Building your spar

Marstrom will apply FEM modelling of global buckling and FEA modelling of local buckling to all projects. For high end projects this is taken one step further: Marstrom is currently one of two mast companies with the inhouse capability of loading the combined mast/rigging/sail structure loading with simulated aerodynamic forces.

Our quality management system is certified according to ISO 9001:2015, which controls our daily operations. The purpose is to work with continuous improvements and to understand the customer's requirements as well as delivering articles that meet requirements and expectations.

Key points of Marstrom spar building

• Carbon/prepreg
• 6 bar Autoclave (up to 8 on specific projects)
• Computer controlled cutting machine
• “Zero fairing” carbon tooling
• One shot build 
• Longitudinal split of tooling

The spars are built in Autoclave Cured Carbon fibre Prepreg with 3 autoclaves on site.

The first step in building is cutting the material with a computer cutting machine similar to what a sailmaker will use. In parallel the tool is prepared to receive the laminate: cleaned and treated with release agent. Marstrom tooling is predominantly carbon for getting the same thermal expansion as the carbon article and with focus in finish to minimize fairing.

Marstrom builds the laminates layer by layer in the tool rather than stacking material on a flat table. “Flat build” will result in the layers straining against each other. Another aspect is the longitudal split rather than the transverse split of the tool. This makes it easier to reach corners preventing “bridging where the laminate is not accurately placed into the corner. The laminate will be built in left and right halves being joined in an overlap system rather than being glued and riveted together.

Through the build the laminate will be debulked at specific intervals with vacuum to ensure that it is properly compacted and air evacuated. Before the cure the tool will sit under vacuum for 12 hours.

The first step in the assembly area is to apply a thin layer of fairing to smooth out minute (a few tenths of a mm) pinholes which will occur on the surface of the laminate, 99% if this compound is sanded away. After this, positions for fittings are measured, holes are cut and fitted with hardware. For maximum accuracy this is done with templates where possible.

After hardware installation is complete it is removed, and the spar is painted in a temperature controlled paint booth.