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  • Recoring Coffin Lid

    Hey guys,

    I've seen a lot of post on recoring a lid. The one on my 19' is definitely overdue. I've read a lot of project threads, and the one thing I haven't settled on is what core material to use. Coosa, Nida-core, marine plywood?

    Secondly, this will be the first time I've tackled a fiberglass job. I come from a more mechanical background. I understand that I need to get the old wood out and sand it down to the bare fiberglass skin. After that things get a bit muddled. It seems that everyone has their own opinion on the correct steps to glassing in a new core. Could someone provide a step by step process that even a first-timer could understand?

    Thanks!
    1989 Classic Mako 191 - \'Tequila Rose\'

  • #2
    From there, you need to rough up the glass so you get a good mechanical bond between old and new fiberglass. After you sand with 80 grit, wipe with acetone to clean the surface. You then need to glue your core down with some buttered up/thickened resin and use weights to press it down tight and no air bubbles. Then start laying fiberglass down on top to seal the core and make it one piece. Last layer is usually chopped strand mat as it lays down smoother for more finished look. That's the 5k foot level instructions. [8D] It's not hard, you just need to watch your ratios when mixing resin and catalyst and practice first on something small so you can see how it kicks off. Too much catalyst and it kicks off way too soon and you don't have any working time, same as if it's hot outside.
    1978 Mako 25 - Blind Hog
    1985 Mako 20c - sold
    Fort Walton Beach, FL
    http://www.classicmako.com/forum/top...TOPIC_ID=42841

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    • #3
      And unless they've changed formulas, be EXTREMELY cautious about getting hardener on skin.

      If I'm not mistaken, it is a extremely carcinogenic. Does not play well with others!!
      1984 Mako 228 w/ 175hp E-Tec [br]1983 SeaRay 26\' Sundancer w/ 454 Big Block spinning Volvo DuoProps (Sold)[br]1989 Wahoo 17\' CC w/ 88hp Evinrude (vacationing in Key West)[br]

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      • #4
        I am getting ready to recore a hatch and here is the advice that has been supplied to me on this forum:

        1. Remove old wood

        2. sand down to skin with 60/80...dont make it smooth

        3. wipe down with acetone, not mekp Per justin below....THANKS

        4. Apply a layer of CSM ,and also wet out the core material on one side.

        5. While the layer is tacky, maybe an hour later, thicken some epoxy and attach core. Use weight as suggested or vacuum bag. Let it fully dry

        6. Scrub away any blush on edges and fillet all edges with thicken epoxy if needed.

        7. Apply several layer of cloth/mat. If using CSM make sure it EPOXY CSM...they make two versions.

        If I have stated something incorrectly, I appreciate the group letting me know. Its not a s hard as it sounds...just try it!
        quote:


        Originally posted by Snekbit


        Hey guys,


        I've seen a lot of post on recoring a lid. The one on my 19' is definitely overdue. I've read a lot of project threads, and the one thing I haven't settled on is what core material to use. Coosa, Nida-core, marine plywood?

        Secondly, this will be the first time I've tackled a fiberglass job. I come from a more mechanical background. I understand that I need to get the old wood out and sand it down to the bare fiberglass skin. After that things get a bit muddled. It seems that everyone has their own opinion on the correct steps to glassing in a new core. Could someone provide a step by step process that even a first-timer could understand?

        Thanks!


        1982 Whaler Montauk 90HP( sold)[br]1977 25 Mako CC 225HP

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        • #5
          Rusty,

          #3 -- wipe down with acetone, not mekp.

          Also, if you sand the bottom (really, top) skin thin, 1 layer of 1708 in addition to a layer of CSM is a good idea.

          then after core, 2 1708s should do you (depending on your core).
          ROGUE I[br]1978 235 CC[br]Newburyport, MA[br]ROGUE II[br]1987 17\' Montauk[br]Camden, ME[br]

          Comment


          • #6
            Snekbit,

            If after sanding (roughing up)the underside of the skin, you have a fairly straight/level surface, you should not need the CSM plus thickened epoxy. The CSM has bulk (fluff) and therefore will fill the surface irregularities on the underside of the skin. Likewise, if you prefer, you can use thickened epoxy without the CSM. Both these materials are being used here to fill irregular surface viods.

            On a personal note, I prefer the CSM because it is so easy the use. Just cut it to size, lay it on the previously resin coated skin, and wet it out. Then apply the core material. You do not have to wait, put the core down immediately (while the resin is still fluid) and apply the weight so that the CSM is compressed between the skin and the core materials. you want the resin to fill all the voids.

            Some of us feel that we should not use epoxy resin with CSM. I normally do and have never had poor results. The link below will give you some insight into question.

            http://epoxyworks.com/index.php/chop...mat-and-epoxy/

            In your case (doing flat work) I don't see any risk.
            Ole Joe
            Just floundering around
            White Hall & Ocean City, Maryland
            1978 Mako 25

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