[bolger] Re: Door skins & glass
Just as an added info, Jacques Mertens of bateau.com is reengineering
his larger boats (Vagabond and Serpentaire) using thin plywood (6 mm)
sandwiched between two layers of biaxial fiberglass (9 oz) in epoxy
resin. The advantages are not only structural: the 6mm plywood is much
easier to bend and wrap around bulkheads than thicker stuff. Jacques
says that such sandwich is significantly stronger than 9 mm plywood.
According to my computations, though, the gain in weight is very
limited if any, and the overall cost is very significantly increased.
And, folks, just think about crawling into a 6 meter hull and laminated
10 square meters of biaxial cloth...
Best, Pippo
ghc <ghart-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=643
his larger boats (Vagabond and Serpentaire) using thin plywood (6 mm)
sandwiched between two layers of biaxial fiberglass (9 oz) in epoxy
resin. The advantages are not only structural: the 6mm plywood is much
easier to bend and wrap around bulkheads than thicker stuff. Jacques
says that such sandwich is significantly stronger than 9 mm plywood.
According to my computations, though, the gain in weight is very
limited if any, and the overall cost is very significantly increased.
And, folks, just think about crawling into a 6 meter hull and laminated
10 square meters of biaxial cloth...
Best, Pippo
ghc <ghart-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=643
> Actually, glass is very, very, very strong. A good fir might be14,000 psi
> in tensile strength (at best with no flaws), but E glass is good forplywood
> 450,000 psi! It's relatively dense, though, and a thin sheet of
> doesn't spread it apart very far for your composite sandwich. Wood isin a
> light, and relatively strong, so it's easier to get a lot more wood
> structure than glass (with minimal resin).the
>
> In bending of a panel, the tensile and compressive stresses do lie on
> surface, but the shear flows through the middle, trying to separateyour
> sandwich. Your core needs to have good material properties, likebalsa or
> klegecell, not like blue styrofoam.with
>
> Gregg Carlson
>
>
>
>
>
> At 02:24 PM 11/1/1999 -0800, you wrote:
> >David Ryan wrote:
> >
> >> I've been wondering about using very thin plywood in combination
> >> a heavier glass job to make very light boat (kayaks, hollow paddlestronger
> >> boards, etc.)
> >
> >This idea seems to stem from the mistaken notion that glass is
> >and lighter than wood, especially plywood. It is not, particularly inIn
> >the stiffness modulus, which is the most important in boat building.
> >fact fiberglass is a relatively limp material. It is also relativelyseams.
> >heavy for its strength. Plywood is still one the strongest material
> >available on a pound of pound basis.
> >
> >Fiberglass is used on plywood boat construction not for strength, but
> >for waterproofing and abrasion resistance. On a plywood boat it adds
> >almost nothing to the overall strength of the boat.
> >
> >To make a very light boat, use the thinnest plywood possible for the
> >boat being built and omit using any glass except perhaps on the
> >two
> >The best way to make something stiff yet light is to separate two
> >materials that are very strong in both shear, tension and compresion
> >with a very light core. Cores are often some type of foam of balsa
> >wood. Strength of the core doesnt matter, whats important is how
> >friable it is (meaning how well the surface is attached. If you rub
> >pieces of foam together and the surface rubs off the material isskins
> >friable and no good for composite construction. The reason is the
> >will separate form the core under stress making the structure nolonger
> >a composite and very weak.) What makes a composite strong is that thevery
> >structure transmits all loads to its strongest part, the skin. A
> >composites strength is directly related to how far the skins are held
> >apart, the farther apart the stronger. Obviously, if you bend a
> >composite structure the skin on the outside of the bend is loaded in
> >tension, the inside skin in compression. Here again, fiberglass is
> >weak in compression, especially compared to plywood. Plywood is very
> >strong in compression. In short, one of the lightest and strongest
> >composites you can make is by gluing very thin plywood to the inside
> >and outside of a foam sheet. Blue polyfoam is used in some airplane
> >construction because it is light, cheep and relatively unfriable.
