After the hull and bulkheads have been glassed in and the entire interior of the boat has been epoxy sealed, the hull can be prepared for decking. The first step is to shape the bulkheads and transom. It is easy to make a tool out of scrap plywood that will give you a perfect crown at the bulkheads. You need to determine how much crown is desired; in this instance I am after a 1 1/2" crown at the forward bulkhead. In the image below, I drew a line from sheer to sheer then I measured up 1 1/2" at the centerline. I then ripped a two 4"x4' pieces of 1/4" plywood and screwed the ends together at the centerline mark with the other ends resting on the shear. If you hold the pencil at the joint as you slide the tool to each side you will end up with a perfect crown. It is important that the tool slides on each sheer and does not lift off. I used this tool for the aft bulkhead and the transom as well. The sheer will also need to be shaped so it is at the same angle as the bulkheads. You will also want to ensure that the top of the sheer is fair fore and aft. A block plane is the best tool to use for shaping the bulkheads and sheer.
Because I am only using 1/4" plywood for the decks I added a 3/4"x6" piece of plywood fore and aft to add extra support to the decks and the mast. (See figure 2) These pieces were installed a little high so I could put the same crown on them as the bulkheads. They were glued in with epoxy and "peanut butter" and well sealed. I also added a piece of wood (2"x3"x12") forward and drilled a 2" hole for the mast step. The hole should be placed 6" aft of the stem.
On the line drawing below, you will see a daggerboard trunk detail. The trunk should be made about 10" high and will be trimmed later to fit the hull. The plywood sides need to be epoxied to the two 3/4"x3/4" hardwood pieces. Make sure to seal all inside faces a couple of times prior to assembly. After the epoxy has cured, round off the four corners so glass can be wrapped around the trunk. When fitting the trunk, you will want the bottom of it to angle aft a few degrees and the top of it should be 8" tall and cut level. When you are happy with the fit, bed the trunk with thickened epoxy to the bottom of the boat. Make sure it is centered and parallel with the fore and aft centerline, as well as plumb side-to-side. A couple of pieces of masking tape wrapped over the top will hold it in place until the epoxy has cured. I didn't cut the slot in the bottom of the hull for the daggerboard to slide through at this time, but I did drill a hole as a locator and later used a router and a trim bit to make the slot. The daggerboard trunk should be filleted around the base and glassed with several layers of 6" tape. It is also good practice to glass the front and aft edges of the trunk itself so the end grain of the plywood is well protected.
For the bench I found a 12" wide mahogany plank and fit it over the daggerboard trunk overhanging 1/2" in front and back. I marked the under side of the bench to locate for the daggerboard slot and cut it out prior to gluing the bench down. Make sure to use plenty of "peanut butter" where the ends of the bench meet the hull when the bench is glued in place. Clean up the excess epoxy and let it cure. If the fit is a little loose you can put a few temporary screws in the hull under the bench to keep it level across the top of the trunk. Use two or thee layer of glass under the bench where it meets the hull and where it meets the daggerboard trunk.
The 1/4" plywood I used for the decking came from the 4'x12' sheets I scarfed up for the side and bottom panels. The extra plywood was enough to do all the decking out of two pieces, one for the port side and one for the starboard side each running stem to stern. I cut the deck pieces so they would fit together down the centerline forward of station 1 and aft of station 2 and screwed the decks down around the sheer and down the centerline. It doesn't matter how things fit in the cockpit because most of it will be cut out. I trimmed the excess decking off around the outside of the sheer and marked the location of the forward and aft bulkheads. The plan I was following called for wider side decks than I wanted, so I had to mock up the locations of the narrower decks. I started the location for the coaming 24" aft of the bow, and you can find the side deck widths on the lower half of fig. 3. I used a batten to see how the line looked in relationship to the sheer. When I was happy with the line, I made the cut for the side decks and marked the location of the coaming on the fore deck and aft deck.
If the sheer and bulkheads were shaped perfectly, the decking will lay down properly. Because it is difficult to get the ever-changing sheer angle just right along the entire length of the boat, I always put a little more angle on it than is needed. This will allow you to hand tighten or loosen the screws along the sheer to get the proper angle on the decking. You will find this most helpful along the side decks area. One of the problems with using two pieces of plywood for the decks the way I did is the tendency to end up with a peak fore and aft instead of a fair crown. Minor adjustments to the fasteners at the sheer and down the center supports will help alleviate this problem. It is a bit of extra work for something that is going to be removed, but you will want to make sure it fits properly before you start gluing up.
Before the decking is glued down, the undersides should be well sealed with epoxy and sanded. It is also a good idea to cut your access holes to the forward and aft compartments before the decks do go down. The sheer should be wet out with clear epoxy then a thick layer of "peanut butter" can be added. When I glue down decks I don't worry about countersinking the fasteners at that time. After the epoxy has cured I will pull and countersink those fasteners that need it. I added a 1"x1" piece of fir under the side decks to glue the cockpit coaming to. It is important that these pieces be shaped to the proper angle. I made them perpendicular to the side deck, a little more or less angle may be wanted depending on what look you are after.
It is now a good time to glass the decks. I had a few high spots along the centerline that needed to be worked down and the top corners at both bulkheads needed to be rounded over in order to apply the glass over the edge of the plywood. Be sure to fill all fastener holes and cracks before you glass. I sheathed the decks with a layer of Dynel, but 6oz. glass will work fine.
Building cockpit coamings can be challenging on a sailboat especially if they are going to be varnished wood. I find it easiest to build a pattern, much like I did for the bulkheads. I first fastened a piece of 1/4" plywood to the inside of the side deck from the forward bulkhead to the aft bulkhead and trimmed it so it extended below the side deck 2 1/4" and above the side deck several inches. I then added several more strips of 1/4" plywood along the side deck that extended forward to the point of the coaming, which is located on the centerline and 24" aft of the bow, and to the transom. You will know where to locate the pattern on the fore deck and aft deck from the line you marked out earlier when using the batten. Use screws in the deck as a stop to keep the pattern bent. The heights of the coaming will vary depending on your own tastes so trim the pattern to find a line you like. I ended up with a coaming that is 3" high at the forward point, 2"at the aft edge of the bench and 3/4" at the aft end.
I laid the pattern on a 1" mahogany board and traced it out leaving it a little high and cut it out. I then ripped the 1 "board down the center and, after surfacing the wood, ended up with two coamings 3/8" thick. I didn't want to use any plugs to cover fastener holes so I made clamps out of 1/4" plywood scrap
I ripped the scrap to 4" widths and cut the lengths a little longer than the distance from one coaming to the other. The clamps work as springs to hold the coamings against the side deck. Screws in the deck will hold the coaming in fore and aft and a little weight can be added to hold it down if needed. At the point I used masking tape to clamp the two sides together. After I glued in the coaming and the epoxy cured, I added a block for the oarlock. It measures 1 1/2" wide, 10" long and is the same height as the coaming. Position it so the forward end is even with the aft edge of the rowing bench. I didn't worry much about the joint at the coaming point because I cut the point flat and added a piece of wood. I also added a filler piece at the backside of the point.
I put a fillet all around the coaming to add a little strength as well as fill any gaps there may have been. I shaped, sanded and sealed the coaming and caught up on all the other sealing on the boat.
This is the Devlin design "Mud Peep", for more information on this design and others offered by Devlin Boat, go to devlinboat.com