Results 1 to 15 of 15

Thread: Adding a bulkhead in a fiberglass hull

  1. #1
    Join Date
    Mar 2009
    Location
    Texas
    Posts
    1,785

    Default Adding a bulkhead in a fiberglass hull

    I've long wanted to add a bulkhead to my Sea Pearl for flotation, security, and storage.

    I think I can figure out how to cut a cardboard template but I had a couple of questions:

    1. Should I install it with a gap between the plywood and hull? E.g. tack it in place with dabs of 4200 and then finish it off with fiberglass tabs or tape the seams? Is 1/8 of an inch sufficient?

    2. Is there an "easy to find" plywood I can use? Anything at home depot or do I need to figure out how to source something better? Note-Dry stored boat and I will paint the plywood. I'd like this to be an easy/cheap project. Maybe poplar 1x6 planks?

    3. 1/2 inch ply or 3/4 or doesn't matter?

    Many thanks.

    Tom

  2. #2
    Join Date
    Oct 2008
    Location
    Walney, near Cumbria UK
    Posts
    38,599

    Default Re: Adding a bulkhead in a fiberglass hull

    Yes, leave a gap so as not to create any hard spots.
    Make sure that the glue is Water/Boil Proof, then it is just about protecting the surface lams from wet and checking.
    Dry stored is irrelevant, the enclosed space will attract condensation and damp, so you need to coat both sides of your bulkhead.
    It really is quite difficult to build an ugly wooden boat.

    The power of the web: Anyone can post anything on the web
    The weakness of the web: Anyone can post anything on the web.

  3. #3
    Join Date
    Jan 2009
    Location
    se pa (Bristol PA)
    Posts
    2,739

    Default Re: Adding a bulkhead in a fiberglass hull

    to match the contours look up " stick and tick " method . epoxy seal the edges of plywood
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  4. #4
    Join Date
    Sep 2004
    Location
    Cape Fear, NC, USA
    Posts
    2,759

    Default Re: Adding a bulkhead in a fiberglass hull

    Nice thread that discusses this:
    https://www.boatdesign.net/threads/p...ss-boat.42817/

    e.g. "It depends on the hull construction. Cored hulls don't usually get print through from hard spots. If the laminate is solid, it is common practice to either leave a small gap or have a foam tapered filler in between."
    This is the first lesson ye should learn: There is so much good in the worst of us, and so much bad in the best of us, it doesn't behoove any of us to speak evil of the rest of us.
    E. Cayce

  5. #5
    Join Date
    May 2015
    Location
    Northfield, NJ, USA
    Posts
    1,073

    Default Re: Adding a bulkhead in a fiberglass hull

    I would fit as neatly as you can get it, epoxy coat both sides and make sure the edges are well encased, and then tab it in. I would also consider putting in an access port so you can both see inside, check for damage, and also so you can leave it open when stored so as not to trap moisture

  6. #6
    Join Date
    Apr 2015
    Location
    St. Helens, Oregon
    Posts
    897

    Default Re: Adding a bulkhead in a fiberglass hull

    An alternative would be to use the thick EVA foam that they use as bulkheads in kayaks. Light, cheap and if installed with a bead of silicone (or maybe Lifecaulk?)
    as they do in the kayaks then it's removable without too much trouble.

  7. #7
    Join Date
    Oct 2000
    Location
    Padanaram, MA USA
    Posts
    9,349

    Default Re: Adding a bulkhead in a fiberglass hull

    I would glass both sides of the bulkhead. It'll be easier to keep a finish on it.

  8. #8
    Join Date
    Jun 2000
    Location
    Pleasant Valley NS Canada
    Posts
    13,498

    Default Re: Adding a bulkhead in a fiberglass hull

    As you are installing this bulkhead, will you have access to both sides so that you can tab it in on both sides? How large will the bulkhead be?
    Hope for the best, but plan for the worst.

  9. #9
    Join Date
    Mar 2001
    Location
    FL
    Posts
    123

    Default Re: Adding a bulkhead in a fiberglass hull

    Difference of opinion here: I wouldn't worry about crating "hard spots" on a Sea Pearl. I doubt the factory does it but you can call them to find out. 26' ocean wave jumping powerboats use 1/2" foam strips under 1/2" thick ply bulkheads and box stringers (heavily glassed in) if that helps put it in perspective. I would use 1/4" or whatever close mm ply for the b'head and glass it both sides with 10 oz cloth before cutting out the exact shape. Its easier to glass each side flat on the bench than vertical in the boat. The cloth is for ding proofing and anything heavier in a Sea Pearl is excess dead weight. Now is the time to cut out access hatch holes. Seal the ply edges and glue in with a thickened epoxy fillet all around like the stitch and glue guys do. No glass tabbing needed.

  10. #10
    Join Date
    Nov 2003
    Location
    Mukilteo, Washington
    Posts
    216

    Default Re: Adding a bulkhead in a fiberglass hull

    Could someone define "Hard Spots"? New term for me

  11. #11
    Join Date
    Jan 2009
    Location
    se pa (Bristol PA)
    Posts
    2,739

    Default

    Quote Originally Posted by schlaboatnic View Post
    Could someone define "Hard Spots"? New term for me
    "hard spot" = when Friday night's 8pm date and Saturday night's date @ 8pm both show up at 7:30 on Friday night.
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  12. #12
    Join Date
    Jan 2008
    Location
    Lake Champlain, Vermont
    Posts
    2,491

    Default Re: Adding a bulkhead in a fiberglass hull

    Not an expert on the subject but my understanding a hard spot occurs when you add a bulkhead, for example, against a lightly built hull, be it FG or ply. Pressure on the outside of the hull might show where the bulkhead fits against the hull. Clear as mud, right? One text suggests quarter inch closed cell foam between bulkhead and hull before tabbing and glassing in place.

    Just read Denise's answer, much better than mine...

  13. #13
    Join Date
    Jan 2009
    Location
    se pa (Bristol PA)
    Posts
    2,739

    Default

    Quote Originally Posted by Oldad View Post
    Not an expert on the subject but my understanding a hard spot occurs when you add a bulkhead, for example, against a lightly built hull, be it FG or ply. Pressure on the outside of the hull might show where the bulkhead fits against the hull. Clear as mud, right? One text suggests quarter inch closed cell foam between bulkhead and hull before tabbing and glassing in place.

    Just read Denise's answer, much better than mine...
    Let's see if this works LOL

    Sent from my LG-M430 using Tapatalk
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

  14. #14
    Join Date
    Sep 2016
    Location
    Tasmania, OZ
    Posts
    87

    Default

    From "From A Bare Hull" by Ferenc Mate.

    Sent from my SM-G935F using Tapatalk

  15. #15
    Join Date
    Mar 2006
    Location
    La Conner, WA
    Posts
    167

    Default Re: Adding a bulkhead in a fiberglass hull

    The above drawing from Ferenc Mate’s book shows a foam piece with 45 degree bevels both sides. This piece both isolates the ply from the hull eliminating any hard spots or deformation, and allows a far stronger path for whatever tabbing pieces you choose to use.
    If the inside of the hull is gel coated, it must be removed wherever you will be tabbing, or else the whole project will detach itself on the firs trailer bump or bit of a wave.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •