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Old 17-03-2013, 08:33   #31
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Re: balsa cored hull

None taken sailvayu.
They are two different worlds.
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Old 17-03-2013, 09:27   #32
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Re: balsa cored hull

I've seen a lot of fiberglass rolls in boat yards sitting on a rack in an open bay just absorbing the misty, rainy, foggy, humid moisture. Seen it at small boat building yards too. Dont know what the big yards do, maybe they use the cloth fast enough it's not a issue. Workers like to have the door open. I would worry about that far more than a little oil on a layup guys hands. Hard to keep much oil on your hands when you dip them in the acetone bucket all the time!
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Old 17-03-2013, 09:49   #33
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Re: balsa cored hull

Jumping in on the Pearson comment; I own a 39-2 and it is cored a little above the water line. Nice boat!
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Old 17-03-2013, 09:59   #34
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Re: balsa cored hull

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Originally Posted by Mark1977 View Post
Doing the same ...

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Old 17-03-2013, 13:16   #35
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Re: balsa cored hull

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Originally Posted by minaret View Post
"I've owned two cored boats for less than a decade, and didn't have a problem with either one. Therefore all cored boats everywhere must be sound and the many tales of rotten core I've heard must be BS!"
Did someone say this and I missed it?

Or did someone really say that there weren't any problems with the 2 boats THEY had had.

Not that the topic has any personal meaning to me anymore as I asked it before I got my first boat. But since then I don't really think it matters, all that really really matters is the condition of the core on the boat YOU are considering!
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Old 19-03-2013, 20:45   #36
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Re: balsa cored hull

I removed a thru-deck solar ventilator last week. The installation was a little sloppy and water had leaked into the core in one spot. Nice to find that only the one tiny 2cm 'tile' of balsa had been affected. Trivial repair if I can find a piece of balsa

Re foam cores. Many of the structural foams, especially from years ago, did not have the structural performance of balsa. For a core material the crushing strength is the most important as the laminate can easily handle all the other forces. Foams were typically far weaker, on a weight basis, than balsa. Honeycomb materials perform well.

I suppose there are modern materials that compete well with balsa, but they probably cost more.

A friend tore a little hole in his honeycomb-cored cat. (Wow was the skin thin!) There was plenty of water ingress. However probably no water damage. All the wet core had to be removed ... and it was a little more widespread than the tear ... before any repair could be made. So the issue is still there.

The downside of solid construction is that for the same stiffness it is just too heavy for a performance boat. Plus it rather annoys the sensibilities of modern engineers and thinkers. If you plan on hitting things then steel or aluminum should be your choice.
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Old 19-03-2013, 21:17   #37
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Re: balsa cored hull

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If you plan on hitting things then steel or aluminum should be your choice.
Or maybe scotch?
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Old 19-03-2013, 21:26   #38
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Re: balsa cored hull

Well, Minaret is right that even my core had rot. I removed it today and it was about 0.5 sq.ft. total. There are no fasteners or anything in the area and upon close inspection I found some tiny cracks in a pattern that suggests impact damage in two close-by spots. It's like somebody had dropped a dumbbell on deck. Water went through the cracks. I'll start a new thread with pictures on that.

But the thing is that it needs to get wet first and that will only happen through stupidity or damage.
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Old 19-03-2013, 21:36   #39
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Re: balsa cored hull

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Builders don't core hulls to save cost. They core hulls to increase strength and reduce weight. That's why cheap production boats like Beneteaus, Jenneaus, Hunters, etc., etc., are never cored, whereas high end super expensive boats like Swans, Halberg-Rasseys, Contests, etc. are almost always fully cored; Oyster being the main exception.
Somebody needs to do his homework.

The sort of broad, uninformed generalization quoted above is almost always wrong. (And that's true for more than just boats.)

It's somewhat bizarre to own a boat that gets criticized from both ends. There are some on this thread who consider my boat "cheap" because it's hull is cored, and others who consider it "cheap" because it's hull is not cored.

Huh? Really?

