"Frank Boettcher" wrote in message
...
On Mon, 23 Jan 2006 04:43:31 GMT, "Maxprop"
wrote:


"Capt. Rob" wrote in message
oups.com...
I wonder if Doug has ever seen a *good Irwin.*





I've never seen any older boat with a wood core in the deck remain dry;
not
even the end-grain balsa cores. A friend's Tartan 34 is so wet over the
forepeak that it squishes when walked upon. Irwins are no worse than
others
in this regard, but the glasswork and layup quality just isn't in the same
league as more expensive boats.

Max

As a sample of one, my experience has been that if a manufacturer puts
fasteners into the core without going all the way through, you are
much more likely to get core rot. I repaired quite a bit of it and
found it all related to that practice. I had a hatch cowl, head
ventilator, several escutcheon plates, and some others which were all
caulk and screw into the core. All eventually resulted in core rot.
When I repaired it I converted all of those to through bolt. I never
had to repair any more core rot. Sure did slice a lot of balsa on my
band saw to make the repairs. Kind of like slicing loaves of bread on
the end grain.

I wont even put a canvas snap into the core since that experience. If
I want a cover, I'll make a decorative teak backer, through bolt it
and then put the snaps into it.

Damned if I can recall what manufacturer did this, but I recall seeing a
boat on which all thru-bolts were first drilled oversize, then filled with
solid resin--epoxy, I presume--and then redrilled to the proper, smaller
diameter. No way any moisture could get into the core with that system. I
have Airex foam cores in my hull and deck, but I still do the same thing if
installing something. It makes for a lot of work, but it's a safe system.
I also overdrill holes into the core through just one laminate (snaps, for
example) and fill them with epoxy, too. Probably overkill in my case, since
Airex won't absorb moisture at all.

Max

I've never seen any older boat with a wood core in the deck remain dry;
not
even the end-grain balsa cores.

I have.

And it's not an issue of "even" the end-grain balsa.
End-grain balsa has several advantages as core. It's light.
The end grain forms a very good bond to fiberglass without a
lot of fuss, fancy materials, or careful workmanship
(although it's much better if these are applied). The end
grain isolates moisture instead of wicking it the full
length of the structure.

As for plywood "core" what's the point? Why not get plywood
that's strong enough in the first place, instead of adding a
skin of something that is heavier & not as resilient & will
trap water in the wood? Actually, the one exception is the
upper face of a deck. Fiberglass is a lot more abrasion
resistant than wood, and makes a great deck surface.


... A friend's Tartan 34 is so wet over the
forepeak that it squishes when walked upon. Irwins are no worse than
others
in this regard, but the glasswork and layup quality just isn't in the same
league as more expensive boats.


Well, any fiberglass lay-up with core that is not kept
sealed will end up squishy, no matter what the original
workmanship.

This is why some people hate cored fiberglass.

"Frank Boettcher" wrote...
As a sample of one, my experience has been that if a manufacturer puts
fasteners into the core without going all the way through, you are
much more likely to get core rot.

Pretty much guaranteed IMHO if that fitting has any stress
at all on it.

... I repaired quite a bit of it and
found it all related to that practice. I had a hatch cowl, head
ventilator, several escutcheon plates, and some others which were all
caulk and screw into the core. All eventually resulted in core rot.
When I repaired it I converted all of those to through bolt.

Ummm, I hate to tell you this, but that's actually worse for
cored lay-ups.

Balsa core is not very strong in compression. Actually,
neither is plywood, but it's stronger than balsa. When you
tighten the bolts, you compress the core. When the fitting
is loaded, the core compresses further (think stantion base
plate) and then when the load is removed, it doesn't expand
again (or at least, not 100%). Now the bolts are very
slightly loose. Repeat. Now water is guaranteed to be let in.

Frank I am very glad to hear you have not had any rot in
your core since making your repair. But that isn't the
textbook method and it's not any more work to do it that way.

The answer to this problem is to not have any core in the
area of fittings.

The original builder, if putting in core in the first place,
should cut the core to a template around all fittings, and
taper the core down all edges so that the two skins come
together and can be reinforced easily in the area of highly
loaded fittings. Ideally the edgees should have a double
radius, S-curve.

Look at a Morris, Oyster, or Baltic, and you will see this.
Look at an Ericson and you will see core with a flat taper
or bevel in the decks. Some eras of C&C did this as well,
but they also put in plywood or milled PVC blanks in place
too for some models in some eras. So did some other
builders. But many builders just toss the core in the mold
and slap cloth over it.


Maxprop wrote:
Damned if I can recall what manufacturer did this, but I recall seeing a
boat on which all thru-bolts were first drilled oversize, then filled with
solid resin--epoxy, I presume--and then redrilled to the proper, smaller
diameter.

The problem with this method of repair is that you're
cutting away the strength memeber... the skin. But the epoxy
filler is stronger in compression than the core, so that's good.

