Balsa deck core
 

If I were going to take this on, I'd turn the boat upside down and use a
vacuum bag.

I say "if" because I know how much work you have in front of you, and I
know what you might pay for a far better replacement.

It would cost you less, and be far less work, to buy a better boat.

Michiel wrote:
Hello,

I'm looking for a little bit of advise. This is more boat repair then
boat building, but I'm figuring you guys here would have the right
kind of knowledge.

At the beginning of the summer I bought a trailerable fiberglass
minicruiser (a 1983 Gloucester 20). When it rained in the fall I found
there were some leaks into the interior and I found out that the
central part of the deck (not all of it) is balsa cored and one side
of this is saturated with water. All of it has some delamination.

I drilled some holes from the inside and found that the port side is
wet and some of the balsa is dark and the starboard side is mostly
dry. The water may have come in at holes for deck hardware and some
cracks in the gelcoat, one of them spiderweb shaped. As an extra piece
of information, the mast rests on a higher area of the deck which
seems to have a thicker core (probably not balsa) which is dry.

I want to stop the water from getting in and I'm also concerned that
the delamination will cause the gelcoat to flex more and thus crack
more. It's been on my mind and I've thought of the following options:

1 - leave it be. put deck hardware back on sealing carefully with
polysulfide or 3M 4200. Perhaps drill a large number of holes in the
inner skin so the balsa can dry out.

2 - cut out inner skin, scrape out old balsa core and glue down new
balsa or plastic core and then cover this with polyester and
fiberglass.

3 - cut out inner skin, scape out old core and add multiple layers of
fiberglass and polyester, building up until the deck is nice and
stiff.

I'm strongly leaning toward option 3, but also considering 1.

Let me know what you think, please!


Thank you,

Michiel van Wessem

Balsa deck core
 

On Thu, 24 Nov 2005 11:56:47 -0500, Michiel
wrote:

On Thu, 24 Nov 2005 16:28:09 GMT, Jim wrote:

(...)
It would cost you less, and be far less work, to buy a better boat.

Do you really think so? Do you have rough estimates or "guesstimates"
and a suggestion for a different boat? It seems that fixing it
wouldn't be so expensive and not even that much work, just messy and
nasty.

I've done this in a small area (port side genoa track, so about two
metres by 15 cm.) and there's no denying it's a messy job. The expense
is in the time to you, because between shuttling back and forth for
supplies, and the raw labour, and the further labour to correct your
mistakes, could eat up the better part of your season.

On the other hand, you will have a stronger, more secure deck. I
suspect the reaction here is to the fact that it's a 20 foot boat and
thus very cheap on the open market, where everyone seems to want over
35 feet. You can pick up a bulletproof Shark (24 feet) for $5,000,
throw in a sleeping bag, a sandwich and a six pack and go sailing.
It's a good time to buy a well-found smaller boat, but repairing boats
is as expensive, or more so in the cost of core materials, epoxy and
so on, as ever.

So it comes down to how much you like this particular boat.

Fix it because you have to in order to restore the structural
integrite of the deck. One solution I haven't heard is to consider
taking off the entire deck and inverting that. In the long run, that
might be easier, but as I'm unfamiliar with your boat, I can't say.
Another option is to cut in from above, removing panels of gelcoat,
dig out the core, replace the core, bond the deck panels back in and
fill the cuts with thickened epoxy. Fair well, and cover the entire
deck with two-part paint to hide the "scars". Or, frankly, just
gelcoat it for protection. If you DO sell it, it's perversely nice to
show the next buyer that you've done the horrible necessary job
already and have the deck scars to prove it...G

A good core is marine grade plywood encapsulated with epoxy for places
where deck hardware is through bolted. On larger, empty stretches, I'd
use synthetic cores for strength and lightness. A sandwich of inner
skin, core and outer skin--when bonded in an epoxy matrix--is stronger
than solid fibreglass itself.

Get some of Don Casey's deck and hull repair books to see if you want
to tackle this. They are simple, full of diagrams and illustrations,
and have the standard techniques for majour renovations like this.

Balsa deck core
 

Not knowing what your requirements are, it's hard to recommend anything.

If you hang around any marina with a pocket full of cash and are
patient, you can do pretty well.

I'd suggest you watch a surveyor or two and learn what to look out for.



Michiel wrote:
On Thu, 24 Nov 2005 16:28:09 GMT, Jim wrote:

(...)

It would cost you less, and be far less work, to buy a better boat.


Do you really think so? Do you have rough estimates or "guesstimates"
and a suggestion for a different boat? It seems that fixing it
wouldn't be so expensive and not even that much work, just messy and
nasty.

Michiel

Balsa deck core
 

Michiel wrote:

On Thu, 24 Nov 2005 16:28:09 GMT, Jim wrote:

(...)

It would cost you less, and be far less work, to buy a better boat.


Do you really think so? Do you have rough estimates or "guesstimates"
and a suggestion for a different boat? It seems that fixing it
wouldn't be so expensive and not even that much work, just messy and
nasty.

Michiel

....and tiring! I spent 2nd last summer with a dremel, cutting off
antiskid and deck in sections, replacing the basla porrige with
plywood, reassembling and then sculpturing the anti skid back to
reasonable. Next year, starboard side deck? ugh!

Leaks are gone, but the difference in price between a soggy deck
boat and the same solid deck boat is still suspect. Still, now I am
an expert, no;-? Oh, and I did a lot of messing about on the boat,
even if it was only yard sailing:)

Terry K

Balsa deck core
 

Somebody wrote:

It would cost you less, and be far less work, to buy a better boat.

Michiel wrote:

Do you really think so? Do you have rough estimates or "guesstimates"
and a suggestion for a different boat?

I'll try to put this into perspective for you.

I buy materials at prices you would dream about getting.

That is because I buy large quantities of epoxy, deck foam, knitted
glass and fairing compound.

My guess is that it will cost me at least $2,000 for materials and at
least a year's time.

You will pay more.

Add in money for tools and supplies.

I'd budget at least $200 for just abrasives and another $200 for sanding
equipment, if you don't already have them.

You'll spend another $500 for misc tools and supplies.

DAMHIKT

Does this give you enough incentive to recognize that attempting to
rehab a 20 ft, 20+ year old fiberglass boat is economically an unsound path.

Lew

Balsa deck core
 

Lew Hodgett wrote:
My guess is that it will cost me at least $2,000 for materials and at
least a year's time.


