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Building a Birdsmouth Mast, Boom and Yard (Part Two)

Waiting to be launched.

I have completed the build of the Mast, Boom and Yard. I am applying the multi-coat varnish to each and my next task will be to launch the boat long enough to lower the center board so I can finish the center board case top.

Setting up the construction table

I used the mast construction table, shortened to build the boom and yard.

Scarf table

First the staves are cut and scarfed together.   Each stave is cut with a birdmouth and tapered as needed to match the design diameters.  The yard has good taper build in while the boom had no taper.

Clamping the scarfs after gluing

Scarf detail

Good view of the birdsmouth

Planning the staves to similar thickness

Fitting the end plugs

Boom glue up

Boom and yard on the table

Epoxy set and ready for shaping, cap to be added later

Thickened epoxy

Used a hand plane to take off first few cuts

Power shaping the Yard

Taking shape

Almost done

A properly sized diameter form used to check final diameter

Boom and Yard, varnishing

Yard and Boom detail showing reef comb

Detail of ends, showing birdmouth construction

 
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Posted by on August 7, 2011 in Building Stage

 

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Building a Birdsmouth Mast, Boom, and Yard. (Part One)

Now that the bulk of the build for “Alice Gale” is completed it is time to tackle the birdsmouth mast, boom, and yard.   I am a bit intimidated by building a 20 ft birdsmouth mast but I am moving forward based on the very good information from the Internet on how to build a birdsmouth mast.

First I finished up a few odds and ends with the trailer.  I finished wiring the lights, and added the side bunks.

Side bunk

I used my table saw and band saw to make the 8 boards for the mast.  Each board is scarfed to the required 20 ft length.   Also I tapered each board to create a narrow diameter at both the bottom and top of the mast.

Takes 8 tapered and cut boards for a birdsmouth mast

Next step was building an accurate construction table that was both level and had the right sized forms to hold the mast straight.   You have to build in the taper on the forms too, else you end up with a warped mast.  I used a normal level and a laser leveler to make the building jig with correct level and taper.   Glue up went well doing the work without help.  I used West Slow Hardener and had the necessary time to get the mast together before the resin went off.   I was careful to put the resin in a large flat pan to prevent excess heat from the resin and worked as quickly as possible in painting the resin on.   As long as I quickly spread the resin out I was able to mix several batches of resin as I worked.  It took about 1/2 an hour to complete the entire glue up and alignment checks. Preplan the entire process and it seems to work out ok. If I had screwed up anypart of the glue up I would have had to start over.

Mast table laser alignment

straight line with a laser leveler

mast construction forms, sized for taper

alignment check prior to epoxy glue up

 
The plans do not call for a hollow mast, but at my age I wanted a mast a bit lighter then solid wood. The finished mast weighs in at 29 lbs, (no hardware) and I am pretty satisfied with that.

More shaping and then on to fitting the halyard sheath and eye-bolts for the stays.

Birdsmouth construction with end plug

 
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Posted by on June 14, 2011 in Building Stage

 

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