Lots of build milestones in the last couple of weeks of working on my Core Sound 17 Mk3. Cockpit locker and icebox bulkheads are in, the buoyancy and ballast tank baffles are in place, and the the bunk tops are done as well. It's a long video, but there's been lots to do in the first couple of weeks in August.

I removed the temporary screws from the centreboard case, and dry fitted the seat top stringers, leaving room for the base of the hatches.

I wet the temporary screw holes in the centreboard case with unthickened epoxy.

Thickened epoxy is spread along a couple of the joints, and they are then screwed down. The squeezed out thickened epoxy gets transferred to the next joint .

The final bit of thickened epoxy is used to fill the screw holes in the centreboard case.

I had glued a strip of fibreglass tape along the leading edge of the centreboard. The scraper removed the thick selvedge from the epoxied tape, and a quick pass with sandpaper smoothed it out. Two extra coats of epoxy were added to each side to completely fill the weave of the fibreglass cloth.

The orbital sander made quick work of the excess thickened epoxy over each of the screw holes, and then the temporary screws were removed from the seat top support stringers.

Finally, it was time to start dry fitting the centreboard case, seat sides and bulkheads! Some of the bulkheads needed a slight tweak with a rasp and some edges had to be trimmed to allow for fillets along the chines.

The tabs were missing on one bulkhead, so I improvised, screwing into the end of the ply through the slots.

I made a doubler for one of the starboard bulkheads, to seal it off from the cabin. This area will become an insulated icebox. Before gluing the bulkheads into the boat, I traced them onto the insulation that will be used in the icebox.

The stringers to the tops of the bulkheads were dry fitted, With that done, the stringers were removed, and then glued in place.

The doubler for the icebox bulkhead was glued and temporarily screwed to the original bulkhead.

Then it was time to dry fit the locker bulkheads, trimming them with a rasp until they fit properly.

Ziplock sandwich bags are great for running a bead of epoxy along a join, before turning it into a fillet. I cut a corner off the bottom of the bag once filled.

When making the fillet, using a radiused spatula, the excess thickened epoxy is removed and used to extend the fillet. All of these new fillets were reinforced with fibreglass tape, wetted out on a plastic covered bench and then transferred to the hull.

Epoxy-soaked tape is unrolled along the fillet and then a brush is used to remove any bubbles and ensure that the tape has good contact with the fillet and the plywood.

The buoyancy tank supports have stringers glued along their top edges, to support the cockpit sole (floor).

The bottom of the hull is too fragile to kneel on at present, so I had rto create a temporary scaffold to kneel on instead.

The stringers were glued to the tops of the buoyancy chamber supports.

The edges of the buoyancy and ballast tanks were filleted.

Then the buoyancy tank supports were glued in place with fillets.

The edges of the fibreglass tapes were scraped to remove the selvedge.

The fillets in the buoyancy tank were reinforced with fibreglass tape.

Fibreglass cloth was used in the water ballast tank, covering the bottom and sides.

Before I fibreglassed the ballast tank I did the first coat of epoxy in the buoyancy tank, as that is behind the ballast tank.

After rolling the epoxy on, the surface was brushed to remove any bubbles.

The small end pieces of cloth were wetted out on the bench and moved to the ballast tank.

I coated the long sides and bottom of the tank with epoxy, and then brought in the dry fibreglass cloth. This was harder than the ends, but I got there in the end. It did take some time to remove all of the bubbles and wrinkles though. I immediately cut off the excess cloth, along the top edges of the long sides. It was easier to cut off the smaller pieces of cloth the next morning after it had cured.

A second coat of epoxy was applied to all of the lockers.

I coated the undersides of the bunk tops. By the time I have the third coat on I will be ready to glue them into the boat, before they are fully cured.

Doublers, on the under side of the sole, strengthen the openings into the buoyancy and ballast tanks. They have to be fitted square to the sides of the sole, to fit between the tank supports. Temporary screws through the doublers are pushed into the plywood of the sole, to stop them moving once glued in place. The screws acting as pins stop it sliding, and the spring clamps give enough pressure for the pieces to glue together properly.

I had a few spare minutes at the end of the day, so it was time to cut and shape the first layer of the sides of the icebox locker, and mark out the second, thicker, layer.

When it was time to fit the bunk tops into the boat there was a bit og planing and rasping edges to make them fit. Lots of time putting the panels in the boat, marking proud spots, and then removing them.  More planing and rasping, and then back to check to see if it fits properly. Then repeat for the other side. Screws were added to make sure that nothing slipped once the panels were glued in place. Once everything had been dry fitted, I could coat the supports with unthickened epoxy. A wider and flatter container for the epoxy was used to slow down the reaction time, giving me more time to coat the edges.

Thickened epoxy was piped along all of the supports of the starboard bunk. The bunk top was placed over the supports, and screwed and weighted in place. Excess epoxy was scraped off. Then the process was repeated for the port berth. The join of the bunk tops was clamped and screwed to ensure a tight and level fit.

At the end of the day the water ballast tank baffles, bunk hatch lids, rudder, and centreboard were scrubbed with hot water and a scourer pad to remove amine blush.

Friday, 15 August was a big day! The water ballast baffles were fitted into place, starting with sanding the edges to ensure a good physisical bond with the epoxy fillet. The centre bulkhead through the water ballast tank was dry fitted. It took several tweaks to get a good fit on all sides, sawing, sanding, and rasping to get it right. Once I was happy with the fit I added some strips of timber along the top edge, to lock in the alignment. The longitudinal baffles were clamped in place with some strips of timber that wrapped around the top edge, to hold them upright and properly aligned. I had to adjust the starboard clamp, to keep the baffles properly aligned. I fitted the same sort of alignment clamps to the forward longitudinal baffles as well. Fillets of thickened epoxy were piped along the edges of the baffles, and then appropriately shaped. The centre water ballast bulkhead was screwed to the upper section of the centreboard case, to align to the opening for the centreboard uphaul line. The fillets in the water ballast tank need a smooth curve, as there will be fibreglass tape added to the fillet in the next couple of days.

The last task today was adding a fillet to the edges of the bunk panels that were glued in place yesterday. The epoxied panels were sanded first to ensure a good mechanical bond, and the bare plywood was coated in unthickened epoxy. Thickened epoxy was used to fill the edges between the hull and the bunks. This fillet will also be taped in the coming days. A radiused filleting tool, made from a spatula, rounded on a grindstone, shapes the fillet, and removes the excess epoxy, greatly cutting down on the sanding needed later.