Repairing and Re-gelcoating Fiberglass canoe

Discussion in 'Fiberglass and Composite Boat Building' started by trailrunner, Sep 18, 2013.

  1. trailrunner
    Joined: Sep 2013
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    Location: Alberta

    trailrunner New Member

    Hello,

    I recently purchased an old Cadorette Lasalle in rougher condition. My plan is to repair scrapes and some old patching and then re-gel coat by brushing. From my cursory reading I realize there is a large amount of work involved in sanding gel coat that has been brushed on, but I am willing to do it because I do not have the tools to spray. I have a few questions since this will be my first time working on something like this

    1. What kind of resin do I need to perform the repairs on this boat? Will I need filler? What kind?

    2. Should I remove the gunnels before beginning these repairs?

    3. Will I need to do anything to the inside of the canoe?

    Any other ideas would be appreciated. I've attached a few pictures so you know what I am working with.
     

    Attached Files:

  2. FMS
    Joined: Jul 2011
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    FMS Senior Member

    In the photo, am I seeing two crimps that need to be straightened in the gunnel?

    You can get an respectable appearance with some time sanding.
    http://www.boatdesign.net/forums/fi...ng/fiberglass-gelcoat-canoe-repair-43877.html

    My preference is epoxy with three fillers on hand that I can adjust for strength and consistency.
    Colloidal silica for thickening and medium density strength
    Micro balloons for light weight and easy sanding
    Chopped strand for areas that need strength that will be covered with another layer for sanding.
     
  3. trailrunner
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    trailrunner New Member

    I'm not quite sure I understand what you mean about crimps? There is an end plate covering the tops of the gunnels at the bow and stern. One of them needs to be straightened.
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    The answers you need are varied. You can use polyester, vinylester or epoxy resin to make these repairs.

    If the damaged areas are within a few inches of the aluminum rub rails, they'll need to be removed, but other wise nope, just leave them for now.

    Ideally, you'll probably need to make repairs on both sides of the heavily damaged areas, but the minor stuff can be done from the outside only.

    You should read up on 'glass repairs in general, of which there's lot of information on line. Make the choice early about epoxy, because the techniques and procedures are slightly different.

    Generally, the repairs boil down to grinding back to good laminate, replacing the missing and damaged laminate with new materials (applying fabrics and goo), then fairing and smoothing in prep for paint.

    Lastly, roll and tipping gel coat isn't going to give you a surface you'll be pleased with. I've never seen a novice, working in his backyard or driveway make reasonable gel coat finish yet. Just too much to go wrong (and it will). You'd be best advised to just paint this puppy, when she's ready, which is much easier to get great results, without a spray outfit (roll and tip).
     
  5. thill
    Joined: Mar 2007
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    Location: Virginia, USA

    thill Junior Member

    I did a canoe for a friend last year that looked just like yours, but it was green.

    I mostly used 1-1/2 oz glass mat and polyurethane resin, which is what the canoe was made from. I sanded the damaged areas with 60 grit, brushed on resin, then pasted on the glass and rolled it out. On a couple of the bad areas, I did the same on the inside.

    I also ran glass tape down the full length of the keel, just to add abrasion resistance.

    After it set, we sanded any bumps out, and then I faired with US Composites fairing mix and poly resin. I had kept everything pretty flat, so it only took one pass, a sand and a touch up. It was really looking good at that point. After that, he spray painted it with Krylon Fusion. That canoe turned out beautifully! I was amazed at how "brand new" it looked, and I was the one who did the work. And I'm also surprised at how tough that paint is. He is really proud of his canoe, now, and he uses it almost every weekend with his 5 kids.

    FWIW, I've done some nice gelcoat work using a foam roller, but you have to put it on pretty thick, and then you will have to sand it down with a random orbit, and then with 3M Fiberglass restorer or rubbing and then polishing compound to make it look good.

    That being said, I used Awlgrip for the first time last week, via roll and tip method that I learned here, and it was SO much easier!!! It didn't come out absolutely flawless, but for what I was doing, it was beautiful.

    I would recommend using one of the paint systems, rather than gelcoat for a canoe. I think the paint might be tougher, anyway. Canoes tend to face a lot of abrasion.

