Above: a rare lapse from Jarvin’s ‘7’ crew following a misjudged encounter with a Sydney Harbour ferry…. but misjudged by whom? Right: every successful fleet has one… Frank Quealey’s devotion to supporting and painstakingly recording 18ft skiff regattas is the main reason that every winter so many sailors around the world are able to take a close interest in the action on Sydney Harbour
It is important that not only is the
finished product light but that every single piece of carbon is in the correct spot. Carbon is an extremely strong material and it doesn’t take much to hold the boat together, but if you get it in the wrong spot it also doesn’t take much for it to blow up in your face. The final stage is to prepare and spray
the hull and deck of the boat to the smoothest possible race-quality finish. This is a lot harder and more time consuming than it sounds as during this process we are again continually conscious of keeping weight to an absolute minimum, as the boat receives an undercoat, primer and then the bare minimum final high-gloss coat. Weight has always been critical in 18ft
skiff racing. We produce the bare hull shell at about 20kg and the overall weight of the boat before fittings are added is ‘approxi- mately’ 65.5kg. By the time it’s ready to race all-up weight is around 170kg, which gives some idea of what goes onto an 18 to get it into race-ready condition.
Moving forward To further improve the accuracy and therefore similarity of our hulls, in 2016 we introduced new much more rigid deck tooling which has made the boats even stronger. We asked the engineers and tech- nical team at Gurit to have a look through and change some of the fibre layout and frames based upon what we had learnt over previous seasons. The idea was not to make the boats go
more quickly but to cope better with the increased loads of the high-modulus rigs and square-top mains that had come into the fleet, plus the trend for heavier crews to add additional righting moment to match. With these increases in overall global structural loads it became essential to beef up the platform to suit if boats weren’t to revert to being consumable items as in the bad old days. We always remain conscious of trying to keep stability in our product. Every boat
has the same fuselage, and we try to give everyone the same opportunity from an equal base. Speaking on behalf of the Australian
18 Footers League, Steve Quigley says: ‘We have a great relationship with Brett, Gurit and our internal design team, to ensure both the continuation of the con- trolled development of the class and to ensure it remains relevant, while protect- ing the heritage and commercial viability of the boats… in which the League has a significant investment! ‘It’s a fine balance and we may not
always get it right in the minds of some of our stakeholders, but at the end of the day our goal is to ensure an accessible class that offers a fair race for all participants. We believe this is best achieved by rigor- ously maintaining the one-design aspect of the hull and foils while allowing develop- ment of the sails and rigs. It’s a formula that continues to work well for us at the moment, but we also need to continue on our path of controlled development; so we look forward to working with Brett on further improving the boats’ longevity as composite technology advances.’
Aloft
– Michael Coxon, North Sails Sydney In the 18-footer class during the early 1980s working sail materials were fill-oriented Dacron with resin coating to add stability with the cross-cut construction. Also tested were some early Kevlar/Aramid-Mylar cross-cut sails tested on Dave Porter’s KB, but at the time the material did not offer the durability required for an 18 where the crew could land on the sail during a swim. Later in the decade fill-oriented Dacron
laminates were introduced that were lighter and lower stretch than the original Dacron. In the 1990s skiff sail materials devel-
oped into warp Kevlar/Aramid laminates that brought with them the use of radial construction. They were constructed with the Aramid fibres in the warp direction, typically polyester fill yarns in a Mylar
sandwich. However, shrinkage was a significant factor in those early days and so cloth manufacturers began to add thread line reinforcement fibres to the material to help combat this to some degree. By the 2000s good Mylar-based materials
for radial panel sails were offered in a range of fibres suitable for 18s, including Aramid, Technora, polyester and carbon fibre. Then in 2006 North Sails developed and introduced the first 3DL moulded Aramid/Mylar working sails which was a big step forward in both weight and shape stability. These were built in one piece on full-
sized moulds in the flying design shape of the sail. The combination of 3DL’s improved engineering together with the replacement of aluminium masts with carbon spars was soon allowing our designers to push the roach sizes of the mainsails towards the enormous fat head sails we see on the harbour today. Then during 2015 North introduced
their 3Di product to the scene. As this product doesn’t have any Mylar film the shrinkage is minimised; 3Di also offered improved strength and durability for a given weight by eliminating the need for Mylar in the sail construction and replac- ing it with fibre. 3Di is now offered in a range and mix of fibres including carbon, Aramid, UHMWPE fibre and polyester. Downwind sail materials have over the
decades been based around nylon, as it is light with relatively high tear strength – again important on an 18ft skiff. The quality of nylon material has also improved, primarily due to developments in weave. Polyester spinnaker cloths have come
and gone over the years with another comeback at present for #2 spinnakers. The upside of polyester is lower absorp- tion of water and less stretch than a nylon equivalent. The downside is polyester has a lot lower tear strength for a given weight, which can be a regatta breaker with the modern skiff only racing with one spinnaker onboard…
SEAHORSE 59
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