help with gel coating canoe repairs

Discussion in 'Boat Yard Basics' started by chiroken, Oct 10, 2012.

  1. chiroken

    chiroken I Love microskiff.com!

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    Hello everyone! Fiberglassing is more than what it initially appears to be!

    Pretty beaten up canoe that I've been repairing, several significant cracks, yoke pulled away on 1 side, 3 cracks thru the keel etc. So far I've sanded and fiberglassed with cloth using non-waxed resin and MEKP catalyst. I believe a mistake I made was to paint resin over areas of the canoe that weren't damaged (ie. about a 16" area between 2 large patches or an extra 4 inches beyond the strips of glass I ran down the keel, or a few inches around each patch) I had the resin made up and figured it wouldn't hurt to apply rather than waste it. The resin dried well where there was fiberglass but stayed tacky in the other areas. It was allowed to dry several days, still tacky (leaving fingerprints). Much internet searching lead me to believe it was a MEKP ratio error (even though I was carefull counting MEKP drops) but then the marine store told me unwaxed resin stays tacky. Is this correct?

    I have now pigmented waxed neutral colour gel coat and applied 1 coat Saturday evening (it is tuesday night now). The boat is in the garage with the heat on, window open several inches. Temp is got to be around 20 celcius (room temperature). I mixed 5 drops/oz of catalyst/gel coat which is the min. recommendation on the can for 20 degrees room temperature. The chart gives an X at this ratio at 18 degrees which I assume to mean that it won't harden a this temp? I made 2 batches of 12 oz so 60 drops each. I went minimum to give me more time as this is my first fiberglassing experience and the gelcoat was $80/gallon plus $15 for pigment!!!

    Where I applied the gelcoat over the existing gelcoat (sanded first) it is hard. Over the areas that were fiberglassed the new gelcoat is hard. Over areas that I had "painted" on the resin that stayed tacky...not hard and slightly tacky, not nearly as tacky as the resin was prior to gelcoating. When you run your hand over the hull it is slightly sticky over these areas. You can also leave a fingernail impression with pressure.

    The colour in these areas is varied as well. Sheen might be a better word than colour. Some parts appear drier and look more dull whereas the other areas still appear more shiny. There is no pattern to this, just random.

    I believe I mixed the gelcoat well in the can before removing to clean containers to colour and add catalyst. I believe I mixed the catalyst well (about 2 1/2 minutes of stirring/scraping) as most of the boat has hardened well other than areas over resin alone.

    The coloured gelcoat was applied with a 4" foam roller then "tipped" with disposable foam brushes.

    Does this just need more time? Cure time on the can said 3 hrs at 20 degrees celcius.

    If this does not set up, can I do a second coat at a slightly higher ratio of MEKP/gelcoat and will this harden the underlying 1st coat? I'd rather not 2nd coat simply due to time and trouble.

    Do I need to sand before a second gelcoat as I used waxed gelcoat? If so, how best to sand over the sticky areas? What grit?

    I tried to "wash/wipe" the original tacky/sticky resin (online suggestion) with acetone but this was unsuccessful, just made the resin more sticky as I assume the acetone was just dissolving the resin slightly.

    Any information/suggestions are greatly appreciated. Apologies for the post length but I'm trying to give as much info as I can on I what I have done so far.

    Cheers,

    Ken
     
  2. DuckNut

    DuckNut Brandon, FL

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    I have had success using a hair dryer/heat gun to heat it up and then it cured.

    Kreepa is the man to wait for a response as fiberglass repair is his living.
     

  3. chiroken

    chiroken I Love microskiff.com!

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    Thanks for the idea Duck, tried the heat gun without success. Think the next step is to try to use acetone to get off the gelcoat and resin in the areas that didn't fully harden. These areas are where I put resin over the original canoe surface (I lightly sanded 1st).
     
  4. DuckNut

    DuckNut Brandon, FL

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    That should not have prevented curing - bad mixture will prevent curing.
     
  5. cutrunner

    cutrunner Cert. Yamaha technician

    How long has it been since you laid it up?
    Ive gotten lucky and sprayed pva over the areas and went over with a heat gun.
    Now when i say heat, i mean till its about to light up. It will start to stink.
    I believe thats the cobalt be reacted. But if its been any longer than 48hours since you put it on, the damage is done. A whole bunch of rags and a couple gallons of acetone are all you can do.
    Sandpaper will just instantly clog.

    Btw, $80 for a gallon of resin?
    A gallon of quality (cook) resin at any of the local fiberglass shops is $30 bucks +-

    Also, you cant use foam rollers with gel coat, the styrene swells them up after about a minute of use, and it will fall right off the roller.

    This is all "i learned the hard way" information
     
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