On Sun, 04 Nov 2007 12:10:43 -0500, HK wrote:

The only
materials I think suitable for the fiberglass "hull" are the various
cloths and resins, not foam or foam boards or fillers.

From the very beginning fiberglass boat builders have been using core
material in strategic places to add thickness and stiffness without
adding weight. Unsupported fiberglass by itself is not a particularly
good structural material. Wood was probably the first core material
and is still very popular. The trick is to properly protect it from
moisture and rot. If you take a look at well built offshore boats
like Bertram, Hatteras and Grand Banks you will find a lot of
structural wood. The secret is to use high quality material and
protect it well. Fiberglass combined with any type of core material
is a composite.

Wayne.B wrote:
On Sun, 04 Nov 2007 12:10:43 -0500, HK wrote:

The only
materials I think suitable for the fiberglass "hull" are the various
cloths and resins, not foam or foam boards or fillers.

From the very beginning fiberglass boat builders have been using core
material in strategic places to add thickness and stiffness without
adding weight. Unsupported fiberglass by itself is not a particularly
good structural material. Wood was probably the first core material
and is still very popular. The trick is to properly protect it from
moisture and rot. If you take a look at well built offshore boats
like Bertram, Hatteras and Grand Banks you will find a lot of
structural wood. The secret is to use high quality material and
protect it well. Fiberglass combined with any type of core material
is a composite.


Yeah, Hatteras is well-known for using a lot of "structural wood" in its
hullsides and bottoms, right, Wayne? Jeez.

Properly protected wood is just fine in stringers, bulkheads, transoms,
et cetera.

But that wasn't what was being discussed. Hulls were.

Does that high transom, dead transmission RV of yours have wood in its
hullsides or bottom? Well, hopefully if it does, it isn't balsa.

On Sun, 04 Nov 2007 21:12:19 -0500, HK wrote:

Properly protected wood is just fine in stringers, bulkheads, transoms,
et cetera.

But that wasn't what was being discussed. Hulls were.

THe hull is more than just topsides and bottoms, and the transom is
part of the hull also, last time I looked. Encapsulation and strength
of core material is the key but I agree that the bottom and hull sides
should ideally be uncored. If you do that however, you have to
stiffen them up in some other way, and increasing the thickness of the
glass laminate is an inefficient way to do it. The traditional way is
to add internal structure, typically encapsulated wood, another form
of composite construction.

Wayne.B wrote:
On Sun, 04 Nov 2007 21:12:19 -0500, HK wrote:

Properly protected wood is just fine in stringers, bulkheads, transoms,
et cetera.

But that wasn't what was being discussed. Hulls were.

THe hull is more than just topsides and bottoms, and the transom is
part of the hull also, last time I looked. Encapsulation and strength
of core material is the key but I agree that the bottom and hull sides
should ideally be uncored. If you do that however, you have to
stiffen them up in some other way, and increasing the thickness of the
glass laminate is an inefficient way to do it. The traditional way is
to add internal structure, typically encapsulated wood, another form
of composite construction.

That's an area of agreement, previously acknowledged.

On Nov 4, 8:12 pm, HK wrote:
Wayne.B wrote:
On Sun, 04 Nov 2007 12:10:43 -0500, HK

Does that high transom, dead transmission RV of yours have wood in its
hullsides or bottom? Well, hopefully if it does, it isn't balsa

"Balsa" = "Bayliner"

On Sun, 04 Nov 2007 20:32:58 -0800, Tim wrote:

Does that high transom, dead transmission RV of yours have wood in its
hullsides or bottom? Well, hopefully if it does, it isn't balsa

"Balsa" = "Bayliner"

Quite a few supposedly high quality sailboats have also been built
with balsa cored hulls. Many of them have turned into expensive
junk.

Wayne.B wrote:
On Sun, 04 Nov 2007 20:32:58 -0800, Tim wrote:

Does that high transom, dead transmission RV of yours have wood in its
hullsides or bottom? Well, hopefully if it does, it isn't balsa
"Balsa" = "Bayliner"

Quite a few supposedly high quality sailboats have also been built
with balsa cored hulls. Many of them have turned into expensive
junk.


I'm sure Chuck will tell us of the virtues of balsa as a core material.
I wouldn't even consider buying a boat with a balsa core. I also don't
buy into the boat broker b.s. that osmosis blistering is no big deal.
Those guys will do anything to move used boats. I don't want a boat
whose bottom is as pustuled and pockmarked as a $3.00 whore.

On Nov 5, 2:51?am, HK wrote:
Wayne.B wrote:
On Sun, 04 Nov 2007 20:32:58 -0800, Tim wrote:

Does that high transom, dead transmission RV of yours have wood in its
hullsides or bottom? Well, hopefully if it does, it isn't balsa
"Balsa" = "Bayliner"

Quite a few supposedly high quality sailboats have also been built
with balsa cored hulls. Many of them have turned into expensive
junk.

