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KBBS Archive 10,000
Re: Check your sources
Posted By: Nick Schade - Guillemot Kayaks
Date: Thursday, 11 November 1999, at 6:05 p.m.
> In the past when we had a discussion about these tables:Here is the discussion: http://www.guillemot-kayaks.com/KBbbsOld/1951.shtml
> I pointed out that the data was bad because it deviated from the standard
> engineering model for composite plates by 40%.When did you point this out and were did you tell us "40%". All you have ever said is it is "bad". You have never made any effort to _demonstrate_ that the data is, in fact, bad or that the "standard engineering model" is, in fact, good. The best you have done is recounted some inaccurately remembered hearsay.
> Someone else contacted the people at West Systems. West said the data had
> too much scatter to be reliable. I understood from that communication that
> the original data had a footnote to that effect. You now say that there
> was no footnote. So bee it.It was I who called West Systems. They made such comments to me about some older data which appears in "On Boat Construction". They made no such comment about the data which now appears in "KayakCraft". Your argument rides on what I said Gougeon told me, and you have remembered it wrong.
> Mr. Watson did not write the book. He is responsible only for the initial
> publication of bad data with or without the footnote.Mr. Watson wrote the part of the book we are commenting on. He did not think the data needed a footnote or he would have put one in.
> If you want to argue that the data is accurate, you lose. (This was
> settled here in the past.)If it was settled, it wasn't settled the way you think.
Even the best data will show scatter. That's a fact of nature. Wood is natural material. Every panel you test will have a different breaking point. Does this make the data from one panel bad? You will need to break a lot of panels to get an average, but every test you do can still be "good". Breaking 100 panels is more informative that breaking 1, but breaking 1 is much better than breaking none. Mr. Watson broke 16 panels - 4 different thickness, with 4 different layups . Even though they were all different, they were enough to establish a trend: Thicker wood is stronger and Thicker glass is stronger. If you want to optimize for the strongest combination there is probably not enough data. He also tested plywood panels using the same test method. With this data you can make gross comparisons to another standard boatbuilding material. The data is informative, though maybe not complete enough to use for engineering a wood-strip space shuttle.
> If you want to argue that you and Mr. Moores are excused because there was
> no footnote, you lose. (You were both free to make your own panels and
> verify the West numbers.)Yes, with more time and more equipment than either of us have, we could have tested hundreds of panels and been able to write a masters thesis on the materials properties of strip construction. But, I know neither Ted nor I had the time or money to do a better test than Gougeon Bros. Instead we used the best available data published by an engineer from one of the top wood composite engineering companies in the country. I will accept Mr. Watson's word for it until better data comes along.
> If you want to argue that I said that there was a footnote in the
> Epoxyworks article and there was not, you win. (I will agree.)That is big of you. Maybe you should have read the article before you said anything.
In summary:
You don't remember what I said. You don't know what the original article said. Your not seeing what Mr. Watson is saying. What basis do you have for what you are saying?
-below are some graphs of the data in question-
wood/glass composite panel strength discussion in Archive
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KBBS Archive 10,000 is maintained by Nick Schade - Guillemot Kayaks with WebBBS 5.12.
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