The mystery of the rig

In Les Sables d'Olonne James Boyd looks heaven-ward at the myriad of different Open 60 rig configurations

For a class that is now around 25 years old, one area of Open 60 design where school would appear to be out still is in the configuration of the rig. Wandering along the pontoons in Les Sables d'Olonne and short of gaff topsails and schooners, there are a huge number of variations looking aloft on the 20 competing yachts.

Open 60 rigs are unique in being almost completely unrestricted by class rules. Sails are limited in their foot lengths - a boom or bowsprit overhang (or a combination of the two) of up to 5ft is allowed. Otherwise the class rule that has the most influence on rig design is the one governing stability - the famous 10deg rule - where a boat without its sails up must not heel by more than 10 degrees when all its movable ballast, such as canting keel and/or water, is fully deployed. It is because of this that Open 60 designers are continually trying to find ways of reducing weight aloft.

In more constrained classes - take the Volvo 60 - where there is a minimum overall weight limit, removing kilos from any part of the boat results in that saving being transferred to the keel to gain stability. On Open 60s where there is no minimum weight limit so designers take a different approach. For every kilo saved aloft they are more inclined to remove lead from the keel to reduce the overall weight of the boat. Because of this modern Open 60s tend to weight around 8.5 to 9 tonnes compared to Volvo 60s - fractionally longer at 64ft - that weight 13.5 tonnes or 50% more.

At the same time as being as light as possible Open 60 rigs must be exceptionally durable if they are to survive being sailed around the world non-stop by a singlehander who is unlikely to handle them with the same precision as a full crew. Thus one of the few common features that all the boats share is in have running backstays, but also spreaders (whether they are on the deck or on the rig) that are swept back by 19-20 degrees.



One man who has been contemplating Open 60 rigs in depth for more than a decade is Marc Lefevre (above). Lefevre made a name for himself on the Open 60 circuit when he worked as shore crew for Alain Gautier's Vendee Globe winning Bagages Superior campaign in 1992-3. He then joined the shore team of the even more successful Christophe Auguin, winner of the 1990 and 1994 BOC Challenges and ultimately the 1996-7 Vendee Globe. Lefevre now runs the V1D2 boatyard in Caen on France's north coast where numerous Open 60s - the most recent being Conrad Humphrey's Hellomoto - go for refit work, modifications and repair.

In terms of their rigs, the most obvious division between boats in the present Vendee Globe fleet are the five - Hellomoto, Arcelor Dunkerque, Hugo Boss and the new Lombard designs Bonduelle and Sill - that have wingmast rigs. The great innovator Yves Parlier was the first to transfer this 60ft trimaran technology across to monohulls with his revolutionary Aquitaine Innovations Open 60 in 1996.

Compared to conventional tubular spars wingmasts are more efficient for their size and more powerful - so why isn't everyone using them? A small part of the reason is that they are more expensive. Lefevre agrees they are more efficient and with the bare minimum of rigging they are aerodynamically very clean, but says that to stay them requires the use of ungainly deck spreaders that limit the size of gennikers and Code Zeros.

Wandering down the dock it is interesting to see Joe Seeten's Groupe Finot design Arcelor Dunkerque (originally Marc Thiercelin's 1998 vintage Somewhere) with her original massive deck spreaders. The recent trend is to make deck spreaders shorter - Lefevre says 0.5m have been lopped off those of Arcelor's sistership Hellomoto (originally Mike Golding's Team Group 4/ Ecover), while those on the latest generation Lombards appear shorter still and, like Alex Thomson's 2000 generation Lombard design Hugo Boss (ex Sill), their deck spreaders are slightly different as they attach to the cabin top roughly 0.5m back from the mast, rather than to the mast step.

This time four years ago there were three boats with rotating wingmasts without deck spreaders - the race winner Michel Desjoyeaux's PRB, Thomas Coville's Sodebo and Dominique Wavre's UBP. This time round there are none. "Without deck spreaders you have to put more structure into the mast to make the mast stronger and as a result it is much heavier," explains Lefevre.



Above: the wingmast and deck spreader combo on Bonduelle

Desjoyeaux's PRB in 2000 was fitted with hinged spreaders similar to those previously used on Tony Bullimore's ill-fated Open 60 schooner Exide Challenger in the 1996 Vendee. Lefevre says that the masts on Sodebo and in particular UBP in 2000 were exceedingly heavy. Aside from being the tallest mast in the 2000 fleet UBP's rig was keel stepped while everyone else's was deck stepped. Lefevre says her mast weighed 800kg - roughly twice that of the wingmasts in the fleet.