One method to dig out the core & leave the skin is to take
an Allen wrench and put it in your drill, and work it around
the edges of the existing hole. Put tape under, fill with
epoxy (I use hi density filler mixed in), then drill out the
original sized bolt hole.


.... No way any moisture could get into the core with that system.

It still can if the fitting is not bedded properly. That's
why the answer is to have solid glass in the area of fittings.

.... I
have Airex foam cores in my hull and deck, but I still do the same thing if
installing something. It makes for a lot of work, but it's a safe system.
I also overdrill holes into the core through just one laminate (snaps, for
example) and fill them with epoxy, too. Probably overkill in my case, since
Airex won't absorb moisture at all.


No, but freeze-thaw cycles will still cause progressive
delamination if any water gets into it. And Airex is also
weak in compression, thru-bolts will crush it and cause leaks.

Cored laminations are a higher level of technology than
solid glass. They're lighter, stiffer, more elastic, can be
engineered to have all kinds of desirable properties. People
who say "I hate cored fiberglass" are saying "I want my boat
to be heavier, weaker, slower, and less stable."

But cores aren't foolproof, they're not even user-friendly.
The real killer of cored structure is lack of maintenance.
How long has it been since all deck fittiings were rebedded?
Going on 2 1/2 years for me, and I'm thinking about doing it
again. But then I was raised in the old school where you do
this *every* year.

This turned out to be really long, sorry about that. But
it's an important issue. This should have come under the
"projects" thread earlier.

Fresh Breezes- Doug King

On Tue, 24 Jan 2006 01:11:52 -0500, DSK wrote:


"Frank Boettcher" wrote...
As a sample of one, my experience has been that if a manufacturer puts
fasteners into the core without going all the way through, you are
much more likely to get core rot.

Pretty much guaranteed IMHO if that fitting has any stress
at all on it.

... I repaired quite a bit of it and
found it all related to that practice. I had a hatch cowl, head
ventilator, several escutcheon plates, and some others which were all
caulk and screw into the core. All eventually resulted in core rot.
When I repaired it I converted all of those to through bolt.

Ummm, I hate to tell you this, but that's actually worse for
cored lay-ups.

I disagree. see below

Balsa core is not very strong in compression. Actually,
neither is plywood, but it's stronger than balsa.

All wood is stronger in compression of the end grain than compression
of the side surface. There is less chance to develop a permanent
depression on the end grain than the side surface. And end grain
balsa is stronger in compression than side grain plywood, plus lighter
which is why it is used. Load up your cabin trunk or deck with
plywood and you have a top heavy craft requiring much more ballast to
get the centroid right. No good.

When you
tighten the bolts, you compress the core. When the fitting
is loaded, the core compresses further (think stantion base
plate) and then when the load is removed, it doesn't expand
again (or at least, not 100%). Now the bolts are very
slightly loose. Repeat. Now water is guaranteed to be let in.

If you put fasteners (which would have to be wood screws or some type
of universal thread screw) into the core once you have achieved the
appropriate torque that is pretty much it. If it moves and leaks you
don't know until the damage is done. And periodic retightening will
only strip out or weaken the bond. When you through bolt with machine
screws and nuts you can 1.) see the leak if it develops because it
will come all the way through, 2.) periodically retorque the fasteners
to tighten up the seal or remove and rebed with the ability to get a
good seal because of the use of machine screws and nuts.

Frank I am very glad to hear you have not had any rot in
your core since making your repair. But that isn't the
textbook method and it's not any more work to do it that way.

The repairs I made solved the problem in the areas they were in. I
sold the boat several years later, checked back periodically with the
new owner and they were still providing trouble free service.

The answer to this problem is to not have any core in the
area of fittings.

Good plan but most builders do not do this.

The original builder, if putting in core in the first place,
should cut the core to a template around all fittings, and
taper the core down all edges so that the two skins come
together and can be reinforced easily in the area of highly
loaded fittings. Ideally the edgees should have a double
radius, S-curve.

Look at a Morris, Oyster, or Baltic, and you will see this.
Look at an Ericson and you will see core with a flat taper
or bevel in the decks. Some eras of C&C did this as well,
but they also put in plywood or milled PVC blanks in place
too for some models in some eras. So did some other
builders. But many builders just toss the core in the mold
and slap cloth over it.

Almost everyone does it for high structural penetrations. very few do
it for the low structural connections that usually end up causing the
problems. My problems were not caused by stantions, standing rigging
chainplate penetrations, pulpits or any other high load items. Mine
were caused by low load items. Many times, after market items like
covers and cowls are attached with snaps or fasteners that are just
screwed into the core and most manufacturers don't make allowances for
these items.


Maxprop wrote:
Damned if I can recall what manufacturer did this, but I recall seeing a
boat on which all thru-bolts were first drilled oversize, then filled with
solid resin--epoxy, I presume--and then redrilled to the proper, smaller
diameter.

The problem with this method of repair is that you're
cutting away the strength memeber... the skin. But the epoxy
filler is stronger in compression than the core, so that's good.