I'm sure Chuck will tell us of the virtues of balsa as a core material.
I wouldn't even consider buying a boat with a balsa core. I also don't
buy into the boat broker b.s. that osmosis blistering is no big deal.
Those guys will do anything to move used boats. I don't want a boat
whose bottom is as pustuled and pockmarked as a $3.00 whore.

In specific locations, balsa is a fine coring material. I don't like
to see it below the waterline. It has been used very successfully for
decks, cabin tops, etc. Balsa is rapidly being replaced by better
materials that won't absorb water, and some of the most respected
brand names core the entire hull. Cabin soles are commonly cored with
Nidacor these days, but that was an application where balsa was
commonly used and seldom a problem in the past.

They overriding principle is that a boat should be well made, with
structural integrity that exceeds the most stringent demands ever
likely to be placed upon it. You encounter competing theories about
how best to go about this, but it is certainly possible to use more
than a single material and more than a single technique to manufacture
a quality hull.

(One of the more humorous marketing stories locally includes two firms
who go after one another tooth and nail pretty regularly. One of the
firms offers boats with a cored hull, the other does not.....*except*
the very largest boat built by the second firm, something retailing
for between $1-2mm does include a cored hull. The salespeople at the
primarily non-cored dealership are quick to condemn cored hulls as
unsafe, unseaworthy, and likely to require catastrophic expense to
maintain and repair- after all 99% of their business is on the smaller
boats and not the flagship. The salespeople at the dealership offering
boats with cored hulls simply keep a few copies of their competitor's
brochure for the megayacht model and when the customers show up and
begin remarking how the guys at Brand X condemned cored hulls, they
simply produce the brochure and say, "If it's good enough for their
top of the line model, it's good enough for all of our customers
regardless of what they decide to budget for a boat.")


With crude oil well over $90/bbl and forecast to hit $100 by the end
of the year, we could easily see $4- $4-50 a gallon at gas stations
and
maybe $6 at fuel docks during next spring's annual gas gouge. If
boating is to survive as a pastime and if the manufacturers hope to
sell enough boats to survive, the industry has to get some weight out
of the boats without sacrificing strength. The solid, hand rolled
laminate hull is being supplanted with better alternatives, made
possible in part by vacuum infused molding.

As for blisters, here are some comments from a marine surveyor who
hates brokers and the marine industry in general almost as much as you
do. :-)

http://www.yachtsurvey.com/BuyingBlisterBoat.htm


It's fine to say you personally prefer to avoid a blistered boat. You
are unlikely to ever have blisters, as you buy your boats new and the
last one logged less than 120 hours in the water over a four year
period of time. But if you want to insist that the common industry
consensus that cosmetic blistering doesn't particularly effect the
structural inegrity of a hull is incorrect, something stronger than
dismissing that consensus as mere "broker BS" would be in order.

By the way, the use of one of the non-glass fiber components in modern
layups ( a layer of vinylester roving under the gelcoat) has
significantly reduced the propensity for most boats to blister.

Chuck Gould wrote:
On Nov 5, 2:51?am, HK wrote:

I'm sure Chuck will tell us of the virtues of balsa as a core material.
I wouldn't even consider buying a boat with a balsa core. I also don't
buy into the boat broker b.s. that osmosis blistering is no big deal.
Those guys will do anything to move used boats. I don't want a boat
whose bottom is as pustuled and pockmarked as a $3.00 whore.

In specific locations, balsa is a fine coring material. I don't like
to see it below the waterline. It has been used very successfully for
decks, cabin tops, etc. Balsa is rapidly being replaced by better
materials that won't absorb water, and some of the most respected
brand names core the entire hull. Cabin soles are commonly cored with
Nidacor these days, but that was an application where balsa was
commonly used and seldom a problem in the past.


You get water entry anywhere near balsa and the balsa starts to rot.
Simple as that. Got balsa under your fiberglass deck? Got a joint
anywhere that lets in water? Loose machine screw not properly sealed?
You got balsa rot under your fiberglass deck.


They overriding principle is that a boat should be well made, with
structural integrity that exceeds the most stringent demands ever
likely to be placed upon it.

Yeah, well, stuff happens out in the real world.



As for blisters, here are some comments from a marine surveyor who
hates brokers and the marine industry in general almost as much as you
do. :-)

As I said, if you want to buy a used boat with as many pustules and
pockmocks on her bottom as a $3 whore...go for it.

"Chuck Gould" wrote in message
oups.com...


With crude oil well over $90/bbl and forecast to hit $100 by the end
of the year, we could easily see $4- $4-50 a gallon at gas stations
and
maybe $6 at fuel docks during next spring's annual gas gouge. If
boating is to survive as a pastime and if the manufacturers hope to
sell enough boats to survive, the industry has to get some weight out
of the boats without sacrificing strength. The solid, hand rolled
laminate hull is being supplanted with better alternatives, made
possible in part by vacuum infused molding.


Making boats lighter has more implications than saving a few bucks worth of
fuel.

Leave them heavy and drive slower, I say.

Eisboch