To get the required fore/aft width, an offcut from a broken America's Cup main sail batten was glued to the front of the mast.

Starting at maximum depth of the mast permissible at the tip (55mm including small crane section at the back of the mast) and tapering down to 5mm, 1200mm down the mast.

While not everyone will have an broken sail batten lying around the yard, a good substitute would be a non-compressable foam or a light weight timber such as Spruce or Oregon.  The reason for having a core is to increase stiffness.

A cored spar is far stiffer then a hollow tube. Tests with hollow cored fairings showed no significant changes to the mast bend figures.

Time could have been spent making a nice shape but I dont think that when travelling at the maximum boat speed of 15 knots, the masts aerodynamical shape is going to be critically important.

Main point was to get the maximum amount of flat surface in the fore/aft plane. The closer this flat plane is to the centreline the softer the mast tip will be.

As the material I used for the core was 14mm thick I left it at that. Simply faired it into the front of the mast).

Carbon layup on the core was four layers of 200gm uni's in parallel with the mast.

To increase the overall stiffness of the mast, six layers of 200gm carbon uni's were layed up on the front and sides of the mast from the heel to a height of 2 meters.

The combination of stiffening the tip and the bottom of the mast resulted in the final mast bend figures in the table below.

The only areas of concern are the tip deflections being higher than target.

The critical measurement of sideways tip stiffness has been achieved. Because the tip of the mast no longer falls off, the top 1/3 of the sail generates more power and lift.

The tip fore/aft stiffness (where wing masts have the edge) results in the sail keeping it's shape in the all important top 1/3 when sheeted home.  Lack of mast curvature means the sail doesn't get flatten when sheeting in.