On Mon, 27 Sep 2010 23:13:45 -0400, I am Tosk
wrote:

In article ,
says...

On Mon, 27 Sep 2010 06:58:45 -0400, I am Tosk
wrote:

In article ,
says...

On Sat, 25 Sep 2010 18:21:02 -0400, I am Tosk
wrote:

In article 084c9f63-3d17-496f-8a21-74c4d53f4a02
, says...

MiniCup #`1 is still sitting on sawhorses while I decide whether or
not to rebuild her. #2 which I have been using developed cracks from
rot in the 3/16" poor quality ply I used on her even though she had
been glassed with 4 oz glass and epoxy. While fixing this I found
more rot so ended up covering her entire rear with another layer of
glass. Am almost done. However, she seems to have absorbed some
water that I cannot get rid of as she seems heavy even with ports cut
in all her spaces.
Am looking over the old MiniCup plans and considering how to design a
modern version that will be much lighter. Considering using 3mm
Okuome Ply covered with 8 oz glass all over with stiffening ribs of
foam and glass. All interior joints would be glass taped and interior
epoxied as well to seal the wood. Transom would be reinforced with
thicker ply and G10 glass composite for the rudder stresses. Cockpit
and mast step would be self bailing and all hardware of either bronze
or SS. Instead of being a "hardware store boat", I'd specify buying
actual boatbuilding screws and pulleys made for boats. I'd reccomend
buying 1/8" Al tubing for the mast and 1/16" for the two other spars.
The sail should be sewn from white polytarp, none of this duct tape
stuff and visqueen. I have devised a much improved gooseneck where
the two spars attach to the mast. Any other ideas?

Sounds to me like you are going to use 1/8 inch ply and glass for
structure.. Glass doesn't add structure really it should be used for
protection if not laminated into a hull... Use 6mm plywood and protect
it with 4 oz tight weave if you need abrasion protection and such...

Err.. why is it that glass over plywood doesn't add structure while
glass cloth over foam does?

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Laminated glass might. One layer over a 3mm plywood, not so much... In
most applications for small boats such as this, the glass is more as a
sealer and protection than a structural component. Especially one layer
of 4 oz tight weave...


Agreed that a layer of glass on one side is inferior to glass on both
sides but I would argue that it is far more then simply a sealer.

Not what I said at all, for smaller boats, glass on both sides only
invites more rotting and moisture retention...

I know that you keep saying that but in my experience it just isn't
true. Example: I built a glass over waterproof plywood, nor 15 years
ago. Glassed it inside and outside - heavy as hell! It is still being
used and has, to date, not started to rot.

Quite a few strip planked boats have been built, glassed inside and
out, with no noticeable decrease in life.

In
fact if it is simply a sealer there would be no sense in applying the
cloth as glass cloth is far from being water proof, quite the contrary
in fact.

Of course there would be "sense" in applying the glass. To understand
you must first understand that glass it to hold resin, resin is to fill
glass.. They work together, it's just the way it is...

That is not true at all. I have finished a number of objects with
nothing but resin. Works perfectly well.

If sealing were the sole purpose then all the boat designers wouldn't
be recommending "glass over...." .

Sure they would, cause glass it to hold resin...

The layer of glass actually makes the 3 mm ply substantially more
resistant to bending then bare ply would be. A parallel might be
fabric covered aircraft where the airframe is covered with a cloth
which is perhaps less strong then a bed sheet, which is then
reinforced with coats of cellulose dope.

Don't know much about airplanes but I bet the framework is substantial
under that skin. Either way, a 4 oz layer of glass over 6mm Occoume does
not all all that much stiffness. Glass is good for adding structure when
laminated into fillets, but trying to use it to stiffen a plywood hull
is a waste of time and poor design.

The guy who taught me to use glass and resin had over 40 years in the
shop, fabricating with glass, resin, and other combinations of
materials. He knew more than either of the two distributors I bought
from as to be expected as his experience was all hands on in the shop.
Most boat builders I know don't really understand as much about glass
and resin as they think they do, but I know how my ideas are taken here
and not to be an ass, I know how you are about being challenged on such
issues so I will leave this as my last post to this thread..

