Wet Grinding to avoiding dust

Discussion in 'Fiberglass and Composite Boat Building' started by raf pali, Nov 12, 2015.

  1. raf pali
    Joined: Mar 2012
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    Location: Australia

    raf pali Junior Member

    I need to grind the all interior of my fiberglass boat, patty it all and sand it and polish all again. A big job, and need suggestions for the right tools to use. Have toyed with the idea of grinding wet in order to avoiding dust.
    Have searched the net and and found that Electric Wet Angle Grinder do seem to exist, I wonder if any one of you have used one and what are they like.
    100 mm / 4” diameter angle grinder is the tool I want, they are light and easy to handle and can be run with a 1 KVA gen set, making it an economical set up.
    Air tools are ideal for the task but need a big petrol compressor or big gen set to run an electric compressor. I have no grid power and would have to buy all the equipment, the thing equating to a bulky and expensive set-up. Not convenient for the one off job I am up to.
    Also I thought of the possibility to make a tool for it, by using a Whipper Sniper motor to run a heavy duty flexible shaft and grinder without electricity and make it safe for wet work.
    Any experience, ideas, suggestions and comments please?
    Thanks in advance.
     
  2. whitepointer23

    whitepointer23 Previous Member

    Sounds like a nightmare job. Why do you have to take so much material off.
     
  3. whitepointer23

    whitepointer23 Previous Member

    My boat is on a jetty with no power. I have a 5000 watt inverter and use a 100 mm grinder. Drill. And disc sander with no problems. A small genset would be good too. A vacuum cleaner hooked up to a sander would be my preference .
     
  4. raf pali
    Joined: Mar 2012
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    Location: Australia

    raf pali Junior Member

    The boat is 30 years old and had a few owners before me.
    There is a few reasons for wanting to grind it all:
    In some places the interior was lined with carpet, now old and filthy, was removed. The remaining contact cement is to get rid of. Have tried with glue stripper gel but the fiberglassing was never finished properly from the very beginning and is too rough, a nightmare to clean.

    Paint over gelcoat was used in some areas and is peeling off. (I presume it is acrylic house paint because it gets gummy/sticky with methylated spirit).

    Patches of very rough unprofessional fiberglassing needs smoothing.

    The electric wet angle grinder is not suitable for the job. Here's the answer from the supplier:
    I would think that if you have to polish in this manner where water is going to falling back down into the grinder you would be better off using a pneumatic polisher, I understand the issues with having to have a compressor to run the polisher but this would allow you to work in a wet environment safely.
    The electric polishers do of course have ground fault interrupters but the units are not designed to be used upside down and you would be putting yourself in a potentially dangerous situation by working in that manner.
     
  5. raf pali
    Joined: Mar 2012
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    Location: Australia

    raf pali Junior Member

    I have a 1 KVA gen-set but it only runs the angle grinder.
    The vacuum cleaner would need another gen-set and doesn’t do the job properly. Lots of dust still escape
     
  6. whitepointer23

    whitepointer23 Previous Member

    I would rather fit new carpet liner than trying to grind the gelcoat off. The proper marine carpet liner is not expensive and prevents condensation.
     
  7. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    I think the same. Use a good scraper to take off what is loose and glue carpet or vinyl over the whole thing.
     
  8. Milehog
    Joined: Aug 2006
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    Location: NW

    Milehog Clever Quip

    Scraping is always preferable grinding. Sometimes you gotta grind, though.
     
  9. Rumars
    Joined: Mar 2013
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    Location: Germany

    Rumars Senior Member

    Rent the compressor and a palm orbital sander. Sander should have a fitting for water. Use the gen-set to run the water pump (if you do not have running water) and bilge pump (you do need to remove all that water from the boat).
    Or just do what gonzo said.
     
  10. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    I usually wet grind fiberglass, either frequently spraying with a water hose to wash stuff away and keep the surface wet enough to prevent dust or with a continual mist or light spray right where I'm grinding. I use regular tools but don't stand in puddles when doing it, the water runs away to somewhere else.

    A slow speed grinder helps a lot with keeping down the dust, along with positive ventilation (fans) and a vacuum cleaner right at the point of work. I believe there are attachments that fit on a grinder that hook to a vacuum cleaner that capture the dust at it's source.

    The few times I've dealt with carpeted liners, I've ripped it off and then pressure washed the interior. When that's dry, a coat of latex porch and floor enamel will solidify all the lumps and hairs and fiberglass splinters. These can then be scraped off with a sharp paint scraper or very course sandpaper with a very minimum of dust. A second coat of paint is usually all that's needed for a somewhat textured but smooth interior that you can run your hand over with no roughness and is easily wiped clean.
     
  11. keith66
    Joined: Sep 2007
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    Location: Essex UK

    keith66 Senior Member

    If you have to get old contact adhesive off the inside of a boat a powerful pressure washer does a rather good job. Some years ago i bought an elderly Sabre 27 yacht & had to strip her out for a major refit. There were large areas covered in old foam & contact glue. The boat was out the water so i put a 2" tank cutter through the hull low down to let the water & junk out. Whole job took one hour from stem to stern & left the grp clean as a whistle.
    No dust, no itching!
     
  12. Udlman
    Joined: Jun 2014
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    Location: Brisbane, Australia

    Udlman New Member

    Raf Pali, Where in Australia are you? I have a wet grinder that I bought to polish my molds that I am willing to sell.

    Brad.
     
  13. boatbuilder41
    Joined: Feb 2013
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    Location: panama city florida

    boatbuilder41 Senior Member

    if you feel the need to wet sand.. i would recommend using a flush mount arbor and diamond blades. I do it quiet often. These tools are typically used for granite and marble fabrication.. which i also do. If your blade gets clogged up... just clean it out on a cement block . And you are back towork. These tools take off massive amounts of material very quickly . And the flush mount arbor does a wonderful job without gouges in your hull. . I have many different types of blades and cup wheels that has proven me many years of good service . .
     
  14. raf pali
    Joined: Mar 2012
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    Location: Australia

    raf pali Junior Member

    Hi Brad I am at anchor in 1770 and sail to Bundaberg asap. Much interested to buy it. Want to know more: how big; heavy; how many watts; is it totally waterproof? Or just brand and model and I google the specs. How much you want for it? Please.
    I couldn't send you a PM. Please email me: eurekaustralia@hotmail.com
    Cheers.
     

  15. raf pali
    Joined: Mar 2012
    Posts: 71
    Likes: 1, Points: 8, Legacy Rep: 12
    Location: Australia

    raf pali Junior Member

    Thank you all for the input. I had some success with wet grinding using a sanding disk mounted on a 12V motor that I made up on the spot with what I had around and keeping wet with a kitchen misting sprier. The motor is not powerful enough though.
     

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