Re: Birdwatcher II, others being built? Foam details...
--- Inbolger@yahoogroups.com, Rick Bedard <sctree@y...> wrote:
intentionally keep them separate and allow for air circulation and
drainage between the foam and ply. Either way, epoxy coat the ply
first!
I wonder if Dave Carnell's preservative technique (borax and boric
acid in ethylene glycol - see MAIB 8/15/2004 p26) wouldn't work well
in the foam/ply sandwich construction. I am thinking of treating
the interior surfaces of all the wood, letting the treatment dry,
then gluing all together. Epoxy seal the outside. It seems that
there is little chance of the treatment being washed away if the
outside surfaces are reasonably sealed. Any water drawn in as vapor
is likely to leave the same way, leaving the glycol and/or borates
behind.
I have a Birdwatcher under construction. Mine will be mostly BW 1,
with a few details borrowed from BW 2 where they suit me. I was
planning on the foam sandwich hull side panels until I saw the
reports of rot here. With the preservative treatment, I think it
stands a good chance.
Doug
> Yep, been my experience that no air voids can be allowed betweenply and foam, or rot will find it's way. That is, unless you
intentionally keep them separate and allow for air circulation and
drainage between the foam and ply. Either way, epoxy coat the ply
first!
I wonder if Dave Carnell's preservative technique (borax and boric
acid in ethylene glycol - see MAIB 8/15/2004 p26) wouldn't work well
in the foam/ply sandwich construction. I am thinking of treating
the interior surfaces of all the wood, letting the treatment dry,
then gluing all together. Epoxy seal the outside. It seems that
there is little chance of the treatment being washed away if the
outside surfaces are reasonably sealed. Any water drawn in as vapor
is likely to leave the same way, leaving the glycol and/or borates
behind.
I have a Birdwatcher under construction. Mine will be mostly BW 1,
with a few details borrowed from BW 2 where they suit me. I was
planning on the foam sandwich hull side panels until I saw the
reports of rot here. With the preservative treatment, I think it
stands a good chance.
Doug
Yep, been my experience that no air voids can be allowed between ply and foam, or rot will find it's way. That is, unless you intentionally keep them separate and allow for air circulation and drainage between the foam and ply. Either way, epoxy coat the ply first! I've seen white foam that tends to get pulled apart if bonded on both sides and the panel stressed. I've been told, but haven't seen it proven that the pink or blue is much better at staying intact... I'll be using pink foam held away from the plywood hull sides by fiberglass vertical spacer battens. I'll get zero added structural strength, however I'm only looking for insulation and floatation.
Rick
Peter Lenihan <peterlenihan@...> wrote:
Rick
Peter Lenihan <peterlenihan@...> wrote:
--- Inbolger@yahoogroups.com, Bruce Hallman <bruce@h...> wrote:
> > 1)The foam MUST be thoroughly glued to the plywood panels
> > Peter Lenihan
>
> What glue did you use?
Hi Bruce,
Haven't begun the insulation just yet but Bolger does specify
setting the Styrofoam onto a well thickened,evenly spread,layer of
epoxy.
A couple of folks around these parts,think this route too
expensive and are suggesting I go with a proven construction grade
adhessive specically designed for attaching foam to
wood,steel,concrete etc...
I'll be writing Bolger before the month is out and will seek
clarification/opinion on the justification for epoxy along with
viable,less costly alternative.Stay tuned... :-)
Sincerely,
Peter Lenihan
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--- Inbolger@yahoogroups.com, "Peter Lenihan" <peterlenihan@h...>
wrote:
is "hydrophobic" (like me:-) and the second waterproof. They also
have a sealing tape available to seal joints, but don't mention an
adhesive.
http://tinyurl.com/yvb7r
There are also many sources for fire-proof paints and coatings as
well as waterproof coatings. One example.
http://www.hytechsales.com/fire_proofing.html
From what I understand, in building BWII, the rigid foam is glued
down between 1x1 longitudinals before the topsides and bottom are
installed around the bulkheads and the outside finished off with
exterior chines, shear strakes, taped seams and painted. (All
exterior surfaces are epoxy coated and glassed flat on the floor,
prior to assembly.) Then the boat is turned upright and the interior
plywood panels are installed.
