plywood for a tiny boat in Sydney, Australia?
 

On 15 Jul 2007 11:30:00 +1000, GB
wrote:

# This is a duplicate of a post I've just made to rec.woodworking,
seeperately posted here in the hope that someone here might be
able to help. thanks. #

Hi folks, this is my first post to this esteemed group. I'm
hoping that there's a few Australian participants besides
myself who might be able to cast some light on this enquiry...

I've recently stumbled across a couple of web sites with designs
for tiny one-sheet or one-and-a-half-sheet boats, and I thought
I might have a go at making one. There are a couple of gaps in
my knowledge though:

First, can someone suggest what I might expect to pay for an
appropriate sheet of circa 2440mm x 1220mm plywood in Sydney
Australia, along with suggestions as to a source. I looked
yesterday at my local 'Bunnings' (not really expecting to
find anything appropriate) and found that I could have any
sort of ply I wanted, so long as I wanted 600mm x 1200mm
sheets :-/ Locations from the city to the north-east are
most accessible to me. (Some indicative pricings from other
parts of the planet would be equally welcome)

Second, is there some sort of finish that I might apply to a
plywood boat that would provide the necessary waterproofing
whilst at the same time being clear, so the grain of the
wood remains visible?

Third, what type of plywood should I be looking for? Am I
correct in assuming that I must use 'marine ply' for this
light-use application in a small one-person boat, or are
there alternatives that I should consider? Price is more
of a consideration than durability, since my interest is
more in the building than the using!


Thanks in advance,


GB

I can't give you much advise about plywood size other then to say that
a 4" X 8" sheet is standard (1220 X 2440mm) and you should have no
problems locating plywood of that size.

You want to use either "marine grade" or "exterior grade" plywood.
They both use waterproof glue and the main difference is the allowable
voids in the cores. If you can find a yard that will let you pick
through a stack of exterior grade and select the one that doesn't show
any voids in the core then it will work perfectly well. If you just
have to take the sheet they give you then I would probably take the
marine grade, although it will be more expensive.

I'm not sure how you plan on building this boat but for a small dinghy
I'd use the "stitch and glue" method where you cut the various panels
to size and tie them together with wire, cable ties, strong string,
whatever, and then smear glue in the joints.

Once the glue has hardened you then fair the joints, using epoxy
filler, to a nice smooth radius and lastly tape over the joints with 4
inch fiberglass tape.

While initially this sounds like a lot of messing about it ends up
being easier then setting up a mold, cutting frames and building a
boat the traditional way. The stitch and glue boat will also be
lighter.

You can use anything to build a boat. BUT is it isn't waterproof it
won;t last long. If you build it out of proper materials you can
always sell it and get a little money back but something that is
splintering and de laminating will be a little hard to get rid of.

If you are interested in a really good small dinghy do a web search
for a "D4" dinghy. The plans are free and the guy's web site has a
wealth of information on building boats.




Bruce in Bangkok
(brucepaigeatgmaildotcom)

--
Posted via a free Usenet account from http://www.teranews.com

plywood for a tiny boat in Sydney, Australia?
 

"GB" wrote in message


concerned that the method didn't look nearly strong enough.
The design I had in mind was flat bottomed, (see the url below)
and I had planned on perhaps going beyond the reccomended jointing
methods screwing the bottom and sides to a piece of wood of
about 1in x 1in for the length of each join. Is that overkill?



http://personal.eunet.fi/pp/gsahv/dinghy1/simboii.htm


Hi
To answer a couple of your queries

The fibreglass taped join is far superior to a glued stringer-
Not overkill as it's not as strong.
Much easier to tape the chine.

To clear finish the best method is epoxy coating and then a clear UV
filtering varnish or polyurethane.
Having said that, if you are not going to store it in the sun for long
periods or keep it in wet conditions, eg if in a garage, then any cheap
varnish equivalent will do.

Peter HK

plywood for a tiny boat in Sydney, Australia?
 

On 15 Jul 2007 13:50:50 +1000, GB
wrote:

Bruce wrote in
:
I'm not sure how you plan on building this boat but for a small dinghy
I'd use the "stitch and glue" method where you cut the various panels
to size and tie them together with wire, cable ties, strong string,
whatever, and then smear glue in the joints.

