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Old 17-03-2013, 06:42   #16
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Re: balsa cored hull

Lots of talk about cored materials etc. solid fiberglass too. No one seems to be talking about quality control on lay ups though?
Even if you get good saturation in solid or cored materials, if the people doing the work are not wearing gloves so the oils in their hands don't get on the glass cloth, the resin be it epoxy,vinyl ester, polyester will not bond ! Therefore you will end up with a delaminations everywhere the cloth was handled.
It gets worse. How is the cloth stored? Is the hull being layer up in a clean air environment ? Are other chemicals being used in the area?
I could go on and on but until the boating industry as a whole , doesn't certify all the materials to be clean, records kept on temperature and shelf life, usable application and setup time. Well then, we will all be in the boat yard year after year sanding an repairing sub standard lay ups of sub standard boats.
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Old 17-03-2013, 07:16   #17
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Re: balsa cored hull

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Originally Posted by edwmama View Post
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
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.

Cored hulls are more expensive because it is much more labor than a solid hull, plus balsa is more expensive than GRP per unit of volume (if not weight), and cored hulls tend to be thicker.

That's not to say that cored hulls are uncontroversially better. Some people don't trust them no matter what, and they are entitled to their opinions. Don will have to make up his own mind.
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Old 17-03-2013, 07:31   #18
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Re: balsa cored hull

Goodwolf, In 40 years building and repairing boats I have never heard of the things you are talking about. Oil on your hands causing delamination and chemicals in the air? This is just not a real problem, it takes a lot more contamination for there to be those kinds of problems. If you have some data to support what you are saying I would love to see it.
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Old 17-03-2013, 07:32   #19
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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.

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).

My current "cheap production boat" is balsa cored above the waterline and solid below the waterline. I would bet lots of "production" boats are same, if not most of the larger models as a minimum. It was a "cheap" production company, Pearson, that got this method going as a standard.

To whatever question I asked at the start when I started this thread, I since have owned 2 boats, both of which were cored hulls. I have had no problems from this. Both were "cheap production boats"!
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Old 17-03-2013, 07:35   #20
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Re: balsa cored hull

Don, there have been a million threads on this and probably nothing new under the sun to say on the matter. Trawling the archives will reward you with more information than you can read.

My boat is fully cored and I like it that way. It is immensely strong and immensely rigid, and a fully cored hull has profound benefits in sound and thermal insulation as well. It is uncanny how quiet it is inside compared to being inside a non-cored hull boat.

Some people here will tell you don't touch a cored hull boat no matter what. You might want to check out what Minaret has said on the subject. He's a boatyard professional, and I think his opinions should be given a lot of weight (even if I don't agree with them ).

As others have said, quality of workmanship is key. The advantage of an older boat like the one you are looking at is that, as others have said, if there was going to be a problem, it surely would have manifested itself by now.

As Nick said, there are different techniques, and the encapsulated block technique, used in the construction of his Sundeer and of my Moody, is supposed to be much more reliable than others.

One clear disadvantage of cored hulls -- you can't add through-hulls. You can, of course, but it is a very, very delicate operation, expensive and risky, which I personally would never do.
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Old 17-03-2013, 07:48   #21
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Re: balsa cored hull

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Don, there have been a million threads on this and probably nothing new under the sun to say on the matter. Trawling the archives will reward you with more information than you can read.

My last post had nothing to do with the pros and cons on cored construction. It was about your false trash talking!
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Old 17-03-2013, 07:56   #22
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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).

My current "cheap production boat" is balsa cored above the waterline and solid below the waterline. I would bet lots of "production" boats are same, if not most of the larger models as a minimum. It was a "cheap" production company, Pearson, that got this method going as a standard.

To whatever question I asked at the start when I started this thread, I since have owned 2 boats, both of which were cored hulls. I have had no problems from this. Both were "cheap production boats"!
"Cheap" is not intended as a pejorative, the way I use it. Something which costs less and provides good function is better than something which costs more and provides the same or only slightly better function. So I like cheap production boats -- especially Beneteaus, which are better engineered than many more expensive boats. But of course for the sake of cost there are various compromises -- iron instead of lead keels, solid hulls (below the waterline), laminate soles, etc.

As to coring above the waterline -- note that I said "fully cored". I mean below the waterline. Nearly every boat, cheap and expensive and everything in between, made in the last 20 years, has cored decks and is cored above the waterline. The controversial bit is below the waterline.

Pearson (and I've owned one!) was actually not a production boat -- it was a fairly expensive and mostly hand made boat in its day, more expensive than the O'Days and Catalinas and so forth of the time. Pearson were never able to compete on cost as the production builders really got going, and so went bankrupt in the late 1980's, just like Moody did 15 years or so later. Pearsons are very heavy, solidly built boats, quite different in character from production boats of the same era. Very seaworthy and seakindly, but the long fin keel ones do not sail as well as the lighter production boats of the same period. The later Pearsons had shorter fins and probably sailed better -- I don't have any experience. The 39-2 is one of the last boats they built so will probably have a more modern underbody than my 365. I am surprised to hear that the 39-2 is fully cored; I was not aware that any Pearsons were.