My guess is that either you work very inefficiently, or else
you're sniffing too much resin.

For $2K and a couple months labor, one could completely
remove the deck, use it as tooling, mold a complete new one,
and install it.

You got this right: sanding materials & tools will both cost
a lot.

DSK

Balsa deck core
 

DSK wrote:

My guess is that either you work very inefficiently, or else you're
sniffing too much resin.

You haven't priced materials lately, have you?

Think OIL.

Lew

Balsa deck core
 

Lew Hodgett wrote:
You haven't priced materials lately, have you?

Think OIL.


Actually, I have- am buying materials for a carbon fiber
rowing dinghy. But I think you grossly (very grossly)
overestimated the cost & amount of materials needed for
replacing core on a 20' deck.

It's not going to be free, that's not what I'm saying.

DSK

Balsa deck core
 

I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables


"DSK" wrote in message
.. .
Lew Hodgett wrote:
You haven't priced materials lately, have you?

Think OIL.


Actually, I have- am buying materials for a carbon fiber
rowing dinghy. But I think you grossly (very grossly)
overestimated the cost & amount of materials needed for
replacing core on a 20' deck.

It's not going to be free, that's not what I'm saying.

DSK

Balsa deck core
 

Just wondering do you guys that use epoxy for everything also use titanium
for auto body repairs after all it's better than steel. It seems rather
silly to repair a polyester and glass boat which is old with epoxy and the
latest high tech fabrics. Why not try resin infusion too
John
"Jim Conlin" wrote in message
...
I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables


"DSK" wrote in message
.. .
Lew Hodgett wrote:
You haven't priced materials lately, have you?

Think OIL.


Actually, I have- am buying materials for a carbon fiber
rowing dinghy. But I think you grossly (very grossly)
overestimated the cost & amount of materials needed for
replacing core on a 20' deck.

It's not going to be free, that's not what I'm saying.

DSK

Balsa deck core
 

"Jim Conlin" wrote ...
I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables

Vacuum bagging it would be the way to go for bond strength,
but knitted glass? I didn't think that was all that cost
effective?

One thing I would like to mention is that hardware store
F'glass cloth is NOT worth it. It's actually a bit more
expensive than most mail order, plus it's crappy quality.

John M wrote:
Just wondering do you guys that use epoxy for everything also use titanium
for auto body repairs after all it's better than steel. It seems rather
silly to repair a polyester and glass boat which is old with epoxy and the
latest high tech fabrics. Why not try resin infusion too


Actually, it's not silly at all. Secondary bonding with
polyester is rather iffy... nowhere near as strong and
what's more important, less reliable (more prone to voids,
imperfectly mixed resin, more temp sensitive, etc etc) so
it's less likely to achieve it's best strength. Epoxy is not
that much more expensive (considering the expense entailed
by owning the rest of the boat too) and that little extra is
very well worth it IMHO.

The last boat I did extensive rebuild work on was an old
Lightning... considering that I bought new trailer tires &
bearings (or would you advocate buying cheaper used ones?),
new running rigging, new sails, and fairly nice paint (now
this could have been economised on, but would it have looked
as good), the 2 gallons of epoxy that I used to do
structural work was trivial... and I sailed that boat in 20+
knot winds many times, never broke anything that I'd worked
on with epoxy. The first few times I was nervous, but after
that became very confident in the strength of my work. BTW
this included relamating some patches of deck as well as
installing a new mainsheet bridle & traveller, which comes
under quite heavy strain.

OTOH I have seen other boats suffer structural failure in
strong winds... it doesn't look like much fun, but perhaps
the skippers are telling themselves they're glad they didn't
spend the money as they take the pieces home.

DSK

Balsa deck core
 

I presume you are saying that all my secondary bonds like bulkheads, liners,
water and fuel tank supports are about to let go. Epoxy has it's place,
ultrlight racing boats where the same strength can be had at much lower
weight and as a glue resorcinol is a pain. I live e in what used to be the
hub of boatbuilding in Canada and have seen many boats new and old repaired
with the same material they were built in that is polyester none that I know
of have yet disintegrated.
John
"DSK" wrote in message
.. .
"Jim Conlin" wrote ...
I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables

Vacuum bagging it would be the way to go for bond strength, but knitted
glass? I didn't think that was all that cost effective?

One thing I would like to mention is that hardware store F'glass cloth is
NOT worth it. It's actually a bit more expensive than most mail order,
plus it's crappy quality.

John M wrote:
Just wondering do you guys that use epoxy for everything also use
titanium for auto body repairs after all it's better than steel. It seems
rather silly to repair a polyester and glass boat which is old with epoxy
and the latest high tech fabrics. Why not try resin infusion too


Actually, it's not silly at all. Secondary bonding with polyester is
rather iffy... nowhere near as strong and what's more important, less
reliable (more prone to voids, imperfectly mixed resin, more temp
sensitive, etc etc) so it's less likely to achieve it's best strength.
Epoxy is not that much more expensive (considering the expense entailed by
owning the rest of the boat too) and that little extra is very well worth
it IMHO.

The last boat I did extensive rebuild work on was an old Lightning...
considering that I bought new trailer tires & bearings (or would you
advocate buying cheaper used ones?), new running rigging, new sails, and
fairly nice paint (now this could have been economised on, but would it
have looked as good), the 2 gallons of epoxy that I used to do structural
work was trivial... and I sailed that boat in 20+ knot winds many times,
never broke anything that I'd worked on with epoxy. The first few times I
was nervous, but after that became very confident in the strength of my
work. BTW this included relamating some patches of deck as well as
installing a new mainsheet bridle & traveller, which comes under quite
heavy strain.

OTOH I have seen other boats suffer structural failure in strong winds...
it doesn't look like much fun, but perhaps the skippers are telling
themselves they're glad they didn't spend the money as they take the
pieces home.

DSK

Balsa deck core
 

John M wrote:
I presume you are saying that all my secondary bonds like bulkheads, liners,
water and fuel tank supports are about to let go.

Umm, no

... Epoxy has it's place,
ultrlight racing boats where the same strength can be had at much lower
weight and as a glue resorcinol is a pain. I live e in what used to be the
hub of boatbuilding in Canada and have seen many boats new and old repaired
with the same material they were built in that is polyester none that I know
of have yet disintegrated.

