extra
time spent building it and its certainly lower resale value, the economy of
cheap plywood is no bargain.

Fat Bass wrote:

I saw luan at the home store, 1/4" thick, seems relatively flexible.. Anyone
use this for building a kayak?

Jim Conlin wrote:
For a kayak from lauan ply to have a hope of structural integrity and a long
life, a full glass sheathing is needed.

Unless you paint it and maintain it properly.

If quality plywood such as bs1088
okoume or even marine fir is used,

It will also fall apart if not properly coated and maintained.

taped seams are fine. For two sheets of 1/4"
ply, you'll save maybe $90 by using the lauan, but the added cost of glass and
epoxy for sheathing will eat up most of those savings.
When you consider also the greater weight of the sheathed lauan boat, the extra
time spent building it and its certainly lower resale value, the economy of
cheap plywood is no bargain.


Realistically, whether built of matchsticks or fiberglass, what is the
resale value of a homebuilt kayak?

Sometimes it is worth standing back and realizing the potential useable
life and future value of a project and to build with appropriate
materials. Built of luann, the boat will last at least 10 years and
longer if properly maintained.

That said, if it is your preference to build a boat that could be bought
for 1/2 the price... more power to you.

Ed

If you have a place to keep the boat indoors when not in use then painted
lauan will last quite a while, the 10 years mentioned earlier is
resonable, depending on how roughly the boat is used. I have a laun
underlayment boat in its 4th season which is as good as new. I hang
it on the garage wall when not in use. For photos see
www.ncf.ca/~ag384/DogSkiff.htm.

I'm never sure when people mention 1/4" lauan what they mean. All we have
in Ottawa is the lauan underlayment, a low quality product with a thick
inner ply and two thin face plys. Its close to 1/4" but is actually metric
(5.22 mm?) and closer to 1/5". Its what the boat I have is made of. If you
find a regular 3 or 5 ply lauan plywood it would likely be better. I've
also read in this newsgroup of a better quality lauan plywood called
meranti available in some parts of the USA. The 1/5" underlayment that
I've used weighs about the same as the okume marine of similar thickness,
half a pound a square foot, or 17 pounds for a 4 x8 sheet.


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William R. Watt wrote:

I'm never sure when people mention 1/4" lauan what they mean. All we have
in Ottawa is the lauan underlayment, a low quality product with a thick
inner ply and two thin face plys. Its close to 1/4" but is actually metric
(5.22 mm?) and closer to 1/5". Its what the boat I have is made of. If you
find a regular 3 or 5 ply lauan plywood it would likely be better. I've
also read in this newsgroup of a better quality lauan plywood called
meranti available in some parts of the USA. The 1/5" underlayment that
I've used weighs about the same as the okume marine of similar thickness,
half a pound a square foot, or 17 pounds for a 4 x8 sheet.


For years, the local (mid-atlantic USA) lauan was the 3 ply stuff you
mention... minor voids (which can be filled in various ways if wanted
but usually it isn't big enough to worry about) and only one real
useable (for show) side. Recently (the past 2 years) it has a label
"Meranti" on it and I've wondered what it is. It is basically the same
plywood but the coloring of the wood is more variable, from yellow (like
birch) to more reddish like mahogany.

I've used both for repairs on boats (and regular interior and exterior
projects) and it holds up fine if painted (including varnish or
polyurethane) and maintained. For small utility type boats, the thing
I've picked up is to 1) install plenty of rub rails (pref. oak) and 2)
keep paint handy so when it gets scuffed (to the point where wood is
exposed) it can be touched up.

Ed

Ed Edelenbos wrote in message ...
Jim Conlin wrote:
For a kayak from lauan ply to have a hope of structural integrity and a long
life, a full glass sheathing is needed.

Unless you paint it and maintain it properly.

If quality plywood such as bs1088
okoume or even marine fir is used,

It will also fall apart if not properly coated and maintained.

taped seams are fine. For two sheets of 1/4"
ply, you'll save maybe $90 by using the lauan, but the added cost of glass and
epoxy for sheathing will eat up most of those savings.
When you consider also the greater weight of the sheathed lauan boat, the extra
time spent building it and its certainly lower resale value, the economy of
cheap plywood is no bargain.


Realistically, whether built of matchsticks or fiberglass, what is the
resale value of a homebuilt kayak?

