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Central to Welbourn’s design philosophy is ‘easy speed’ and this has touched all areas of the Infiniti 52, most aided by the DSS foil. For example while there is a trend in offshore yacht design to have ever greater hull volume and form stability, especially around the bow, this is unnecessary on a DSS boat as the conditions when it is beneficial are when the DSS foil is generating maximum righting moment.
Thus the Infiniti is a ‘small’ (ie relatively low volume) 52 with noticeably less freeboard. It has a modest deck chamfer, a significant chine and a very flat underbelly. With the foil adding righting moment in ultimate stability conditions, the keel bulb doesn’t need to be as heavy, thereby keeping displacement light, again increasing speed.
The highly successful Infiniti 46 Maverick (class winner in the Rolex Middle Sea Race twice; in the RORC Transatlantic Race; Newport Bermuda Race, and overall winner of the SoCal 300), has all the ‘bells and whistles’, including twin ‘flip out’ DSS foils, plus a canting keel and canard. In comparison the 52 is simpler with a single DSS foil sliding laterally across the bottom of the boat within its case.
Instead of a canting keel and canard, it has a fixed keel and 600kg water ballast, split into twin tanks each side aft to add grunt upwind. While the canting keel/canard is effective, it comes with complexity and a fixed weight, whereas water ballast can be jettisoned at any time, maintaining light displacement.
The DSS foil is designed to be deployed and then left to do its job, but the water ballast does also permit the boat to be trimmed slightly stern down, which of course adds angle of attack to the foil, increasing its lift.
When submerged, the DSS foil provides lift to leeward, translating into reduced heel and displacement and ultimately considerably increased speed. Photo: Rick Tomlinson / www.rick-tomlinson.com
Less obvious is that while sailing upwind, the DSS foil may provide less lift, but one of its secondary features comes into play – in addition to reducing heel, the foil also significantly reduces pitching by up to 40%, thereby improving the stability of the wind’s flow over the sails and maintaining driving force, especially when the sea state gets lumpy, improving VMG.
Since the Infiniti 52 is optimised for offshore usage, much effort has been made to keep water out. Thus the mast is deck stepped and with no apertures – all lines run out of the bottom of the spar through the deck and then aft to the cockpit through channels on either side of its shallowest of cabin tops. This also reduces windage aloft.
The Doyle sail wardrobe has been designed by Kiwi pro sailor Stu Bannatyne with number crunching from Stefano Nava. The mast from New Zealand Rigging has three tapering spreaders, held up with carbon fibre ECsix rigging. The 3m long bowsprit, above the reverse sheer bow, permits six tack points from the big downwind gear and jibtops at the end of the bowsprit to the furling J4/staysail and storm jib on the foredeck. This enables separation between the headsails to be optimised when sailing triple-headed.
The sails, made in carbon/Technora aramid, benefit from Doyle’s ‘structured luff’ technology that shares the load between the forestay and luff, reducing the overall load at the masthead (thus enabling structure/weight to be removed from the spar).
One of the biggest developments has been the push button operation of the powered Air 300 winches from Harken (which has supplied all the deck gear) and the hydraulic package from Diverse. On what is a quick boat, this enables the fastest possible trimming, via neat waterproof, deck-mounted switching units from CZone.
While a full-on, thoroughbred offshore racer, the keel foil and single rudder are relatively large and forgiving and the hull shape not overly sensitive to heel angle, recognising that Tulikettu has an enthusiastic owner-driver and a semi-professional crew. This can be adapted for a different crew configurations, for example if the boat is to be used for doublehanding.
At a time when many rating rules are attempting to ‘protect the fleet’ – constraining the ability of boats to fly by effectively limiting the amount of vertical lift their foils can produce, the DSS configuration has the benefit of just falling within these limits. The Infiniti 46 Maverick, for example, has been regularly competing under IRC in RORC races and under ORR in the Transpac. Tulikettu, and the Infiniti 52 #2 that is soon to be completed, will do the same.
Designed to be sailed offshore with a crew of as few as seven, the program for Tulikettu is to compete in some RORC races in the Channel and the North Sea Race before heading up to the Baltic for Gotland Runt and the RORC’s new Baltic 600 race. This is the build-up to the Sevenstar Round Britain & Ireland Race and the Rolex Middle Sea Race, before the Infiniti 52 heads transatlantic for next year’s RORC Caribbean 600.
With the Infiniti 52 #2 due for launch at the end of this year, Infiniti Yachts has expanded its production capabilities by appointing a European builder for the Infiniti 52 to look after clients outside of the USA.
