Need advice on non-destructive testing equipment

Discussion in 'Boat Design' started by Alik, May 30, 2008.

  1. Alik
    Joined: Jul 2003
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    Alik Senior Member

    Need advice on non-destructive testing equipment for FRP/metal/wood for survery purposes.

    What brands/models are known to work good and have reasonable price? Please share experience.

    Thanks!
     
  2. charmc
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    Location: FL, USA

    charmc Senior Member

  3. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    My unit is about 20 years old now, it is a simple ultrasonic unit cost about 140 at the time, and is quite reliable in wood. When used if FRP, it does show certain differences in moisture content, I do not believe the figure produced, but they are certainly quite noticable, so there must be some sort of referrece back to the meter. i have tested the unit with brand new laminates, vacuum bagged laminates and resin infusion laminates all the same thickness and all very different readings, but low in moisture. I tried it with a very old glass boat that was out of the water for a few weeks, and it was definately different below the LWL area to above, the weather line decreased as the meter went up the topsides, so i would consider them to be beneficial to surveying. I do not believe the moisture content displayed though as being gospil, but it does have its uses. Particularly, I believe it is relevant to show that there is a problem, it certainly does not show correct percentages, but that is almost irrelevant in real life situations.

    I think mine is a Thales, but as I am in China working and my meter is at home in Brisbane I cannot check.
    I do not think it would matter what brand it was, as long as it is only used as a refference piece, not as a gosple recorder.
     
  4. Knut Sand
    Joined: Apr 2003
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    Knut Sand Senior Member

    I have a TM8812 Ultrasonic tester, as mentioned above, its a guidance. I would not trust it, if not able to open some areas to check real thickness, and use these for calibration and comparison. Absolutely nothing wrong with the meter, just me and my mental state :rolleyes:

    The meter I have, can be calibratet to most "hard" materials, steel, plastic, glass etc.. Have never used it at wood though.

    Bought it at ebay, from this fellow and experieced fast delivery, good service:

    http://cgi.ebay.com/Digital-Ultraso...ryZ58235QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

    Sorry for the "advertisement", but I'll get nothing out of it. :D
     
    Last edited: May 30, 2008
  5. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

    Sorry Alik, I tried to resist but then again humour..... A good hole borer (makes a plug of what is removed) and a patch-up kit? - or else make the plug from a scrap/offcut of the material used in that part?

    Logically I cannot think of any ultra-sonic or x-ray that would demonstrate structural integrity better than a core, as most non-invasive methods need be "tuned" to get a base value..... so that you can say "For this reading the probability is that this is what is there"....

    Metal may be different.... but multiple layers of different stuff??? then it is the integrity and skill of the builder and the trust in that builder - or pay to have a surveyor observe every stage...

    I intend to go with a builder who will let me be there - even if I only sweep the floors, and to watch progress. - - Then I will really know my boat as well - which, I think, is good and important...
     
  6. Knut Sand
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    Knut Sand Senior Member

    Masalai; your view is quite true, but some of it is pretty destructive.:D

    An utrasonic thickness gauge, will only give you (relyably) the measured thickness of homogenous material. So, if you have a hull lay-up with 4 mm GRP on the outside, Divinycell core, and inside with 3 mm GRP, you will only be able to measure 4 mm, and 3 mm. You will not have a clue of the thickness of the core, and this distance, adds strength. (thats where the hole drill comes in..). Also, as Masalai stated; sweep the floors and watch the process. The manufactor may also add some "stringers" (not shure of the name) in the layup of the corematerial, binding the outside laminate to the inside laminate, that you'll probably never see again - ehh hopefully never see again. ;)
     
  7. rwatson
    Joined: Aug 2007
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    rwatson Senior Member

    You need an Xray machine or one of those container sized scanners that customs use - looks right through everthing inlcuding pottery and machine parts.
    You might be able to hire it!
     
  8. masalai
    Joined: Oct 2007
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    masalai masalai

    Then (with x-ray) you need to have an expert tune it and he will need core samples to see what he is looking at and then only able to verivy consistency as "apparently similar"
     
  9. Knut Sand
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    Knut Sand Senior Member

    Easy solved:
    Borrow a block of hashisj from a suspicious looking kinda fella, rub it on the deck and seats of the boat, deliver it back, remember; you only want the scent of it to stick to the boat, so deliver all of it back. Now get an export/ reimport licence for the boat (motor overhaul or something). Drive it slowly past the costom dogs... Make sure they pick the scent. Now, when the costoms don't find anything, they will call for this X-ray truck, with even a pro to run the inspection for you. Be polite and nice and ask for a copy/ printout of the inspection (say you may need it to aviod further problems up the road).

    Another pluseffect of this is that you'll probably get all screws retightned by the costoms. :D
     
  10. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    Knut Sand,

    You reign supreme my friend, that would have to be the best advice ever offeren on any international net for a free X ray job......

    Ya got ta luv ut!
     

  11. CTMD
    Joined: Dec 2007
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    CTMD Naval Architect

    This is great advice. I'll even help you out by providing the "product". You'll need to come and pick it up but when you're finished with it rather than sending it all the way back to Australia I'll get you to give it to one of my friends over there.
     
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