Take it for what it's worth... I will note that I have built over 50
plywood, glass, and resin, stitch and tape, tack and tape, and glue and
screw type boats in my day...

Cheers to you too
Scotty from SmallBoats.com

so?? I built, albeit with considerable help from my father, my first
boat in 1941... I don't think it is such an accomplishment though as I
knew an old fellow up in Maine that had been building boats, or
helping to build boats in his younger days, for 70 years.



Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Sep 28, 8:49*am, Bruce in Bangkok
wrote:
On Mon, 27 Sep 2010 23:13:45 -0400, I am Tosk



wrote:
In article ,
says...

On Mon, 27 Sep 2010 06:58:45 -0400, I am Tosk
wrote:

In article ,
says...

On Sat, 25 Sep 2010 18:21:02 -0400, I am Tosk
wrote:

In article 084c9f63-3d17-496f-8a21-74c4d53f4a02
, says...

MiniCup #`1 is still sitting on sawhorses while I decide whether or
not to rebuild her. *#2 which I have been using developed cracks from
rot in the 3/16" poor quality ply I used on her even though she had
been glassed with 4 oz glass and epoxy. *While fixing this I found
more rot so ended up covering her entire rear with another layer of
glass. *Am almost done. *However, she seems to have absorbed some
water that I cannot get rid of as she seems heavy even with ports cut
in all her spaces.
Am looking over the old MiniCup plans and considering how to design a
modern version that will be much lighter. *Considering using 3mm
Okuome Ply covered with 8 oz glass all over with stiffening ribs of
foam and glass. All interior joints would be glass taped and interior
epoxied as well to seal the wood. Transom would be reinforced with
thicker ply and G10 glass composite for the rudder stresses. *Cockpit
and mast step would be self bailing and all hardware of either bronze
or SS. *Instead of being a "hardware store boat", I'd specify buying
actual boatbuilding screws and pulleys made for boats. *I'd reccomend
buying 1/8" Al tubing for the mast and 1/16" for the two other spars.
The sail should be sewn from white polytarp, none of this duct tape
stuff and visqueen. *I have devised a much improved gooseneck where
the two spars attach to the mast. *Any other ideas?

Sounds to me like you are going to use 1/8 inch ply and glass for
structure.. Glass doesn't add structure really it should be used for
protection if not laminated into a hull... Use 6mm plywood and protect
it with 4 oz tight weave if you need abrasion protection and such....

Err.. why is it that glass over plywood doesn't add structure while
glass cloth over foam does?

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Laminated glass might. One layer over a 3mm plywood, not so much... In
most applications for small boats such as this, the glass is more as a
sealer and protection than a structural component. Especially one layer
of 4 oz tight weave...

Agreed that a layer of glass on one side is inferior to glass on both
sides but I would argue that it is far more then simply a sealer.

Not what I said at all, for smaller boats, glass on both sides only
invites more rotting and moisture retention...

I know that you keep saying that but in my experience it just isn't
true. Example: I built a glass over waterproof plywood, nor 15 years
ago. Glassed it inside and outside - heavy as hell! It is still being
used and has, to date, not started to rot.

Quite a few strip planked boats have been built, glassed inside and
out, with no noticeable decrease in life.

In
fact if it is simply a sealer there would be no sense in applying the
cloth as glass cloth is far from being water proof, quite the contrary
in fact.

Of course there would be "sense" in applying the glass. To understand
you must first understand that glass it to hold resin, resin is to fill
glass.. They work together, it's just the way it is...

That is not true at all. I have finished a number of objects with
nothing but resin. Works perfectly well.



If sealing were the sole purpose then all the boat designers wouldn't
be recommending "glass over...." .

Sure they would, cause glass it to hold resin...

The layer of glass actually makes the 3 mm ply substantially more
resistant to bending then bare ply would be. A parallel might be
fabric covered aircraft where the airframe is covered with a cloth
which is perhaps less strong then a bed sheet, which is then
reinforced with coats of cellulose dope.

Don't know much about airplanes but I bet the framework is substantial
under that skin. Either way, a 4 oz layer of glass over 6mm Occoume does
not all all that much stiffness. Glass is good for adding structure when
laminated into fillets, but trying to use it to stiffen a plywood hull
is a waste of time and poor design.