> >
> >Bernie
> >Change is a proccess not an event.
> >
> >
Actually, glass is very, very, very strong. A good fir might be 14,000 psi
in tensile strength (at best with no flaws), but E glass is good for
450,000 psi! It's relatively dense, though, and a thin sheet of plywood
doesn't spread it apart very far for your composite sandwich. Wood is
light, and relatively strong, so it's easier to get a lot more wood in a
structure than glass (with minimal resin).
In bending of a panel, the tensile and compressive stresses do lie on the
surface, but the shear flows through the middle, trying to separate your
sandwich. Your core needs to have good material properties, like balsa or
klegecell, not like blue styrofoam.
Gregg Carlson
At 02:24 PM 11/1/1999 -0800, you wrote:
in tensile strength (at best with no flaws), but E glass is good for
450,000 psi! It's relatively dense, though, and a thin sheet of plywood
doesn't spread it apart very far for your composite sandwich. Wood is
light, and relatively strong, so it's easier to get a lot more wood in a
structure than glass (with minimal resin).
In bending of a panel, the tensile and compressive stresses do lie on the
surface, but the shear flows through the middle, trying to separate your
sandwich. Your core needs to have good material properties, like balsa or
klegecell, not like blue styrofoam.
Gregg Carlson
At 02:24 PM 11/1/1999 -0800, you wrote:
>David Ryan wrote:
>
>> I've been wondering about using very thin plywood in combination with
>> a heavier glass job to make very light boat (kayaks, hollow paddle
>> boards, etc.)
>
>This idea seems to stem from the mistaken notion that glass is stronger
>and lighter than wood, especially plywood. It is not, particularly in
>the stiffness modulus, which is the most important in boat building. In
>fact fiberglass is a relatively limp material. It is also relatively
>heavy for its strength. Plywood is still one the strongest material
>available on a pound of pound basis.
>
>Fiberglass is used on plywood boat construction not for strength, but
>for waterproofing and abrasion resistance. On a plywood boat it adds
>almost nothing to the overall strength of the boat.
>
>To make a very light boat, use the thinnest plywood possible for the
>boat being built and omit using any glass except perhaps on the seams.
>
>The best way to make something stiff yet light is to separate two
>materials that are very strong in both shear, tension and compresion
>with a very light core. Cores are often some type of foam of balsa
>wood. Strength of the core doesn�t matter, what�s important is how
>friable it is (meaning how well the surface is attached. If you rub two
>pieces of foam together and the surface rubs off the material is
>friable and no good for composite construction. The reason is the skins
>will separate form the core under stress making the structure no longer
>a composite and very weak.) What makes a composite strong is that the
>structure transmits all loads to its strongest part, the skin. A
>composites strength is directly related to how far the skins are held
>apart, the farther apart the stronger. Obviously, if you bend a
>composite structure the skin on the outside of the bend is loaded in
>tension, the inside skin in compression. Here again, fiberglass is very
>weak in compression, especially compared to plywood. Plywood is very
>strong in compression. In short, one of the lightest and strongest
>composites you can make is by gluing very thin plywood to the inside
>and outside of a foam sheet. Blue polyfoam is used in some airplane
>construction because it is light, cheep and relatively unfriable.
>
>Bernie
>Change is a proccess not an event.
>
>
>------------------------------------------------------------------------
>-- Check out your eGroup's private Chat room
>--http://www.egroups.com/ChatPage?listName=bolger&m=1
>
>
>
David Ryan wrote:
and lighter than wood, especially plywood. It is not, particularly in
the stiffness modulus, which is the most important in boat building. In
fact fiberglass is a relatively limp material. It is also relatively
heavy for its strength. Plywood is still one the strongest material
available on a pound of pound basis.
Fiberglass is used on plywood boat construction not for strength, but
for waterproofing and abrasion resistance. On a plywood boat it adds
almost nothing to the overall strength of the boat.
To make a very light boat, use the thinnest plywood possible for the
boat being built and omit using any glass except perhaps on the seams.
