the rule allows a 7kg tolerance, since spars must not weigh less than 240kg or more than 247kg.
‘Our validation process then involves an ultrasound test for laminate integrity and a flex test to ensure the rigs have the correct stiffness. We know the guys who are going to use our masts will push hard because they’re the world’s best shorthanded racers, so it’s critical we do absolutely everything we can to make sure our product isn’t to blame should a dismasting occur. ‘We have also introduced rigorous quality control processes upstream, which include careful sourcing of the carbon we use, checking the weight and stiffness. In terms of the final flex test, so far all our spars exhibit near-identical bend character- istics with a maximum variation of 1%.’ Lorima has been building wingmasts for a long time, due to their historic involve- ment with offshore multihulls. As such the company has developed a distinctive pro- duction technique that eliminates the need to add reinforcements on the outside of the spar once the two halves have been cured. ‘Once the mast comes out of the auto- clave,’ Vincent explains, ‘there is no scarf- ing or overlay to be done, and all necessary reinforcements are already designed in. ‘What this means is that we are always thinking about how to maintain the chosen aerodynamic shape, and not compromising or disrupting it by adding fittings to the outside of the spar. Think for example of the shroud attachments: properly executed, a simple T-bone slotted into an internally reinforced opening in the spar allows us to cut aero drag to an absolute minimum.’ The Lorient-based manufacturer uses only female moulds for its rigs, ruthlessly
They are built for the most rugged of applications but the detailing and finish on the new one-design Imoca spars from Lorima remain exceptional. Lorima also supply the deck-spreaders which perhaps surprisingly given their frequent immersion at speed have proved among the most reliable components of today’s multihull-style Imoca rigs
avoiding these external ‘protrusions’. The two halves (front and back) are designed with built-in overlaps so that they achieve the finished shape prior to curing: ‘It is then all cured in one go, there is no bolting or gluing involved after this phase.’ In terms of standing rigging, the latest evolutions in fibre technology allow the use of spliced fittings anywhere that stays are connected: ‘Wherever they can be found aerodynamic gains and weight savings are significant,’ says Vincent. ‘Today we are down to about 700g to replace a steel part that previously weighed closer to 3kg…’ Under the new rules Lorima is respons - ible for the mast itself, and also the 6.25m deck-spreaders and the lateral standing rigging that hold everything up. The fore- and-aft rigging is not part of the standard package, since the rule allows for varia- tions in mast placement that obviously impact the type and length of the J2 (main forestay) and the various backstays. The fibre choice for the longitudinal rigging is regulated but the choice of supplier remains open. In terms of the rake of the spar, skippers can still ‘play’, but now only
within a maximum range of 4°. ‘Material-wise, it’s now only PBO or carbon for the rigging, as in the end Dyneema was rejected by the Imoca com- mittee as there were questions around it following the Desjoyeaux/Gabart dismast- ing.’ Dyneema will nevertheless still be used for many strops and attachments. As previously mentioned, the new rigs come complete with a hefty user’s guide which details the various sail configura- tions and their associated rig set-ups, several of which it is absolutely critical to have in place – especially when the boat is sailing under J1 (genoa/Solent) and full main or J0 and full main. In these condi- tions the topmast is particularly vulnerable to pumping and having the J3 stay in place significantly helps stabilise things. As Vincent underlines, ‘You can never treat a wingmast like a conventional spar, the way loads are distributed is something to be understood and then always taken account of.’ Which of course adds to the already very long list of things to bear in mind for solo sailors handling these rapid high-tech machines…
SEAHORSE 31
q
JEAN MARIE LIOT/DPPI
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76