Monday, December 15, 2008

Double Coaming Hatches - Continued

A couple of days of warmer, but still wet and cloudy weather have allowed me to make a fair amount of progress on the boat. Many of these jobs are hardly worth posting about: such crawling up into the ends of the forward and aft bunks to make interior epoxy fillets in the hard to reach deck to hull joints there. I've also made some changes in the starboard hull that include relocating the head (more on this later) and have started the starboard companionway steps.

The double coaming hatch project was finished today, except for final fairing, finish work and painting. The first step in completing these was done yesterday, when I finished both outer coamings with the installation of the forward pieces, shown below:

Although I'm a big fan of Wharram's rope hinges, such as those used to hang the rudders, I chose to use stainless steel piano hinges on the forward hatches. One reason is that David Halladay gave me a bundle of these in various lengths and sizes that he intended to throw away while cleaning up his shop. It was a simple matter to select two of these in the right width and then cut them to length with a Dremel tool and cut-off wheel, and then radius the corners with a belt sander.

The hinges have to be mortised so that the hatches will sit flush on the outer coamings. Since the coamings are already installed on the boat, I let the hinges into the aft lip of the hatch lid. This required a mortise 3/16" deep. One of the neatest tricks I've learned from David while working on various Boatsmith jobs is his quick and easy method of setting up router templates with Super Glue. This is the same InstaCure, gap-filling glue I've mentioned here before that I often use for assembling parts prior to making epoxy fillets. It can also be used for temporary work such as attaching templates to a work piece. Here, I marked my line 3/16" from the edge of the hatch lip, then glued on a straight piece of 9mm ply by spraying the accelerator on one surface and putting just two drops of glue on the other surface. Used this way, the glue lets go cleanly when forced but will hold the template in place while doing the routing.

The mortise was cut using a top-bearing, straight pattern bit in the one-hand laminate router.

Here is the finished mortise, showing the hinge installed. The hatch lips touch the coamings all the way around. Since it is the inner coaming which keeps water from entering the hatch opening, is doesn't matter that the hinge is not waterproof. Note the two drain holes in the aft corners, which are the lowest points of the inner channel between the coamings. I located the hinges on the aft side since this is the side least likely to get hit by the full force of green water coming across the decks.

A view of the closed hatch, showing the hinge and drains aft. The hatches will be secured by either hatch dogs or hasps and locks on the forward end. There is a clearance of several inches between the foward ends of the hatches and front crossbeam.

Here is a view of the open hatch with the hinge temporarily installed. It took some work to get everything aligned and at the correct height, but now when the hatch closes the lips on the lid sit flat on the outer coamings and the bottom of the lid itself also closes flat on the top of the inner coaming. It will be very difficult for water to get inside these hatches.

Another view of the open hatch from the bow. With the hatch covers permanently attached like this, unlike on my Tiki 21 and Hitia 17, I won't have to worry about losing a cover overboard while getting stuff out of the forward holds.

After the final fitting and alignment was done, I removed the hinges and coated the coamings and insides of the hatch covers with epoxy. When this cures larger fillets will be made between the outer coamings and the deck, then glass cloth will be laminated over them to reinforce them. The outsides of the hatch covers will, of course, also be sheathed in fiberglass cloth. The other epoxy-coated part that you can see curing on the deck here is the beginnings of the companionway step assembly for the starboard hull.

One reason for the focus on the foredeck and forward hatches at this stage is that once these areas are finished and coated with at least primer, if not paint, I can then move the hulls about ten feet forward out the front of my shed so that I'll have room in the back to work on such parts as the cockpit. At the same time I'm working on both cabin interiors to I can move forward to closing in the inner cabin sides and installing the coach roofs. I'm about to have to spend some money at this point on Lexan for the portlights and companionway drop boards, as well as the additional manufactured deck hatches and port lights I intend to install. In each coach roof at the forward end there will be an opening deck hatch of at least 16"x16". An opening portlight will be installed in each aft cabin bulkhead just above the aft crossbeam. This kind of cross ventilation is necessary to make this boat inhabitable in the hot climates in which I intend to sail.

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