So no one posted a comment saying, “What’s wrong with this picture?”
The day following my prior post, I hoisted the sail for the first time, to horror. The boom (the stick at the bottom of the sail) wouldn’t clear the deck. I couldn’t believe it. (I still can’t believe it.) The mast was too short. A quick check of the drawings showed the obvious dimension I had missed.
In between the next 24-hours of rants to self (“Unbelievable”, “Just read the plans for once.”), I imagined a life of boat builder shame (Wife leaves in disgust, kids disavow eccentric father, the soft whispers of friends just beyond ear-shot). I also realized the only path that even closely resembled redemption was to build another, better mast ASAP and just get the darn boat in the water. On the bright side, the lessons learned on the first mast would make this a faster build. And the second build would allow me to photo-document the process, which I had previously neglected to do.
HOW TO BUILD A MAST
There are a number of ways to build a mast. I did not find JM’s book particularly descriptive. While there are varied methods described by other builders, I used a method loosely based on a Wikihow instruction, albeit with far fewer than 37 steps. Here’s how.
1. Laminate a mast blank
The mast is 2.5 inches wide at its base, so a 5/4 x 4 and two 1 x 4’s were needed. I got lucky and found good-looking 12-foot boards at a big box store. I went home and laminated them directly using Titebond III wood glue. With only 3 suitable clamps, I wrapped the boards with duct tape at 1-foot intervals.
Mast blank glue-up the following morning.
UPDATE 7/10/14 – This mast developed separations between the laminations because of glue starvation. Be sure to clamp the boards more aggressively than I did. This mast was repaired by flooding the open seams with glue, then reclamping. We’ll see how it holds up after launch.
UPDATE 9/2015 – The boat has been out in variety of conditions and the mast has performed well.
2. Taper the mast
The specification for the lowest 2-feet is a 2.5-inch diameter. The mast tapers to 1.5-inches at the top. To dimension the mast blank, mark the center on each end of a mast face, and at the location where the taper begins. At each of these points, measure from the center line outward 1/2 of the planned diameter and mark. Connect the marks with lines as shown below. I snapped chalk lines for tapers on the two edges, which turned out to be faster and more accurate than drawing a pencil line using a straight-edge.
The chalk lines connect the marks and define the taper of the mast.
On the prior mast, I used a circular saw to cut the excess material, forming a tapered square mast. But I did not like running a circular saw along narrow boards, and this time used a power planer. This required additional time, but was much more controllable.
After trimming two sides, roll the mast 90 degrees and repeat.
Square-Tapered Mast Blank
3. Place octagonal marks
The corners need to be trimmed to convert the four-sided blank to an octagonal piece. To accurately locate the intermediate edges, mark the blank as follows:
At the ends of the mast and the beginning of the taper, use a compass to draw a circle that spans the entire face.
Draw tangent lines to form a box. Using a compass, measure the distance from the center of the circle to the corner of the box.
Put the point of the compass on the each of the 4 line ends and mark the line at the measured distance.
Draw or snap lines to mark the boundaries for planing off corners.
4. Plane to the intermediate marks to convert the blank to an octagon
The bricks were enough to hold the mast in place, at lease when using a power planer. Some manual block planing later required weights on the saw horses.
Octagonal section after planing.
5. Round-off the corners
At this point, I used a low-angle block plane and a random orbital sander with 60-grit paper to knock down the eight edges. This left a symmetrical tapered mast with eight rounded corners. To round it all out, I cut open a 3″ x 21″ 40-grit sanding belt and sanded across the grain by hand. Leather gloves were needed as 40-grit rips open skin. Sanding went on for an hour, and required that I straddle the mast in lieu of a bona fide mast holder.
A sanding belt rounded off the corners. More sanding with the random orbital and 60-grit removed the sanding marks left by the 40-grit paper.
After more planing and sanding, the mast came out round after all.
6. Trial fit to boat
This boat already had a mast partner and a mast step. More planing and sanding was needed to fit the base of the mast to those parts, but now the mast bolts up rock-solid, even stronger than before.
A 3/8-inch hole was drilled for passing the 1/4-inch halyard used to raise the sail. I used a round sanding stone on a drill bit to bevel the edges.
I’m sure that if I ask six boat builders how to build a mast, I’d get twelve-and-a-half answers. This method worked for me, and including primer application, took 10 hours over three days. I’m pleased with the result, which seems stronger than the first mast. And getting the build back on track has enabled me to look at myself in the mirror again … if only with one eye. Maybe this thing will actually see water next week.