If you're talking about the structural 2ndary bonds as put
in by the builder, consider this:
1- they are made under ideal conditions by workmen who
presumably are expert with the materials
2- they still break often enough that it's not uncommon at
all to see grid work, bulkhead tabbing, etc etc, pop loose
from inside the hull.

I was talking about repairs/upgrades done in a garage by the
home handy-man (who in some cases is more expert & produces
higher standard of craftsmanship than the "pro" in the
boatbuilding shop), of which I have also seen many break
loose. If you hang around boats & sailors that push their
boats in hard conditions for a few years, you'll see it
too... and probably hear more. In some cases, a single such
bond failure provides years worth of amusing stories.

Regards- Doug King

Balsa deck core
 

Lew Hodgett wrote:


Somebody wrote:

It would cost you less, and be far less work, to buy a better boat.


Michiel wrote:

Do you really think so? Do you have rough estimates or "guesstimates"
and a suggestion for a different boat?


I'll try to put this into perspective for you.

I buy materials at prices you would dream about getting.

That is because I buy large quantities of epoxy, deck foam, knitted
glass and fairing compound.

My guess is that it will cost me at least $2,000 for materials and at
least a year's time.

You will pay more.

Add in money for tools and supplies.

I'd budget at least $200 for just abrasives and another $200 for sanding
equipment, if you don't already have them.

You'll spend another $500 for misc tools and supplies.

DAMHIKT

Does this give you enough incentive to recognize that attempting to
rehab a 20 ft, 20+ year old fiberglass boat is economically an unsound
path.

Lew

It depends entirely on how you value the labour required. My labour
is free for me, but for this job, I wouldn't work for less than 15
bucks / hour.

I would pay 10 bucks an hour to mess about on a boat, if it was mine
and the value of the labour remains in the boat.

The rest is arithmatic.

Terry K

Balsa deck core
 

John,

Do you do body repairs with window screen and plastic filler?
You can make it look just as good as steel?

If you would go to sea in a boat patched with polyester, be my guest.
One of the famous ones in the book is "Tomahawk". She sank during a
Bayview Mackinac in the mid 80's. That was a polyester patch job.

A clients mast came down when it buckled at the spreaders because the
tabbing for the anchor for the lower came away from the hull side.

I helped recover a sloop that lost its steering because one of the
turning blocks came adrift.

Those last two were both bond failures of parts installed at teh
builders yard.

We are set up for resin infusion in several versions (skrimp, spike and
texp2) but none are well suited to most non-molded assemblies (that most
repairs).

Epoxy is used in repairs for two reasons, it has cohesive and adhesive
bond properties that far exceed that of poly or vinylesters. We
specialize in fixing things - once. Our clients only talk to us if they
want a first class job. We clould save the client 1or 200$ on a 5k$ job
by using cheap materials. We use only epoxy.

You can do what you want, but some of are not interested in doing it ont
he cheap - cheap is the price of low value.

Matt Colie

John M wrote:
Just wondering do you guys that use epoxy for everything also use titanium
for auto body repairs after all it's better than steel. It seems rather
silly to repair a polyester and glass boat which is old with epoxy and the
latest high tech fabrics. Why not try resin infusion too
John
"Jim Conlin" wrote in message
...

I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables


"DSK" wrote in message
...

Lew Hodgett wrote:

You haven't priced materials lately, have you?

Think OIL.


Actually, I have- am buying materials for a carbon fiber
rowing dinghy. But I think you grossly (very grossly)
overestimated the cost & amount of materials needed for
replacing core on a 20' deck.

It's not going to be free, that's not what I'm saying.

DSK

Balsa deck core
 

Matt:
Actually I don't do repairs on cars.
You mention Tomahawk and her "polyester patch job" how about the other five
boats that lost their masts or the eight that were damaged or for that
matter the 96 that dropped out. All polyester patches?
There are many boats built down to a price that will have parts falling off.
But think off all the plain old polyester and glass boats that have been
around the world with little or no problems.
Which brings to mind a British catamaran whose name escapes me at present,
that was built for a round the world record attempt in 1999 or 2000. Built
of prepreg epoxy, carbon fiber all the latest high tech. On its first test
run in weather that wasn't to bad its bows fell off. I won't blame the epoxy
or carbon fiber.
My point is epoxy and polyester have their place but nothing replaces proper
building practices.
With prices of epoxy at $74 a gallon and polyester at $105 for 5 gallons
it's hard to believe there is only a $200 difference in a $5000 job.
John



"Matt Colie" wrote in message
...
John,

Do you do body repairs with window screen and plastic filler?
You can make it look just as good as steel?

If you would go to sea in a boat patched with polyester, be my guest.
One of the famous ones in the book is "Tomahawk". She sank during a
Bayview Mackinac in the mid 80's. That was a polyester patch job.

A clients mast came down when it buckled at the spreaders because the
tabbing for the anchor for the lower came away from the hull side.

I helped recover a sloop that lost its steering because one of the turning
blocks came adrift.

Those last two were both bond failures of parts installed at teh builders
yard.

We are set up for resin infusion in several versions (skrimp, spike and
texp2) but none are well suited to most non-molded assemblies (that most
repairs).

Epoxy is used in repairs for two reasons, it has cohesive and adhesive
bond properties that far exceed that of poly or vinylesters. We
specialize in fixing things - once. Our clients only talk to us if they
want a first class job. We clould save the client 1or 200$ on a 5k$ job
by using cheap materials. We use only epoxy.

You can do what you want, but some of are not interested in doing it ont
he cheap - cheap is the price of low value.

Matt Colie

John M wrote:
Just wondering do you guys that use epoxy for everything also use
titanium for auto body repairs after all it's better than steel. It seems
rather silly to repair a polyester and glass boat which is old with epoxy
and the latest high tech fabrics. Why not try resin infusion too
John
"Jim Conlin" wrote in message
...

I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables


"DSK" wrote in message
t...

Lew Hodgett wrote:

You haven't priced materials lately, have you?

Think OIL.


Actually, I have- am buying materials for a carbon fiber
rowing dinghy. But I think you grossly (very grossly)
overestimated the cost & amount of materials needed for
replacing core on a 20' deck.

It's not going to be free, that's not what I'm saying.