The best way to make something stiff yet light is to separate two
materials that are very strong in both shear, tension and compresion
with a very light core. Cores are often some type of foam of balsa
wood. Strength of the core doesnt matter, whats important is how
friable it is (meaning how well the surface is attached. If you rub two
pieces of foam together and the surface rubs off the material is
friable and no good for composite construction. The reason is the skins
will separate form the core under stress making the structure no longer
a composite and very weak.) What makes a composite strong is that the
structure transmits all loads to its strongest part, the skin. A
composites strength is directly related to how far the skins are held
apart, the farther apart the stronger. Obviously, if you bend a
composite structure the skin on the outside of the bend is loaded in
tension, the inside skin in compression. Here again, fiberglass is very
weak in compression, especially compared to plywood. Plywood is very
strong in compression. In short, one of the lightest and strongest
composites you can make is by gluing very thin plywood to the inside
and outside of a foam sheet. Blue polyfoam is used in some airplane
construction because it is light, cheep and relatively unfriable.
Bernie
Change is a proccess not an event.
> I've been wondering about using very thin plywood in combination withThis idea seems to stem from the mistaken notion that glass is stronger
> a heavier glass job to make very light boat (kayaks, hollow paddle
> boards, etc.)
and lighter than wood, especially plywood. It is not, particularly in
the stiffness modulus, which is the most important in boat building. In
fact fiberglass is a relatively limp material. It is also relatively
heavy for its strength. Plywood is still one the strongest material
available on a pound of pound basis.
Fiberglass is used on plywood boat construction not for strength, but
for waterproofing and abrasion resistance. On a plywood boat it adds
almost nothing to the overall strength of the boat.
To make a very light boat, use the thinnest plywood possible for the
boat being built and omit using any glass except perhaps on the seams.
The best way to make something stiff yet light is to separate two
materials that are very strong in both shear, tension and compresion
with a very light core. Cores are often some type of foam of balsa
wood. Strength of the core doesnt matter, whats important is how
friable it is (meaning how well the surface is attached. If you rub two
pieces of foam together and the surface rubs off the material is
friable and no good for composite construction. The reason is the skins
will separate form the core under stress making the structure no longer
a composite and very weak.) What makes a composite strong is that the
structure transmits all loads to its strongest part, the skin. A
composites strength is directly related to how far the skins are held
apart, the farther apart the stronger. Obviously, if you bend a
composite structure the skin on the outside of the bend is loaded in
tension, the inside skin in compression. Here again, fiberglass is very
weak in compression, especially compared to plywood. Plywood is very
strong in compression. In short, one of the lightest and strongest
composites you can make is by gluing very thin plywood to the inside
and outside of a foam sheet. Blue polyfoam is used in some airplane
construction because it is light, cheep and relatively unfriable.
Bernie
Change is a proccess not an event.
I have some experience to relate on both subjects: bad news first - I set
out to build a fishing pram "light enough for one person to handle in a
pickup truck and big enough for two people to fish". It is built of 3/4
inch blueboard (peeled of its polyethylene scrim, a chore in itself) with
taped seams and 6 oz cloth/epoxy inside and out. A little over 11 feet
long, it weighs 80 lb, has a built - in fishbox amidships which stiffens the
structure somewhat. Alas, it is so flimsy and fragile that it fails the
"handle in a pickup" test. It has to be trailered or handled on a separate
padded skid. I glued in doorskin floorboards so that I could walk on the
sole. It rows nicely, but I got impatient and fitted a 6 hp outboard which
is rapidly disintegrating the boat. I'll probably give her away to somebody
who can drag her up on a pond or creek shore. I/4 ply would have been a
much better choice of materials, probably about the same weight, much more
rugged, quicker to build and much less expensive. I think blueboard
laminated on or both sides with doorskin may be interesting for light
"furniture", but I'm over it as a structural core.