One method to dig out the core & leave the skin is to take
an Allen wrench and put it in your drill, and work it around
the edges of the existing hole. Put tape under, fill with
epoxy (I use hi density filler mixed in), then drill out the
original sized bolt hole.


.... No way any moisture could get into the core with that system.

It still can if the fitting is not bedded properly. That's
why the answer is to have solid glass in the area of fittings.

.... I
have Airex foam cores in my hull and deck, but I still do the same thing if
installing something. It makes for a lot of work, but it's a safe system.
I also overdrill holes into the core through just one laminate (snaps, for
example) and fill them with epoxy, too. Probably overkill in my case, since
Airex won't absorb moisture at all.


No, but freeze-thaw cycles will still cause progressive
delamination if any water gets into it. And Airex is also
weak in compression, thru-bolts will crush it and cause leaks.

Cored laminations are a higher level of technology than
solid glass. They're lighter, stiffer, more elastic, can be
engineered to have all kinds of desirable properties. People
who say "I hate cored fiberglass" are saying "I want my boat
to be heavier, weaker, slower, and less stable."

But cores aren't foolproof, they're not even user-friendly.
The real killer of cored structure is lack of maintenance.
How long has it been since all deck fittiings were rebedded?
Going on 2 1/2 years for me, and I'm thinking about doing it
again. But then I was raised in the old school where you do
this *every* year.

This turned out to be really long, sorry about that. But
it's an important issue. This should have come under the
"projects" thread earlier.

Fresh Breezes- Doug King

Balsa core is not very strong in compression. Actually,
neither is plywood, but it's stronger than balsa.


Frank Boettcher wrote:
All wood is stronger in compression of the end grain than compression
of the side surface.

That's true.

However, *balsa* is not stronger that way than even cheapo
pine plywood (unless of course there are gaps in the ply).



.... And end grain
balsa is stronger in compression than side grain plywood

I don't think so, but I bet there are figures out there
somewhere.

... plus lighter
which is why it is used.

Plus the bonding properties and lack of wicking.

... Load up your cabin trunk or deck with
plywood and you have a top heavy craft requiring much more ballast to
get the centroid right. No good.


Agreed, but a lot of boats are built that way. And a lot of
people assume 'heavy = strong.'


The repairs I made solved the problem in the areas they were in. I
sold the boat several years later, checked back periodically with the
new owner and they were still providing trouble free service.


Good work, then... you must have done an excellent job
bedding them. I'm never that confident, plus I really hate
deck leaks.

DSK

"DSK" wrote in message
news
Balsa core is not very strong in compression. Actually, neither is
plywood, but it's stronger than balsa.


Frank Boettcher wrote:
All wood is stronger in compression of the end grain than compression
of the side surface.

That's true.

However, *balsa* is not stronger that way than even cheapo pine plywood
(unless of course there are gaps in the ply).



.... And end grain
balsa is stronger in compression than side grain plywood

I don't think so, but I bet there are figures out there somewhere.

Check out the Wooden Boat magazine archives. There is so much esoteric data
on the properties of wood as to be tedious. I'm sure this issue has been
addressed, and probably redundantly.

Max

"DSK" wrote in message
...

I've never seen any older boat with a wood core in the deck remain dry;
not
even the end-grain balsa cores.

I have.

And it's not an issue of "even" the end-grain balsa. End-grain balsa has
several advantages as core. It's light. The end grain forms a very good
bond to fiberglass without a lot of fuss, fancy materials, or careful
workmanship (although it's much better if these are applied). The end
grain isolates moisture instead of wicking it the full length of the
structure.

That was the theory behind end-grain balsa, but ultimately it didn't work.
Eventually the wood will tranfer water a great distance between lamina. It
may take quite a bit longer than with a ply core, but it will eventually
happen. A 25-30 year old balsa core will be fairly wet if exposed to water
at hardware attachment points.

As for plywood "core" what's the point? Why not get plywood that's strong
enough in the first place, instead of adding a skin of something that is
heavier & not as resilient & will trap water in the wood? Actually, the
one exception is the upper face of a deck. Fiberglass is a lot more
abrasion resistant than wood, and makes a great deck surface.

It's probably not a lot more abrasion resistant than dry teak, which makes
the best non-skid of all IMO. For those boats with ply decks, many
manufacturers covered the decks with canvas and later Dynel or fiberglass.

... A friend's Tartan 34 is so wet over the
forepeak that it squishes when walked upon. Irwins are no worse than
others
in this regard, but the glasswork and layup quality just isn't in the
same
league as more expensive boats.


Well, any fiberglass lay-up with core that is not kept sealed will end up
squishy, no matter what the original workmanship.

This is why some people hate cored fiberglass.

"Frank Boettcher" wrote...
As a sample of one, my experience has been that if a manufacturer puts
fasteners into the core without going all the way through, you are
much more likely to get core rot.

Pretty much guaranteed IMHO if that fitting has any stress at all on it.