Boat snobs: if you want to cast aspersions a boat, at least learn about the boat first. When you engage it the type of critique quoted above, your posts end up as nothing more than examples of intellectual laziness.
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Old 19-03-2013, 21:44   #40
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Re: balsa cored hull

Jedi's experience is why I decided against buying what is probably the best designed custom cruising sailboat I have seen and it was built to a very high, "no expense spared" standard at a well known top end yard.
After 2 circumnavigations, the probability of impact damage on the hull below the waterline was not low. So I chickened out. Every time I read a thread like this with a rational view to balsa, I wonder if I blinked too early.
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Old 19-03-2013, 22:17   #41
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Re: balsa cored hull

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Jedi's experience is why I decided against buying what is probably the best designed custom cruising sailboat I have seen and it was built to a very high, "no expense spared" standard at a well known top end yard.
After 2 circumnavigations, the probability of impact damage on the hull below the waterline was not low. So I chickened out. Every time I read a thread like this with a rational view to balsa, I wonder if I blinked too early.
I afraid you did, because below the waterline the laminate is much much more substantial than for the decks. I have parts of my hull where the outer layer is 1/4" thick followed by 1" balsa, followed by 1/2" laminate.
When built by one of the good yards, these hulls are a dream.
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Old 19-03-2013, 23:25   #42
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Re: balsa cored hull

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I don't believe for a moment that a cored hull will end up being more expensive than a non cored hull. It is done this way to save cost so why would it be more expensive
The cheapest way to mass produce a boat is to simply spray chopstrand fibreglass and polyester resin into a female mould. Cored construction is more time consuming, so more expensive.
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Old 19-03-2013, 23:36   #43
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Re: balsa cored hull

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Jedi is a Sundeer 64 built by TPI in Newport... Pierson is the "P" in TPI so we're related ;-)

We have a full balsa core in the hull & decks too and have had no problems at all. The Sundeers are built using the SCRIMP process which might be a factor as each piece of balsa is completely encapsulated in resin and thus protected. They used vinylester instead of polyester and we never have blisters.

The trick is the extra work for thru-hulls, fasteners etc. The core must be replaced with solid before doing that. I use 2 methods:

1. big holes like for thru-hull: I use the final size holesaw and make the hole. Next, I use the bigger diameter drum-sander on the dremel to remove the core between the fibreglass layers as far as possible. I fill that space with 3M structural vinylester filler and run the holesaw through again to remove the excess. Works great.

cheers,
Nick.
I was going to use this technique, and still believe it would be effective, but I was concerned about the filler possibly cracking, so I came up with what I think is a more "bulletproof" method, I originally used it when installing portlights and hatches, but adopted it to install my skin fittings too.

I hole saw from the inside, but leave the outer skin intact. Then remove the plug, decore about 20mm around the hole, (I had a special router bit, but a sharpened allen key works) paint the inside liberally with epoxy, then insert a "sausage" of epoxy saturated unidirectional glass tape. This about half fills the decored section, the rest I overfill with "structural bog" a mix of epoxy, filler powder and cabosil glue powder.

When it's cured run the holesaw through from the outside, using the original pilot hole.
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Old 20-03-2013, 08:53   #44
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Re: balsa cored hull

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Originally Posted by 44'cruisingcat View Post
I was going to use this technique, and still believe it would be effective, but I was concerned about the filler possibly cracking, so I came up with what I think is a more "bulletproof" method, I originally used it when installing portlights and hatches, but adopted it to install my skin fittings too.

I hole saw from the inside, but leave the outer skin intact. Then remove the plug, decore about 20mm around the hole, (I had a special router bit, but a sharpened allen key works) paint the inside liberally with epoxy, then insert a "sausage" of epoxy saturated unidirectional glass tape. This about half fills the decored section, the rest I overfill with "structural bog" a mix of epoxy, filler powder and cabosil glue powder.

When it's cured run the holesaw through from the outside, using the original pilot hole.
I did that too but later learned that it is overkill for something like a 3/4" thru-hull fitting. This is for installing refrigeration keel coolers:
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Old 20-03-2013, 09:18   #45
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Re: balsa cored hull

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Originally Posted by Don L View Post
Well this is at least the second time I have read you post this using the words "why cheap production boats ..........". And it is just plain false and you should be ashamed by your statement on production boat construction when you apparently do not know what you are talking about and instead are giving false statements as facts (even though it was pointed out as false in another past thread to you it apparently has not resulted in any knowledge gain).
Dockhead is right. The current Jeanneaus, Beneteaus, Hunters, Catalina's are the "cheap(er) production boats". They are built for a mass market.

With modern CNC tooling and RTM infusion, it is cheaper, in a mass production assembly line, to lay up a solid core hull with a stiffening liner, than a fully cored hull (balsa or otherwise).

If this technique was tried back when your pearson was built (by hand, when there was no CNC or RTM techniques) that boat would have been a LOT more expensive to build.
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