The guy who taught me to use glass and resin had over 40 years in the
shop, fabricating with glass, resin, and other combinations of
materials. He knew more than either of the two distributors I bought
from as to be expected as his experience was all hands on in the shop.
Most boat builders I know don't really understand as much about glass
and resin as they think they do, but I know how my ideas are taken here
and not to be an ass, I know how you are about being challenged on such
issues so I will leave this as my last post to this thread..

Take it for what it's worth... I will note that I have built over 50
plywood, glass, and resin, stitch and tape, tack and tape, and glue and
screw type boats in my day...

Cheers to you too
Scotty from SmallBoats.com

so?? I built, albeit with considerable help from my father, my first
boat in 1941... I don't think it is such an accomplishment though as I
knew an old fellow up in Maine that had been building boats, or
helping to build boats in his younger days, for 70 years.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Thinking a bit about Tosk's discussion of painting instead of epoxying
the interior surfaces of wood on a glass/epoxy/marine ply boat leaves
me wondering which way to go.
My experience with painting the interior of the MiniCups has been bad
although this may be a bad data set because the wood was poor quality
to start. I wish I had not painted it because removing the paint once
I had problems was such a big problem (on the inside, not the outside)
that I never epoxied the insides. Worse, I felt that in many cases,
the paint actually did trap water that had gotten through it. I see
this happening on other wood painted surfaces where water gets under
the paint and then gets trapped making it rot faster. By contrast,
pieces of epoxied ply left over from building my Tolman Skiff sitting
out in the yard in the Florida sun, rain and heat seem
indestructible. I have seen some pieces of 2X6" that had been glassed
and epoxied immersed in water lose adhesion of the glass and the epoxy
then cracks allowing water to get in and then trapped.
Regardless of whether you paint or epoxy the insides, I do think all
end grain needs to be epoxied.
Given my bad experience with painting, I think I will epoxy the
insides but just in case, I will provide opening ports in all chambers
so water can be emptied. The MiniCups originally had no such ports
and this was a major problem. My remaining MiniCup now has 5 such
ports although it may be too late to dry her completely.

On Wed, 29 Sep 2010 07:22:22 -0700 (PDT), Frogwatch
wrote:

On Sep 28, 8:49*am, Bruce in Bangkok
wrote:
On Mon, 27 Sep 2010 23:13:45 -0400, I am Tosk



wrote:
In article ,
says...

On Mon, 27 Sep 2010 06:58:45 -0400, I am Tosk
wrote:

In article ,
says...

On Sat, 25 Sep 2010 18:21:02 -0400, I am Tosk
wrote:

In article 084c9f63-3d17-496f-8a21-74c4d53f4a02
, says...

MiniCup #`1 is still sitting on sawhorses while I decide whether or
not to rebuild her. *#2 which I have been using developed cracks from
rot in the 3/16" poor quality ply I used on her even though she had
been glassed with 4 oz glass and epoxy. *While fixing this I found
more rot so ended up covering her entire rear with another layer of
glass. *Am almost done. *However, she seems to have absorbed some
water that I cannot get rid of as she seems heavy even with ports cut
in all her spaces.
Am looking over the old MiniCup plans and considering how to design a
modern version that will be much lighter. *Considering using 3mm
Okuome Ply covered with 8 oz glass all over with stiffening ribs of
foam and glass. All interior joints would be glass taped and interior
epoxied as well to seal the wood. Transom would be reinforced with
thicker ply and G10 glass composite for the rudder stresses. *Cockpit
and mast step would be self bailing and all hardware of either bronze
or SS. *Instead of being a "hardware store boat", I'd specify buying
actual boatbuilding screws and pulleys made for boats. *I'd reccomend
buying 1/8" Al tubing for the mast and 1/16" for the two other spars.
The sail should be sewn from white polytarp, none of this duct tape
stuff and visqueen. *I have devised a much improved gooseneck where
the two spars attach to the mast. *Any other ideas?

Sounds to me like you are going to use 1/8 inch ply and glass for
structure.. Glass doesn't add structure really it should be used for
protection if not laminated into a hull... Use 6mm plywood and protect
it with 4 oz tight weave if you need abrasion protection and such...