... I repaired quite a bit of it and
found it all related to that practice. I had a hatch cowl, head
ventilator, several escutcheon plates, and some others which were all
caulk and screw into the core. All eventually resulted in core rot.
When I repaired it I converted all of those to through bolt.

Ummm, I hate to tell you this, but that's actually worse for cored
lay-ups.

Balsa core is not very strong in compression. Actually, neither is
plywood, but it's stronger than balsa. When you tighten the bolts, you
compress the core. When the fitting is loaded, the core compresses further
(think stantion base plate) and then when the load is removed, it doesn't
expand again (or at least, not 100%). Now the bolts are very slightly
loose. Repeat. Now water is guaranteed to be let in.

Frank I am very glad to hear you have not had any rot in your core since
making your repair. But that isn't the textbook method and it's not any
more work to do it that way.

The answer to this problem is to not have any core in the area of
fittings.

Well built yachts generally have this feature, such as Pacific Seacraft.


The original builder, if putting in core in the first place, should cut
the core to a template around all fittings, and taper the core down all
edges so that the two skins come together and can be reinforced easily in
the area of highly loaded fittings. Ideally the edgees should have a
double radius, S-curve.

Look at a Morris, Oyster, or Baltic, and you will see this. Look at an
Ericson and you will see core with a flat taper or bevel in the decks.
Some eras of C&C did this as well, but they also put in plywood or milled
PVC blanks in place too for some models in some eras. So did some other
builders. But many builders just toss the core in the mold and slap cloth
over it.

Those same builders never anticipated being in business years later when
those cores were soaking wet, either.

Maxprop wrote:
Damned if I can recall what manufacturer did this, but I recall seeing a
boat on which all thru-bolts were first drilled oversize, then filled
with solid resin--epoxy, I presume--and then redrilled to the proper,
smaller diameter.

The problem with this method of repair is that you're cutting away the
strength memeber... the skin. But the epoxy filler is stronger in
compression than the core, so that's good.

You're cutting away such a small diameter of the skin that I think the
result is negligible, especially if the unit of hardware being installed is
quite a bit larger. Some craftsmen recommend using an angled piece of wire
to "route out the balsa core within a 1" radius or so around the hole, and
filling that with epoxy and microballoons. I've done this on other peoples'
boats, and it seemed to work reasonably well, too. This preserves the skin,
but I was always unsure if the epoxy was getting into the voids between the
glass laminates adequately. With my overdill method, I am assured the area
is completely resin-filled. That's why I switched.

One method to dig out the core & leave the skin is to take an Allen wrench
and put it in your drill, and work it around the edges of the existing
hole. Put tape under, fill with epoxy (I use hi density filler mixed in),
then drill out the original sized bolt hole.

Hmmm, sounds familiar. See above. g



.... No way any moisture could get into the core with that system.

It still can if the fitting is not bedded properly. That's why the answer
is to have solid glass in the area of fittings.

Agreed. That's why it's worthwhile to invest in quality boats--one's that
have this feature, for example.


.... I have Airex foam cores in my hull and deck, but I still do the
same thing if installing something. It makes for a lot of work, but it's
a safe system. I also overdrill holes into the core through just one
laminate (snaps, for example) and fill them with epoxy, too. Probably
overkill in my case, since Airex won't absorb moisture at all.


No, but freeze-thaw cycles will still cause progressive delamination if
any water gets into it. And Airex is also weak in compression, thru-bolts
will crush it and cause leaks.

It's surprisingly stiff and rigid. I installed a sheet stopper on the cabin
roof, and I was preparing to route out some of the Airex and replace it with
epoxy and West System's colloidal filler, but the local glass man told me it
wouldn't be necessary with Airex. I couldn't detect any undue compression
when I tightened the fasteners. Of course I bedded them and the stopper in
polysulfide caulk, tightened only slightly until the caulk had a chance to
set up slightly, then tightened it further.

Cored laminations are a higher level of technology than solid glass.
They're lighter, stiffer, more elastic, can be engineered to have all
kinds of desirable properties. People who say "I hate cored fiberglass"
are saying "I want my boat to be heavier, weaker, slower, and less
stable."

But cores aren't foolproof, they're not even user-friendly. The real
killer of cored structure is lack of maintenance. How long has it been
since all deck fittiings were rebedded? Going on 2 1/2 years for me, and
I'm thinking about doing it again. But then I was raised in the old school
where you do this *every* year.

Then there's the school of thought that if you bed everything in
polyurethane (3M5200, for example) you'll never have to do it again. That's
true, because you'll never be *able* to do it again, and of course it will
leak with time. Terrible idea.


This turned out to be really long, sorry about that. But it's an important
issue. This should have come under the "projects" thread earlier.

I think some of us enjoy projects of this nature. And some of us are
pedantic enough to want to do it in the best possible technological manner.
Most owners are clueless. ("You mean you have to rebed those things? What
the hell . . .?")

Max

... The end
grain isolates moisture instead of wicking it the full length of the
structure.


