So I did some digging over the weekend and I can say few things regarding deck and core along the genoa tracks for C&C38 mk2 from 1976.
Top laminate is 3/16” thick. Balsa is ½”. In my case, wet areas are pretty extensive. Tapping and sounding the top got me to mark out a big rectangular area. It extends from about 2” inboard of the genoa track and its about 12” wide. It runs the length of the track. There is a 4” wide section of marine ply (also 1/2” thick) under the track itself. I wonder if I do the same or just keep balsa. I posted some horrifying photos on cruisers forum. Warning, pics are pretty disturbing. http://www.cruisersforum.com/forums/showthread.php?p=2039627#post2039627 Haven’t done the bevel yet, and still have about an hour to get all the rot out. As I said on CF, I’ll do epoxy repairs and use the double bias stitch mat and toss out the top laminate. I’ve had enough of polyester. Its porous nowhere near as strong, and if you go to trouble of doing this much work, might as well not skimp out on material. The big question is how to transition to gelcoat again? The cutout is the length of the track so I am not worried about genoa cars getting stuck on the track due to deck transitions. Petar Horvatic Sundowner 76 C&C 38MkII On the hard at Stanley’s in Barrington From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Hoyt, Mike via CnC-List Sent: Wednesday, February 03, 2016 1:23 PM To: cnc-list@cnc-list.com Cc: Hoyt, Mike Subject: Re: Stus-List repairing large wet deck core areas Petar This link shows a recoring project on our former boat http://users.eastlink.ca/~mhoyt/Projects/recore/recore.htm Initially we had 4 stanchions that had cracked deck (not just gelcoat) at the stanchion bases. The first year I recored these four areas only. The link above details that job. The following year I had a surveyor check out the entire deck and hull for moisture. We noted the wet areas (all on the decks) and replaced the core in all remaining wet areas except the cockpit seats (done another year). This project involved replacing the core under the genoa tracks and also under the primary winches among the 14 areas of problem. When I replace core material I never save the top skin. However I do know a lot of people do and that is your option. Most of the wet areas on a deck are in non skid areas so it is very easy to rebuild your own top skin and I find that process a whole lot simpler. This is my preference but not necessarily better nor worse than keeping the top skin and reusing. The two benefits of not reusing top skin are 1. It is more work to remove the top skin than to discard it and 2. You may get air voids under the replaced top skin if not done well. The benefits of retaining the top skin are that you have the contours of the deck area saved. This is nice on a coach roof for example When I start removing the core I normally drill some pilot holes to determine how far the wetness and the rot extends. Typically the rot is localized but the moisture travels quite far. I cut out the area that I know is wet and then if I am still in wet core I continue removing until I get to dry core. Note that wet core is not soft. Rotten core is soft. Wet balsa can actually still adhere quite well to the bottom and top skin and be strong. However why would you leave it? It is not much more work to replace core in a 1 x 4 ft section of deck than it is a 6” by 2 ft section. For an idea of the labour involved compare to a bottom job. Nut Case our J27 took 50 hours to strip the bottom to gel coat (by hand), apply barrier coat and then antifoul. By comparison was only 30 hours to replace four sections of core material that same year. Note that I have done this job using polyester resins (large areas and cost) as well as epoxy. If you have any questions do not hesitate to ask. Mike From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Petar Horvatic via CnC-List Sent: Wednesday, February 03, 2016 12:45 PM To: cnc-list@cnc-list.com Cc: Petar Horvatic Subject: Stus-List repairing large wet deck core areas Hi all, I am getting ready to tackle the wet deck along the port genoa track and before I start cutting, I have few questions for the group. Gelcoat cracks and delamination is appearing almost the length of the track on my 38 Mk2. I realize that not all spider cracks are due to wet core, but there is some strong indication that at least ¾ section of geona track area is rotten. Namely, top deck is noticeably indented along the track from compression of backing plate and track screws. I also remember that water was coming out of the tracks in areas where track was under load. Especially area in the aft section. I pulled the track off last night and there is strong oxidation along the aluminum backing plate where ss washers and nuts were. Any idea on how to determine how far athwartship to go when cutting out the top laminate? I guess tap with a mallet? Do people mostly save the top laminate or decide to lay new one from scratch? I am also thinking that it would be better to cut the area so entire genoa track is included so that I don’t have to deal with potential of uneven surface between repair area and untouched area where genoa track lies. I can foresee potential issues with the car not riding smoothly in area of that transition. Thanks Petar Horvatic Sundowner 76 C&C 38MkII On the hard at Stanley’s in Barrington
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