DSK

Balsa deck core
 

John M wrote:
I presume you are saying that all my secondary bonds like bulkheads, liners,
water and fuel tank supports are about to let go. Epoxy has it's place,
ultrlight racing boats where the same strength can be had at much lower
weight and as a glue resorcinol is a pain. I live e in what used to be the
hub of boatbuilding in Canada and have seen many boats new and old repaired
with the same material they were built in that is polyester none that I know
of have yet disintegrated.
John

Hey, I've seen many boats built with polyester that had the
tabbing pull free from plywood bulkheads. You can use
polyester if you like, but given the amount of epoxy you're
talking about for a 20' deck repair, the cost difference is
trivial. And I think 2 x 12 oz biaxial would be ample :)
for an inside skin, given typical spans you'd find on this
size of boat and a core thickness of = 1/2".

Evan Gatehouse

Balsa deck core
 

Subject

Epoxy is an adhesive, polyester is not.

Next.

Lew

Balsa deck core
 

John,

Any part, piece -whatever of any racing yacht can fail at any time, I
mentioned "Tomahawk" because I knew some of the cast involved and it was
a polyester bond that failed in this case and caused the loss of the
vessel.

I agree that there is no substitute for proper practice.

My problem with polyester is simple, the bond strength is poor. If you
can do it all as a wet assembly, that is fine, but if you need to put
pieces together - polyester can be problems. I have done whole boats
with poly and vinylester (which is another animal). I completely agree
that it has its place. Most of them are in a mold.

If a guy is going to work under less than ideal conditions and do small
patches (less than a mold section), I always that they look at the
additional cost of epoxy. If you could get p or vest resin that had
nice little measuring pumps and was as well behaved, I still would be
hard pressed to advise it for repairs.

At the prices I pay 5 gallons (the smallest we buy) of poly is about
85$us, vinyl is about 140$us and 250$us for gallon mix - includes harder
of epoxy. The way any job works, labor is the big cost and the labor to
use gallons of resin is a big number.

The only problem with epoxy for repairs that require cosmetic surfacing
is taht you have to do a intermediate coat of vinyl to bond the
polyester gelcoat to the epoxy. Gelcoat will just fall right out of an
epoxy patch - given half a chance - it will has been know to do the same
to a poly repair but vinylester is good enough to bond the two.

And - when it come to the failures of super-lights - I don't even count
them as real. Like the ICAA boat that folded and sank off San Diego.
There is a reason why the shipwrights that I knew as a child worked the
way that they did. I have come to understand that all the wouldful new
analysis stuff like FEA, CFD and such are nice, but the people that have
been out there better not use it to determine what the sea can do.

Matt Colie



John M wrote:
Matt:
Actually I don't do repairs on cars.
You mention Tomahawk and her "polyester patch job" how about the other five
boats that lost their masts or the eight that were damaged or for that
matter the 96 that dropped out. All polyester patches?
There are many boats built down to a price that will have parts falling off.
But think off all the plain old polyester and glass boats that have been
around the world with little or no problems.
Which brings to mind a British catamaran whose name escapes me at present,
that was built for a round the world record attempt in 1999 or 2000. Built
of prepreg epoxy, carbon fiber all the latest high tech. On its first test
run in weather that wasn't to bad its bows fell off. I won't blame the epoxy
or carbon fiber.
My point is epoxy and polyester have their place but nothing replaces proper
building practices.
With prices of epoxy at $74 a gallon and polyester at $105 for 5 gallons
it's hard to believe there is only a $200 difference in a $5000 job.
John



"Matt Colie" wrote in message
...

John,

Do you do body repairs with window screen and plastic filler?
You can make it look just as good as steel?

If you would go to sea in a boat patched with polyester, be my guest.
One of the famous ones in the book is "Tomahawk". She sank during a
Bayview Mackinac in the mid 80's. That was a polyester patch job.

A clients mast came down when it buckled at the spreaders because the
tabbing for the anchor for the lower came away from the hull side.

I helped recover a sloop that lost its steering because one of the turning
blocks came adrift.

Those last two were both bond failures of parts installed at teh builders
yard.

We are set up for resin infusion in several versions (skrimp, spike and
texp2) but none are well suited to most non-molded assemblies (that most
repairs).

Epoxy is used in repairs for two reasons, it has cohesive and adhesive
bond properties that far exceed that of poly or vinylesters. We
specialize in fixing things - once. Our clients only talk to us if they
want a first class job. We clould save the client 1or 200$ on a 5k$ job
by using cheap materials. We use only epoxy.

You can do what you want, but some of are not interested in doing it ont
he cheap - cheap is the price of low value.

Matt Colie

John M wrote:

Just wondering do you guys that use epoxy for everything also use
titanium for auto body repairs after all it's better than steel. It seems
rather silly to repair a polyester and glass boat which is old with epoxy
and the latest high tech fabrics. Why not try resin infusion too
John
"Jim Conlin" wrote in message
...


I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables


"DSK" wrote in message
et...


Lew Hodgett wrote:


You haven't priced materials lately, have you?

Think OIL.


Actually, I have- am buying materials for a carbon fiber
rowing dinghy. But I think you grossly (very grossly)
overestimated the cost & amount of materials needed for
replacing core on a 20' deck.

It's not going to be free, that's not what I'm saying.

DSK

Balsa deck core
 

Matt:
Some figures taken from West Epoxy web site where they did tests on bonding
strength of epoxy and polyester.
Tensile strength of original glass 26,198 PSI
Tensile strength of poly repair 18,460 PSI
Tensile of epoxy repair 21,404 PSI
Therefore polyester has a strength 13% less than epoxy at a cost of about
500% more.

"Matt Colie" wrote in message
...
John,

Any part, piece -whatever of any racing yacht can fail at any time, I
mentioned "Tomahawk" because I knew some of the cast involved and it was a
polyester bond that failed in this case and caused the loss of the vessel.

The way many boats are built today anything can fall off.

I agree that there is no substitute for proper practice.

My problem with polyester is simple, the bond strength is poor. If you
can do it all as a wet assembly, that is fine, but if you need to put
pieces together - polyester can be problems. I have done whole boats with
poly and vinylester (which is another animal). I completely agree that it
has its place. Most of them are in a mold.

See the beginning paragraph 13% difference.

If a guy is going to work under less than ideal conditions and do small
patches (less than a mold section), I always that they look at the
additional cost of epoxy. If you could get p or vest resin that had nice
little measuring pumps and was as well behaved, I still would be hard
pressed to advise it for repairs.

Polyester isn't that fussy but I use a Nalge dispenser and never had a
problem.


At the prices I pay 5 gallons (the smallest we buy) of poly is about
85$us, vinyl is about 140$us and 250$us for gallon mix - includes harder
of epoxy. The way any job works, labor is the big cost and the labor to
use gallons of resin is a big number.