Sometimes it is worth standing back and realizing the potential useable
life and future value of a project and to build with appropriate
materials. Built of luann, the boat will last at least 10 years and
longer if properly maintained.

That said, if it is your preference to build a boat that could be bought
for 1/2 the price... more power to you.

Ed


I have been for years an advocate of luan (only type III exterior) and
only if inspected very carefully both visually, and by running your
hand over it to listen for voids. I have recently started using only
okoume... if you can find it cheap enough the ease of work, the fair
bending, the easier to maintain finish, the extra strength, and did I
mention, because of the characteristics of the wood used, it is a lot
easier to work with... Personally, I have nothing against cheap
plywood, it is how I got started... but now with experience, I have
given up using it pretty much all together and I have not had a hull
crack under construction at an unseen void in years (trust me, the
first time it happens, you will curse your luan. Everyone touts the
money savings with cheap ply... but that is not my issue. All in all,
in every way, the okoume is a pleasure to work with and will in the
long run save you much time and energy... So on a two sheet skiff, you
might save 100 bucks but if you can build it a whole lot faster and
easier, the $ savings don't mean much.
Scotty from SmallBoats.com
Did I mention that Mahogany is a lot easier to work with than fir for
the trim and seats??? ) Flame suit.... ON....

Backyard Renegade wrote:

I have been for years an advocate of luan (only type III exterior) and
only if inspected very carefully both visually, and by running your
hand over it to listen for voids. I have recently started using only
okoume... if you can find it cheap enough the ease of work, the fair
bending, the easier to maintain finish, the extra strength, and did I
mention, because of the characteristics of the wood used, it is a lot
easier to work with... Personally, I have nothing against cheap
plywood, it is how I got started... but now with experience, I have
given up using it pretty much all together and I have not had a hull
crack under construction at an unseen void in years (trust me, the
first time it happens, you will curse your luan. Everyone touts the
money savings with cheap ply... but that is not my issue. All in all,
in every way, the okoume is a pleasure to work with and will in the
long run save you much time and energy... So on a two sheet skiff, you
might save 100 bucks but if you can build it a whole lot faster and
easier, the $ savings don't mean much.
Scotty from SmallBoats.com
Did I mention that Mahogany is a lot easier to work with than fir for
the trim and seats??? ) Flame suit.... ON....

Yeah, but is it easier to work with? (grin)

If I were building a boat for show or as advertising or for rougher
water, I would most likely use better materials... or maybe some
fiberglass. If I were building a boat to sell, I would offer the option
of better materials (with advice on what it provides, practically and
aesthetically and what it would cost). But for a little tub for me to
run up and down the creek, I see no reason to. If I come up with a
design I really like and think I'll want it to last for my lifetime
(which is getting shorter by the day), I'll probably use something else
(after building the first with cheap materials). But, the whole point
right now (for me at least) is doing it. Including breaking that first
hull during construction. (grin) And, I think the longest I've ever
owned a given boat is about 5 years. The lauan, even poorly maintained,
will outlast that milestone (grin).

Ed

Ed Edelenbos wrote in message ...
Backyard Renegade wrote:

I have been for years an advocate of luan (only type III exterior) and
only if inspected very carefully both visually, and by running your
hand over it to listen for voids. I have recently started using only
okoume... if you can find it cheap enough the ease of work, the fair
bending, the easier to maintain finish, the extra strength, and did I
mention, because of the characteristics of the wood used, it is a lot
easier to work with... Personally, I have nothing against cheap
plywood, it is how I got started... but now with experience, I have
given up using it pretty much all together and I have not had a hull
crack under construction at an unseen void in years (trust me, the
first time it happens, you will curse your luan. Everyone touts the
money savings with cheap ply... but that is not my issue. All in all,
in every way, the okoume is a pleasure to work with and will in the
long run save you much time and energy... So on a two sheet skiff, you
might save 100 bucks but if you can build it a whole lot faster and
easier, the $ savings don't mean much.
Scotty from SmallBoats.com
Did I mention that Mahogany is a lot easier to work with than fir for
the trim and seats??? ) Flame suit.... ON....

Yeah, but is it easier to work with? (grin)

If I were building a boat for show or as advertising or for rougher
water, I would most likely use better materials... or maybe some
fiberglass. If I were building a boat to sell, I would offer the option
of better materials (with advice on what it provides, practically and
aesthetically and what it would cost).

