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Thread: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

  1. #1
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    Default Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    One of the guys I work with lives aboard his Coronado 35, but the deck's balsa core is gone in some spots and soft in others. His budget is minimal, boat will be sailed on SF Bay when repaired.

    He bought a book that recommends using the original material for replacement, as otherwise the compression, strength and other elements of the boat's hull and decking will be changed - not always for the best.

    He's also found an article in Good Old Boat about cutting off the top layer of glass decking, replacing the balsa with ply, then sealing it back up. Is this the usual low-budget process?

    I was wondering if you could cut a number of access holes in the deck, powerwash out the balsa and inject some sort of foam to replace it -- leaving the cutouts open to relieve the excess foam?

    Any recommendations or horror stories?
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  2. #2
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    Quote Originally Posted by Thorne View Post
    I was wondering if you could cut a number of access holes in the deck, powerwash out the balsa and inject some sort of foam to replace it -- leaving the cutouts open to relieve the excess foam?
    plus one for originality!
    Simpler is better, except when complicated looks really cool.

  3. #3

    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    Replacement core material is a composite honeycomb sheet.... very stable, and doesn't absorb or allow water to travel. Ply is a waste of time. He needs to identify the soft spots,. cut the deck out and get the balsa out..... not all of it will be rotten usually. Keep in mind the deck provides most of the rigidity for the rig on a modern boat. A failure to make it so during replacement can have catastrophic results, including dismasting. Most the of the work is labour not materials, and then the time involved in fairing the deck and making it look decent in the end.

  4. #4
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    Paul == "I got yer emoticon raght heer, Buddy..." (grin <-analog emoticon, bejabbers!)

    Peter - thanks!

    Any idea of the product names for this honeycomb sheet material, and/or costs?
    Last edited by Thorne; 07-14-2010 at 12:24 PM.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  5. #5
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker


  6. #6
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    I hate trying to diagnose from a distance. From your description, though, I'd be thinking about an approach like Mr. Jardine describes. For core material, I've used honeycomb from Tricell:

    http://www.tricelcorp.com/index.html
    David G
    Harbor Woodworks
    http://www.harborwoodworking.com/boat.html

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

  7. #7
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    The plastic classic forum is probably the place to go for answers to this question.

  8. #8
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    What Noah said.

    Without removing the top skin, there's no hope of getting the mush out and getting a good bond.
    Acceptable replacement core materials are end-grain (not plank) balsa, plastic (not paper) honeycomb, foam such as Corecell or plywood.
    Some have re-used the cut-out top skin by grinding bevels and scarphing in some glass tape at the joints. Getting pressure for a good bond is iffy. You can replicate most molded nonskid patterns, but it's fussy work.
    I think it's more practical to lay up new glass over the new core and paint the entire deck with an LPU paint system.

  9. #9
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    Tricell is IMO very cool stuff, for interior bulkheads and cabinetry. It is not generally used in this type of an application. The procedure is to remove the
    glass
    skin on one side of the damaged area, replace the coring and re-skin. The balsa core can be used (not that expensive) or a structural foam such as Divinycell. Either would be
    OK
    . David
    Boatsmith Inc
    We Build Your Dreams
    (561) 744-0855
    www.boatsmithfl.com

  10. #10
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    Balsa core deck? My failing memory seems to recall the Coronado 35 had a plywood core deck. My work on those boats was limited to the first half dozen or so off the production line so that spec could have changed in later boats.

    Have your buddy exercise some caution. Falling overboard from the cockpit could cause one to die of fright before hitting the water.

  11. #11
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    Normally I would say take that critter out to deep water and sink it...it's not a boat but a poorly constructed barge...they were built as cheap live aboards and don't sail worth crap....
    Wakan Tanka Kici Un
    ..a bad day sailing is a heckuva lot better than the best day at work.....
    Fighting Illegal immigration since 1492....
    Live your life so that whenever you lose, you're ahead."
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  12. #12
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    Quote Originally Posted by paladin View Post
    Normally I would say take that critter out to deep water and sink it...it's not a boat but a poorly constructed barge...they were built as cheap live aboards and don't sail worth crap....
    I didn't want to say that, but yeah, that boat is one of the worst from a manufacturer that wasn't very good to begin with. That aluminum "H" channel to join hull and deck with aluminum pop rivets---uggghhh!!!! Extensive use of chopper gun in the layup---resin rich chopper gun---uggghhh. Particularly bad job of bonding plywood bulkheads to fiberglass hull---uggghhh. I won't even mention raising the cockpit sole to provide 6' headroom in the walkway between main salon and aft cabin, or the packing gland that was nearly inaccessible because of the v-drive that was necessary because of the poor choice of engine location that was made necessary to provide the "luxurious" interior accommodations.

    I commissioned hull #1 for a dealer in Long Beach. The owner was so proud of his new baby. To stop ranting about the problems with that boat, I had to chew a hole in my lip everytime he showed up to check on progress.

    When drilling a hole in the hull of one of these boats for a knotmeter, I found a ham and cheese sandwich sandwiched in the laminate. It was remarkably well preserved.

    97% of the boats produced by Coronado give a bad name to the rest. (insert appropriate smiley here)
    Last edited by SchoonerRat; 07-14-2010 at 02:12 PM.

  13. #13
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    When drilling a hole in the hull of one of these boats for a knotmeter, I found a ham and cheese sandwich sandwiched in the laminate. It was remarkably well preserved.
    ROFL! What kind of bread?

  14. #14
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    Default Re: Rotted balsa core on Coronado 35 deck - any suggestions? For a coworker

    Quote Originally Posted by Donn View Post
    ROFL! What kind of bread?
    Wheat, can't remember the brand! (insert appropriate smiley here)

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