The only problem with epoxy for repairs that require cosmetic surfacing is
taht you have to do a intermediate coat of vinyl to bond the polyester
gelcoat to the epoxy. Gelcoat will just fall right out of an epoxy
patch - given half a chance - it will has been know to do the same to a
poly repair but vinylester is good enough to bond the two.

And - when it come to the failures of super-lights - I don't even count
them as real. Like the ICAA boat that folded and sank off San Diego.
There is a reason why the shipwrights that I knew as a child worked the
way that they did. I have come to understand that all the wouldful new
analysis stuff like FEA, CFD and such are nice, but the people that have
been out there better not use it to determine what the sea can do.

Matt Colie

My main problem with epoxy is the people who think it's the holy grail,
I think anyone who
recommends epoxy to repair a deck on a 25 year old 20 foot boat has either
too much money or has been reading too many newsgroups.
I would think that the boat that started this discussion could be repaired
at minimum cost and be as strong as the good side of the deck. No more is
needed.
John


John M wrote:
Matt:
Actually I don't do repairs on cars.
You mention Tomahawk and her "polyester patch job" how about the other
five boats that lost their masts or the eight that were damaged or for
that matter the 96 that dropped out. All polyester patches?
There are many boats built down to a price that will have parts falling
off. But think off all the plain old polyester and glass boats that have
been around the world with little or no problems.
Which brings to mind a British catamaran whose name escapes me at
present, that was built for a round the world record attempt in 1999 or
2000. Built of prepreg epoxy, carbon fiber all the latest high tech. On
its first test run in weather that wasn't to bad its bows fell off. I
won't blame the epoxy or carbon fiber.
My point is epoxy and polyester have their place but nothing replaces
proper building practices.
With prices of epoxy at $74 a gallon and polyester at $105 for 5 gallons
it's hard to believe there is only a $200 difference in a $5000 job.
John



"Matt Colie" wrote in message
...

John,

Do you do body repairs with window screen and plastic filler?
You can make it look just as good as steel?

If you would go to sea in a boat patched with polyester, be my guest.
One of the famous ones in the book is "Tomahawk". She sank during a
Bayview Mackinac in the mid 80's. That was a polyester patch job.

A clients mast came down when it buckled at the spreaders because the
tabbing for the anchor for the lower came away from the hull side.

I helped recover a sloop that lost its steering because one of the
turning blocks came adrift.

Those last two were both bond failures of parts installed at teh builders
yard.

We are set up for resin infusion in several versions (skrimp, spike and
texp2) but none are well suited to most non-molded assemblies (that most
repairs).

Epoxy is used in repairs for two reasons, it has cohesive and adhesive
bond properties that far exceed that of poly or vinylesters. We
specialize in fixing things - once. Our clients only talk to us if they
want a first class job. We clould save the client 1or 200$ on a 5k$ job
by using cheap materials. We use only epoxy.

You can do what you want, but some of are not interested in doing it ont
he cheap - cheap is the price of low value.

Matt Colie

John M wrote:

Just wondering do you guys that use epoxy for everything also use
titanium for auto body repairs after all it's better than steel. It
seems rather silly to repair a polyester and glass boat which is old
with epoxy and the latest high tech fabrics. Why not try resin infusion
too
John
"Jim Conlin" wrote in message
...


I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables


"DSK" wrote in message
. net...


Lew Hodgett wrote:


You haven't priced materials lately, have you?

Think OIL.


Actually, I have- am buying materials for a carbon fiber
rowing dinghy. But I think you grossly (very grossly)
overestimated the cost & amount of materials needed for
replacing core on a 20' deck.

It's not going to be free, that's not what I'm saying.

DSK

Balsa deck core
 

John,

The numbers you quote are (again) for a repair done under ideal
conditions.

Please use whatever materials you choose to do the repairs on YOUR boat.
I/we have a reputation to maintain and can not afford to work on the
cheap.

In four plus decades of doing boat repair (I did not start with
plastic), I have had some experience that I care to share so that other
might benefit. As stated below, the epoxy is going to be something like
5~7% of the job cost. - I still don't know why you pay more than the
retail price for epoxy. Try going to Boat/West they will have adeal for
you.

I have had to clean up after too many mix failures with poly and have
never had one with epoxy run from a pump set. We even used to mix poly
on a balanace, and we still had a crash set. I have had to repair
numerous bond failures (never my own) in poly assemblies (as described
prior).

I assign no supernatural powers to epoxy. I mearly state that it is a
much better material for the DYI owner repair.

My own personal sloop is the first of its class (hull#1). It is
twenty-four years old. It is still competitive and I am expecting it to
be my last boat.

The repairs the out friend Michiel is outlining are about 5mh/ft2 and he
could lose a lot of that if he has a mix or bond failure. I don't like
to give work away.

Matt Colie

John M wrote:
Matt:
Some figures taken from West Epoxy web site where they did tests on bonding
strength of epoxy and polyester.
Tensile strength of original glass 26,198 PSI
Tensile strength of poly repair 18,460 PSI
Tensile of epoxy repair 21,404 PSI
Therefore polyester has a strength 13% less than epoxy at a cost of about
500% more.

"Matt Colie" wrote in message
...

John,

Any part, piece -whatever of any racing yacht can fail at any time, I
mentioned "Tomahawk" because I knew some of the cast involved and it was a
polyester bond that failed in this case and caused the loss of the vessel.


The way many boats are built today anything can fall off.


I agree that there is no substitute for proper practice.

My problem with polyester is simple, the bond strength is poor. If you
can do it all as a wet assembly, that is fine, but if you need to put
pieces together - polyester can be problems. I have done whole boats with
poly and vinylester (which is another animal). I completely agree that it
has its place. Most of them are in a mold.


See the beginning paragraph 13% difference.


If a guy is going to work under less than ideal conditions and do small
patches (less than a mold section), I always that they look at the
additional cost of epoxy. If you could get p or vest resin that had nice
little measuring pumps and was as well behaved, I still would be hard
pressed to advise it for repairs.


Polyester isn't that fussy but I use a Nalge dispenser and never had a
problem.



At the prices I pay 5 gallons (the smallest we buy) of poly is about
85$us, vinyl is about 140$us and 250$us for gallon mix - includes harder
of epoxy. The way any job works, labor is the big cost and the labor to
use gallons of resin is a big number.