I would expect that there has to be vertical wood supports on the
topsides and transverse frame supports on the bottom, for the
attachement of the bulkheads right? Because you can't attach the
bulkheads directly to the foam. So in essence the sides and bottom
are web frames and very rigid by themselves especially once the foam
is cemented in.
Therefor the interior panels could simply be installed as removable
panels and could in fact have air circulation vents installed that
would allow any moisture to evaporate. One could also install
horizontal natural wood strips, as in Lestat, allowing air to
cirulate freely behind. Any actual water would run down into the
bilge troughs that are a part of the design and could be wiped up
with a rag.
This is the route that I might choose as this hull would be much
stronger than the instant line of boats, even without the interior
layer of plywood. After all, BW is simply a variation of the Scooner
and HH Schooner hulls which only have one layer of 1/4" plywood!
Cheers, Nels
wrote:
> I'll be writing Bolger before the month is out and will seekHere is a link to two types of one brand of 1" rigid foam. One
> clarification/opinion on the justification for epoxy along with
> viable,less costly alternative.Stay tuned... :-)
>
> Sincerely,
>
> Peter Lenihan
is "hydrophobic" (like me:-) and the second waterproof. They also
have a sealing tape available to seal joints, but don't mention an
adhesive.
http://tinyurl.com/yvb7r
There are also many sources for fire-proof paints and coatings as
well as waterproof coatings. One example.
http://www.hytechsales.com/fire_proofing.html
From what I understand, in building BWII, the rigid foam is glued
down between 1x1 longitudinals before the topsides and bottom are
installed around the bulkheads and the outside finished off with
exterior chines, shear strakes, taped seams and painted. (All
exterior surfaces are epoxy coated and glassed flat on the floor,
prior to assembly.) Then the boat is turned upright and the interior
plywood panels are installed.
I would expect that there has to be vertical wood supports on the
topsides and transverse frame supports on the bottom, for the
attachement of the bulkheads right? Because you can't attach the
bulkheads directly to the foam. So in essence the sides and bottom
are web frames and very rigid by themselves especially once the foam
is cemented in.
Therefor the interior panels could simply be installed as removable
panels and could in fact have air circulation vents installed that
would allow any moisture to evaporate. One could also install
horizontal natural wood strips, as in Lestat, allowing air to
cirulate freely behind. Any actual water would run down into the
bilge troughs that are a part of the design and could be wiped up
with a rag.
This is the route that I might choose as this hull would be much
stronger than the instant line of boats, even without the interior
layer of plywood. After all, BW is simply a variation of the Scooner
and HH Schooner hulls which only have one layer of 1/4" plywood!
Cheers, Nels
--- Inbolger@yahoogroups.com, Bruce Hallman <bruce@h...> wrote:
Haven't begun the insulation just yet but Bolger does specify
setting the Styrofoam onto a well thickened,evenly spread,layer of
epoxy.
A couple of folks around these parts,think this route too
expensive and are suggesting I go with a proven construction grade
adhessive specically designed for attaching foam to
wood,steel,concrete etc...
I'll be writing Bolger before the month is out and will seek
clarification/opinion on the justification for epoxy along with
viable,less costly alternative.Stay tuned... :-)
Sincerely,
Peter Lenihan
> > 1)The foam MUST be thoroughly glued to the plywood panelsHi Bruce,
> > Peter Lenihan
>
> What glue did you use?
Haven't begun the insulation just yet but Bolger does specify
setting the Styrofoam onto a well thickened,evenly spread,layer of
epoxy.