I'd looked at similar approaches used on various web pages and
was concerned that the method didn't look nearly strong enough.
The design I had in mind was flat bottomed, (see the url below)
and I had planned on perhaps going beyond the reccomended jointing
methods screwing the bottom and sides to a piece of wood of
about 1in x 1in for the length of each join. Is that overkill?


[...]
If you are interested in a really good small dinghy do a web search
for a "D4" dinghy. The plans are free and the guy's web site has a
wealth of information on building boats.

That D4 does look like a very nice little boat. A bit more advanced
than what I had in mind though. Something like this:

http://personal.eunet.fi/pp/gsahv/dinghy1/simboii.htm

is where I'd planned to start. If that works out OK, then this
D4 design looks like a good next step!


Thank-you,


GB

Actually a properly made "stitch and glue" joint is probably stronger
then using a batten to screw to. Remember that there is a epoxy filler
fillet, usually about a half by half inch at each place the plywood
joins, which is then covered with a 4 inch fiberglass tape. I tape my
joints both inside and outside, which may be over kill, and while I
have never actually tested one to destruction I am willing to bet that
the joint is stronger then the parent plywood.

Of course it is your boat and you should build it the way you think
best but do take into consideration that literally thousands of stitch
and glue boats and if the method wasn't effective certainly there
would be comments all over the net.


Bruce in Bangkok
(brucepaigeatgmaildotcom)

--
Posted via a free Usenet account from http://www.teranews.com

plywood for a tiny boat in Sydney, Australia?
 

GB wrote:
Bruce wrote in
:
I'm not sure how you plan on building this boat but for a small
dinghy I'd use the "stitch and glue" method where you cut the
various panels to size and tie them together with wire, cable
ties, strong string, whatever, and then smear glue in the joints.

I'd looked at similar approaches used on various web pages and
was concerned that the method didn't look nearly strong enough.
The design I had in mind was flat bottomed, (see the url below)
and I had planned on perhaps going beyond the reccomended jointing
methods screwing the bottom and sides to a piece of wood of
about 1in x 1in for the length of each join. Is that overkill?

It is both overkill and a nuisance. A nuisance because it creates
more surfaces to sand and finish but primarily because those surfaces
also catch and hold water (and dirt) and water encourages rot.
____________________

If you are interested in a really good small dinghy do a web search
for a "D4" dinghy. The plans are free and the guy's web site has a
wealth of information on building boats.

That D4 does look like a very nice little boat. A bit more advanced
than what I had in mind though. Something like this:

It doesn't take that much more work and would be very little more
difficult if you made it for rowing only. The author of the one you
linked made a good point about a single lengthwise seat; it would need
more than one position for oarlocks.

Regardless of which you make, if you use "glue and stitch" practice
making the thickened epoxy fillets so that you can make them neatly
and uniformly - you'll save a ton of sanding. IMO, the easiest tool
to apply them is a sphere...possibly a rubber ball. Foam cylinders
work well too...I bought one of the foam pool toys...a cylinder about
2 1/2" in diameter and maybe four feet long. Cut off a piece about 2"
wide, apply/fair epoxy putty, throw away.

Also, do the gunnels well...they really stiffen everything up.


--

dadiOH
____________________________

dadiOH's dandies v3.06...
....a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico

plywood for a tiny boat in Sydney, Australia?
 

On Mon, 16 Jul 2007 11:23:21 GMT, "dadiOH"
wrote:

GB wrote:
Bruce wrote in
:
I'm not sure how you plan on building this boat but for a small
dinghy I'd use the "stitch and glue" method where you cut the
various panels to size and tie them together with wire, cable
ties, strong string, whatever, and then smear glue in the joints.

I'd looked at similar approaches used on various web pages and
was concerned that the method didn't look nearly strong enough.
The design I had in mind was flat bottomed, (see the url below)
and I had planned on perhaps going beyond the reccomended jointing
methods screwing the bottom and sides to a piece of wood of
about 1in x 1in for the length of each join. Is that overkill?

It is both overkill and a nuisance. A nuisance because it creates
more surfaces to sand and finish but primarily because those surfaces
also catch and hold water (and dirt) and water encourages rot.
____________________

If you are interested in a really good small dinghy do a web search
for a "D4" dinghy. The plans are free and the guy's web site has a
wealth of information on building boats.

