A taller,
narrower bigger spinnaker will make the timeless high performer even more exciting and
tactical
THE INTERNATIONAL 505, the two-handed
performance dinghy class with seemingly eternal appeal, is freshening up with the decision
to go for a bigger, longer-luffed, higher-aspect spinnaker.
The main performance gains are expected to come with from a spinnaker that is not only
three square meters bigger, but taller and narrower. It will be a better apparent wind
chaser on the runs and easier to handle on powered-up reaches.
After two seasons of
trailing the new spinnaker in 505 strongholds around the world,
including Australia, the International 505 Class Yacht Racing Association has voted about
two to one in a ballot to approve the alternations to the spinnaker dimensions in the
class rules.
The change will be introduced on October 1, just after the next world championship at
Lisbon, Portugal, in September and in plenty of time before the following worlds, to be
sailed from Fremantle SC, WA, from November 30 to December 2002.
While the 505 is a development class, it has been cautious to accept major change since it
gained international status in November 1955. It began from an immediate development,
beginning as an 18-footer at International Yacht Racing Union trials in 1953 at La Baule,
France, to find the “best possible two-man centreboarder”.
That winter, the Caneton Association – a small-boat racing body in France –
asked John Westell, the British designer of the Coronet, if he could modify her to suit
their needs. Westell reduced the overall length to 16ft 6in, lightened and modified the
hull and cut the sail area to produce a new design that retained the good features of the
Coronet. The 505 was born.
The class, from a strong initial organisation in France, quickly spread internationally
and is still sailed keenly today in 18 countries. The sleek and efficient hull shape has
certainly not been out-moded in the intervening years and is still being modified subtly
within the tolerances permitted by this limited development class.
Cockpit layout structure has been changed too and foils are becoming longer and narrower
as competitors experiment with gibing centerboards.
The spinnaker, however, was stuck with the broad spherical shape that was typical of the
1950s though all dinghy classes but has now become outmoded with the world, led by the
skiff movement, trending towards asymmetrical shapes.
The move towards the taller, bigger spinnaker has been on for five or six years with
five-times world champion Krister Bergstrom of Sweden one of its main proponents.
The class’ annual general meeting in July 1999 voted overwhelmingly to authorize the
international executive to arrange trials and present a rule modification proposal.
Australian 505 sailors who tried spinnakers made to the new dimensions, or modified to
meet them, supported it enthusiastically. Among them was immediate past international
president Pip Pearson of Adelaide, who first sailed in 505s as crew for Paul Elvstrom in
the world championship at Adelaide in 1965 and still sails forward.
Reporting on racing in a mixed club fleet aboard Blue Slip with Dave Colebatch, with the
wind freshening to above 20, he says: “In 39 years of sailing 505s I have never been
so fast. In one gust we actually left the crest of a wave, became airborne and
‘flew’ to the next wave. The power in the big spinnaker is incredible.
“But the remarkable thing is it lifts the bow and actually make the boat easier to
steer in the big seas and big winds. What a ride!!!”
Mike Quirk, from the Toronto (Lake Macquarie) fleet, who was fifth in last year’s
nationals, describes himself as an average sailor who has spent most of my time sailing
around the middle of the fleet.” He was skeptical before trying the big spinnaker. He
already found the boats challenging to handle in a breeze, particularly on reaches and
gybing. The big kite was only going to be pushed by the top guys. The 505 was a dinghy and
if you wanted to sail a skiff there were plenty to choose from.
But he changed his mind after sailing with the big kite for two months in a range of winds
from 5 knots to 30 knots. He explains:
“Yes, there is more sail area but the real issue is that the proposed dimensions
result in a far more stable and manageable spinnaker. It is bigger, it is more powerful.
The boat is much faster.
“The boat is more fun on square runs when you can trapeze downwind in 8-10 knots.
Exactly when to do this, and which way to go on the run will add a tactical dimension to
sailing the boats that we have not had before.
“The boat is more fun on the reaches because the crew is on the trapeze in about 5-6
knots of breeze. The boat is also easier to sail on the reaches, particularly in strong,
gusty conditions. The boat doesn’t want to round up every time you get slightly out
of balance or you don’t see the gust coming. The rudder almost never cavitates.