Now the good news - I have made several sets of oars using doorskins
laminated in 6 oz cloth both sides. I'll try to paste in a post I made to
rec.boats.building recently on this subject:
I have made several pairs of oars using split studs as previously described;
additionally, I set my circular saw at 45 degrees and rip the stock to
octagonal shape. I make blades in bulk by laminating 6 oz. glass to both
sides of 1/8 luan doorskin. My blades are 5 inches by 22 inches, with a
taper from the 17 inch point to the 22 inch point from 5 inches down to the
dimension of the stock. The tapered part of the blade fits into the slit
in the stock, the slit (about 10 inches long) is just the ordinary kerf of a
saw blade. I also
radius the corners of the blades using a coin to mark the curve tangent to
the edges. These oars take a few more minutes but are quite satisfactory .
If you want curved blades, leave a 1-inch tab on the ends of the blades,
drill a 1/8 hole and precurve the blades with a piece of wire, cord or
fishline
before laminating. The blade will retain about half the curve. Saw off the
tabs before painting the blades.
I have also made kayak paddle blades from doorskin, cupped by cutting a
narrow "dart" in them and putting in a wire stitch before laminating. These
blades are as designed by Glen-L for their Sea Kayak kit. My shaft,
however, is laminated by placing black pipe insulating foam over a "Spanish
windlass" and winding it tight, creating a lightweight form. I laminate
this with fiberglass tape; makes a 100 inch shaft weighing about a pound.
Finally, Kurt Hughes used to recommend laminating doorskins into coldmolded
panels using his "Constant Camber" method, but in recent years he has gone
to structural foam, reportedly because the doorskin quality was so poor that
he is wary of penetration/rot in immersed structure. I think it would be OK
in structures dry-sailed or trailered, but would not bet several hundred or
thousand hours of labor on it in a big project.
Don Hodges
dhodges@...
http://www.ecoastlife.com
Your Cyber-Vacation - Loafing on the Emerald Coast
Small Boats, Building, Fishing, Paddling, Rowing, Sailing
out to build a fishing pram "light enough for one person to handle in a
pickup truck and big enough for two people to fish". It is built of 3/4
inch blueboard (peeled of its polyethylene scrim, a chore in itself) with
taped seams and 6 oz cloth/epoxy inside and out. A little over 11 feet
long, it weighs 80 lb, has a built - in fishbox amidships which stiffens the
structure somewhat. Alas, it is so flimsy and fragile that it fails the
"handle in a pickup" test. It has to be trailered or handled on a separate
padded skid. I glued in doorskin floorboards so that I could walk on the
sole. It rows nicely, but I got impatient and fitted a 6 hp outboard which
is rapidly disintegrating the boat. I'll probably give her away to somebody
who can drag her up on a pond or creek shore. I/4 ply would have been a
much better choice of materials, probably about the same weight, much more
rugged, quicker to build and much less expensive. I think blueboard
laminated on or both sides with doorskin may be interesting for light
"furniture", but I'm over it as a structural core.
Now the good news - I have made several sets of oars using doorskins
laminated in 6 oz cloth both sides. I'll try to paste in a post I made to
rec.boats.building recently on this subject:
I have made several pairs of oars using split studs as previously described;
additionally, I set my circular saw at 45 degrees and rip the stock to
octagonal shape. I make blades in bulk by laminating 6 oz. glass to both
sides of 1/8 luan doorskin. My blades are 5 inches by 22 inches, with a
taper from the 17 inch point to the 22 inch point from 5 inches down to the
dimension of the stock. The tapered part of the blade fits into the slit
in the stock, the slit (about 10 inches long) is just the ordinary kerf of a
saw blade. I also
radius the corners of the blades using a coin to mark the curve tangent to
the edges. These oars take a few more minutes but are quite satisfactory .
If you want curved blades, leave a 1-inch tab on the ends of the blades,
drill a 1/8 hole and precurve the blades with a piece of wire, cord or
fishline
before laminating. The blade will retain about half the curve. Saw off the
tabs before painting the blades.
