I concur with Dave’s approach. Faced with building up a large area around Calypso’s mast collar (we replaced the original plywood with solid glass/epoxy board) I used both epoxy board and many layers of 25 oz. bi-ax. We worked from below as the deck’s inner skin is only 1/8” and the outer skin is ¼” to 7/16” thick. I fabricated shapes of epoxy board that were used as an insert. I built up the insert’s thickness with laminations of bi-ax and thickened epoxy.
To completely replace the plywood I needed ½” of build thickness. The insert ran between ¼” and 3/8”. It took 7 to 8 additional layers of 25 oz. bi-ax (includes a layer of mat). To reduce sanding I planned to complete the lamination in one session. Even using vacuum bagging the weight of all that resin, cloth, and inserts was difficult to manage. I ended up using the inserts as the last layer and physically applying pressure to aid the vacuum in removing voids. Given my easy access to epoxy board, for the C&C 25’s keel bolt area build up I would use two thinner pieces of epoxy board (easier to shape) then build it up with cloth and resin. I would follow Dave’s recommendations of prep steps to insure a good bond. To protect the keel bolt threads I would use a piece of sheet Mylar or similar slipper film stuffed along the bolt with some 5 minute epoxy used to seal the edges. If access to the repair area is difficult, consider the time trade off of opening up the floor above the bolt vs. working in very confined spaces. Rebuilding a flat floor area may be faster than time spent fighting an awkward location. Martin DeYoung Calypso 1971 C&C 43 Seattle [Description: Description: cid:D1BF9853-22F7-47FB-86F2-4115CE0BAF2F] From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Dave via CnC-List Sent: Wednesday, November 25, 2015 8:23 AM To: cnc-list@cnc-list.com Cc: Dave Subject: Re: Stus-List Epoxy fillers and other stuff... Ahmet - I think I get what you are trying to do. A pre laminated and fitted angle would work. Make a form, wider than you need and build up layers. Make it way to big, then Trim and bevel to fit. (Angle grinder). Epoxy in place, fill the void(pre drill) then laminate in place. Btw, mat is NOT structural. it fills the spaces between the warp and weft of cloth or roving, making a denser laminate. Others may disagree - would be interested in alternative approaches. Dave Ahmet - my approach to making flat pieces is to first laminate on a sheet of glass. With polyester, I build-up glass/mat alternating and laminated to a high glass content with a consolidator. (A kind of roller) With epoxy you can use biaxial stitch-mat with fine cloth or peel ply on top, then squeegee out resin. Use a layer of waxed paper between the glass (or Mdf) as a release layer. If cured on the glass you can make amazing sheet parts, and assemble them with with fillets of epoxy. You can also do the work above on a sheet of waxed paper and apply the resulting laminate before it kicks. You basically make a band-aid and plop it in place. (Essentially)Much easier and better than laminating in situ. You can take these laminates and lay on a form, pre cure. By progressively sizing the pieces, you can make band aids thicker in the middle, often useful. In your case, if I understand correctly, I would combine both pre made pieces and pre laminated 'band aids). I would fill the void with glass-rich epoxy. If you need it to flow and level, use only a little cabosil. You can get a veterinary syringe or make a piping bag out of a ziplock if you need to inject into a space. Consider laying cloth on its bias for corners bridging seams. Remember to feather edges to maximize gluing. Dave.
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