    -TH
     
  6. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    Use paint, gelcoat is not suitable for your refit
     
  7. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    My own inclination with this canoe would be grind it back with 40 or 60 grit after cutting out any obvious hole. Then rebuild with polyester and woven rovings probably around 280 gsm weight maybe with a lighter 200 gsm on the surface. Roving is much better than CSM (chopped strand) in my experience and it will equally go round smooth 3 dimensional curved surfaces quite well.
    Polyester is cheap, goes off fast and you can get a lot done in a short time.

    If you have structural issues in certain areas then epoxy in those places would be a better bet. Note not all fillers and tissues work with both polyester and epoxy resin so choose the right thing for the right job.

    If you did want to gelcoat ,you can but it is a bit tougher than you think. The best method I have used (spray gelcoat is 25Kg minimum order in the UK) is to use a gloss mini roller (cut down to half length) and use that. It will give a decentish finish. However you MUST add styrene monomer (sometimes called wax) so it cures in air. This must then be abraded and all the surface fully scratched clean to remove the monomer from the surface for a subsequent coat. You will need 3 or 4 coats like this to build up the 0.6 to 0.8mm gelcoat thickness the canoe should have had when new. I've done reasonable size patches say 1200mm square but not a whole canoe. It is pretty time consuming, and the key is to cut the gelcoat at exactly the right time in the cure. It must be hard enough to cut with say 320 wet and dry and not pull or clog. Leave it too long and it is hard to get a fast cutting time.

    To finish just cut with finer grade, down to 800 and 1000 grit then polish out. The finish now will be as new or better.

    Now you know why it has been recommended you paint it!.
     
  8. PAR
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    PAR Yacht Designer/Builder

    Suki, that's the technique I use when someone insists on gelcoat and I can't get it into the booth. I apply enough coats to insure once I've flattened out the hand applied imperfections, there's enough left to buff out a few times. It's all labor and tedious, but the result is usually better then a factory finish, assuming using the proper materials.
     
  9. SukiSolo
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    SukiSolo Senior Member

    Cheers PAR, I hoped I was doing it right. It's always worked OK. Had a few customers insist on gelcoat instead of paint on fair sized areas. Small bits are OK but a vertical 6' length... and about 18" deep is a pain....
     
  10. PAR
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    PAR Yacht Designer/Builder

    I've redone whole topsides and/or bottoms this way and it's a *****, but the results are rewarding, especially when you cash the check. The price usually makes most go with paint, because it's so labor intensive, but some just insist on gelcoat and some boats don't fit in the booth.
     
  11. SamSam
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    SamSam Senior Member

    Well, styrene monomer is a reducer for thinning polyester resins and gelcoats and doesn't by itself contain wax and so it won't work to get a tack free surface. But you can get styrene monomer that has paraffin wax dissolved in it, that when added to resins will give a tack free surface. It is usually called a 'surfacing agent'.
     
  12. SukiSolo
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    SukiSolo Senior Member

    Thanks SamSam. Generally in the UK the monomer has the wax in it. Mostly I've used Scott Bader and Polyfibre products. The labelling is slightly but not very different for the thinning only version. I always ask for the 'wax' version and the can labelling is 'Styreme Monomer'. Good point for those looking to get a refreshed gelcoat. It has a short shelf life, nominally 2 months but will last up to about a year if stored carefully. In the US you may get slightly different labelling, just one of those things, like Perspex in UK is Plexiglass in US, same product though.

    PAR, I would agree, when it is all cut down and buffed out it is probably better than the original finish. The fun bit is the colour matching on local repairs..... I'm getting a lot better at it. So far only one builder uses a base white colour, every thing else I have to custom mix. The worst are the 'white' Swedish 2.4s and the current Charger Composites Norlin 3 needs a bit of salmon pink added to the white to get a seamless match. Lot of green/grey whites out there amongst this lot.

    Best base clean white pigment is the Scott Bader Super White.
     
  13. michael pierzga
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    michael pierzga Senior Member

    Gelcoat work is a special skill. If you find a good gelcoat guy.....pay him well.
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Gelcoat isn't hard, if you're setup for it. Matching colors is just experience and experimentation at the professional level and guess work in the back yard or driveway..
     

  15. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    Gelcoat certainly is capable of hiding the 'High Crimes and Misdemeanours' of certain boatbuilders. At least with wood you can generally see the problem(s).

    When I find 4mm thick of the stuff used in the original construction or one hull bonded into another (a 2.4 technique) without the gelcoat being abraded on the inner one....grrrrrrr :(:(

    I've managed to get a hell of a lot of the colours (99%) from around 8 base pigments. No glitterflake repairs yet, thank goodness.
     
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