Jean-Francois, Not sure where you got the research info? I've got hull number 2 in the 34/36 series and I am holding a 4" circle of the deck I cut out for a solar fan and I find the balsa is 3/4" thick and the rest of your layup list is probably right. As I look at the edge and count the layers of glass and Kevlar, I see the outer layer is thicker than the inside layer.
Another thing I see is they tapered the edges of the balsa to where the hull is solid. Some areas of the hull are solid laminate from the hull/deck flange down to about 4" from the sheerline. The deck is solid laminate about 4" in from the outer edge making a waterway, and all vertical panels in the cockpit sides and along the cabin sides where the windows are, have no balsa. I was surprised to find the transom is solid laminate. But most horizontal surfaces have balsa coring for stiffening. Including the spray hood that covers the companionway slide which has 3/8" balsa coring, while the forward slanted surface and vertical sides of it are solid. The floors on our boat (what the floorboards sit on) are built of two or three layers of 3/4" marine grade plywood and are covered in at least 13 alternating layers of glass and kevlar which become about 1/4" of solid laminate over the wooden beams. (I had to repair some damage and counted the layers before duplicating the original.) It's important that all edges are well rounded and inner angles are filleted. A boat builder told me the wood was really just a mold and the laminate provides the strength and stiffens the hull. You sound as passionate about your 34+ as I am about my R. Chuck Resolute 1990 C&C 34R Atlantic City, NJ ----- Original Message ----- From: "Jean-Francois J Rivard" <[email protected]> To: [email protected] Sent: Monday, March 3, 2014 8:34:22 PM Subject: Stus-List Understanding Composites So the Kevlar in the 34+ series and 37+ a well was not 'straight' Kevlar but a hybrid and E-glass I guess this way you'd get the lightweight resiliency of Kevlar with the stiffness of the glass: DuPont Aramat C72K/200 seems to have been an E-glass/Kevlar hybrid weave. (>From research on the web): Composition of the glass/Kevlar hybrid, DuPont's Aramat 72K/200: Component G/SQ.M OZ/SQ.YD Wt. % in Base Fabric Wt. % inTotal Fabric Glass Fiber 245.6 7.2 63 41.1 Kevlar 49 144.0 4.2 37 24.0 Mat Backing 200.0 5.9 -- 33.5 Stitching Yarn 8.0 0.2 -- 1.4 Total 597.6 17.5 Also, in keeping with the stiffness / resiliency theme, the grid area on those boats is a combo of the aforementioned Kevlar hybrid along with the keel / mast step area containing Epoxy resin and Nomex (Also Kevlar based) Honeycomb mat which was known for high cost but high strength / stiffness with low weight and came from the Aerospace industry Here's the lay-up schedule: Topsides (total thickness 1.19") 1. Gelcoat 2. 1.5 oz. Chop 3. 1.5 oz. Mat 4. C72K/100 Kevlar Fabmat 5. 1” Balsa Core 6. C72K/100 Kevlar Fabmat Bottom (total thickness 1.23") 1. Gelcoat 2. 1.5 oz. Chop 3. 1.5 oz. Mat 4. C77K/200 Kevlar Fabmat 5. 1” Balsa Core 6. C72K/100 Kevlar Fabmat To avoid the potential issues with the balsa core on the factory mounted through hulls, the through hull areas are devoid of balsa core made of solid composite kevlar / Hydrex isophatlic resin (A type of Vinylester). The isophtalic resin cures from the inside out and is very water resistant (Read blister resistant) So what does all that mean? No Blisters, (My boat has one about half the size a pencil eraser) No chalking, very stiff: all bulkhead doors open and close like a safe, less weight means it can carry more ballast in the keel and handle a pretty high power to weigh ratio (Around 12,500 lbs for 795 SQ ft using the 135 gib, 96 base phrf) while having a fully teak lined cabin, almost king sized bed in the aft cabin, separate shower with stand--room. / shower curtain, and all the cruising amenities.. -Francois 1990 C&C34+ "Take Five" Lake Lanier, Georgia _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com [email protected]
_______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com [email protected]