Pearsons are much more what people would call "blue water boats" -- narrowish beam, very small interior volume for their length, heavily built, with huge sail lockers, large tankage, excellent handholds everywhere, a real seagoing galley, and so forth. They are also very pretty! Mine was a very poor sailer, but I suppose the 39-2 will be much better.
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Old 17-03-2013, 07:59   #23
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Re: balsa cored hull

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My last post had nothing to do with the pros and cons on cored construction. It was about your false trash talking!
That was a response to Post #1. For the "false trash talking" theme , see Post #22. Peace, brother
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Old 17-03-2013, 08:01   #24
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Re: balsa cored hull

I'm glad you asked, and may I say congrats to forty years of boat building.
I take no offense to any comment as it is always good to learn from others what maybe eye opening.
I do have over thirty years of experience in composite bonding.
That being said, composites are very diverse in materials , resins and such.
Most of my experience is in aviation. We deal with wet layup, prepreg, hot bond, and auto- clave . Materials consist of fiberglass , Kevlar , graphite, and many newer versions not yet talked about.
To get to the meat of it all, we must sign out and document ALL materials.
Before that even happens all materials must pass inspection of minimum certification requirements. All material hours are counted down ( some 200 hours, 240, 300, to 360 hours) if not used during that time ,they are thrown away, garbage. Each layup has what we call test coupons which are layer up beside the parts to be used. These are put to a test of either or all stresses , tension , compression or torsion. If the coupons fail the test, the part or repair is not good. It is cut up and scraped or the repair is redone.
Did I mention this is mostly done in a clean room where temperature and humidity are kept at a constant? And yes , white cotton gloves are used 100% of the time handling all materials.
I guess no one wants to see a wing , flap , tail , or roof delam in air at 30,000 feet. So we have no problem here in America going the extra step to see this happens very little, or at all if possible.
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Old 17-03-2013, 08:02   #25
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Re: balsa cored hull

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My last post had nothing to do with the pros and cons on cored construction. It was about your false trash talking!
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Old 17-03-2013, 08:14   #26
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Re: balsa cored hull

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Originally Posted by Goodwolf View Post
I'm glad you asked, and may I say congrats to forty years of boat building.
I take no offense to any comment as it is always good to learn from others what maybe eye opening.
I do have over thirty years of experience in composite bonding.
That being said, composites are very diverse in materials , resins and such.
Most of my experience is in aviation. We deal with wet layup, prepreg, hot bond, and auto- clave . Materials consist of fiberglass , Kevlar , graphite, and many newer versions not yet talked about.
To get to the meat of it all, we must sign out and document ALL materials.
Before that even happens all materials must pass inspection of minimum certification requirements. All material hours are counted down ( some 200 hours, 240, 300, to 360 hours) if not used during that time ,they are thrown away, garbage. Each layup has what we call test coupons which are layer up beside the parts to be used. These are put to a test of either or all stresses , tension , compression or torsion. If the coupons fail the test, the part or repair is not good. It is cut up and scraped or the repair is redone.
Did I mention this is mostly done in a clean room where temperature and humidity are kept at a constant? And yes , white cotton gloves are used 100% of the time handling all materials.
I guess no one wants to see a wing , flap , tail , or roof delam in air at 30,000 feet. So we have no problem here in America going the extra step to see this happens very little, or at all if possible.


Ah, an aerospace guy, that explains it. Every time we hire someone who has worked at Boeing for decades, they go on and on about their vast experience with laminates. They have to be totally retrained every time. Most quit very quickly when they realize they are expected to produce serious results in a short period of time, ie do actual hard work! We don't hire ex Boeing employees anymore, it's easier to train them up from scratch than to retrain someone who's convinced he has all the answers, but they happen to be all the wrong answers.
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Old 17-03-2013, 08:15   #27
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Re: balsa cored hull

Mark, trash talk is only for those that see life in the negative all the time.
My comment was more in the positive realm of how things could improve in boat building. If you or any others see it otherwise, try to think of it in the more positive way.
After all , I'm not perfect and I don't expect you to be either.
FYI materials handling is very important, no matter what your building.
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Old 17-03-2013, 08:22   #28
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Re: balsa cored hull

Quote:
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).

My current "cheap production boat" is balsa cored above the waterline and solid below the waterline. I would bet lots of "production" boats are same, if not most of the larger models as a minimum. It was a "cheap" production company, Pearson, that got this method going as a standard.

To whatever question I asked at the start when I started this thread, I since have owned 2 boats, both of which were cored hulls. I have had no problems from this. Both were "cheap production boats"!


This attitude always tickles me. "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!" Lol! Get a bigger sample of the market over more time. I've worked on thousands of cored boats, and every one of them had some sort of core issue at some point, be it minor or major. Even Jedi, who goes on and on about how his block encapsulated core cannot rot, was talking about a soft spot in his deck the other day. Balsa core rots, period. I've seen it again and again, on some of the most high end boats in the world.
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Old 17-03-2013, 08:27   #29
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Re: balsa cored hull

Speaking of trash talk...wow
Must have hit a nerve there.
Haven't every worked for Boeing , but if I had I'm sure I would have learned more in five minutes than I could from your shop in a year or two.
Every time we get some guy who's built make shift boats in our shop we have to retrain him because all his parts fail the test. And they are the slowest workers, incase you don't ask! They usually quit because they can't handle the failures they produce over and over .
What's your address , maybe if any come by we can send them your way.
Enough said?
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Old 17-03-2013, 08:28   #30
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Re: balsa cored hull

Goodwolf, Ahh yes I agree if I were building hi tech composites for the aerospace industry what you say is very important. But we are talking boats not 747s. If boat builders had to follow those requirements a 30 foot boat would sell for 5-6 mill lol. Boat builders build in extra safety factor and everything is over done as weight is not as important as it is in aerospace. As one employer told me "we are building boats not space shuttles." Have to keep things in prospective so I have to say your comments although interesting simply do not apply to boat building in general and may make some feel that all boats are poorly built and this is just not the case. I think it would be more helpful to those wanting to understand boat construction to talk about boat construction not airplane construction. And please do not take that the wrong way I mean no disrespect.
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