The only problem with epoxy for repairs that require cosmetic surfacing is
taht you have to do a intermediate coat of vinyl to bond the polyester
gelcoat to the epoxy. Gelcoat will just fall right out of an epoxy
patch - given half a chance - it will has been know to do the same to a
poly repair but vinylester is good enough to bond the two.

And - when it come to the failures of super-lights - I don't even count
them as real. Like the ICAA boat that folded and sank off San Diego.
There is a reason why the shipwrights that I knew as a child worked the
way that they did. I have come to understand that all the wouldful new
analysis stuff like FEA, CFD and such are nice, but the people that have
been out there better not use it to determine what the sea can do.

Matt Colie


My main problem with epoxy is the people who think it's the holy grail,
I think anyone who
recommends epoxy to repair a deck on a 25 year old 20 foot boat has either
too much money or has been reading too many newsgroups.
I would think that the boat that started this discussion could be repaired
at minimum cost and be as strong as the good side of the deck. No more is
needed.
John


John M wrote:

Matt:
Actually I don't do repairs on cars.
You mention Tomahawk and her "polyester patch job" how about the other
five boats that lost their masts or the eight that were damaged or for
that matter the 96 that dropped out. All polyester patches?
There are many boats built down to a price that will have parts falling
off. But think off all the plain old polyester and glass boats that have
been around the world with little or no problems.
Which brings to mind a British catamaran whose name escapes me at
present, that was built for a round the world record attempt in 1999 or
2000. Built of prepreg epoxy, carbon fiber all the latest high tech. On
its first test run in weather that wasn't to bad its bows fell off. I
won't blame the epoxy or carbon fiber.
My point is epoxy and polyester have their place but nothing replaces
proper building practices.
With prices of epoxy at $74 a gallon and polyester at $105 for 5 gallons
it's hard to believe there is only a $200 difference in a $5000 job.
John



"Matt Colie" wrote in message
...


John,

Do you do body repairs with window screen and plastic filler?
You can make it look just as good as steel?

If you would go to sea in a boat patched with polyester, be my guest.
One of the famous ones in the book is "Tomahawk". She sank during a
Bayview Mackinac in the mid 80's. That was a polyester patch job.

A clients mast came down when it buckled at the spreaders because the
tabbing for the anchor for the lower came away from the hull side.

I helped recover a sloop that lost its steering because one of the
turning blocks came adrift.

Those last two were both bond failures of parts installed at teh builders
yard.

We are set up for resin infusion in several versions (skrimp, spike and
texp2) but none are well suited to most non-molded assemblies (that most
repairs).

Epoxy is used in repairs for two reasons, it has cohesive and adhesive
bond properties that far exceed that of poly or vinylesters. We
specialize in fixing things - once. Our clients only talk to us if they
want a first class job. We clould save the client 1or 200$ on a 5k$ job
by using cheap materials. We use only epoxy.

You can do what you want, but some of are not interested in doing it ont
he cheap - cheap is the price of low value.

Matt Colie

John M wrote:


Just wondering do you guys that use epoxy for everything also use
titanium for auto body repairs after all it's better than steel. It
seems rather silly to repair a polyester and glass boat which is old
with epoxy and the latest high tech fabrics. Why not try resin infusion
too
John
"Jim Conlin" wrote in message
...



I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables


"DSK" wrote in message
.net...



Lew Hodgett wrote:



You haven't priced materials lately, have you?

Think OIL.


Actually, I have- am buying materials for a carbon fiber
rowing dinghy. But I think you grossly (very grossly)
overestimated the cost & amount of materials needed for
replacing core on a 20' deck.

It's not going to be free, that's not what I'm saying.

DSK

Balsa deck core
 

Michiel,
Discussion is always valuable. As I often remark (to clients that find
the proposal that they have just received to be overwhelming), thinking
is the cheapest and most valuable thing to do.

In the time this discussion has ben on the wire, I have contracted to do
a very similar job. I will gladdly write a quote for this job if you
are in 1hr striking range from the highway exit nearest Detroit River
Light. I do, however, have confidence that the assmebled quote will be
more than you were expecting.

Good Luck with the job, keep us informed.

Matt Colie

Michiel wrote:

Hehe, I had no idea this would set off such a discussion! This is
great stuff.. lots of input. Thanks!

Too bad I can't make you guys fix the boat for me.. I think it would
already be done!

Michiel


On Tue, 29 Nov 2005 21:06:57 -0500, "John M" wrote:


Matt:
Some figures taken from West Epoxy web site where they did tests on bonding
strength of epoxy and polyester.
Tensile strength of original glass 26,198 PSI
Tensile strength of poly repair 18,460 PSI
Tensile of epoxy repair 21,404 PSI
Therefore polyester has a strength 13% less than epoxy at a cost of about
500% more.

"Matt Colie" wrote in message
...

John,

Any part, piece -whatever of any racing yacht can fail at any time, I
mentioned "Tomahawk" because I knew some of the cast involved and it was a
polyester bond that failed in this case and caused the loss of the vessel.

The way many boats are built today anything can fall off.


I agree that there is no substitute for proper practice.

My problem with polyester is simple, the bond strength is poor. If you
can do it all as a wet assembly, that is fine, but if you need to put
pieces together - polyester can be problems. I have done whole boats with
poly and vinylester (which is another animal). I completely agree that it
has its place. Most of them are in a mold.

See the beginning paragraph 13% difference.


If a guy is going to work under less than ideal conditions and do small
patches (less than a mold section), I always that they look at the
additional cost of epoxy. If you could get p or vest resin that had nice
little measuring pumps and was as well behaved, I still would be hard
pressed to advise it for repairs.

Polyester isn't that fussy but I use a Nalge dispenser and never had a
problem.



At the prices I pay 5 gallons (the smallest we buy) of poly is about
85$us, vinyl is about 140$us and 250$us for gallon mix - includes harder
of epoxy. The way any job works, labor is the big cost and the labor to
use gallons of resin is a big number.

The only problem with epoxy for repairs that require cosmetic surfacing is
taht you have to do a intermediate coat of vinyl to bond the polyester
gelcoat to the epoxy. Gelcoat will just fall right out of an epoxy
patch - given half a chance - it will has been know to do the same to a
poly repair but vinylester is good enough to bond the two.

