interior fiberglass crack repair

Discussion in 'Fiberglass and Composite Boat Building' started by frog man, Jun 4, 2011.

  1. frog man
    Joined: Jun 2011
    Posts: 3
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Maryland, USA

    frog man New Member

    Hi,

    I am thinking about buying a Hobie 16 catamaran that I've found on the market. The right hull has some cracks where the rudder attaches to the hull that will need to be fixed.
    I have no fiberglass experience, but would like to learn.
    The owner of the boat has experience but no time right now to do the job, so I would like to try to do this repair myself.
    The owner says the repair could be done from the inside of the hull by cutting a "door" into the top of the hull.
    Once again, I have no fiberglass experience.
    If I could feasibly do this repair on my own, could someone give me instructions for the full procedure?

    Thanks
     
  2. hoytedow
    Joined: Sep 2009
    Posts: 5,784
    Likes: 359, Points: 93, Legacy Rep: 2489
    Location: The Land of Lost Content

    hoytedow Fly on the Wall - Miss ddt yet?

    Welcome to the forum, frog man.

    At the bottom of this page are several threads full of advice on your situation.
     
  3. hoytedow
    Joined: Sep 2009
    Posts: 5,784
    Likes: 359, Points: 93, Legacy Rep: 2489
    Location: The Land of Lost Content

    hoytedow Fly on the Wall - Miss ddt yet?

  4. hoytedow
    Joined: Sep 2009
    Posts: 5,784
    Likes: 359, Points: 93, Legacy Rep: 2489
    Location: The Land of Lost Content

    hoytedow Fly on the Wall - Miss ddt yet?

  5. hoytedow
    Joined: Sep 2009
    Posts: 5,784
    Likes: 359, Points: 93, Legacy Rep: 2489
    Location: The Land of Lost Content

    hoytedow Fly on the Wall - Miss ddt yet?

  6. frog man
    Joined: Jun 2011
    Posts: 3
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Maryland, USA

    frog man New Member

    Thanks for the welcome and the links, hoytedow.
    I think they might be helpful.

    In the link titled "Fibreglass Crack Repair", someone mentioned using epoxy and cloth versus polyester and mats. What would be the difference? (I guess I could look this up, but since I'm here...)

    Thanks to any repliers
     
  7. hoytedow
    Joined: Sep 2009
    Posts: 5,784
    Likes: 359, Points: 93, Legacy Rep: 2489
    Location: The Land of Lost Content

    hoytedow Fly on the Wall - Miss ddt yet?

    Always use epoxy when repairing over polyester. Old polyester doesn't bond well with new polyester and will be prone to delamination. Epoxy will form a much stronger bond. Cloth is superior in strength to mat and is more user friendly to boot..
     
  8. alan white
    Joined: Mar 2007
    Posts: 3,731
    Likes: 121, Points: 0, Legacy Rep: 1404
    Location: maine

    alan white Senior Member

    I might be more inclined to cut a window on the inner hull face rather than the deck. There's the problem of the flange getting in the way and disturbing the texturing. If you can match the color, the (inner face) patched area will be better for both access for repair and aesthetics as well.
    I'm assuming the original holes can only be repaired from inside----- I've done that same repair from outside but there was no damage to the transom to speak of, whereas your transom is apparently mashed up.
    Cloth makes the strongest repair (many layers to build up to the desired thickness). Make sure the threaded gudgeon mount holes can be drilled and tapped in very solid glass/resin with no air pockets. Use longer-than-original screws into a thicker transom and hopefully the next time the transom will hold up better.
     
    1 person likes this.
  9. tunnels

    tunnels Previous Member

    Use vinlyester resin !!it easy to work with !easyer to clean up than smelly epoxy and just as strong and makes as good a job The repairs i have done i have cut a good sized hole in the side of the hull a little bit away from the damaged area big enough to work through comfortably and even get a grinder inside if need be . After its all finished refitted the patch back in and glassed it and painted and and most time after its weatherded a little you cant see the repaired patch :D:p:p
     
  10. frog man
    Joined: Jun 2011
    Posts: 3
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Maryland, USA

    frog man New Member

    Thanks for the advice, alan and tunnels.
     