I have also made kayak paddle blades from doorskin, cupped by cutting a
narrow "dart" in them and putting in a wire stitch before laminating. These
blades are as designed by Glen-L for their Sea Kayak kit. My shaft,
however, is laminated by placing black pipe insulating foam over a "Spanish
windlass" and winding it tight, creating a lightweight form. I laminate
this with fiberglass tape; makes a 100 inch shaft weighing about a pound.
Finally, Kurt Hughes used to recommend laminating doorskins into coldmolded
panels using his "Constant Camber" method, but in recent years he has gone
to structural foam, reportedly because the doorskin quality was so poor that
he is wary of penetration/rot in immersed structure. I think it would be OK
in structures dry-sailed or trailered, but would not bet several hundred or
thousand hours of labor on it in a big project.
Don Hodges
dhodges@...
http://www.ecoastlife.com
Your Cyber-Vacation - Loafing on the Emerald Coast
Small Boats, Building, Fishing, Paddling, Rowing, Sailing
----- Original Message -----
From: Ron Badley <badley@...>
To: <bolger@egroups.com>
Sent: Sunday, October 31, 1999 12:24 AM
Subject: [bolger] Re: Door skins & glass
> David,
>
> Glass/resin is not a very light weight material for building
> boats. If you were to use 1/8" ply and cover it with several
> layers of glass you would quickly meet or exceed the weight of
> painted 1/4" plywood and spend a bunch more money.
>
> In pounds per sqft....
>
> 1/8" door skin .35 (estimate)
>
> 1/4" ply/fir .80
>
> 3/8" ply 1.13
>
> 10 oz cloth/resin .12
>
> If the boat is small, like a kayak, then 1/8" will be plenty
> strong enough with one or two layers of glass on the outside.
> Quite light as well.
>
> If the boat is bigger than a kayak and light weight is the
> ultimate goal the best way to go is foam core (not blue foam)
> with carbon fibre. Next will be foam with a less high tech and
> more affordable cloth. Strip cedar is also very light and among
> the more cost effective, depending on where you live. Foam core
> and cloth is not much more expensive than the very good quality
> plywoods. Makes for a light boat that has some insulating
> value, wont sweat and has some built in floatation. Still works
> very well as flat panels for chine construction.
>
> That said, I built two simple 11'6" double paddle canoes in
> the Bolger fasion a couple years ago. They aren't Bolger boxes,
> but they're close. They have 1/4" ply bottoms with door skin
> for the sides and for the half decks. I taped the seams with
> cloth/epoxy and gave them a good coat of paint. They have held
> up very well, always stored outside, upside down, but not under
> cover. One meet an eary demise this spring due to poor aim by
> me while pitching rocks out of the yard, but the other is still
> going strong. I've never weighed them but I'd guess at about 30
> pounds each. Both were built in about about 12 hours and cost
> less than $100. Thats hard to beat with glass/resin.
>
> Ron
>
> >From: David Ryan <david@...>
>
> > Fellow Bolger Boat Builders --
> >
> > I've been wondering about using very thin plywood in combination with
> > a heavier glass job to make very light boat (kayaks, hollow paddle
> > boards, etc.)
> >
> > The function (in my mind, at least, ) of the ply is to provide a
> > shape to lay the glass over. The real strength of the whole thing is
> > in the framing and glasswork.
> >
> > Anyone have any insights into whether or not this is a good idea, and
> > why or why not?
> >
> > Yours in boat building,
> >
> > David Ryan
> > Minister of Information and Culture
> > Crumbling Empire Productions
> > (212) 247-0296
>
> ------------------------------------------------------------------------
> A shopper's dream come true! Find practically anything on earth at eBay!
> Come and browse the more than 2 million items up for bid at any time.
> You never know what you might find at eBay!
>http://clickhere.egroups.com/click/1140
>
>
> eGroups.com home:http://www.egroups.com/group/bolger
>http://www.egroups.com- Simplifying group communications
>
>
>
>
>From: David Ryan <david@...>It depends on how extreme you want to get. The stiffness of a panel depends
>I've been wondering about using very thin plywood in combination with
>a heavier glass job to make very light boat (kayaks, hollow paddle
>boards, etc.)