And - when it come to the failures of super-lights - I don't even count
them as real. Like the ICAA boat that folded and sank off San Diego.
There is a reason why the shipwrights that I knew as a child worked the
way that they did. I have come to understand that all the wouldful new
analysis stuff like FEA, CFD and such are nice, but the people that have
been out there better not use it to determine what the sea can do.

Matt Colie


My main problem with epoxy is the people who think it's the holy grail,
I think anyone who
recommends epoxy to repair a deck on a 25 year old 20 foot boat has either
too much money or has been reading too many newsgroups.
I would think that the boat that started this discussion could be repaired
at minimum cost and be as strong as the good side of the deck. No more is
needed.
John


John M wrote:

Matt:
Actually I don't do repairs on cars.
You mention Tomahawk and her "polyester patch job" how about the other
five boats that lost their masts or the eight that were damaged or for
that matter the 96 that dropped out. All polyester patches?
There are many boats built down to a price that will have parts falling
off. But think off all the plain old polyester and glass boats that have
been around the world with little or no problems.
Which brings to mind a British catamaran whose name escapes me at
present, that was built for a round the world record attempt in 1999 or
2000. Built of prepreg epoxy, carbon fiber all the latest high tech. On
its first test run in weather that wasn't to bad its bows fell off. I
won't blame the epoxy or carbon fiber.
My point is epoxy and polyester have their place but nothing replaces
proper building practices.
With prices of epoxy at $74 a gallon and polyester at $105 for 5 gallons
it's hard to believe there is only a $200 difference in a $5000 job.
John



"Matt Colie" wrote in message
...


John,

Do you do body repairs with window screen and plastic filler?
You can make it look just as good as steel?

If you would go to sea in a boat patched with polyester, be my guest.
One of the famous ones in the book is "Tomahawk". She sank during a
Bayview Mackinac in the mid 80's. That was a polyester patch job.

A clients mast came down when it buckled at the spreaders because the
tabbing for the anchor for the lower came away from the hull side.

I helped recover a sloop that lost its steering because one of the
turning blocks came adrift.

Those last two were both bond failures of parts installed at teh builders
yard.

We are set up for resin infusion in several versions (skrimp, spike and
texp2) but none are well suited to most non-molded assemblies (that most
repairs).

Epoxy is used in repairs for two reasons, it has cohesive and adhesive
bond properties that far exceed that of poly or vinylesters. We
specialize in fixing things - once. Our clients only talk to us if they
want a first class job. We clould save the client 1or 200$ on a 5k$ job
by using cheap materials. We use only epoxy.

You can do what you want, but some of are not interested in doing it ont
he cheap - cheap is the price of low value.

Matt Colie

John M wrote:


Just wondering do you guys that use epoxy for everything also use
titanium for auto body repairs after all it's better than steel. It
seems rather silly to repair a polyester and glass boat which is old
with epoxy and the latest high tech fabrics. Why not try resin infusion
too
John
"Jim Conlin" wrote in message
...



I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables


"DSK" wrote in message
h.net...



Lew Hodgett wrote:



You haven't priced materials lately, have you?

Think OIL.


Actually, I have- am buying materials for a carbon fiber
rowing dinghy. But I think you grossly (very grossly)
overestimated the cost & amount of materials needed for
replacing core on a 20' deck.

It's not going to be free, that's not what I'm saying.

DSK

Balsa deck core
 

John M wrote:

Matt:
Some figures taken from West Epoxy web site where they did tests on bonding
strength of epoxy and polyester.
Tensile strength of original glass 26,198 PSI
Tensile strength of poly repair 18,460 PSI
Tensile of epoxy repair 21,404 PSI
Therefore polyester has a strength 13% less than epoxy at a cost of about
500% more.

"Matt Colie" wrote in message
...

John,

Any part, piece -whatever of any racing yacht can fail at any time, I
mentioned "Tomahawk" because I knew some of the cast involved and it was a
polyester bond that failed in this case and caused the loss of the vessel.


The way many boats are built today anything can fall off.


I agree that there is no substitute for proper practice.

My problem with polyester is simple, the bond strength is poor. If you
can do it all as a wet assembly, that is fine, but if you need to put
pieces together - polyester can be problems. I have done whole boats with
poly and vinylester (which is another animal). I completely agree that it
has its place. Most of them are in a mold.


See the beginning paragraph 13% difference.


If a guy is going to work under less than ideal conditions and do small
patches (less than a mold section), I always that they look at the
additional cost of epoxy. If you could get p or vest resin that had nice
little measuring pumps and was as well behaved, I still would be hard
pressed to advise it for repairs.


Polyester isn't that fussy but I use a Nalge dispenser and never had a
problem.



At the prices I pay 5 gallons (the smallest we buy) of poly is about
85$us, vinyl is about 140$us and 250$us for gallon mix - includes harder
of epoxy. The way any job works, labor is the big cost and the labor to
use gallons of resin is a big number.

The only problem with epoxy for repairs that require cosmetic surfacing is
taht you have to do a intermediate coat of vinyl to bond the polyester
gelcoat to the epoxy. Gelcoat will just fall right out of an epoxy
patch - given half a chance - it will has been know to do the same to a
poly repair but vinylester is good enough to bond the two.

And - when it come to the failures of super-lights - I don't even count
them as real. Like the ICAA boat that folded and sank off San Diego.
There is a reason why the shipwrights that I knew as a child worked the
way that they did. I have come to understand that all the wouldful new
analysis stuff like FEA, CFD and such are nice, but the people that have
been out there better not use it to determine what the sea can do.

Matt Colie


My main problem with epoxy is the people who think it's the holy grail,
I think anyone who
recommends epoxy to repair a deck on a 25 year old 20 foot boat has either
too much money or has been reading too many newsgroups.
I would think that the boat that started this discussion could be repaired
at minimum cost and be as strong as the good side of the deck. No more is
needed.
John


John M wrote:

Matt:
Actually I don't do repairs on cars.
You mention Tomahawk and her "polyester patch job" how about the other
five boats that lost their masts or the eight that were damaged or for
that matter the 96 that dropped out. All polyester patches?
There are many boats built down to a price that will have parts falling
off. But think off all the plain old polyester and glass boats that have
been around the world with little or no problems.
Which brings to mind a British catamaran whose name escapes me at
present, that was built for a round the world record attempt in 1999 or
2000. Built of prepreg epoxy, carbon fiber all the latest high tech. On
its first test run in weather that wasn't to bad its bows fell off. I
won't blame the epoxy or carbon fiber.
My point is epoxy and polyester have their place but nothing replaces
proper building practices.
With prices of epoxy at $74 a gallon and polyester at $105 for 5 gallons
it's hard to believe there is only a $200 difference in a $5000 job.
John



"Matt Colie" wrote in message
...


