Saturday, December 05, 2009

Hatch Openings and Companionways

I've had the main hatch/companionway structures complete for awhile now, and have also built level hatch landings for installing the opening Bomar hatches on the forward ends of the cabins.

For this type of hatch to be watertight and to keep it from distorting, it is essential to have a dead flat surface to mount it on. I incorporated the longitudinal carlins under the cabin roofs (as shown in my previous post) as part of the hatch opening framework. The raised section above the cabin roof is topped with a 9 millimeter plywood ring cut to match the hatch perimeter. It was then faired to the cabin roof with a large fillet, as shown below:

These opening hatches with their screens are going to make the interior infinitely more pleasant while sleeping at anchor.

For the companionway openings and drop board arrangement, I opted for the sleeker, more modern design of the Tiki 30, rather than the Tiki 26 style. One big difference is that with this design, there is no external framing for the drop board, and the top of the drop board extends straight up to the top of the coaming, unlike the Tiki 26 style with it's horizontal section.

This requires gluing spacer blocks to the insides of the openings, to provide enough clearance for the 6 mm drop boards.

Another inner flange in line with the openings in the cabin sides retains the drop boards. Here you can see the slot between the cabin sides and this inner flange, where the drop boards fit in. At the bottom of the opening, a raised inner retaining flange prevents water draining down the drop boards from entering the cabins. At the top, the flanges fair into the adjoining hatch coamings.

The coamings themselves are made of two layers of 9mm ply, laminated together for a total thickness of 18mm. Triangular blocks of solid teak reinforce the corners. After these were glued in and the tops of the coaming were leveled off, I used a router to radius the edges so that a layer of 6 oz. fiberglass can be laminated over them.

Here's view of the coamings looking from the outboard side of the port hull. The glass sheathing has not been done yet, but the structure is all finished and shaped.

Here is a view of the port companionway with a temporary drop board of plywood in place. The final drop boards will be made of 6mm Lexan. As it turned out, the Lexan panel I had for this was about an inch too short to get these out, so I have to order some more. These ply drop boards will be carried on board as spares. One disadvantage of the straight drop board design like this is that it can be lost overboard if gets dropped through the slot between the cockpit seat and the cabin side. David Halladay found this out the hard way on his Tiki 30, Abaco. After that incident the drop boards are always placed below on a bunk when not in use.

At this point, all that remains to be done on the hull exteriors, other than building the main hatches is more fairing and then priming and painting. It's been unusually cold here for the last couple of weeks, and today the forward decks are covered with about two inches of snow. But there will be some warm days here and there where bit by bit I can finish these details.