Peter, When we (the yard) re-did the side decks on my 35-3, they used divyncell high density foam. It has the good compression resistance you need under the track and will not rot.
Tim On Mon, Feb 8, 2016 at 9:40 AM, Petar Horvatic via CnC-List < cnc-list@cnc-list.com> wrote: > 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 > <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 > > > > > > _______________________________________________ > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go to the > bottom of page at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > >
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