Genoa Sheet Turning Block Rebedding Project
During the return from Cat Harbor there was significant water on the deck resulting in leaks of the Genoa Sheet Turning Blocks. Unfortuantely this project mushroomed out of control and took several weeks to complete. The port side was especially bad, a hose run on the deck for an hour resulted in about a gallon of water coming through the deck! Fortunately, no other significant leaks were found with this test. The first step on the port side is to remove the air conditioning vent panel. This is held in place with 4 screws, the vent system behind the cabinetry was pushed in and was very kinked, this ended up turning into the aft air conditioner vent project. This provided access to the back side of the deck and the four bolts which hold down the Genoa Sheet Turning Blocks. Unfortunately the backing plate on the port side was 1" stainless washers on 3/8" bolts, in addition the block overlaps the deck core and the uncored portion of the deck. Upon pulling the bolts out of the deck it was clear that the bedding of the foot block after removing the teak deck in Mexico was inadequate, a very small amount of silicone sealant was dabbed on the bolts but little else. Luckily none of the three bolts which went through deck core had not caused any moisture penetration. Based upon the bedding of the port turning block we pulled  the starboard turning block for inspection. This block is in the clothing locker in the aft stateroom which required pulling all of the covers in the locker to expose the hull and the underside of the deck. This locker has always seemed a bit musty even when I was inspecting the boat originally. With the covers removed there was a small amount of water down in the lowest point in the locker. Luckily, like the rest of the vessel all of the exposed woodwork has been coated with gelcoat. There was a small amount of darkening of the teak outside of the locker which is fading nicely with the use of a dehumidifier. When I pulled the starboard turning block up it was clear that while the block was not leaking badly it had managed to intrude into the deck core on this side. The first step in the repair was to drill out the holes through the deck to 1/2" and examine the balsa core coming from the holes, all three of the holes had damp but not rotted balsa come up so I overdrilled the holes to 3/4" from the backside of the deck with a countersink bit and then used a 1/8" alan wrench chucked into the drill to pull out the core as far as possible, probably about 1" all around all of the holes through the balsa on both sides. I then  dried out the deck with a small amount of acetone and heat prior to filling the holes with a mixture of West Systems epoxy slightly thicked with 404 High density filler which helps to avoid cracks and chipping when drilling. This completely repaired the deck core, improved the compressive strength of the deck locally and provided a watertight seal to ensure that should the bolts leak again the moisture will no penetrate into the deck core but rather leak through. Then the holes were drilled through and inspected to be sure that there is no exposed deck coring material which could wick water into the core. The second step was to create a conformal backing plate which matches the shape of the deck, this is a very thick plate because the variation of the deck is as much as 1.5". The technique I use to make these plates is to first make an aluminum backing plate which is at least 1" larger than the base of the piece of hardware being installed, then the holes are drilled through the hardware and down through the aluminum plate, The goal is for the plate to  be perpendicular to all of the bolts to form a good seal and spread the load evenly to the deck. The next step is to tape wax paper to the underside of the deck and the top of the aluminum plate to keep the epoxy putty from sticking to either the deck or plate. A heavily thickened West Systems epoxy (thick cookie dough) putty made with 404 high density filler is used to form a plug the same shape as the area between the deck and the flat plate. This mixture needs to be made with the extra slow epoxy hardener (West Systems 209 Tropic Hardener) due to the thickness of the putty which could get very hot. Once the plug has cured the bolts are pulled out and the plug removed and trimmed to match the backing plate. Any imperfections caused by wrinkles in the wax paper are filled with putty and then 5 layers of fiberglass (three layers of random mat, two layers of heavy woven roving) between the plug and the backing plate and 3 layers (two layers of random mat, one layer of heaving woven roving) were built up with a layer of wax paper between the whole plug buildup and the deck on top and the backing plate below. Tension was then applied to the bolts to compress the fiberglass. Once cured the whole mess was then taken apart again, the plug trimmed to the size of the plate using an upside down belt sander. Due to the beginnings of what could be crevice corrosion on the bolts all of the bolts were replaced, some of the bolts needed additional length, 8 bolts, 3/8" in diameter, 8-18 stainless steel, 6" long were needed along with 1.5 inch fender washers, lock washers, and hex nuts. Parts From Lovelady Hardware      6" long 3/8" stainless steel (8-18) bolts - 8 items      1" diameter 3/8" hole stainless steel (8-18) fender washers - 8 items       3/8" stainless steel (8-18) lockwashers - 8 items       3/8" stainless steel (8-18) hex nuts - 8 items Parts from West Marine      2 small tubes of white polysulfide (one for each side)      1 small can of West Systems 404 high density filler      1 gallon of west systems epoxy      1 quart of slow epoxy hardener      1 quart extra slow expoy hardener      1 pack of epoxy spreaders Parts on hand      fiberglass cloth (heavy woving)      fiberglass mat      latex gloves      acetone - cleanup backside of deck prior to using gorilla tape      gorilla duct tape - to seal backside of deck while filling holes with epoxy      mineral spirits - to clean up polysulfide      epoxy syringes (at least 4 used)      wax paper (wish I could find that special cloth which West Systems Epoxy used to make, it left a nice surface and came off cleanly, wax paper is not a perfect replacement)      blue masking tape Polysulfide sealant was used to bed the two foot blocks, approximately 1 small tube of sealant was needed to do each foot block or one large tube if rebedding both sides at the same time. A thick coat of polysulfide was applied to the deck, the underside of the wedge on deck, the top of the wedge on deck, and the underside of the turning block. Additionally the interface between the backing plate plug and the deck had a thick coating of polysulfide applied to ensure even pressure to the backside of the deck. Initial tensioning used a wrench to apply moderate force close to the bolt (i.e. just enough to snug things up). Due to the size of the foot block I allowed the polysulfide to cure for 3 weeks prior to applying final tension. Final tension pulled down about 1/2 turn further and the force applied was significant but not painful force on a normal length 9/16" wrench. Even after 3 weeks there were a couple of places where a very string of polysulfide was extruded over the next day or so which was easily trimmed. Cleanup of the polysulfide on deck was first cleaned up with a rubber putty knife and then a small amount of mineral spirits for final cleanup and then washed with soapy water and rinsed with water. October xx, 2009 - Ran water on port deck with backside of cabinetry pulled to determine where leak was coming from, over 1 gallon came through in an hour!!! October yy-zz, 2009 - Pulled up Port and Starboard Turning Blocks, started deck repair process October zz-aa, 2009 - Made custom backing plate for Port Side and installed with polysulfide October bb-cc, 2009 - Made custom backing plate for Starboard Side and installed with polysulfide November aa, 2009 - Final tensioning of backing plate (1/2 to 3/4 turn for each bolt) , project complete December aa, 2009 - Verified final tensioning held due to high load nature of the foot blocks (less than 1/4 turn on each bolt) Total time for this portion of the project was 3 complete weekends (two people) and then a few minutes on two occasions for tensioning