A couple of folks around these parts,think this route too
expensive and are suggesting I go with a proven construction grade
adhessive specically designed for attaching foam to
wood,steel,concrete etc...
I'll be writing Bolger before the month is out and will seek
clarification/opinion on the justification for epoxy along with
viable,less costly alternative.Stay tuned... :-)
Sincerely,
Peter Lenihan
> 1)The foam MUST be thoroughly glued to the plywood panelsWhat glue did you use?
> Peter Lenihan
I've not the plans for BWII but Bolger does call for insulation to
be used throughout Windermere in an attempt to make her a full four
season live-a-board.PCB&Fs call specifically for the use of the 2"
blue Styrofoam board to be used both in the hull sides and the cabin
roof.
Both in conversation with "him" and several letters addressing the
foaming stages from "them",this is what I now think I know :-)
1)The foam MUST be thoroughly glued to the plywood panels
2)All remaining voids found along the perimeter of a glued foam
panel must be filled with expanding foam.
3)Sandwich construction is very strong for its weight.
As great luck would have it, a wonderful little sedan cruiser is
wintering besides Windermere and is scheduled to have both her coach
and pilot house roofs replaced due to rot. The preliminary
inspection has revealed that the Styrofoam was originally installed
with only globs and big lazy "S" applications of glue.This left lots
of un-glued and un-seen gaps between the plywood shell and foam.
Over a relatively short period of time,condensation has done its'
evil work of rotting out several deck(roof) beams and given rise to
soft wood along the corner posts of the coach sides.
I was,at first, simply go to "tack" my Styrofoam in place on
Windermere while trusting the outside shell to keep the water
away.Thankfully,this in-the-flesh example of the effects of
condensation appears to have been sent to me by the God of Silly
People just in the nick of time :-) It'll be mighty tough skimping
on the glue this Spring while from my near neighbors shelter will be
heard the racket of gutting and repair......
As to the question of strength with sandwich construction, Phil
Bolger related a story to me of his own gradual conversion to this
method of construction.A method which he confesses to having been
leary of for years.Today,he looks back at those years with with
amused dismay. In essence;Brad Story built a ply/foam/ply sandwich
with door skins,suspended the finished product between two saw-
horses and invited Phil to stand up on it to see if it would break
or deflect much. Well....Phil did,the panel didn't and the rest is
history. Thus we see more of this construction technique being
applied to recent PCB design work.
The ultimate success of this technique however,depends on being very
thorough with all your gluing and sealing stages.Leave no "holidays"
nor voids for moisture to come a roostin' in. It is a marvel for
strength and light weight which hopefully will see further
applications expressed in new designs to come.
So...that's all I know or can contribute to this subject. I can't
wait to hear from a few of our engineers to enlighten us with some
raw figures or examples.
Sincerely,
Peter Lenihan,blissfully un-engineered and close to becoming un-
hinged,if the New Year festivities don't stop soon, from along the
frozen shores of the St.Lawrence...........
be used throughout Windermere in an attempt to make her a full four
season live-a-board.PCB&Fs call specifically for the use of the 2"
blue Styrofoam board to be used both in the hull sides and the cabin
roof.
Both in conversation with "him" and several letters addressing the
foaming stages from "them",this is what I now think I know :-)
1)The foam MUST be thoroughly glued to the plywood panels
2)All remaining voids found along the perimeter of a glued foam
panel must be filled with expanding foam.
3)Sandwich construction is very strong for its weight.
As great luck would have it, a wonderful little sedan cruiser is
wintering besides Windermere and is scheduled to have both her coach
and pilot house roofs replaced due to rot. The preliminary
inspection has revealed that the Styrofoam was originally installed
with only globs and big lazy "S" applications of glue.This left lots
of un-glued and un-seen gaps between the plywood shell and foam.
Over a relatively short period of time,condensation has done its'
evil work of rotting out several deck(roof) beams and given rise to
soft wood along the corner posts of the coach sides.