They said:
 Hugh Welbourn, creator of DSS, Infiniti Yachts designer: “The 52 is designed to be a good, fast all-round boat. She is quick in the light with a narrow, easily-driven hull and enough sail. Upwind, when you start to need the power, then water ballast and sometimes DSS provide the necessary grunt, and then as you shift into wider and faster angles then the emphasis shifts rapidly towards solely using the foil and keeping the boat light.
“Sailing into the high 20s at true wind angles as high as 90 degrees already is nice! Right now though the learning curve is pretty high, and you have to establish the optimum combinations of water ballast, DSS and all the sail configurations.
“Typically though with all these foil assisted craft I expect to see a 15-20% improvement in performance over the next few months as the guys learn the boat and how it likes to be sailed.
“Easy speed in all conditions is the goal on this design – no marginal rudder or keel sizings, well balanced hull and not critical on trim, and then topped with a flexible sail plan to quickly shift gears.
“DSS is a key part of the equation here – generally it makes the boat easier to sail as it damps the motion and reduces rudder inputs, and then with speed you get more lift that lets the hull respond better to the waves and the rig becomes more efficient too. Add in the massive righting moment for when you need it when really up to speed and it all adds up to less stress on a small crew on the offshore races.
“Learning to unlock the really high averages that win offshore races will be a good challenge, but already we see that the boat is more than matching the design polars and will be a formidable competitor wherever she is raced.”
 Arto Linnervuo, owner Tulikettu, Infiniti 52 #1: “The first project with our Xp 44 was to see where we were as a team and what is required to do well in bigger RORC races. We got to the stage where we could be competitive as a team, but had reached our peak – if we wanted to seriously do well and win something big, we needed a new boat. I saw that boat design was moving fast and everything was ‘foiling, foiling, foiling…’ and that was becoming mainstream. Plus, I wanted to have a future-proof boat.
“We want to do long distance races so it is really important to have a boat that will finish every race. DSS has been used for 15 years on various boats is now into its 16th or 17th generation. They are very reliable, bringing proven efficiency and gains, so I felt it was a proven concept which still hasn’t reached its full potential and of course the Infiniti 46 Maverick had caught my eye. I also saw what happened in the last Vendée Globe to boats that were fully flying, so I thought this is a good balance – we want to finish, but still be foiling. I am from Finland and I like conservative things – this is revolutionary, but not too drastic.
“So far I have found the DSS foil really simple to use, very logical. When we were just doing normal stuff, like upwind and reaching, it was much the same as usual but when we had some good reaching in heavier winds, it was actually much easier than I had thought. With this boat we like to have a heeling angle of 10-16 degrees and I thought it must be quite difficult to hit that range, but it was much easier than I thought. The boat is very stable and the rudder is really good and has good bite and with the foil you are less concerned about the amount of sail area you are carrying and broaching the boat.”
 Stu Bannatyne, pro sailor and Doyle Sails expert: “The Infiniti 52 is primarily a coastal and offshore racer and the whole package has been designed around that. If it was to line-up against a Super Series 52 in 12 knots upwind we would probably be a bit slower, but hopefully by not too much. Any reaching or downwind sailing, the Infiniti should be faster and not just in conditions where the DSS foil is being used – it should also be faster in underpowered conditions too, the boat has lower form stability and should therefore have lower drag. Then as soon as you get powered up reaching and running it should be a good chunk faster when using the DSS foil.
“We decided that the rig plan should be similar to a PAC 52 in terms of the sail areas but we stretched the J slightly and have a longer bowsprit to allow more room for efficient triple headed reaching and running.
“Thanks to the structured luff sails, particularly with the jibs, we don’t have to carry as many, because we can get more range out of the sails. One key feature we have is a furling J4 which makes the balance of the boat much nicer and it goes upwind efficiently because the centre of effort of the sail plan moves aft, which keeps the rudder loaded.”
 Gordon Kay, Infiniti Yachts founder: “On the Infiniti 46 we did over 30 knots four times in one night. This is a much bigger boat and less impacted by the waves, so will comfortably do 30+ knots. I also expect to see high averages at good angles as we have all the sails to do that too. Then it will be down to developing techniques as it is good averages that win races, not top speeds!
“The boat is set up in a way that is incredibly uncomplicated. There are no mysteries when you look at the deck layout. You could step off a J/111 and on to this and if you knew how to work the halyard locks, you’d be off yachting. There is nothing particularly complex.”
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The first Infiniti 52 Tulikettu has been undergoing sea trials in the Solent, following delivery to her new Finnish owner Arto Linnervuo, in anticipation of a busy offshore racing program. Already during her first sea trials she has hit 28+ knots, with more than 30 anticipated and she has impressed her crew with her easy speed and bow-out attitude.