That D4 does look like a very nice little boat. A bit more advanced
than what I had in mind though. Something like this:

It doesn't take that much more work and would be very little more
difficult if you made it for rowing only. The author of the one you
linked made a good point about a single lengthwise seat; it would need
more than one position for oarlocks.

Regardless of which you make, if you use "glue and stitch" practice
making the thickened epoxy fillets so that you can make them neatly
and uniformly - you'll save a ton of sanding. IMO, the easiest tool
to apply them is a sphere...possibly a rubber ball. Foam cylinders
work well too...I bought one of the foam pool toys...a cylinder about
2 1/2" in diameter and maybe four feet long. Cut off a piece about 2"
wide, apply/fair epoxy putty, throw away.

Also, do the gunnels well...they really stiffen everything up.

A trick I learned from a guy who does it every day is to grind a
radius on one corner of a putty-knife. He had several in different
sizes and radius. With the metal blade he could pretty well scrape all
the excess filler off the panels leaving only the fillet and then,
before the filler had hardened he taped over the fillet and rolled it
out. It takes a bit of practice but cuts out all the sanding of the
fillets.




Bruce in Bangkok
(brucepaigeatgmaildotcom)

--
Posted via a free Usenet account from http://www.teranews.com

plywood for a tiny boat in Sydney, Australia?
 

On 16 Jul 2007 22:18:28 +1000, GB
wrote:

Bruce wrote in
:
Of course it is your boat and you should build it the way you think
best but do take into consideration that literally thousands of stitch
and glue boats and if the method wasn't effective certainly there
would be comments all over the net.

I agree. I'm not questioning the method so much as questioning
my own knowledge of what works and what doesn't. I grew up in an
environment where tradesmen were never called, we figured out and
fixed /everything/ ourselves, be it plumbing, home extensions,
electricals and electronics. I've kinda developed a bit of a
feel for materials, and what works and what doesn't. You know,
certain types of glue will fix certain materials, and will be
completely ineffective on others, etc, etc. I have a bit of
difficulty with the concept of a near-solid (as in almost brittle)
epoxy contributing any sort of strength to a butted joint between
two bits of ply. I'm not saying it won't work, just that it
conflicts with my own experiential knowledge of how things 'work'.

On PVA type glues, I'm very much aware (and continually
amazed) by just how strong a join that stuff makes between two
pieces of timber, but again, I have conceptual problems with
using it on a join that's designed to be dunked in a pond!

My own exposure to fibreglass is limited to canoe-building class
in high school. Those were well before OHS days, so we were all
so high on the fumes that there wasn't much consciousness left
to develop a feeling for just how strong a fibre-tape/epoxy
join might be!!!


Hence all the questions! I'm sailing (pardon the pun) in
uncharted waters!


Thanks, I appreciate your comments.


GB

Try the epoxy before you ignore it.

Make a 90 degree butt joint with 1/4 inch plywood and glue it with
epoxy. Mix up some epoxy and some sort of filler, sanding dust from
the same kind of wood you are glueing works fine, and form a fillet
approximately 1/2 inch wide on the inside of the 90 degree joint, Then
wet out a 4 inch wide piece of glass tape with epoxy and place that
over the fillet. Roll out any bubbles and let it harden for 48 hours
and then try to break it. Twist it, pry it, whatever you want, and
you'll find that the plywood fails long before you can break the joint
itself.




Bruce in Bangkok
(brucepaigeatgmaildotcom)

--
Posted via a free Usenet account from http://www.teranews.com

plywood for a tiny boat in Sydney, Australia?
 

"GB" wrote in message
...
completely ineffective on others, etc, etc. I have a bit of
difficulty with the concept of a near-solid (as in almost brittle)
epoxy contributing any sort of strength to a butted joint between
two bits of ply. I'm not saying it won't work, just that it
conflicts with my own experiential knowledge of how things 'work'.

Well, take a look at this dinghy: www.customware.nl/boats
It is entirely glued together. Not a singe screw and even the skeg (20mm)
wide is simply glued to the keel.

I once did a test: everone keeps telling me that oak doesn't glue well with
epoxy so this was a good starting point for my experiment. I sanded the oak
with grit 40 across the grain, applied some epoxy and let it cure without
clamping.

Next day I drove a 3/16" nail straight through the seam, trying to break the
epoxy. It didn't. the wood around the nail gave up eventually.

