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From a Bare Hull:  Deckbeams (Page 2)


Foredeck Beams:  Permanent Installation
beamdetail1.jpg (31756 bytes)Since the beams spanning the foredeck would be exposed from inside the boat, I routed a chamfer detail on the forward and after edges of each beam.  For a consistent appearance, and to allow for whatever sort of ceiling (interior hull covering) detail I might install later, I stopped the chamfer detail 6" shy of the point where the beam intersected with the sheer clamps.  Then, I sanded each beam smooth up to 220 grit.


foredeckbeamsin3.jpg (51677 bytes)I installed each beam permanently in a bed of thickened epoxy (using plastic mini-fibers), which I spread on the butt ends of the beams and  in the notches or bearing surfaces where they rested on the sheer clamps.  To further secure the beams, I drove a single bronze screw (#14 x 3") through each beam end into the clamp, setting the head of the screw well below the beam tops to allow for any minor beam fairing that could be needed later.  When these six exposed beams were secured in place, and the excess epoxy cleaned up, I applied a sealer coat of varnish thinned 50% with thinner to three sides of each beam, except for the tops.  The final finish on the beams was to be varnish, so I applied the sealer coat to prevent the beams from becoming stained or discolored by continuing construction processes.  Later in the process, before final deck installation, I'll apply the remaining coats of varnish needed for the look I want.


foredeckbeamsin1.jpg (51572 bytes)The aftermost of these full-width beams on the foredeck butted directly against the forward edge of the curved carlin.  I bolted the carlin to the beam with a couple of bronze bolts during an earlier installation, described here.


Afterdeck Beams:  Permanent Installation
aftbeam3.jpg (40616 bytes)Fitting the carlins required installing one of two final full-width beams, which beam marked the after end of the cockpit area.  Since the carlins' final shape was determined by this location, the beam needed to be in place before I could proceed with their installation.  I installed this beam in exactly the same manner as the foredeck beams.  Once the carlins were installed, I added a small support block beneath the carlin mortises on each side to help secure the carlins in place.  I attached the small blocks with bronze screws and epoxy, effectively putting a "bottom" on the mortises for additional support.  No one will probably ever see these blocks, but just the same I routed a chamfer detail on the lower edges for a more finished appearance.


aftbeam2.jpg (47352 bytes) couple days later, I installed a second full-width beam 16" aft of the one demarking the end of the cockpit, completing the framing in that area.

Short Deck Beams:  Fitting and Installation
With the longitudinal carlins installed permanently, running from the curved piece at the forward end of the eventual cabin trunk to the aft end of the cockpit, I was ready to install the short deck beams running between the hull (supported by the sheer clamp) and the carlin.  For several weeks, I had been laminating the required beams, so I had a stockpile of nearly enough to complete the job.

I began at the planer, where I smoothed both sides of all the beams to remove excess glue and to clean up the wood, as well as to make all the beams a consistent thickness.  During the sheer clamp installation, I had more or less marked out all the beam locations, but I took several minutes to double check the locations and make minor adjustments as needed.  I did find a few places where the spacing ended up differently than I had initially expected, mainly because of the after cockpit edge (beam), since at the initial layout I had not yet known its location.  In general, with one or two exceptions, the beam spacing remained consistent throughout the entire length of the boat, at 18" on center (16" between beams).


Next, I had to address the glued-up carlins.  Before installing the beams, I dressed off the top edge of the carlin to approximate the deck camber.  I found a belt sander was the best tool for this operation, as using a plane on the rough surface and over all the glue spillout was difficult and unsatisfactory.  Fortunately, the process was not difficult with the sander.  In the areas where the carlin might be highly visible from the interior or interior lockers, I spent a bit of time smoothing the bottom sides of the carlins perfectly; in the areas aft of the midships bulkhead, I simply smoothed the bottom edges to remove glue and rough edges, but didn't worry about making them perfect.  These areas will be painted out later, so I went only as far as needed for a good paint finish.

For each of 22 short deck beams, the installation process was the same.  To ensure that each beam ended up square to the centerline, as well as directly across from its counterpart on the other side, I used a long straightedge across the hull to properly line everything up, and double-checked the measurements from known accurate points, such as the midships bulkhead.

I did some research on appropriate means of securing the inner beam ends to the carlins.  In the end, I decided upon the most commonly used method:  an angled mortise with the additional support of a screw through from the inside of the carlin into the end of the deck beam.  Joints like a half-lap or dovetail might at first thought seem appropriate, but in reality, given the real stresses on these joints, this sort of attachment actually weakens the deck beam significantly, in proportion to however much material on the beam is removed in order to make the joint.  True mortise and tenon joints are not possible because of the physical limitations of getting the beams in place, and would be overkill anyway.


shortbeam1.jpg (22237 bytes)For each beam location, I marked out the angled mortises by drawing a line 3/4" in from the outer edge of the carlin, along the longitudinal length of the carlin, and plumbed lines down the outer face of the carlins equal in width to the deck beam.  I used a hand saw to cut first the shoulder (outer) cuts, making the cut so that the mortise tapered from the 3/4" depth at the top edge down to nothing at the bottom edge.  Then I made additional cuts in between the first cuts to make it easier to chisel out the waste.

shortbeam2.jpg (41879 bytes)Once I chiseled out the waste,  I marked the deck beam for the various cuts using a combination square and the same methodology I used for marking the foredeck beams.  The process is a bit confusing to attempt to describe in writing, so once again I refer you to the myriad texts already detailing the process.  I referred mostly to How to Build a Wooden Boat, by David C. (Bud) McIntosh, and would recommend this book to anyone interested in the process.   With the beams resting on top of the hull (or on top of the eventual deck surface, if you can imagine that), I had to raise the inner edge of the beam (on the carlin) a distance equal to the thickness of the deck (3/4"), so I used a measuring scrap that I had around to do this.  If I had not done this, the cuts would have ended up wrong.

beaminmortise1.jpg (36373 bytes)Each beam required several cuts in order to make it fit.  By using a combination square to plumb up the various points on the carlins and sheer clamp, I ended up with a series of marks from which I could draw out the cuts needed to, in theory, make the beam fit in the space provided.

beamsdone1.jpg (51660 bytes)Over the course of three days in the shop, I cut, fit, and permanently installed all 22 short deck beams.  I installed each beam in a bed of epoxy and secured them with bronze screws, just as I did with the full-width beams.  The process became smoother as I went, with practice, but I was happy to be done nonetheless.  I tried for good, clean fits in all cases, but the undulations of the fiberglass inside the hull and other factors prevented perfect fits in some areas; the epoxy made up the small differences easily. 


beamsdone7.jpg (41994 bytes)     beamsdone8.jpg (41673 bytes)


beamsdone4.jpg (48423 bytes)With all the deck beams in and fully secured, the boat really took shape--and became extremely strong and stiff, as well.  I was pleased to find that the sidedecks outboard of the cockpit (where the unsupported run is, at maximum, six feet) showed little signs of flexing once the beams were in place and the epoxy cured.  They would get even stiffer during later steps.


beamsdone2.jpg (49724 bytes)     beamsdone3.jpg (42113 bytes)

 

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