“When a gust hits, the nose of the boat lifts up, the boat bears away the takes of.
The driver doesn’t even have to lean any harder or ease the main.
“Gybing is easier because you are moving much faster and have correspondingly more
rudder control.
“Over the years 505 sailors have developed a spinnaker that is very difficult to
handle due to the luff length restriction. It is very deep and long at the foot. Far too
much of it is behind the mainsail and there is a lot of spinnaker too far aft.
“In an effort to provide power on dead runs and reaches, we have developed a sail
which is a real bitch to handle on reaches when the boat invariably feels unbalanced. To
obtain a forward driving force, we have to endure a lot of heeling moment and drag.
“The new kite is much further away from the mainsail, leaving a much bigger slot. The
boat just doesn’t choke up as much. The higher exit point on the mast causes the top
to be pulled to leeward and the boat depowers much more quickly.”
New
dimensions
The rule change increases the spinnaker luff length from 5000mm to 6000mm and sets the
greatest width at 4500mm, which used to be the half width restriction. It sets the half
width at not less than 75 per cent.
This also means raising the spinnaker halyard 500mm and lowering the pole fitting about
500mm to accommodate the bigger chute.
505 builder and top competitor from the Lake Macquarie fleet, Brett Van Munster, like many
others, has been experimenting with alterations to older spinnakers as well as trialing
new ones.
He says modifying older spinnakers is an inexpensive way of moving into the new bigger
chute scene and avoids making them totally obsolete. With the changes to the fittings
location, he says the conversion cost is only about $180.
Another Lake Macquarie sailor, Andrew Hewson (second in the nationals), says: “The
new spinnaker will make the boat more skiff-like in nature with gibing angles more
imperative. It will make it more attractive to the new generation of sailor.”
New
hull shape
Van Munster Shipwright & Boatbuilding, at Narara, NSW, has built ten boats from a new
female mould. The mould is constructed from a low shrink polylite tooling system that
enables elevated temperature curing during construction. The low movement and shrinkage
properties of this system allow accurate reproduction of a hull shape that takes full
advantage of class tolerances.
The original plug, based on the successful Kyrwood hull shape, was altered during
construction of the new tooling. The alternations included straightening the stem and
flattening the spring. This has produced a finer entry to the bow section, Van Munster
says.
Subtle modifications have also straightened the buttock lines, providing a flatter run aft
and a slightly softer turn of the bilge. These changes reduce wetted surface area and
maximize the waterline length.
The centreboard case has been modified to allow the latest generation of high-aspect
gibing boards to fit into the smallest possible centrecase. The centercase slot has been
shortened and the volume minimised in an effort to increase the buoyancy of the hull.
Nine of the new boats are of vacuum-bagged carbon composite construction – extremely
stiff and light in the ends. The deck weighs less than 22 per cent of the boat’s
finished sailing weight. Bare hull weight is 83kg and some of the carbon boats are
carrying up to 15kg of lead to bring them up to sailing weight.
The cockpit layout of the Van Munster boats has been re-designed to provide the crew with
a clean and simple work area. The smaller centerboard console allows find-tune systems to
be led straight to the helmsperson while in the normal hiking position, helping “gear
changing”.
The console design allows for the fine tune purchase to be contained close to the
centrecase.
Foil
efficiency
Recently, there has been great focus on foil design. Foils have become smaller in area and
more efficient with the combined surface area of the modern rudder and centerboard similar
to those of smaller boats like the NS14 and Tasar.
Long and extremely narrow gybing centerboards have been developed. With the head of the
centerboard a parallelogram shape, the centreboard’s leading edge angles to windward
on either tack going upwind as the head bears against the side of the centercase.
These new high-aspect ratio boards provide the boats with greater lift at lower speeds and
seem to be most advantageous in marginal planing conditions an flat water when they
provide greater power than conventional boards. The smaller overall surface area provides
less drag.
More information
on the class, contacts:
www.int505.org
