Carbon fibre masts

Southern Spars' David Barnaby looks at the new rigs on Volvo Ocean 60s

All masts are dimensionally the same in terms of height (a requirement of the rule) but not all masts will be the same with regard to section size. This is dependent on the designers and manufacturers who have varying theories and design their tools accordingly. Most however, have chosen the rule minimum sectional size of 300mm x 150mm.
With seven out of the eight competing boats carrying rigs built by Southern Spars in either their US or NZ facilities, deviation from this standard has been minimal.

Booms for this race are also constructed in carbon fibre, which results in a significant weight advantage over their old aluminium cousins. Interestingly the rule makers have disallowed the use of any core material within the mast or boom. This has made for some imaginative design work in the boom sidewalls to prevent local buckling, which appears as the rippling effect in very thin walled sections.

Simply, carbon is so strong that a minimum wall thickness of around 2mm can be achieved, but without careful attention can end up being very fragile. One resolution to this local buckling issue was to use 'top hat' stiffeners along the inside of the boom sidewalls.

So what is the impact of all this lightweight technology! Not only can the crews sail the boats harder knowing that the masts are stronger but they will also be going faster. This is precisely the intent of the rule - "to foster gradual design development". What will we see next race?

Above right: Southern Spars' low windage spreader attachement. Below: broken headboard car on djuice from leg one