  11. tunnels

    tunnels Previous Member

    repairs ! First off you need to understand what happened and could the same thing happen again ! Its always the weakest point that gives away ! If the boat is poly and glass i would use Vinylester resin and differant glass to do the repair . Unidirectionall glass is my choice to do repairs where there are loadings ,where things are mounted etc etc . Its how aircraft construction is done with things mounted straight onto a skin and they dont have problems . Distribution of loads over a wider area and better quality glass and you dont have problems no more !.
    Have repaired the rudder mounts on Cats also deck repairs where there are cross beams and heres things are mounted on thin skins and always do it from inside buy cutting a hole in the hull big enough to work through comfortably then refit and reglass . :D.
     
  12. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 482, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Epoxy doesn't smell Tunnels, not even a little, though working with polyester and vinylester sure stinks to high heaven. When you first open a container of epoxy, you might get a whiff of a weak ammonia like smell, but this dissipates in seconds from the high molecular pressure of the diglycidol molecule. Epoxy will make a better bond, though a high quality vinylester and tight laminate will come fairly close. Unidia's would be nice, but again not what I'd recommend for a novice repair. Knitted fabrics (biax) will make the work go faster and offer fiber orientation options too. For a novice working in his driveway, epoxy is the logical choice, just because it's less sensitive to screw ups, ease of use and it's additional bond strength can over come less then ideal laminating skills.
     
  13. tunnels

    tunnels Previous Member

    I can smell epoxy from a 100 mtrs away and polyester from the other side of the road while driving . Have worked with guys that are so sensitive to the muck the vomit if the get a wiff of it . Its to messy for me i cant stand the stuff . Vinylester is a styrene / epoxy the stuff i used and boy does it stick . :D.
     
  14. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 482, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I'm not sure what epoxy you are using, but if you can smell it, it's had crap (likely solvents) added, which makes it completely unsuitable for marine work.

    Vinylester isn't chemically related at all to epoxy, though some elements of the epoxy molecule are incorporated into it, Tunnels. Typically epoxy is diglycidol Ether of Bisphenyl A, while vinylester is still a peroxide cured polyester resin system. The epoxy "pieces" added to the polyester molecule "backbone", increase stiffness and water proofness, though much better the polyester, has only 25% of the secondary bond strength of a real epoxy (typical vinylesters are 450 - 500 PSI, while epoxy is 1,800 - 2,000 PSI). Couple this with mixing sensitivity,, good quality vinylesters costing nearly as much as epoxy, especially after you count the solvents necessary to "keep up" with it, material handling difficulties, high VOC's (styrene) and difficult environmental concerns in regard to humidity and temperatures when applied (hell, sometimes the stuff can't kick!), make vinylester a poor choice for the novice laminater, not to mention the back yard builder or repair.

    Vinylester is a huge step in the right direction with the polyester resin family, but still not really much of a comparison to real epoxy, particularity for a novice, especially if you're looking to get maximum strength to weight ratios with a minimum of materials.
     

  15. tunnels

    tunnels Previous Member

    West system , and any other brand you can name . it all smells horrible !!!. :)
     
Loading...
Similar Threads
  1. fiberglass newbie
    Replies:
    3
    Views:
    939
  2. David Melling
    Replies:
    3
    Views:
    706
  3. BrettinVA
    Replies:
    3
    Views:
    1,621
  4. bodicotom
    Replies:
    2
    Views:
    1,683
  5. catsketcher
    Replies:
    5
    Views:
    1,712
  6. patrick99
    Replies:
    1
    Views:
    1,338
  7. powerabout
    Replies:
    8
    Views:
    2,670
  8. stephendehong
    Replies:
    2
    Views:
    2,125
  9. PickNasty
    Replies:
    17
    Views:
    487
  10. First Boat
    Replies:
    8
    Views:
    481
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.