Maxprop wrote:
That was the theory behind end-grain balsa, but ultimately it didn't work.
Eventually the wood will tranfer water a great distance between lamina.

Yes, but "eventually" Mt Everest will be reduced to beach
sand, too. The progression of rot is much much slower with
end grain core than encapsulated plywood. I would not call
that failure, myself.


As for plywood "core" what's the point? Why not get plywood that's strong
enough in the first place, instead of adding a skin of something that is
heavier & not as resilient & will trap water in the wood? Actually, the
one exception is the upper face of a deck. Fiberglass is a lot more
abrasion resistant than wood, and makes a great deck surface.


It's probably not a lot more abrasion resistant than dry teak,

Guess it depends on how you define "a lot" and what kind of
abrasion you expose it to. Fiberglass will basically have
almost no wear at all from foot traffic. Teak will... I know
this for a fact, having just removed a 20 year old teak deck.

BTW this teak deck was screwed into balsa core, which had a
dessert-plate sized spots of rot. If it had been plywood, it
would all have gone to mush.

.... which makes
the best non-skid of all IMO.

Disagree, but then that's based on personal experience
rather than heeding the opinions of others. Heresy!


.... For those boats with ply decks, many
manufacturers covered the decks with canvas and later Dynel or fiberglass.


I've read the Dynel is supposed to be better, not used it
myself.


.... Look at an
Ericson and you will see core with a flat taper or bevel in the decks.
Some eras of C&C did this as well, but they also put in plywood or milled
PVC blanks in place too for some models in some eras. So did some other
builders.

The older Pacific Seacrafts, sure. The last ones I looked at
(2003 & 2004 models) they had deliberately built the boat
with glued-in molding & fabric liners so that you could not
see or access any part of the structure. Frustrating... and
suspicious IMHO.

I should have asked first... you know Pacific Seacraft was
bought up by a conglomerate? Personally I think they're
playing the sausage game. Nothing stays good for long.


But many builders just toss the core in the mold and slap
cloth
over it.


Those same builders never anticipated being in business years later when
those cores were soaking wet, either.


They might not have thought it made that much difference,
and couldn't afford the labor to do it right anyway.



Maxprop wrote:

Damned if I can recall what manufacturer did this, but I recall seeing a
boat on which all thru-bolts were first drilled oversize, then filled
with solid resin--epoxy, I presume--and then redrilled to the proper,
smaller diameter.

The problem with this method of repair is that you're cutting away the
strength memeber... the skin. But the epoxy filler is stronger in
compression than the core, so that's good.


You're cutting away such a small diameter of the skin that I think the
result is negligible, especially if the unit of hardware being installed is
quite a bit larger.

That's a good point. If the hardware is a lot larger, or has
at least 3 mounting holes, it's probably just fine. I was
thinking of single bolt stuff.

I also drill out areas and fill with epoxy to mount small
stuff with self-tapping screws.


No, but freeze-thaw cycles will still cause progressive delamination if
any water gets into it. And Airex is also weak in compression, thru-bolts
will crush it and cause leaks.


It's surprisingly stiff and rigid. I installed a sheet stopper on the cabin
roof, and I was preparing to route out some of the Airex and replace it with
epoxy and West System's colloidal filler, but the local glass man told me it
wouldn't be necessary with Airex. I couldn't detect any undue compression
when I tightened the fasteners. Of course I bedded them and the stopper in
polysulfide caulk, tightened only slightly until the caulk had a chance to
set up slightly, then tightened it further.


Interesting to see what the results will be. Airex and
Divinycell and Klegecell and there some new German stuff
that's supposed to be miraculous but is tediously expensive
are all less supject to compression failure, and certainly
less prone to rot but they are still not strong enough
to have rigging components thru-bolted to it. It may be that
the caulk is resilient enough to keep it watertight anyway,
in your application.

If you're interested, I can recommend some fairly technical
books on composite aircraft construction, which is what I've
been studying because there aren't any books on fancy
composite boat construction. Same stuff, same issues, though.


..... The real
killer of cored structure is lack of maintenance. How long has it been
since all deck fittiings were rebedded? Going on 2 1/2 years for me, and
I'm thinking about doing it again. But then I was raised in the old school
where you do this *every* year.


Then there's the school of thought that if you bed everything in
polyurethane (3M5200, for example) you'll never have to do it again. That's
true, because you'll never be *able* to do it again, and of course it will
leak with time. Terrible idea.


I used to use 5200 for everything, and then of course had to
peel/scrape/wirebrush it off, very tedious. Now I use
4200. And I own stock in 3M.....




This turned out to be really long, sorry about that. But it's an important
issue. This should have come under the "projects" thread earlier.


I think some of us enjoy projects of this nature. And some of us are
pedantic enough to want to do it in the best possible technological manner.
Most owners are clueless. ("You mean you have to rebed those things? What
the hell . . .?")


