Below waterline fibreglass repair, paint or gelcoat?

Discussion in 'Fiberglass and Composite Boat Building' started by Andrew Waddington, Mar 21, 2018.

  1. Andrew Waddington
    Joined: Mar 2018
    Posts: 1
    Likes: 0, Points: 1
    Location: Netherlands

    Andrew Waddington New Member

    I have deep gouges below the waterline on a fibreglass hulled Riva. I can easily follow You Tube videos for fibreglass repair, however, can I ask:

    Is it advisable to paint over a West System epoxy, or should I Gel Coat repair.
    Or can I just leave the West System bare?

    Many thanks in advance
  2. jorgepease
    Joined: Feb 2012
    Posts: 1,620
    Likes: 51, Points: 48, Legacy Rep: 75
    Location: Florida

    jorgepease Senior Member

    If it has Gelcoat then use gelcoat but first fill the gouges with filler material, you can buy ready made stuff for that.
  3. gonzo
    Joined: Aug 2002
    Posts: 16,889
    Likes: 1,759, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Epoxy has low UV resistance, so you should coat it with something. Either gelcoat or paint will work.
  4. Blueknarr
    Joined: Aug 2017
    Posts: 1,475
    Likes: 431, Points: 83
    Location: Colorado

    Blueknarr Senior Member

    Scrapes and gouges are part of the life of a hull in use. The thickness of gelcoat provides better protection to the underlying glass structure than thin paint.

    I repair many many gouged hulls. My process is as follows;

    Clean wet sand with 1000 and polish to find true color to match to.

    Remove any damage and drammel sand gouges

    Repair any damaged fiberglass

    Brush VE onto any exposed glass. (I don't worry about excess on surface)

    Brush and squeegee several coats of unwaxed gelcoat into grooves until full.

    PVA or wax paper or tape to suffocate gelcoat.

    Sand fair with 80 grit in one direction then 120 in the other.

    Chines often need extra attention.

    Spray a thick coat of gelcoat.

    Suffocate with PVA

    Wet sand and polish
  5. gonzo
    Joined: Aug 2002
    Posts: 16,889
    Likes: 1,759, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    A repair done with epoxy has higher resistance to moisture than polyester gelcoat does. The coating is only needed for cosmetic purposes.
  6. PAR
    Joined: Nov 2003
    Posts: 19,126
    Likes: 498, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Blueknarr has it the way it'll usually be performed at a yard, though some may elect to use polyester, instead of the preferred vinylester. These repairs are very common and last quite will, assuming reasonable prep and buff out. Getting a good color match will be the butt kicker for the novice, but it'll work/last fine. For deeper repairs other than dings, chips and scratches, I'd use epoxy and fabrics to fill, then overcoat with vinylester.

  7. Steve W
    Joined: Jul 2004
    Posts: 1,871
    Likes: 80, Points: 48, Legacy Rep: 608
    Location: Duluth, Minnesota

    Steve W Senior Member

    Is this a boat that lives on a trailer or in the water? ( I don't know my powerboats) If there is bottom paint involved there would be no reason to dick around with gelcoat, you would use epoxy filler, primer then bottom paint. If it lives on a trailer then go the gelcoat route.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.