Building an epoxy mast proved surprisingly easy and cheap. In case you are interested I'll tell you how we did it, saved a bundle and got a mast far stronger and lighter than normal masts. The method we choose was based on a PU-foam core. It is an easy and quick way of making one mast. If more than on mast has to be made than it is better to make a female or male mold. Masts can be made from either epoxy-glass or epoxy-carbon. Epoxy-glass gives a very flexible mast. This is advantageous for cruising as it takes the sting out of strong gusts of wind by bending in gusts. Carbon masts are more suitable for competitive sailing. As carbon masts bend less, the sails set better.
Obviously you need to have some idea about the size of the mast you want to build. The building specifications usually specify the dimensions of a wooden or aluminum mast. We used the dimensions of the wooden mast as an indication for the size of our mast.
PU-foam can be bought in 100x50x4 cm pieces. With a sharp saw we made 100x7x4 cm pieces out of this. These where glued together into one piece of 540x7x8 cm using normal contact adhesive. In this stage the core is easily damaged so we fixed it on a long piece of wood (600x20x5 cm) for protection and to keep it straight.
The core is than formed into the final shape by hand using sandpaper.
This is not as difficult as it sounds. I used my eyes to make
a nice oval shaped section and to introduce a slight tapering
towards the top and it worked out nicely. I could have used some
cardboard templates to check the sections but I was to lazy.
On those spots where we had to fix things like forestay, mainsail block etc. we put ply-wood pieces (about 30x5x1.8 cm) sunk flush into the core. The idea was that the ply-wood would make it possible to simply screw the fittings to the mast. Although this worked out fine, looking back I now know that lashing these fittings to the mast is also feasible and is more flexible and easier to repair.
It is possible to buy strips of glass roving but cutting it out yourself is cheaper. We used 300 gr/m2. The number of layers should be calculated carefully but I don't know how! I guestimated and used 10 layers in the bottom part which was reduced gradually to 4 layers in the top part. In practice this turned out fine. The mast bends through 1.2 m in gusts without stays and 0.5 m with stays.
We cut the layers to such a width that they partly overlap for strength. The first two layers are the most difficult as the core is easily damaged. But once the first two layers are cured, the rest is easy and fast. By sanding slightly between layers the end-result is pretty smooth. It is probably possible to reach the same kind of finish as professional mast-builders but it will take a lot of elbow-grease.
Epoxy must be painted as it is not totally UV resistant. Painting
was done using two part PU paint. It gave a nice finish. We have
used the mast during two seasons and the paint didn't flake.
I had calculated that the mast should be able to carry 100 kg
while being supported at the ends. With my 114 kg I took the gamble
and stood on the mast. I did bend strongly but didn't break! The
next final test was sailing with the mast. This also was a big
success. So we now have a very strong mast for very little money.
We were impressed by the end-result of what started as an experiement!
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