The Cockpit Gets a Coaming

Standoff for coaming

Cockpits need coamings.

What is a coaming? Simply stated a coaming is a vertical surface whose purpose is to prevent or help prevent the egress of water.  Hatches have coamings and so do cockpits.We had this idea that what would look really cool and would be really practical at night is to use LED rope lighting along the underside edge of coaming to provide a glowing courtesy light on the cockpit floor.  So, to do this we started with a 5/8" x 1-3/4" strip of yellow pine that is epoxied in place around the deck edge.  You can see it in the first photo posted. The mahogany coaming itself will overhang this by 1-1/4".  This creates a 5/8" x 1-1/4" slot under the coaming for the LED rope light.  We'll wire it through the pilothouse wall to a rocker switch.
We choose mahogany to add a little elegance to this social area.  The stock was planed to 5/8" to help take the slight curve of the cockpit.  It flexed just fine and was carefully measured for length and using a bevel gauge, we angled the side to rear joint which was 99 degrees. Basically just had to set the saw to 9 degrees and cut carefully.  Make it slightly long and creep up on it.  Once in place, the long sweep from 6" to 3" was sprung from a batten and cut with the circular saw.  The corresponding bottom cut was marked using a compass setting of 3" held along a pencil line marked along the deck's edge.
Again, we buttered it up with epoxy glue mix and used countersunk screws to be bunged over before coating the entire coaming in epoxy.

Notice the shadow on the coaming as it stands proud of the cockpit walls. At night, soft light will flood down from that groove.

The rear coaming board was installed in much the same manner.  Cut to length, 9 degree bevel. Sneak up on the final cut.  Glue and screw.  I also glued the vertical joint and put one screw at the top to pull it tight.  It will disappear when bunged and sanded final.

Now the cap and back to the wood shop to make it...

cutting the miter with a Shark saw
and using a wood block guide to
keep the blade vertical

The miter joint photo shows the cap.  It is almost too heavy to slip over the walls and bend to the curve of the walls, as well as, make the curve horizontally.  I'll go ahead and explain the dimensions.  It was milled 3/4" thick by 1-3/4" wide.  A groove was dado-ed 11/16" wide for a little slop for the epoxy to hide and all edges rounded over with a 1/4" round-over bit.
I will advise that two steps are taken before "horsing" it into place for fitting and please fit all pieces before gluing.  One, slightly round over or bevel the top edges of the coaming walls to help slip the cap over; and two, put a C-clamp across the edge of the coaming.  You can see in the photos of the glue up what I am talking about.  It is really easy to snap off the wood adjacent to the dado as it is twisted sideways.

Fitting the starboard cap, note the C Clamp insurance.

The first miter is determined by marking the inner corner and outer corner of the vertical coaming on the underside of the cap.  One could also use a bevel gauge to mark this.  Either method gets the intersection of this odd angle marked.

The back cap is placed over the top cap and marked and cut.

With everything fitted final, we mixed a bag of glue, loaded the Wilton cake decorator bag and laid a generous bead in the groove as the clamping, pushing, coaxing and cussing finally persuaded the caps into place.  Lots of clean up on the squeeze out and wipe down with denatured alcohol.