Wednesday, September 19, 2007

Mast Building

The Tiki 26 laminated hollow mast is well-designed and simple to build compared to most wooden mast building techniques. There are a lot of parts to cut and assemble, but each step is straightforward. The construction begins with preparing the wood by ripping it to width and then scarfing it to the required length. All scarf joints are cut with a minimum 12:1 ratio for strength. Below are the scarfs for the two main half panels. These are 3/4" thick, as that is the required wall thickness of the finished spar.

Inside the mast are triangular fillets of solid wood that hold the four outer plates together and provide enough wood inside to maintain the wall thickness when the mast is cut down to the round section. These fillets are cut on a 45 degree angle from two-by fir stock that was first scarfed to full length.

To establish a straight line and compensate for any natural crown in the mast lumber, I first clamped the halves to the bench and lined them up with the straight edge of the top surface, double checking with a taunt line. The first fillet is glued in place, and when this joint cures the laminate helps hold the plank in line.

All of the fillets are now glued in place on both halves, and everything came out straight and true. The next step is to make and install the many parts that make up the masthead and the mast foot.

Below at left is the mast heel that fits inside the spar at the foot and pivots on the mast step that will be laminated into the top of the mast beam. The step and heel are made of laminated mahogany. To the right are the ply parts that make up the mast crane.


Kim said...

Perseverance furthers. . .Element is going to be a wonderful boat, Scott.

Scott B. Williams said...

Thanks Kim. The building is a voyage in itself. Like any voyage there are times of doubt and uncertainty, and it takes a single-minded fixation on the destination to persevere to the goal.