Painting prep part 2: sanding the deck

Now that the weather is nicer & more suitable for restoring old sailboats, I returned to making a lot of dust by sanding Cantara's deck clean of all old non-skid and paint in preparation for a new boat paint job.

One of the curious discoveries after sanding away the old deck paint were the aluminum plates under the stern cleats. Not sure who put them there or why; they were only lightly glassed-over so I am guessing they were not meant as backing plates to the cleats but were top plates instead? Are they original to the design? The pink filler matches that around the rest of the stern deck suggesting these were original to the boat. Cape Dory famously used mild steel backing plates for chainplates but flush aluminium top plates for stern cleats? Doesn't make sense. Anyway the whole stern deck is going to have to come off along with these plates due to extenive moisture damage around the deckplate holes, which extends all the way down to the cockpit seats too.

Sanding the original nonskid off the deck was slow going as the pattern was made of solid resin raised proud of the deck about an 1/8" in., coated with some sort of rubbery sand that laughed at my palm sander and glazed-over the lowest grit sanding discs. It even wore down the 40 grit wheel on Dusty the burnisher but it is indeed coming off, albeit slowly & with lots of dust. I did half the deck today, and will do the rest tomorrow.

Sanding the deck revealed may trouble spots where the top layer of fiberglass had been compromised and damaged for one reason or another, allowing moisture to intrude and rot the balsa core around the the damaged areas. 

In some places the damage is extensive leaving very large exposed gaps between the two fiberglass layers where the balsa core used to be, particularly along the stern deck and cockpit cabin bulkheads. Deckplates, cleats, and instruments had once been mounted here without adequate care to protect the mounting hokes from water intrusion so the core was long gone. These areas gad to be fixed before I could prime and paint the deck & was going to involve significant glasswork to re-core the areas with foam. 

Usually recoring rotted deck core areas on a sailboat involves removing the top layer of fiberglass to scrape away the damaged core, replacing the core (with foam here)  then covering the area again with a new top layer of fiberglass ( I dont recomnend using the old pieces of the top layer of fiberglass to re-cover newly cored areas, as air bubbles will be caught below the layer.) and fairing over the repaired area to make it match the surrounding before painting

The difficulty here was that the rot was not in a flat area like the cockpit sole, but had grown around comoplicated curved areas, down from the horizontal deck through vertical surfaces of bulkheads and then again horizontally through part of the cockpit seating. These are difficult curves to recreate by hand so I have to fix those areas from underneath and below-deck (where accessible) by removing the bottom layer of fiberglass yo access the core, becauase I want to maintain the exterior shapes & curves of the top fiberglass layer & I don't want to try to match the curves on both sides of the boat to keep them symmetrical.

Unfortunately, there is no way to access the extensively rotted stern deck and nearby cockpit seats from below so those areas will be a little tougher to re-core and shape especially as they involve inside corners, which have to be sanded by hand in a future entry. Yay! 


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