My point is that the cost is minimal as the good stuff is sooooo much
easier to work with, not only with the finish as some have noted, but
with construction itself... it holds fasteners better. Drills and saws
easier, bends fairer etc...


But for a little tub for me to
run up and down the creek, I see no reason to. If I come up with a
design I really like and think I'll want it to last for my lifetime
(which is getting shorter by the day), I'll probably use something else
(after building the first with cheap materials). But, the whole point
right now (for me at least) is doing it.

Doing it! Yes, doing it is worth much more than the few bucks or time
we will save or not on a cheap boat. Well then I say, have at it...
Fill the voids well and choose your luan well. Sometimes I have to
wait for another pallet for a couple of good pieces. Enjoy, as I have
said before, no man should die until he has wet a hull of his own
hand. And another thing, a salty old local told me long ago... "a good
paint job hides a lot of stuff".
Scotty from SmallBoats.com


Including breaking that first
hull during construction. (grin) And, I think the longest I've ever
owned a given boat is about 5 years. The lauan, even poorly maintained,
will outlast that milestone (grin).

Ed

I agree with the bending and creasing and splitting and breaking issue. I
check the bending radius of the plywood against the smallest bending
radius on the boat. I used lauan underlayment on a one sheet boat which I
bent as much as possible to get as much carrying capacity as possible, and
creased the underlayment a bit but not so that I couldn't use it. I even
soaked the panels in a rain barrel for two weeks to see if it would bend
more. I called taht boat a Loonie and sent the desgin and construction
details to Duckworks magazine where it appeared as an article. They've
archived it to CD now but I recently scanned some of the photos and put
them on my website at www.ncf.ca/~ag384/LULoonie.htm. If you look in the
index to the website www.ncf.ca/~ag384 you'll find a file called
BendingPlywood.txt which has the bending radius of some plywoods,
including what I found for lauan underlayment. However bending gunwales
and chine logs is a lot bigger problem than bending the plywood skin. I
had no trouble with the underlayment skin on the small skiff I built but
lots of trouble with the chinelogs and gunwales.

I've also posted in this newsgroup a technique I've used for finding and
filling voids in lauan underlayment. In a dark room you run a reading lamp
over the surface and look on the other side for the red streak which
indicates a void, and mark it with a pencil. Then you drill small holes
through a piece of tape and one face ply. With a caulkling gun you shoot
in some sort of goop to fill the void. I've used ordinary latex house
caulk and PL Premium polyurethane construction adhesive. Just keep
squeezing until the stuff runs out of the next hole. The piece of tape
keeps the goop from getting all over the surface of the plywood. I've
recently used the same technique to repair a crack in a small daggerboard,
drilling holes along the split, pumping in PL Premium, and weighing the
board down flat with bricks over plastic sheeting until the goop dried.
Although it sounds a bit involved there are some people who will walk a
mile to save a dime. I'm one of them. I have the dimes to prove it.

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Backyard Renegade wrote:

hand. And another thing, a salty old local told me long ago... "a good
paint job hides a lot of stuff".
Scotty from SmallBoats.com


Or, as an old carpenter told me once... "caulk, putty, and paint, makes
a carpenter what he ain't".

For some stuff (i.e. joints that are sound but aren't perfect), varnish
or primer mixed with the sawdust from a belt sander makes a great filler.

For a few years, I built guitars and dulcimers and such so my joinery is
(If I'm allowed to say so) not half bad. To some extent, building some
of these "tortured plywood" boats is very similar to some instrument
construction... just on a very large scale.

Ed

On Thu, 03 Jul 2003 13:50:08 GMT, "Fred Williams"
wrote:

Actually I have found 24C Gold plated (corrosion resistance) Titanium far
superior to any type of low life, proltarian, cheap, shoddy plywood. My
great great grandfather built one as a youth, and it is still in the family.

Fun with carrots:

Precious stones are measured in "carats" or "C" which is a unit of
weight. An engagement ring might have a 1 carat diamond in it.

Purity of gold is measured in "karats" or "K". It represents a
fraction of 24, so 12K gold is 12/24 or 50% gold and 50% other metals,
IIRC usually silver. It ain't no big thing, but Fred meant "... 24K
gold plated..."

Now back to your regularly scheduled discussion of plywood quality.

- Rick Tyler