Stealth i14 out of China

by Neil Patchett on 17 Aug 2014 Innovation and boat handling are synonymous with the International 14 which has remained remarkably progressive considering it is one of the oldest racing classes in the world.

Encouraged by a semi-restricted class rule, the i14 is all about controlled evolution. From trapeze and asymmetrical kites, to foils and carbon, the class has a good record of embracing change, albeit with the inevitable pain.

Innovation however comes at a financial cost and carbon is a good example. It is a fabulous boat building material that delivers incredible high strength to weight ratios. Not surprising, i14 sailors love carbon but that love affair can be expensive due to relatively high material costs and labour-intensive construction demands.

The class, fortunately, is not short of its fair share of resourceful sailors. For several years, a small group of Australian i14ners, led by an unbreakable class president Stewart Vickery, have tinkered with production-run boats.

The challenge of course has been to settle on a design that will give top end performance and to source a builder who has the systems, resources and ability to build in carbon at prices affordable to a wider audience and not just the well-financed class fanatics.

It would seem the Australians have hit on an attractive formula with the Stealth design and a carbon boat builder in China who has built moulds and refined processes to produce a significantly less expensive, light, strong, quality boat.

The result is a super stiff i14 at approximately $13k (all dollars are in US) for hull and racks clear finished plus approximately $2k for duty and freight; or for $15k you are looking at hull, racks, centre board, rudder, foils, rudder box clear finished; plus duty and freight. This means a saving of more than $10k.

Peter Newman of China New Yachts Ltd says they were using products that were available in China at a competitive price which were thoroughly tested in other boats. The 'other boats' from this builder have included the 44ft Veloce which finished second overall in IRC in the 2013 Sydney to Hobart Yacht Race.

'The laminate is carbon pre-preg and Corecell SAN foam construction in female moulds which are cured in our controlled oven,' Peter said. 'We use a woven carbon prepreg cloth on the outside to get excellent impact without adding much weight, all other materials are unidirectional carbon prepregs at various constructs to gain maximum strength to weight ratios. The semi-monocoque construction gives a very stiff, finished hull, clear painted at less than 46kg.'

Newman said they were able to ship to all parts of the world from Qingdao, which was home to the fourth largest container port in China.

Designer David Lugg of Western Australia said Stealth was designed a couple of years ago and has since proven to be an easily driven, stable hull well suited to today’s rigs.

'The boat was designed for the moderate to strong winds and relatively flat water that make a 14 such as great boat to sail,' according to Lugg. 'Although the boat’s light weather performance has been good, it was considered some small modifications would further enhance its performance with minimal impact on speed in the stronger wind conditions.

'The construction of new moulds offered the opportunity to tweak the lines. The chine was lifted slightly at the stem and narrowed by 30mm a metre aft of the stem. The Stealth design had a very straight, flat run aft. A small amount of keel rocker has now been added.'

Multi national champion in the Australian i14 fleet Brad Devine knows Lugg well and said: 'I really like Luggy’s design and like the concept of having a cheap builder that can build to high standard with a good design.

'The designs (eg., B5, K3 and Stealth) within the class now are all that similar, that as long as the hull is light and stiff, that is all you need. The next step in the equation is getting a good rig, which is pretty standard now days and a good rudder and centerboard, which is also very standard.

'The way things are shaping up with the boat at this stage, I would suggest that it will be a great success.'

Victorian Dave McGeoch was one of the first to order a Stealth from China.

'I can let you know that for someone who has watched the 14 class develop since 1977 to today, it shows to me that the imagination from many sailors in regard to design, construction and fitouts is exceptional.

'The impressive way this build was handled by Peter Newman from the legal documentation of the contract of sale to the regular information supplied at milestones of the build and of course the final delivery has left me in no doubt that his professional competence has been outstanding.

'It appears to me that the light weight 44.5 kg less spin pole, racks and fittings would seem to give me some concern (regarding strength), but having carried out some destructive testing on a sample of the hull it has barely marked the outer skin with no compaction of the inner core.'

'The boat's hull looks great and is clean with a simple deck design for ease to fit out.'

The Royal Geelong Yacht Club has opened online entries for the 2015 International 14 World Championships, which are to be held from third to 17th January 2015 in Geelong, Australia.

The 2015 event will mark only the third time that Australia has hosted this World Championships, with the previous event being run on Sydney Harbour in 2010 when more than 100 i14s lined up to start.

Designer Notes:

The hull sections, although fine forward, rapidly become very flat aft of midships and lift to a low chine. The end result is a hull form that has significantly reduced draft compared to other current designs, promoting earlier planning. Modern i14’s sail upwind at speeds in the 8 to 12 knot range. Stealth makes a very smooth transition between displacement and full planning mode.

The more powerful, lower drag rigs used today suit a hull form that is flatter and fuller in the ends. The effect is to increase what Naval Architects refer to as the prismatic coefficient, a ratio describing the longitudinal distribution of underwater volume. Higher prismatic coefficients are closely associated with higher hull speeds.

The i14 rule measures the mast height above the sheer line at the mast station, consequently the higher the sheer, the higher the mast. Additionally the increase in sheer height has the benefit of making the boat much stiffer longitudinally and keeps the rack tubes well clear of the water.

The sides of the boat are slightly cambered to increase panel stiffness allowing a thinner, lighter core to be used.

The angle of the bowsprit has been increased from the original design to give the spinnaker tack a greater clearance to the water when the crew weight is moved forward in light weather.