Butyl tape On Sun, Apr 17, 2022 at 11:39 AM Matthew via CnC-List <[email protected]> wrote:
> Listers: > > > > FYI, while trying to determine what caused water infiltration into the > balsa core above the water line up forward (the last place that hasn’t been > repaired), a few days ago we identified the fittings securing the forestay > chainplate as the likely culprit. Although I’m sure there are more > accurate names, the two fittings work together to make a stemhead fitting. > One fitting runs vertically on the uppermost portion of the bow, just below > the deck, and has the forestay chainplate (looks like a large tang) welded > on it. The forestay chainplate/tang comes through a slot cut into the > deck. The second fitting is bolted onto the deck and has a slot for the > chainplate/tang at the forward end and some hardware to connect jib tacks > at the aft end. > > > > We believe there are two issues at work that caused water infiltration: 1) > the lower set of bolts holding the chainplate/tang fitting were drilled > through the uppermost area of balsa core, thereby providing a pathway to > the core if not properly sealed (which they were not); and 2) the deck > fitting that fits around the chainplate/tang was allowing water in > (probably a lot over the years). When we removed the deck fitting, we > discovered that it was originally installed about ¾” aft of where it should > have been. This was immediately obvious because the originally drilled > holes and the aft portion of the slot where the chainplate/tang comes > through the deck had been re-glassed. We then realized that the forward > portion of this fitting had been modified to fit the more forward location > (the forward rectangular corners had been cut off so the fitting/plate > would fit). We also noted that the slot for the chainplate/tang was not > centered, with the tang pushing against the deck opening on the port side > while leaving a 3/16” or so gap on the starboard side. We widened the slot > on the port side to accommodate sealant. > > > > We will be putting everything back together when it warms up a few > degrees. We are debating what sealant to use for the deck fitting, > particularly in the slot around the chainplate/tang. My expert is thinking > Sikaflex 295. What say you? > > > > Matt > > C&C 42 Custom > > > > *From:* Dennis C. via CnC-List <[email protected]> > *Sent:* Tuesday, March 22, 2022 2:50 PM > *To:* Stus-List <[email protected]> > *Cc:* Dennis C. <[email protected]> > *Subject:* Stus-List Re: Chainplate Sealing - now sealants in general > > > > Some thoughts on sealants. Sealants are primarily silicone, polysulfide, > polyurethane and blends of them. Add to that butyl rubber. > > > > First, as a rule, I like butyl for any hardware that has the potential to > flex or move. Chainplates fit that criteria. > > > > My default sealant for most everything else except plastic is LifeSeal. > For plastic I generally use silicone. > > > > Here's a reference for where to use sealants: > https://drive.google.com/file/d/12WmFxRiqzUw2xiqLaEtfBpS1pYocZID-/view?usp=sharing > > > > Note that Life Calk is a polysulfide. Do not use polysulfide for plastic. > > LifeSeal is a blend of silicone and polyurethane. > > 4200 is polyurethane. I don't use 4200. Got too many partially cured > tubes. Look at the expiration date before you buy. > > > > 5200 is NOT a sealant. It's an adhesive. From the 3M website: > > > > "3M™ Marine Adhesive Sealant 5200 is a one-component, high-strength, > moisture-curing, gap-filling polyurethane for permanent bonding of wood, > gelcoat and fiberglass." Note the word "permanent"! > > > > A bit off the subject, but Flexpaste seems to fix gouges in rubber rub > rails fairly well. Who'd a thunk it? An "as seen on TV product" that > actually works on a boat! > > -- > > Dennis C. > > Touche' 35-1 #83 > > Mandeville, LA > -- Sent from Gmail Mobile