Maybe it is pedantry, but my belief is that it's less work
to do things the right way. Especially if you don't want it
to fail at an inconvenient time.

Another of my theories is that 'if it works, it must have
been done right.' I'd like to see some of Frank's work & learn.

Fresh Breezes- Doug King

On Wed, 25 Jan 2006 07:07:14 -0500, DSK wrote:


Another of my theories is that 'if it works, it must have
been done right.' I'd like to see some of Frank's work & learn.

Fresh Breezes- Doug King


Pretty much beginners luck, I think,done because the yard had charged
a fortune for a small repair that did not hold several years before.

All the core repairs were done from the outside in rather than the
inside out. I don't know if this was right, but seemed to me the
primary structural layers were on the inside and I didn't want to
tamper with them. But it meant that it had to end up cosmetically
pleasing. Also meant that I had to learn how to spray catalyzed
polyurethane which was easier than I thought it would be. Did the
whole boat with Imron.

All the repairs were done with expoxy rather than polyester. I
worried about the bond between the two but it was needless worry.

Don't know the status, boat was sold again several years ago. For all
I know Katrina got it.

Frank

"DSK" wrote in message
...
... The end grain isolates moisture instead of wicking it the full length
of the structure.


Maxprop wrote:
That was the theory behind end-grain balsa, but ultimately it didn't
work. Eventually the wood will tranfer water a great distance between
lamina.

Yes, but "eventually" Mt Everest will be reduced to beach sand, too. The
progression of rot is much much slower with end grain core than
encapsulated plywood. I would not call that failure, myself.

Your Mt. Everest analogy is not really appropriate in this case. End-grain
balsa core material will be wet during the reasonable lifespan of the boat,
whereas Mt. Everest may see the nova of our sun before becoming a beach. We
ran a moisture meter over a 22 year old C&C 36, whose topsides and deck are
cored with balsa, and there is considerable water in the deck, and some, if
not a lot, in the topsides near the hull/deck union. The moisture is
significant enough to repeatedly thwart the sale of the boat, as the owner
has discovered. Too bad--the boat is otherwise immaculate, and it's fast.



As for plywood "core" what's the point? Why not get plywood that's strong
enough in the first place, instead of adding a skin of something that is
heavier & not as resilient & will trap water in the wood? Actually, the
one exception is the upper face of a deck. Fiberglass is a lot more
abrasion resistant than wood, and makes a great deck surface.


It's probably not a lot more abrasion resistant than dry teak,

Guess it depends on how you define "a lot" and what kind of abrasion you
expose it to. Fiberglass will basically have almost no wear at all from
foot traffic. Teak will... I know this for a fact, having just removed a
20 year old teak deck.

I'm assuming that you didn't own that teak deck for the past 20 years,
therefore you may not know how it was cared for. Or perhaps you know it was
not cared for correctly. Most people are clueless as to how to care for
teak decking. Many scrub it along the rays with a stiff brush while wet
(disaster), and some sand it repeatedly to reestablish the nice brown teak
color (another disaster). I owned a ketch with a teak deck that had been
properly maintained--washed with TSP and a *string mop*, and rinsed with
brine. The boat was built in 1972, and the deck was perfect, save for a
couple of bungs that had popped and had to be replaced. The yacht
Dorade--the namesake of the famous dorade box and cowl vent--sold a few
years ago, and its original deck was completely replaced. The wood from the
removed deck was in such good shape that much of it was used to re-deck
another boat. Dorade was one of Olin Stephens' most famous designs, built
in 1929.

BTW this teak deck was screwed into balsa core, which had a dessert-plate
sized spots of rot. If it had been plywood, it would all have gone to
mush.

That may be a characteristic of balsa itself, which is generally more
impervious to rot than pine or fir. Being an exotic species, it has
genetically evolved to resist rot, which is ubiquitous in the climate where
it grows.

.... which makes the best non-skid of all IMO.

Disagree, but then that's based on personal experience rather than heeding
the opinions of others. Heresy!

Mine is based upon experience as well. Most people think teak is terrible
underfoot. If I listened to others, I'd probably dislike it too.

.... For those boats with ply decks, many manufacturers covered the decks
with canvas and later Dynel or fiberglass.


I've read the Dynel is supposed to be better, not used it myself.

When applied and painted, Dynel is really no different than cotton canvas.
Being a synthetic fabric, however, it lasts about 5 times longer than
canvas. It is harder to work with, however.


.... Look at an Ericson and you will see core with a flat taper or bevel
in the decks. Some eras of C&C did this as well, but they also put in
plywood or milled PVC blanks in place too for some models in some eras.
So did some other builders.

The older Pacific Seacrafts, sure. The last ones I looked at (2003 & 2004
models) they had deliberately built the boat with glued-in molding &
fabric liners so that you could not see or access any part of the
structure. Frustrating... and suspicious IMHO.

Sorry to hear that. I always thought they were excellent boats, if a bit
diminutive in beam and interior volume for their length. I haven't followed
them since the company was sold, but I suspect PS is facing the same
constraints other builders now face: with rising crude oil prices and
labor costs, builders must cut some corners to keep their boats in their
given price niches.

