Opposite: the Norwegian Landmark 43 Game lifting out on the Estonian X-41 Olympic during an inshore race at last year’s ORC Europeans in Hankø, Norway. Mark Mills’ Landmark 43 continues to be a competitive option in ORC; however, in IRC the growing number of lighter, offshore designs are making life difficult. Bottom line, IRC continues to see new builds or updates of pure racing yachts which above 42-odd foot simply outpoint, out-plane and out-accelerate even the best cruiser-racers. Once a novelty, most performance foils now feature the hollow aft sections that first became prevalent on the final IOR designs of the early ’90s, before IMS took over… albeit, as it turned out, both very briefly and very painfully. Left top to bottom: The original rudder on Intermezzo; reshaped with hollower aft sections and more parallel mid-sections allowing more of the volume to be pushed forward for better stall characteristics; the original rudder – which is stalling much earlier than its 2022 replacement (above)
the ORC certificate you declare a maximum crew weight. You are allowed to have less, but you can’t have more. Another ORC trick is to trim the boat a little on the transom, so it sits deeper in the aft section. This will increase the measured wetted sur- face and can result in a better rating… then underway you trim forward again. Funny to think this is the opposite of how we did it in the days of the IOR system, where boats were measured “standing” on the bow!’
Sailplan ‘Finally, there are the rig and sails. Typical questions are what kind of spinnakers: asymmetric or classical? If asymmetric, is the tack going on the centreline or on a pole? If you use a pole, how long should it be? If there’s a bow sprit, is there an advantage in making it longer, or shorter? ‘Obviously we also look at the size of
the spinnakers, and whether there’s some- thing to be gained from going with only masthead or fractional kites. Then there’s the position of the forestay attachment on the deck, and the actual sailplan for the jib – how much overlap? ‘For the mainsail the first important issue
is deciding the choice of a pin head or square top. You could go for a square-top mainsail with a shorter P measurement,
which means a shorter luff. This can be an advantage, because you will have the same sail area in a more efficient plan form, and with a lower centre of effort. Square-top mainsails are also more aerodynamically efficient, because they can demonstrate a better twist profile while minimising the induced drag from the tip vortex… the ORC VPP rule doesn’t assess this very well. ‘What the rule does calculate, though, is
an advantage from having the sail area higher up, since the wind is stronger the higher you go. So the ORC VPP assumes that a mainsail with a shorter P can’t produce as much power as a mainsail with the headboard higher up. ‘Certainly it is true that when you
transit from a long P pin-head mainsail to a short P square-top mainsail, the mainsail will not generate as much thrust – but it will generate significantly less drag and the end result is normally a net gain, the oppo- site of what the VPP predicts. Thus the rule tends to punish high-aspect sails, which is another argument to exploit a shorter P.’
But my own budget is not unlimited… Very few boat owners have sufficient budget to do all of these modifications. But if you want to optimise your rating, or
simply make your boat perform better on a more basic level – and do it on a finan- cially modest, amateur level – where do you get the most value for money? ‘Well, for quite some years I’ve been
arguing for more focus beneath the water- line,’ says Nielsen. ‘Let’s say you sail upwind in waves with a standard NACA keel profile. Every so often you steer a bit too high, or the boat knocks into a wave. As a result your speed drops significantly, often by a knot or more and you will need to bear off for quite some time to rebuild speed. ‘With a better optimised keel section,
and profile, the boat will lose much less speed every time this happens. And you will regain lost speed much faster. Also a new, optimised rudder does not cost much more than a new jib and could similarly easily give you added speed and more joy than a new sail. Besides, a new rudder lasts the entire lifetime of the boat. The same is definitely not true for a sail! ‘As I said, your keel and rudder are like
the tyres on your car: the place where power is transferred into motion. However much you spend on your sailplan, and however big the changes you make, it will still always be a shame if all of this poten- tial isn’t transformed into actual speed because you lack grip in the water.’
SEAHORSE 53
q
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126