While a development of the hinged spreader system is to be seen on the rig on Mike Golding's new Ecover this time round (more on this later), tellingly the same PRB now in the hands of Vincent Riou, Desjoyeaux's technical and shore manager in 2000 has a fixed mast.

By far the most significant disadvantage of a wingmast is that they are substantially heavier than a conventional carbon fibre tube. LeFevre cites the example of Hellomoto's 25m tall wingmast which on its own weighs around 200kg compared to the new similar-sized tubular spar on his old Geodis (now Herve Laurent's UUDS) that is only 120kg.

This time round the majority of the fleet have tubular masts. On the lower budget campaigns this is for reasons of cost, but there are some where it is for reasons of light weight.

Even on the tubular masts boats there are widely different configurations. The Southern Spars-built mast on Jean-Pierre Dick's Farr design Virbac Paprec, aside from being the tallest mast in the fleet this time at around 28.5m off the deck, is a close cousin of a Volvo 60 rig and has four sets of spreaders.

The new rigs on PRB and Seb Josse' VMI (the former Sodebo) are minimum weight choices with tiny tubes and just one set of spreaders on PRB and two on VMI. Lefevre says they had been considering this option as far back as 1994 with Christophe Auguin's Geodis: Aside from shedding yet more weight, fewer spreaders and diagonals also helps reduce windage.

Unlike other classes there is still an unusually large number of spar builders in the Open 60 class, probably because boat builders have now realised that it is not a quantum leap to go from building a carbon fibre boat to building a carbon fibre spar. Saying this an interesting observation that Lefevre makes is that despite the supposed poorer resin-fibre ratio of filament winding in his experience carbon fibre spars manufactured using this technique rather than a pre-preg hand lay-up somehow come out lighter.

Aside from the wingmasts and the fixed tubes there are two more exceptions (ignoring the yawl rig on Jean-Luc van den Heede's old steed - now Karen Leibovici's Benefic): One is the rig on Bruce Schwab's Ocean Planet which is a freestanding rotating mast with a hefty looking boom gnav. The other, which wins the Lefevre mast-of-choice 2004 prize, is the rig on Mike Golding's new Ecover.

We have written about Ecover's rig (see left) in the past, but the concept of this Owen Clarke-design is primarily to reduce weight - the lightweight tube has a small elliptical section braced by two sets of diamonds - but gains some benefit of the rotating wingmast concept by allowing the spar to rotate. Rotation of the mast is carried out through the use of a single set of spreaders that are hinged on the mast. Thus when sailing on board there is the unusual sight of the shrouds and the spreaders remaining fixed, while the mast and diamonds rotate.

Finally, aside from the general configuration of the rig, a significant choice that skippers/designers must also make is on the size of the rig. The Open 60 class is one of the few where mast height and sail area are mostly unrestricted and generally you would think that bigger was always better. In fact this is not so obvious if the boat has to be sailed around the world singlehanded and it is interesting to see how rig sizes have found their own equivlibrium. This time around aside from a few anomolies like Virbac and Temenos, most of the leading Open 60s all have masts around 26-7m tall.

Lefevre points out that with a tall mast there can be pitching issues upwind. If you are having to reef constantly there will regularly be an unused section of mast that is adding both unnecessary weight and windage aloft. There is also once again the stability/weight issue - a taller mast and sail plan will be heavier and will require more weight to be put into the bulb or more movable ballast to stay 10deg legal. In the last Vendee Globe Michel Desjoyeaux observed that the three leading boats all had modest sail plans in terms of mast height and mainsail area.

In terms of saving weight aloft Lefevre says that tube weights have changed little since the days of Geodis 10 years ago. However looking back to 1989 he estimates that the rig (without sails) on Titouan Lamazou's winner Ecureuil d'Aquitaine weighed around 1 tonne, compared to today's equivalent is around 400kg. Where much greater weight reductions have been made is in changing to the latest materials for sails, standing and running rigging. This we will look at tomorrow.

Below: looking up Ecover 's rig showing the mast rotated relative to her hinged spreaders