I was,at first, simply go to "tack" my Styrofoam in place on
Windermere while trusting the outside shell to keep the water
away.Thankfully,this in-the-flesh example of the effects of
condensation appears to have been sent to me by the God of Silly
People just in the nick of time :-) It'll be mighty tough skimping
on the glue this Spring while from my near neighbors shelter will be
heard the racket of gutting and repair......
As to the question of strength with sandwich construction, Phil
Bolger related a story to me of his own gradual conversion to this
method of construction.A method which he confesses to having been
leary of for years.Today,he looks back at those years with with
amused dismay. In essence;Brad Story built a ply/foam/ply sandwich
with door skins,suspended the finished product between two saw-
horses and invited Phil to stand up on it to see if it would break
or deflect much. Well....Phil did,the panel didn't and the rest is
history. Thus we see more of this construction technique being
applied to recent PCB design work.
The ultimate success of this technique however,depends on being very
thorough with all your gluing and sealing stages.Leave no "holidays"
nor voids for moisture to come a roostin' in. It is a marvel for
strength and light weight which hopefully will see further
applications expressed in new designs to come.
So...that's all I know or can contribute to this subject. I can't
wait to hear from a few of our engineers to enlighten us with some
raw figures or examples.
Sincerely,
Peter Lenihan,blissfully un-engineered and close to becoming un-
hinged,if the New Year festivities don't stop soon, from along the
frozen shores of the St.Lawrence...........
I too have pondered the question of to glue or not the foam to the
ply. It seems to me that gluing would provide the maximum structural
benefit but, if not done, the foam would still fulfill its principle
function of keeping the two plywood skins apart.
Other issues have been raised regarding outgassing and toxicity in
case of fire. I would assume that the surrounding surfaces, in most
cases, will be epoxy sealed. If we extend this to encapsulating the
foam, we should be able to avoid most of the outgassing and
possibilities of entrapped moisture. Even if outgassing occurs, BW and
BWII are inherently well ventilated craft. Fire hazard may be more of
an issue, not from the foam but from the epoxy and other coatings
which will be the first to burn. The foam will actually be somewhat
protected by the plywood.
The hard hatches are another area which give me fits. I've spent may
hours sketching alternative constructions. Problems unresolved are
hold downs, stowage and the loss of walk through capability. I'm
thinking of doing away with the foam and substituting a curved
laminate which might, more easily, be stowed. I think it was Phil
Smith who said that Bolger preferred BWI. Maybe I will accept that as
permission to incorporate some but not all of the new design.
Finally, I am concerned about the sheet lead with the new BWII
configuration. I haven't done a mockup yet but it appears that there
may be chaff along the back edge of the raised deck
ply. It seems to me that gluing would provide the maximum structural
benefit but, if not done, the foam would still fulfill its principle
function of keeping the two plywood skins apart.
Other issues have been raised regarding outgassing and toxicity in
case of fire. I would assume that the surrounding surfaces, in most
cases, will be epoxy sealed. If we extend this to encapsulating the
foam, we should be able to avoid most of the outgassing and
possibilities of entrapped moisture. Even if outgassing occurs, BW and
BWII are inherently well ventilated craft. Fire hazard may be more of
an issue, not from the foam but from the epoxy and other coatings
which will be the first to burn. The foam will actually be somewhat
protected by the plywood.
The hard hatches are another area which give me fits. I've spent may
hours sketching alternative constructions. Problems unresolved are
hold downs, stowage and the loss of walk through capability. I'm
thinking of doing away with the foam and substituting a curved
laminate which might, more easily, be stowed. I think it was Phil
Smith who said that Bolger preferred BWI. Maybe I will accept that as
permission to incorporate some but not all of the new design.
Finally, I am concerned about the sheet lead with the new BWII
configuration. I haven't done a mockup yet but it appears that there
may be chaff along the back edge of the raised deck