My own exposure to fibreglass is limited to canoe-building class
in high school. Those were well before OHS days, so we were all
so high on the fumes that there wasn't much consciousness left
to develop a feeling for just how strong a fibre-tape/epoxy
join might be!!!

Epoxy does not produce fumes. You're mixing it up with polyester.

Meindert

plywood for a tiny boat in Sydney, Australia?
 

Bruce wrote:


A trick I learned from a guy who does it every day is to grind a
radius on one corner of a putty-knife. He had several in different
sizes and radius. With the metal blade he could pretty well scrape all
the excess filler off the panels leaving only the fillet and then,
before the filler had hardened he taped over the fillet and rolled it
out. It takes a bit of practice but cuts out all the sanding of the
fillets.




Bruce in Bangkok
(brucepaigeatgmaildotcom)


Bruce, you've been most helpful, so I'll add a tip of my own.

I've learned to mask off the area to be taped.

Make the area a touch larger than the width of the glass tape to be
used. You don't want the glass laying over teh mask!
Duct tape works fine as epoxy will not stick to it.

Then lay in the filet and glass tape and epoxy.

This makes for very neat seams with little clean up required.

Well, it works for me, anyway!

Richard
http://www.home.earthlink.net/~cavelamb/index.htm

plywood for a tiny boat in Sydney, Australia?
 

On Tue, 17 Jul 2007 18:34:12 GMT, cavelamb himself
wrote:

Bruce wrote:


A trick I learned from a guy who does it every day is to grind a
radius on one corner of a putty-knife. He had several in different
sizes and radius. With the metal blade he could pretty well scrape all
the excess filler off the panels leaving only the fillet and then,
before the filler had hardened he taped over the fillet and rolled it
out. It takes a bit of practice but cuts out all the sanding of the
fillets.




Bruce in Bangkok
(brucepaigeatgmaildotcom)


Bruce, you've been most helpful, so I'll add a tip of my own.

I've learned to mask off the area to be taped.

Make the area a touch larger than the width of the glass tape to be
used. You don't want the glass laying over teh mask!
Duct tape works fine as epoxy will not stick to it.

Then lay in the filet and glass tape and epoxy.

This makes for very neat seams with little clean up required.

Well, it works for me, anyway!

Richard
http://www.home.earthlink.net/~cavelamb/index.htm


Most guys in the business do exactly the same thing anytime they are
using something that can make a mess. If you are putting in ports with
sikaflex, for example, Mask around the area the sika will contact,
maybe leave a very tiny gap. Then after you set the port and the seka
just starts to harden you strip off the tape and you are left with
almost no clean-up at all.
Great stuff, masking tape.

Bruce in Bangkok
(brucepaigeatgmaildotcom)

--
Posted via a free Usenet account from http://www.teranews.com

plywood for a tiny boat in Sydney, Australia?
 

Bruce wrote:
On Tue, 17 Jul 2007 18:34:12 GMT, cavelamb himself
wrote:


Bruce wrote:


A trick I learned from a guy who does it every day is to grind a
radius on one corner of a putty-knife. He had several in different
sizes and radius. With the metal blade he could pretty well scrape all
the excess filler off the panels leaving only the fillet and then,
before the filler had hardened he taped over the fillet and rolled it
out. It takes a bit of practice but cuts out all the sanding of the
fillets.




Bruce in Bangkok
(brucepaigeatgmaildotcom)


Bruce, you've been most helpful, so I'll add a tip of my own.

I've learned to mask off the area to be taped.

Make the area a touch larger than the width of the glass tape to be
used. You don't want the glass laying over teh mask!
Duct tape works fine as epoxy will not stick to it.

Then lay in the filet and glass tape and epoxy.

This makes for very neat seams with little clean up required.

Well, it works for me, anyway!

Richard
http://www.home.earthlink.net/~cavelamb/index.htm



Most guys in the business do exactly the same thing anytime they are
using something that can make a mess. If you are putting in ports with
sikaflex, for example, Mask around the area the sika will contact,
maybe leave a very tiny gap. Then after you set the port and the seka
just starts to harden you strip off the tape and you are left with
almost no clean-up at all.
Great stuff, masking tape.

Bruce in Bangkok
(brucepaigeatgmaildotcom)


Yep, but I'll stick with Duct Tape -
so I'm not stuck with stuck tape!

g
Richard