> Here are a couple specific questions: 1. What would the balsa typically be replaced with? An appropriate thickness of mat?
2. Should I attempt to save the fiberglass skin I remove to be re-used or just use new fabric to glass over the repair? 3. Assuming I work from the inside, how do I defy gravity to keep the new mat or fabric from falling down until it cures? Does the resin have enough mastic properties to keep it up? Burt, we are deep into a similar project on Calypso. 1. We replaced balsa core with balsa core except where there are holes through the deck. For any area with holes we used filled epoxy and/or various types of fiberglass (bi-ax, roving, different thicknesses of cloth, and G10 epoxy board). 2. We have mostly worked from the inside owing to how much thinner the inside layup is and the size of repair areas. We have retained and re-used much of the inner skin but engineered the repair so there is new epoxy layup involved to be sure the structural integrity is maintained. 3. We have been using lifting devices including a scissor jack, adjustable shower rods, and blocks of wood to apply upward pressure. We have found it important to have a vent hole (or several based on square area) at the top of repairs to vent out trapped air and allow epoxy to be "topped off" You mentioned hope that the wet areas will dry out. Our experience indicates that wet balsa will only dry if it exposed. I have seen a section of balsa that is dry as new with wet balsa ¾" away. If possible drill some exploratory holes around the affected area. If you find dark wet balsa keep going. If you find tan colored balsa that is dry or just barely indicates dampness (place on paper and look for the moisture) it may be OK to stop drilling. Baltek, balsa core supply company has info on their web site that indicates balsa core will retain structural integrity with up to 30% moisture content. We worked for much lower moisture content in all areas that are under any type of load. Balsa core repair is straight forward but messy. We use West Systems epoxy and fillers along with materials from TAP Plastics and several balsa core suppliers. Take a look around West Systems web site including their tech and FAQ sections if you want some more info. Let me know if you want more free advice. Martin Calypso 1971 C&C 43 Seattle [Description: cid:D1BF9853-22F7-47FB-86F2-4115CE0BAF2F] From: CnC-List [mailto:[email protected]] On Behalf Of Burt Stratton via CnC-List Sent: Thursday, January 15, 2015 6:26 AM To: [email protected] Subject: Stus-List balsa core I have resigned myself to the fact that I need to address my decks and cockpit sole. The PO installed wood strips fore to aft on the cockpit sole ostensibly to provide some lateral traction. They were not properly bedded and as you might imagine, the wood strips did not last long. There are open screw holes and if I step next to them water comes out. That is an obvious problem. The reason I am concerned about my decks, particularly my cabin roof is the fact that a brown wet film will form over time on the inside of the cabin roof. My roof has no headliner. The paint was peeling badly when I bought the boat and I have stripped it off. If I clean the fiberglass and wait a few days the film gradually appears. My assumption is that there may be a wet core in the roof. I will get a surveyor to take readings with his moisture tool to confirm but assuming that is the case, I would appreciate any insight by listers who have tackled this problem. I am not an experienced fiberglass guy. I don't particularly like working with fiberglass but I am pretty handy otherwise and would be willing to attempt this work in order to save a few hard earned bucks. Here are a couple specific questions: 1. What would the balsa typically be replaced with? An appropriate thickness of mat? 2. Should I attempt to save the fiberglass skin I remove to be re-used or just use new fabric to glass over the repair? 3. Assuming I work from the inside, how do I defy gravity to keep the new mat or fabric from falling down until it cures? Does the resin have enough mastic properties to keep it up? It is starting to look like the coming season may be lost for me. I have a lot to do and can't do most of it until the temps increase. I do want to rehabilitate this boat and do it right. I think it will be worth it whether I keep the boat or sell her when I'm done. The boat is covered so I am hoping it will dry out a bit before I start. Thanks as always Skip 1974 CNC 33 3/4tonner On the hard in Walpole, MA
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