>
>The function (in my mind, at least, ) of the ply is to provide a
>shape to lay the glass over. The real strength of the whole thing is
>in the framing and glasswork.
>
>Anyone have any insights into whether or not this is a good idea, and
>why or why not?
on the cube of its thickness, so reducing thickness by half reduces
stiffness to one eighth of its original value. This might not matter if the
boat was originally ridiculously overengineered and superstiff, but if it's
Bolger we're talking about here, he tends to cut these things very fine.
Of course the glass will help stiffen things up a little, but the secret of
light weight is to build out of thick, very light material (say foam, or
balsa) and put on a strong glass skin either side. That's why foam core
construction is so common among mean, lean racing machines.
Bill
>--bill.samson@...
>Yours in boat building,
>
>David Ryan
>Minister of Information and Culture
>Crumbling Empire Productions
>(212) 247-0296
>
>------------------------------------------------------------------------
>A shoppers dream come true! Find practically anything on earth at eBay!
>Come and browse the more than 2 million items up for bid at any time.
>You never know what you might find at eBay!
>http://clickhere.egroups.com/click/1140
>
>
>eGroups.com home:http://www.egroups.com/group/bolger
>http://www.egroups.com- Simplifying group communications
>
>
>
>
>
Chebacco News can be viewed on:
http://members.xoom.com/billsamson
David,
Glass/resin is not a very light weight material for building
boats. If you were to use 1/8" ply and cover it with several
layers of glass you would quickly meet or exceed the weight of
painted 1/4" plywood and spend a bunch more money.
In pounds per sqft....
1/8" door skin .35 (estimate)
1/4" ply/fir .80
3/8" ply 1.13
10 oz cloth/resin .12
If the boat is small, like a kayak, then 1/8" will be plenty
strong enough with one or two layers of glass on the outside.
Quite light as well.
If the boat is bigger than a kayak and light weight is the
ultimate goal the best way to go is foam core (not blue foam)
with carbon fibre. Next will be foam with a less high tech and
more affordable cloth. Strip cedar is also very light and among
the more cost effective, depending on where you live. Foam core
and cloth is not much more expensive than the very good quality
plywoods. Makes for a light boat that has some insulating
value, wont sweat and has some built in floatation. Still works
very well as flat panels for chine construction.
That said, I built two simple 11'6" double paddle canoes in
the Bolger fasion a couple years ago. They aren't Bolger boxes,
but they're close. They have 1/4" ply bottoms with door skin
for the sides and for the half decks. I taped the seams with
cloth/epoxy and gave them a good coat of paint. They have held
up very well, always stored outside, upside down, but not under
cover. One meet an eary demise this spring due to poor aim by
me while pitching rocks out of the yard, but the other is still
going strong. I've never weighed them but I'd guess at about 30
pounds each. Both were built in about about 12 hours and cost
less than $100. Thats hard to beat with glass/resin.
Ron
Glass/resin is not a very light weight material for building
boats. If you were to use 1/8" ply and cover it with several
layers of glass you would quickly meet or exceed the weight of
painted 1/4" plywood and spend a bunch more money.
In pounds per sqft....
1/8" door skin .35 (estimate)
1/4" ply/fir .80
3/8" ply 1.13
10 oz cloth/resin .12
If the boat is small, like a kayak, then 1/8" will be plenty
strong enough with one or two layers of glass on the outside.
Quite light as well.
If the boat is bigger than a kayak and light weight is the
ultimate goal the best way to go is foam core (not blue foam)
with carbon fibre. Next will be foam with a less high tech and
more affordable cloth. Strip cedar is also very light and among
the more cost effective, depending on where you live. Foam core
and cloth is not much more expensive than the very good quality
plywoods. Makes for a light boat that has some insulating
value, wont sweat and has some built in floatation. Still works
very well as flat panels for chine construction.
