Carbon fiber layer:

Using the same method than for the glass, pull the carbon fiber sleeve around the spar.

Again, tension is important, pull the sleeve as tight as possible.

(See building notes for complete text)

(This picture shows the peel ply on a dry mast)

(See building notes for complete text)

Optional post cure:

(See building notes for complete text)

Larger spars on a rigid foam mandrel:

Longer spars can be built with the method described above but as the length increases, it becomes difficult to keep the mandrel straight.
For that reason, we prefer to build the mast around a rigid foam mandrel on a perfectly straight narrow bench.

(See building notes for complete text)

We will look at the building step by step, first, building the bench.

In this case, we used plain 2x4's precisely aligned with a laser level.

The foam mandrel is built exactly like a hollow wooden mast.
We will need local reinforcements for mast step, mast top, shroud and spreaders attachments etc.
Those reinforcements can be made of high-density foam inserts or extra fiberglass layers.

(See building notes for complete text)

Once the box is made, we can shape it in a round mast.
We will cut the corners to make an octagon, round those corners until we have a round shape.

To make an octagonal mast, we mark the corners of the box with a mast maker gauge:

With the sides of the gauge pressed against the sides of the box, the gauge will draw a perfect taper.
The gauge can be made of any material: a piece of wood with nails or pens like above but the proportions are always as below:
7-10-7
Beware, the pictures is wrong, it should read 7-10-7

(See building notes for complete text).

(See building notes for complete text)

Oops, in this picture we did not grind enough foam to compensate for the mast step reinforcement.

We follow . . .
(See building notes for complete text)

The sleeve covers the reinforcements and should be stretched as much as possible.

Apply the resin the same way than in the previous example and follow with more layers including carbon fiber according to your lamination schedule.

Go to Part 3: