American 15 stringers

Discussion in 'Fiberglass and Composite Boat Building' started by Jeff_40, Aug 7, 2018.

  1. Jeff_40
    Joined: Jul 2018
    Posts: 14
    Likes: 0, Points: 1
    Location: Winnipeg

    Jeff_40 Junior Member

    Just curious as to what material to use under my stringers I’ve been reading that it’s definitely not good to have the stringers touching the hull. Would epoxy with the silica thicking agent work or would two part foam be better then cutting it to shape after?how thick does the material under the stringers need to be? Any suggestions would be appreciated as I’m a rookie at this. The picture I attached is before i removed the foam and cut out the old rotten stringers out. Also should I grind everything flush or leave a little lip where the old matting was to hold the new stringers in?
     

    Attached Files:

  2. Glenn Tranchon
    Joined: Jul 2018
    Posts: 8
    Likes: 1, Points: 3
    Location: Wilmington,NC

    Glenn Tranchon Junior Member

    Yeah your best bet would be epoxy thickened with silica and high density filler or just silica. Gonna need alot but its the best way to do it. The tab into the hull 4-6-8 inches layer by layer
     
  3. Blueknarr
    Joined: Aug 2017
    Posts: 239
    Likes: 18, Points: 18
    Location: Colorado

    Blueknarr Senior Member

    All of the old tabbing doesn't need to be removed. Everything loose needs to go. No sense trying to attach stringers to glass that isn't firmly attached. Also scrub any detritus out of roving. Bilges are often contaminated with fuel/oil. Rinsing with solvents alone won't suffice. It also requires powerful degreasers. The cleaner the surface the better the bond.

    Every time I encounter expansion foam in a boat, it is adjacent to rotten wood. Bed the stringers in thickened epoxy. Use the excess to create fillits to ease fiberglass transitions

    I usually recumend rebuilding in same manner as original construction. Tabbing is the exception. Roving is a dinosaur. It is very difficult to lay well and it's coarse texture inhibits additional layers of glass from adhering well. 1700 or 1708 makes much gooder tabbing.

    To achieve a strong bond to roving:
    +slightly thicken resin with fumed silica
    +use a layer of CSM to fill in crevices of roving
    +lay new cloth into still gooey CSM
    +bubble buster the he'll out of it
    +1708 lays CSM and biaxial cloth simultaneously.

    Stringers should have heavy fabric strands running longitudinally. Not just on the 45s that the 1700/8 provided

    Again best of luck
     

  4. rwatson
    Joined: Aug 2007
    Posts: 5,539
    Likes: 214, Points: 63, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

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