John,

Do you do body repairs with window screen and plastic filler?
You can make it look just as good as steel?

If you would go to sea in a boat patched with polyester, be my guest.
One of the famous ones in the book is "Tomahawk". She sank during a
Bayview Mackinac in the mid 80's. That was a polyester patch job.

A clients mast came down when it buckled at the spreaders because the
tabbing for the anchor for the lower came away from the hull side.

I helped recover a sloop that lost its steering because one of the
turning blocks came adrift.

Those last two were both bond failures of parts installed at teh builders
yard.

We are set up for resin infusion in several versions (skrimp, spike and
texp2) but none are well suited to most non-molded assemblies (that most
repairs).

Epoxy is used in repairs for two reasons, it has cohesive and adhesive
bond properties that far exceed that of poly or vinylesters. We
specialize in fixing things - once. Our clients only talk to us if they
want a first class job. We clould save the client 1or 200$ on a 5k$ job
by using cheap materials. We use only epoxy.

You can do what you want, but some of are not interested in doing it ont
he cheap - cheap is the price of low value.

Matt Colie

John M wrote:


Just wondering do you guys that use epoxy for everything also use
titanium for auto body repairs after all it's better than steel. It
seems rather silly to repair a polyester and glass boat which is old
with epoxy and the latest high tech fabrics. Why not try resin infusion
too
John
"Jim Conlin" wrote in message
...



I figure it'd be somewhat over $10/ft^2.
Core-cell $4-
maybe 4 laminations of:
12 oz. knitted Glass $10/yd = $.80/ft^2/ply
epoxy $70/gal = $.60/ft^2/ply

paint $1/ft^2
plus abrasives, peel ply, fillers, vacuum bag consumables


"DSK" wrote in message
.net...



Lew Hodgett wrote:



You haven't priced materials lately, have you?

Think OIL.


Actually, I have- am buying materials for a carbon fiber
rowing dinghy. But I think you grossly (very grossly)
overestimated the cost & amount of materials needed for
replacing core on a 20' deck.

It's not going to be free, that's not what I'm saying.

DSK







All this puts me in mind of patching an old goatskin water bladder
with a piece of new leather.

Also, cost benefit analysis, proper surface preparation, who knows what?

All ties in with chemical bond curing. How about contact cement or
other "primer" over old poly, followed by more poly / glass?

Terry K

Balsa deck core
 

Terry
Please note I never said the epoxy repair would not be stronger than the
same in polyester. Lets take this to the extreme and say epoxy is 100 times
stronger and many think this is the case. Why on a 25 year old boat would
anybody want one side to be 100 times stronger than the original deck. I
think I did mention proper workmanship counts which precludes contact
cement.
No doubt Matts repair will be stronger and probably prettier than mine but
strong enough is strong enough.
John

"
All this puts me in mind of patching an old goatskin water bladder with a
piece of new leather.

Also, cost benefit analysis, proper surface preparation, who knows what?

All ties in with chemical bond curing. How about contact cement or other
"primer" over old poly, followed by more poly / glass?

Terry K

Balsa deck core
 

Terry K said

All this puts me in mind of patching an old goatskin water
bladder with a piece of new leather.

Also, cost benefit analysis, proper surface preparation, who
knows what?

All ties in with chemical bond curing. How about contact cement
or other "primer" over old poly, followed by more poly / glass?


John M wrote:
Terry
Please note I never said the epoxy repair would not be stronger than the
same in polyester. Lets take this to the extreme and say epoxy is 100 times
stronger and many think this is the case. Why on a 25 year old boat would
anybody want one side to be 100 times stronger than the original deck. I
think I did mention proper workmanship counts which precludes contact
cement.
No doubt Matts repair will be stronger and probably prettier than mine but
strong enough is strong enough.
John


My sentiment, too. With whom are you in dispute?

I am interested in knowing if there might be a primer of some sort
that might improve the mere 13,000 lb(whatever!) per sq inch bond of
poly on poly that is supposedly not sufficient to be trustworthy
when compared to 18,000 (whatever!) epoxy glue.

How did the old guys work up the nerve to trust oakum and white lead
jammed in all those lapstrake planks? Wonder what it's bond strength
was, 10 lbs per sq inch? The nails would each contribute, what, 200
lbs per nail? Could structure and configuration and application have
anything to do with it?

My HR28 seemed quite happy with the approx 9:1 taper, one sided, one
splot, external conical wad patch over a removed 1.5" thru hull
hole, with one layer of glass inside just for worries sake, as per
the Gougeon brothers advice. Of course, the HR was about 1/4" thick
solid glass, and some will say, built like a brick tank to begin
with. (Cobham armour, anyone?)

Neither welded titanium nor epoxy could have performed better in any
imaginable circumstace. After the boat was destroyed by arson and
nearby glass burned and melted, the patch was still unnoticable,
still trustworthy, still about 5 bucks cheaper, still gelcoatable,
if one wanted to gelcoat under bottom paint. Another gold plating
option unexcercised.

I can not see where using a thinner epoxy splot would actually save
any appreciable weight, either. Of course, new construction maxi
racers, engineered all to hell for every imagined marginal advantage
doesn't exactly reccommend itself either, after what seems to happen
to aramid and carbon fibre racing boats exposed to one inch higher
or one knot faster waves and winds than designed up against.

This epoxy thing seems like a sickness, mania, or sales hype to me.

My whacko buddy was rabid about Mission brand speakers being
unarguably, vastly superior while arguing in his commonly
bewildered, strangely motivated state. My test equipment was
irrelevant in that it did not appreciate subjective, sensible colour
of sound, and phase, or something. I simply maintained that the
possible .00001% undetectable "improvement" over my old EPIs was
irrelevant to the application, cost benefit wise, considering the
way premium prices. He went incohate, popped his wads! Too much
meth? Stock in the company? Or, just innocent testosterone?

I would really like to believe, but no epistle has arrived, as yet,
and the light required to see such epistle remains dark.

As far as the material for replacement core is concerned, balsa is
primarily spacer. It's strength really isn't appreciable. Old
plywood scraps is as good or stronger, if a little heavier, if kept
dry. Small pieces, isolated by plasic dams is adequate, at least.

Terry K