Centerboard Trailing Edge

Discussion in 'Fiberglass and Composite Boat Building' started by Jasonsansfleece, Feb 22, 2010.

  1. Jasonsansfleece
    Joined: Oct 2009
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    Jasonsansfleece Junior Member

    I am going to build a wooden cored dinghy centerboard covered in 10oz boat cloth.
    I have made four other foils of various size using similar methods.
    This board calls for a very fine trailing edge.
    The angle between the sides of the board at the trailing edge is 20 degrees and taken out to a fine 1/16"
    I have previously faired the wooden edge as fine as practical then drawn the cloth together at the trailing edge so they over lap beyond the core. Trim and fair.
    Is there a better way?
    I imagine truncating the faired wooden edge and building it up with a filled epoxy. But if the density of the filler is much higher than that of the wood (mahogany) then there will be issues with sanding.
    The reason I ask is my concern over the strength of the trailing edge,
  2. Hunter25
    Joined: Mar 2006
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    Hunter25 Senior Member

    A trick I have seen used is to cut a groove and fit an aluminum strip on edge into it. You could build up an epoxy edge maybe using Mylar sheets to keep fairing down. A centerboard trailing edge is pretty safe from damage, but a daggerboard is just the opposite needing a really tough trailing edge.
  3. gonzo
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    gonzo Senior Member

    If you are using true mahogany, it is hard enough that it shouldn't be a problem
  4. Herman
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    Herman Senior Member

    I used a sailbatten, instead of a wooden or alu strip. Worked fine every time.
  5. waikikin
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    waikikin Senior Member

    This is similar to what we used to do & clever for a strait edge, alternatively we used to drape one side & let cure & then lay uni fibre in the edge, sand flat & drape the other side. All the best from Jeff.
  6. mark775

    mark775 Guest

    Funny that the aluminum came up as I just finished fairing my keel to a knife edge, chickened out and rounded it to 1/8" radius. It worked very well to simply leave the heavy fabric an inch long, sawzall it to a quarter-inch long when cured (with poly one could green-knife) and sand to an edge that would cut you. Fine fabric or cloth would be a little floppy to control. I ran a bead of neat epoxy down from the top to insure no holidays, then closed up, rolled, and touched up a little off-center crookedness by (gloved) hand. Now I'm kickin' myself for not putting a piece of metal stock in there...
  7. wet feet
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    wet feet Senior Member

    I have had success by vacuum bagging the glass sheathing into contact with a strip of Formica laminate and adding an extra strip of glass to add bulk.The Formica strip is around three inches wide and projects half an inch or so.When the resin has cured,I tidy things up and apply a small flat trailing edge.The strip of solid glass has proved to be quite durable.
  8. kflarsh
    Joined: Feb 2010
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    Location: port charlotte florida

    kflarsh salisbury

    hi, I'm new to this forum and not a professional fiberglass repairer but I had a similar challenge 10-15 years ago when i faired a keel on my Sun 34 sloop.I used a strip of aluminum window or door screen neatly cut & held with I think( or can't remember,) spring clamps,(temporary tacks, staples or hot melt glue would suffice also), to which i applied west system epoxy and layers of cloth. The screen, when stretched tight and fastened, provided a very thin , straight, and relatively firm surface to start laying up the cloth and resin . I was able to sand the trailing edge to where it was almost too sharp yet very strong.It still looked flawless when i sold the boat 6 years later!

  9. Jasonsansfleece
    Joined: Oct 2009
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    Jasonsansfleece Junior Member

    Thanks for the replies!
    In this case the trailing edge is a curve in profile which precludes the use of a batten. As Gonzo says, with a mahogany core (as opposed to cedar) it should be strong enough.
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