Hull repair

Discussion in 'Fiberglass and Composite Boat Building' started by Covers, May 9, 2017.

  1. Covers
    Joined: Aug 2012
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    Location: Midlands UK

    Covers Junior Member

    Hi Guys,

    I have a small 4m Avon Searider rib with a flooding hull. It is not cored, just fibreglass and gelcoat. It has some trailer bracket damage. Is it OK to repair this from the outside?
     

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  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    That is not likely to last. You should grind a wide taper on the crack and then laminate the repair. Also, all the gelcoat should be ground for better adhesion.
     
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Typically a good repair removes considerably more gelcoat around the area, tapers back the crack, at a significant slope, on both sides, replaces fabric that has been ground away (on both sides) and finally bulks up the area flush with surrounding surfaces, in prep for more gelcoat or paint. That repair looks to have barely removed any gel coat and it has new mat only fabric (offers little strength) over existing gelcoat. Gonzo is correct, it's not going to take much to get that cracking and peeling off, not to mention get it fair.
     
  4. Covers
    Joined: Aug 2012
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    Location: Midlands UK

    Covers Junior Member

    Yes, I understand the methods and thankyou. So, to summarise, a repair from the outside is OK, use some 450csm on a 12:1 taper, then fair and add flow coat, fair, polish, done?
     
    Last edited: May 11, 2017
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    How much CSM was applied into the damaged area - total laminate thickness? Any roving or cloth used?
     
  6. Covers
    Joined: Aug 2012
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    Location: Midlands UK

    Covers Junior Member

    I don't know, looks like they just filled the gouge with resin then laid some cloth over it and added gelcoat. There are a couple of 'bits' where they stuffed something in a ball to stop the resin falling through, the rest of it just looks like a minor split from the inside. The original thickness seems to be about 6mm.
     

  7. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 473, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    So, you don't know the condition of the surrounding laminate, transition taper, material thickness, etc., what could go wrong? Generally you need to repair the damaged laminate, with at least as much in replacement materials, not just resin and an overlay of mat. Additionally and as you know, the whole area is tapered back so the work has a suitable transition from old to new, which offers enough surface area for a good mechanical bond. Also this approuch is done on both sides of the damaged area. A quick test would be to climb up onto the overturned boat and jump up and down on the repaired area. Impact and bottom loading will certainly be higher than this, hopping off waves and such. Do this for a half hour and see if you can find areas where the "repair" has separated from the boat. I'll bet you do, but you wouldn't if it was done right.
     
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