Bedding stringers and bulkheads?

Discussion in 'Fiberglass and Composite Boat Building' started by tdvjensen, Mar 30, 2009.

  1. tdvjensen
    Joined: Feb 2009
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Edmonton Alberta Canada

    tdvjensen Junior Member

    I am currently in the process of restoring an 18' fiberglass boat (1984 Tempest), and have installed the new transom (not laminated in yet) and mocked up the stringer/bulkhead grid to be glassed in aswell. I still have to pre-coat them with resin and bed them down to the hull, then glass them over. I have read that they should be cushioned from the hull as to ensure there are no stress fractures etc. I am curious as to what a person should bed them down with? What I have for materials that are already purchased or will be purchasing shortly:

    -System Three General Purpose Epoxy Resin
    -Silca Powder
    -3M 5200 Sealant/adhesive
    - System Three Silver Tip QuickFair compound
    -System Three Silver Tip EasyFillet compound

    I was thinking of two possible options:

    1) Run a bead of 3M 5200 on the bottum side of the 3/4" plywood and set them down, then use the EasyFillet compound to fillet the edges to ease the lamination process. Is there any possible issues with this such as the stringer moving too much inside the fiberglass causing it to crack?

    2) Bed them in with the EasyFillet compound and fillet them also. My concern with this option is that it will be too hard of a compound under the plywood and still create a hard spot.

    This is the first time doing something like this for me, but I am having fun so far and have another boat in mind that needs a restoration also. Any help would be much appreciated.
     
  2. pescaloco
    Joined: Feb 2006
    Posts: 301
    Likes: 10, Points: 18, Legacy Rep: 81
    Location: so. california

    pescaloco Senior Member

    Since no one has replied I will give you my input.
    The reason you do not want a tight fit with a bulk head against the hull is you will create a hard spot where the stress loads are not evenly distributed.

    I see that with plywood people cut them short (basicly a slopy fit against the hull and then just glass in) You can also use coring foam strips with beveled edges flat against the hull sides then butt the ply bulk head to it. This will spread the load and made an easier transition for glassing. The main thing however you do it is all inside radius should be large. Make those with filler putty and resin.

    Hope that helps
     
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