I should have asked first... you know Pacific Seacraft was bought up by a
conglomerate? Personally I think they're playing the sausage game. Nothing
stays good for long.

See above.


But many builders just toss the core in the mold and slap cloth
over it.

Some layup cloth/roving/matt on the outside and simply chopper the inside.
Did you know that several lamina in the layup schedule of Hallberg Rasseys
are choppered? Disappointed me to learn that.



Those same builders never anticipated being in business years later when
those cores were soaking wet, either.


They might not have thought it made that much difference, and couldn't
afford the labor to do it right anyway.

No doubt there was some builder ignorance involved, but I suspect many of
them knew exactly what would happen. A disgruntled ex-Sea Ray executive
told a SOUNDINGS editor that the company's policy, from the 70s on, is to
use ply in the transoms of their stern drive boats, knowing full well that
it would be soaked and soft in 20-30 years. Planned obsolescense.




Maxprop wrote:

Damned if I can recall what manufacturer did this, but I recall seeing a
boat on which all thru-bolts were first drilled oversize, then filled
with solid resin--epoxy, I presume--and then redrilled to the proper,
smaller diameter.

The problem with this method of repair is that you're cutting away the
strength memeber... the skin. But the epoxy filler is stronger in
compression than the core, so that's good.


You're cutting away such a small diameter of the skin that I think the
result is negligible, especially if the unit of hardware being installed
is quite a bit larger.

That's a good point. If the hardware is a lot larger, or has at least 3
mounting holes, it's probably just fine. I was thinking of single bolt
stuff.

I also drill out areas and fill with epoxy to mount small stuff with
self-tapping screws.


No, but freeze-thaw cycles will still cause progressive delamination if
any water gets into it. And Airex is also weak in compression, thru-bolts
will crush it and cause leaks.


It's surprisingly stiff and rigid. I installed a sheet stopper on the
cabin roof, and I was preparing to route out some of the Airex and
replace it with epoxy and West System's colloidal filler, but the local
glass man told me it wouldn't be necessary with Airex. I couldn't detect
any undue compression when I tightened the fasteners. Of course I bedded
them and the stopper in polysulfide caulk, tightened only slightly until
the caulk had a chance to set up slightly, then tightened it further.


Interesting to see what the results will be. Airex and Divinycell and
Klegecell and there some new German stuff that's supposed to be miraculous
but is tediously expensive are all less supject to compression failure,
and certainly less prone to rot but they are still not strong enough
to have rigging components thru-bolted to it. It may be that the caulk is
resilient enough to keep it watertight anyway, in your application.

Guess I should have explained in more detail: in the case of the sheet
stopper, I mounted a 3/4" teak backing plate and large diameter washers
underneath, and a slightly larger-than-the-stopper 1/2" teak mounting plate
on top.


If you're interested, I can recommend some fairly technical books on
composite aircraft construction, which is what I've been studying because
there aren't any books on fancy composite boat construction. Same stuff,
same issues, though.

Probably too esoteric for my needs, but thanks anyway. While on the
subject, though, I'm surprised that honeycomb aluminum hasn't been utilized
as a core material in boats. Virtually no weight, nothing to wick mositure,
and rigid and crush-proof like a cast iron beam when between laminates. But
I suppose the stuff is really costly. I know it was (is?) used in composite
aircraft construction. There were some skis with it as a core material some
years back, and they were successful, if expensive. It was never picked up
by other manufacturers, however.

..... The real killer of cored structure is lack of maintenance. How long
has it been since all deck fittiings were rebedded? Going on 2 1/2 years
for me, and I'm thinking about doing it again. But then I was raised in
the old school where you do this *every* year.


Then there's the school of thought that if you bed everything in
polyurethane (3M5200, for example) you'll never have to do it again.
That's true, because you'll never be *able* to do it again, and of course
it will leak with time. Terrible idea.


I used to use 5200 for everything, and then of course had to
peel/scrape/wirebrush it off, very tedious. Now I use 4200. And I own
stock in 3M.....

Our ketch had a deck prism through the teak deck right over the head of the
V-berth, and of course it leaked as all deck prisms eventually do. Trying
to remove it proved a bit much for my self control. I probably said a few
things that caused mothers to rush their kids out of the parking lot. But
eventually I found the former owner and asked with what he re-bedded the
damn thing. 5200, of course. 20 hours of hard labor, swearing, and bloody
fingers later it was re-bedded and leak-free. People who bed with
polyurethane should be glued to the mast approximately at the spreaders with
the stuff and left there for the cormorants to roost upon. It's great for
hull to deck bonding, however.


This turned out to be really long, sorry about that. But it's an
important issue. This should have come under the "projects" thread
earlier.


I think some of us enjoy projects of this nature. And some of us are
pedantic enough to want to do it in the best possible technological
manner. Most owners are clueless. ("You mean you have to rebed those
things? What the hell . . .?")