That said, I built two simple 11'6" double paddle canoes in
the Bolger fasion a couple years ago. They aren't Bolger boxes,
but they're close. They have 1/4" ply bottoms with door skin
for the sides and for the half decks. I taped the seams with
cloth/epoxy and gave them a good coat of paint. They have held
up very well, always stored outside, upside down, but not under
cover. One meet an eary demise this spring due to poor aim by
me while pitching rocks out of the yard, but the other is still
going strong. I've never weighed them but I'd guess at about 30
pounds each. Both were built in about about 12 hours and cost
less than $100. Thats hard to beat with glass/resin.
Ron
>From: David Ryan <david@...>
> Fellow Bolger Boat Builders --
>
> I've been wondering about using very thin plywood in combination with
> a heavier glass job to make very light boat (kayaks, hollow paddle
> boards, etc.)
>
> The function (in my mind, at least, ) of the ply is to provide a
> shape to lay the glass over. The real strength of the whole thing is
> in the framing and glasswork.
>
> Anyone have any insights into whether or not this is a good idea, and
> why or why not?
>
> Yours in boat building,
>
> David Ryan
> Minister of Information and Culture
> Crumbling Empire Productions
> (212) 247-0296
Actually, this is "cored" fiberglass construction; just like the guy who
built a Skimmer using blue insulation material as the core for lightness
and it seems to have worked).
The guys at Fiberglass Coatings indicated if you were building for "stiff"
(as opposed to "abrasion") you would use lots of mat and woven roven to
build thickness fast. Mat gives rigidity, glass cloth give abrasion
resistance and hardness.
Most core construction happens in a mold because the underlying coring is
usally quite fragile (balsa, klegecell) and won't hold fastenings prior to
glassing. Doorskins might be a workable idea.
Robert Lundy
St. Petersburg, Fla.
built a Skimmer using blue insulation material as the core for lightness
and it seems to have worked).
The guys at Fiberglass Coatings indicated if you were building for "stiff"
(as opposed to "abrasion") you would use lots of mat and woven roven to
build thickness fast. Mat gives rigidity, glass cloth give abrasion
resistance and hardness.
Most core construction happens in a mold because the underlying coring is
usally quite fragile (balsa, klegecell) and won't hold fastenings prior to
glassing. Doorskins might be a workable idea.
Robert Lundy
St. Petersburg, Fla.
> -----Original Message-----
> From: David Ryan [mailto:david@...]
> Sent: 30 October, 1999 4:17 PM
> To:bolger@egroups.com
> Subject: [bolger] Door skins & glass
>
>
> Fellow Bolger Boat Builders --
>
> I've been wondering about using very thin plywood in combination with
> a heavier glass job to make very light boat (kayaks, hollow paddle
> boards, etc.)
>
> The function (in my mind, at least, ) of the ply is to provide a
> shape to lay the glass over. The real strength of the whole thing is
> in the framing and glasswork.
>
> Anyone have any insights into whether or not this is a good idea, and
> why or why not?
>
> Yours in boat building,
>
> David Ryan
> Minister of Information and Culture
> Crumbling Empire Productions
> (212) 247-0296
>
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Fellow Bolger Boat Builders --
I've been wondering about using very thin plywood in combination with
a heavier glass job to make very light boat (kayaks, hollow paddle
boards, etc.)
The function (in my mind, at least, ) of the ply is to provide a
shape to lay the glass over. The real strength of the whole thing is
in the framing and glasswork.
Anyone have any insights into whether or not this is a good idea, and
why or why not?
Yours in boat building,
David Ryan
Minister of Information and Culture
Crumbling Empire Productions
(212) 247-0296
I've been wondering about using very thin plywood in combination with
a heavier glass job to make very light boat (kayaks, hollow paddle
boards, etc.)
The function (in my mind, at least, ) of the ply is to provide a
shape to lay the glass over. The real strength of the whole thing is
in the framing and glasswork.
Anyone have any insights into whether or not this is a good idea, and
why or why not?
Yours in boat building,
David Ryan
Minister of Information and Culture
Crumbling Empire Productions
(212) 247-0296