Err.. why is it that glass over plywood doesn't add structure while
glass cloth over foam does?

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Laminated glass might. One layer over a 3mm plywood, not so much... In
most applications for small boats such as this, the glass is more as a
sealer and protection than a structural component. Especially one layer
of 4 oz tight weave...

Agreed that a layer of glass on one side is inferior to glass on both
sides but I would argue that it is far more then simply a sealer.

Not what I said at all, for smaller boats, glass on both sides only
invites more rotting and moisture retention...

I know that you keep saying that but in my experience it just isn't
true. Example: I built a glass over waterproof plywood, nor 15 years
ago. Glassed it inside and outside - heavy as hell! It is still being
used and has, to date, not started to rot.

Quite a few strip planked boats have been built, glassed inside and
out, with no noticeable decrease in life.

In
fact if it is simply a sealer there would be no sense in applying the
cloth as glass cloth is far from being water proof, quite the contrary
in fact.

Of course there would be "sense" in applying the glass. To understand
you must first understand that glass it to hold resin, resin is to fill
glass.. They work together, it's just the way it is...

That is not true at all. I have finished a number of objects with
nothing but resin. Works perfectly well.



If sealing were the sole purpose then all the boat designers wouldn't
be recommending "glass over...." .

Sure they would, cause glass it to hold resin...

The layer of glass actually makes the 3 mm ply substantially more
resistant to bending then bare ply would be. A parallel might be
fabric covered aircraft where the airframe is covered with a cloth
which is perhaps less strong then a bed sheet, which is then
reinforced with coats of cellulose dope.

Don't know much about airplanes but I bet the framework is substantial
under that skin. Either way, a 4 oz layer of glass over 6mm Occoume does
not all all that much stiffness. Glass is good for adding structure when
laminated into fillets, but trying to use it to stiffen a plywood hull
is a waste of time and poor design.

The guy who taught me to use glass and resin had over 40 years in the
shop, fabricating with glass, resin, and other combinations of
materials. He knew more than either of the two distributors I bought
from as to be expected as his experience was all hands on in the shop.
Most boat builders I know don't really understand as much about glass
and resin as they think they do, but I know how my ideas are taken here
and not to be an ass, I know how you are about being challenged on such
issues so I will leave this as my last post to this thread..

Take it for what it's worth... I will note that I have built over 50
plywood, glass, and resin, stitch and tape, tack and tape, and glue and
screw type boats in my day...

Cheers to you too
Scotty from SmallBoats.com

so?? I built, albeit with considerable help from my father, my first
boat in 1941... I don't think it is such an accomplishment though as I
knew an old fellow up in Maine that had been building boats, or
helping to build boats in his younger days, for 70 years.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Thinking a bit about Tosk's discussion of painting instead of epoxying
the interior surfaces of wood on a glass/epoxy/marine ply boat leaves
me wondering which way to go.
My experience with painting the interior of the MiniCups has been bad
although this may be a bad data set because the wood was poor quality
to start. I wish I had not painted it because removing the paint once
I had problems was such a big problem (on the inside, not the outside)
that I never epoxied the insides. Worse, I felt that in many cases,
the paint actually did trap water that had gotten through it. I see
this happening on other wood painted surfaces where water gets under
the paint and then gets trapped making it rot faster. By contrast,
pieces of epoxied ply left over from building my Tolman Skiff sitting
out in the yard in the Florida sun, rain and heat seem
indestructible. I have seen some pieces of 2X6" that had been glassed
and epoxied immersed in water lose adhesion of the glass and the epoxy
then cracks allowing water to get in and then trapped.
Regardless of whether you paint or epoxy the insides, I do think all
end grain needs to be epoxied.
Given my bad experience with painting, I think I will epoxy the
insides but just in case, I will provide opening ports in all chambers
so water can be emptied. The MiniCups originally had no such ports
and this was a major problem. My remaining MiniCup now has 5 such
ports although it may be too late to dry her completely.


Try contacting various people who make and sell plywood boats, like
www.bateau.com, or West Systems and see what they say.

My own feelings is that a small open boat, that invariably will get
wet inside and out, will benefit from being completely encapsulated in
plastic.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)