Another stringer replacement question

Discussion in 'Fiberglass and Composite Boat Building' started by mongo75, Feb 20, 2008.

  1. mongo75
    Joined: Aug 2007
    Posts: 262
    Likes: 6, Points: 0, Legacy Rep: 95
    Location: Orange County California

    mongo75 Senior Member

    I'm doing a total restore on a 1968 Luhrs 25' Flybridge. It has 4 stringers, with the two center stringers supporting the engine/velvet drive/ v-drive. I need to replace the two center stringers because (a) the company that bought out Luhrs in the 60's did crappy glass jobs in the bilge by not glassing the limber holes and (b) somewhere along the line some dummy cut into the stringers to mount an engine (?) and neglected to cover his work, so they are shot.

    My question is, can I take them both out at the same time while the hull is on the trailer, and will the 4 bunks and two remaining outside stringers support it, or do I have to do one at a time? I can't do it on a cradle as much as I'd like to. Also I need to get an exact 25" between the two new stringers so that's why I'd like to do them at the same time- I can pre-make them (laminate 2 pieces of 3/4" ply w/matt in between them, glass 2 layers of 18oz roven and one of 1708 over that) and then bed them to the hull in a jig that keeps them centered and parallel to eachother.

    Thanks !!!!!
     

    Attached Files:

  2. rotfix
    Joined: Oct 2007
    Posts: 19
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: austin

    rotfix Junior Member

    i'm no engineer but in my opinion...my boat looks similar to yours, 23' w/all of the stringers out...the hull didn't flex that much compared to only 1 side out. a good fitting trailer is important. i don't think in the 20-30 mph range, there will be any adverse affects.

    rather than worrying about it, can you form the stringers and then make a jig that works off an existing stringer? that can be helpful to maintain previous deck height...
     
  3. PAR
    Joined: Nov 2003
    Posts: 18,602
    Likes: 377, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Danny, the hull shell laminate on your old Luhrs is more then stout enough to permit you to remove both stringers. Unless you're a particularly well fed person and the hull distorts under your weight as you work, don't worry about it. If you haven't missed too many meals and the boat does move a bit, then add some additional support on the exterior of the hull, like jack stands, blocks of wood with shims, etc. to get the hull solidly fixed (support the trailer too, so the springs don't come to play)

    I mention this because you can shape the crap out of some stringers, while you're in the boat, just to climb out and have the distortion go away, making your nice fitting stringers a poor fit.
     
  4. the1much
    Joined: Jul 2007
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    Location: maine

    the1much hippie dreams

    run a cross brace about a foot from ya transom,,then another across about 5 or so feet forward the start of the stringers,,,if room permits 1 running diag. from 1 corner of your cross brace to the opposite corner of the other cross brace. with all that even if a "fluffy" person gets in or leans on it from the outside , everything should be o.k. ,,,that said,,,,everything "should" be o.k without any bracing,,,but 3 or 4 2x4's is cheap ease of mind heh ;)
     

  5. mongo75
    Joined: Aug 2007
    Posts: 262
    Likes: 6, Points: 0, Legacy Rep: 95
    Location: Orange County California

    mongo75 Senior Member

    Thanks for the reassuring replies everyone- these pics are kinda old- since taking these a few months ago I've added the gunwales to the sides up to the v-berth bulkhead, and they have a 7' opening between them, so they are between 14 and 17" wide, so that adds a lot of supprt to keep the hull from flexing.

    I think I will make a jig that ties in the two outside stringers and forces the two inside ones to be dead on. Phew- one less headache to ponder over!
     
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