Maybe it is pedantry, but my belief is that it's less work to do things
the right way. Especially if you don't want it to fail at an inconvenient
time.

Another of my theories is that 'if it works, it must have been done
right.' I'd like to see some of Frank's work & learn.

Ditto.

Max

... Fiberglass will basically have almost no wear at all from
foot traffic. Teak will... I know this for a fact, having just removed a
20 year old teak deck.


Maxprop wrote:
I'm assuming that you didn't own that teak deck for the past 20 years,
therefore you may not know how it was cared for. Or perhaps you know it was
not cared for correctly.

The latter. Well, that may be unduly harsh... I have pretty
good evidence that it received no care at all.


... Most people are clueless as to how to care for
teak decking.

Sure. Most people are clueless, period.


....The yacht
Dorade--the namesake of the famous dorade box and cowl vent--sold a few
years ago, and its original deck was completely replaced. The wood from the
removed deck was in such good shape that much of it was used to re-deck
another boat. Dorade was one of Olin Stephens' most famous designs, built
in 1929.


Yep and a design worth studying IMHO. As for teak, one of
the reasons it's used so much on boats is that it's ppretty,
it's dense (fairly strong in several different aspects), and
it's very resistant to rot.

The teak that I removed was sought after by several
craftsmen I know, the wood itself was in great shape;
although it had caulk stuck to it & came up in pieces less
than 3' long. But hey, free teak! If I wasn't seriously
downsizing, I'd have kept it all myself.



.... which makes the best non-skid of all IMO.

Disagree, but then that's based on personal experience rather than heeding
the opinions of others. Heresy!


Mine is based upon experience as well. Most people think teak is terrible
underfoot.

Hardly.
I've very rarely heard anybody not rave about teak. In fact
I have never heard anybody else say it's poor nonskid. Ask
over at rec.boats.cruising and see what they say.

However I've sailed a lot of boats with teak decks, cared
for a variety of ways, and it struck me *every* time that if
it weren't for the caulk in the seams, walking a teak deck
would be shockingly similar to rollerskating. And some teak
decks are worse.

For a power boat, it's less of an issue. Our tugboat has
never once needed a headsail change while heeling 30 degrees
I took off our teak deck because of structural issues in the
core underneath. Many many many boats with screwed-in teak
decks get a trampoline deck when they're younger than ours.



Some layup cloth/roving/matt on the outside and simply chopper the inside.
Did you know that several lamina in the layup schedule of Hallberg Rasseys
are choppered? Disappointed me to learn that.


The only bad thing about chopper gun is that it's heavy &
overly stiff for it's yield point (ie breaks too soon
relative to how much it bends). But if sandwiched between
layers of roving, it would be just fine to build up
thickness. Less likely to wick moisture thru the laminate,
less likely to be irregularly catalyzed.

I have a buddy who used to have a 100% chopper gun canoe.
Weighed about 200#.




Those same builders never anticipated being in business years later when
those cores were soaking wet, either.


They might not have thought it made that much difference, and couldn't
afford the labor to do it right anyway.


No doubt there was some builder ignorance involved, but I suspect many of
them knew exactly what would happen. A disgruntled ex-Sea Ray executive
told a SOUNDINGS editor that the company's policy, from the 70s on, is to
use ply in the transoms of their stern drive boats, knowing full well that
it would be soaked and soft in 20-30 years. Planned obsolescense.


Well, sure. American business at it's finest. Besides, after
they sell the boat the first time, why should they care what
happens to it? It's too easy to build a "reputation for
quality" by buying lots of expensive advertising. Shucks,
this works in politics too.



Interesting to see what the results will be. Airex and Divinycell and
Klegecell and there some new German stuff that's supposed to be miraculous
but is tediously expensive are all less supject to compression failure,
and certainly less prone to rot but they are still not strong enough
to have rigging components thru-bolted to it. It may be that the caulk is
resilient enough to keep it watertight anyway, in your application.


Guess I should have explained in more detail: in the case of the sheet
stopper, I mounted a 3/4" teak backing plate and large diameter washers
underneath, and a slightly larger-than-the-stopper 1/2" teak mounting plate
on top.


OK, it may be that you've spread the compression over a
large enough area that it's not a problem. But there will be
a concentration of stress at the edge facing the direction
the line pulls from.

Hey if it works, it must have been done right!


.... While on the
subject, though, I'm surprised that honeycomb aluminum hasn't been utilized
as a core material in boats. Virtually no weight, nothing to wick mositure,
and rigid and crush-proof like a cast iron beam when between laminates. But
I suppose the stuff is really costly. I know it was (is?) used in composite
aircraft construction.

From what I've read, the issue is bonding the skin to the
core. Airplanes use some exotic technology to achieve this,
and it could be done (I believe it has been done) with some
high end boats for critical components. The easiest way to
get a good bond is to fill the cell with resin, but then you
don't have such a light structure any more!

DSK