13 Feb, 2021
Prada Cup Final - Day 1
It’s going to sound wise after the event, but the fact is that for British supporters the evidence for a difficult day on the water was there from the start. The weather forecast said light winds to start with before a NE sea breeze filled in later on. The direction of this stronger breeze was significant as it comes straight in from the open ocean and is a very stable direction. Two sets of conditions that earlier assessments, (read personal guesses), suggested might expose Britannia’s vulnerabilities. Over the last couple of weeks I guess I’ve convinced myself that shifty conditions, preferably with a reasonable breeze that would ensure flight, was where the Brits could do best. And this is exactly what they didn’t get today. So, given that Ben and the gang spent a great deal of time working on the boat over the last few weeks trying to overcome their speed deficits, why were they caught out today? My guess, and it is only that, is that one of the issues is power. The sail plan and rig is still a problem. My rationale is that when you compare the straight line speeds between Luna Rossa and INEOS they are very similar, there really isn’t much to separate them upwind or down. This suggests that the Brit foils are just as good as the Italians’. If they generated less lift, (and hence be more prone to dropping off them early), they would also generate less drag and therefore be quicker - They’re not. If they generated more lift they wouldn’t drop off so readily but would be slower - They’re not. Their problem seems to be that they drop off the boil a shade earlier than Luna Rossa and then struggle to get back up. In the pre-start in the first race Luna Rossa came very close to ending up in displacement mode too, but avoided it by resiting the temptation to place a pre-start punch on INEOS in favour of sailing angles that would keep them in flight. You could hear Spithill and Bruni talking about it on the comms. Now, you could argue that Britannia’s aggressive hull form presents more wetted surface area and is therefore more difficult to get going. Maybe this is true, but it doesn’t explain why they drop off the foils before the Italians. So, if we assume that the foils are there or thereabouts and when it comes to staying up the hull isn’t an issue, the next factor must surely be power – the rig. I know I’ve been banging on about this for a few months now but the more I hear about what all three teams have been up to the more I think that the some of the biggest differences between the boats lie in this area. One of the helicopter shots today, when the two boats were heading upwind, seemed to show the Italians sailing with the head of their mainsail over rotated to leeward. At the very least it seemed far more open, as if they were spilling breeze out of the top of the rig, while the Brits had a leech profile that stood up along the full range of the sail. To me this suggested that the Italians at least had power to spill and if they really were over-rotating the head, they were generating windward righting moment aerodynamically, although I freely admit that I don’t know if this is actually possible with these mainsails. It was with the solid wings on the AC50s. Another interesting issue is that Britannia has a boom and Luna Rossa doesn’t. presumably this makes the Italian maisail more efficient when they do the equivalent of letting the outhaul off to generate more power lower down. Luna Rossa’s sail looks deep and tidy low down, Britannia’s looks awkward and flat in this area by comparison. The jib is another area that looks different although again, I’m guessing and it may not have anything to do with the flight issue. But to me the Italian jib clew looks under much more control through the tacks than that of Britannia’s. In short, the Brit jib flaps more through the tack. So, putting 2 and 2 together and making five, my conclusion is that as the clew is free to rise it opens the leech of the sail and spills power quickly towards the top of the sail. Keep it under control and you keep the power on. Self-tacking jibs and jib tracks to suit aren’t allowed under the AC75 class rules. But watching the Kiwis yesterday their jib moved from tack to tack like it was a solid wing. The Italians’ looked similar. Could this be another area? I say again, I’m guessing and very happy to be told otherwise, but what seems clear is that the Brits still have an issue in the lower wind range. So why did they still lose when the breeze was up? They gave away a good position off the start through a couple of mistakes and miscommunications. Having won the start and bounced Luna Rossa off, when they came back on port tack for the first cross there seemed to be a difference of opinion on what was going to happen next. I’m sure I heard someone say ‘lee bow tack’ although I can’t swear that it was from INEOS and not Luna Rossa anticipating the Brit move. Had they lee bowed the Italians they may have benefitted from the slight right-handed shift that followed rather than ending up not benefitting from a lift that gave Luna Rossa a couple more boat lengths. Instead, they ducked the Italians and headed out to the right hand side of the course. The duck wasn’t good as Ben mentioned at the time on the comms (and referred to in the press conference later), gave away too much distance in the process something he could be heard pointing out to Giles Scott at the time. The next time they came back together Luna Rossa were ahead and manged to control their position from there on. The time between the two most of the way round was only seconds and at the finish the delta was only 26 seconds. Had the Brits rounded the windward mark in the lead it could well have been a different result. But the fact is they didn’t and it wasn’t and it is important to give credit to Luna Rossa for sailing two flawless races which is precisely what Ben did in the press conference that followed. Luna Rossa are an impressive outfit and will be a very tough team to beat. Tomorrow, (Sunday) looks set to be breezier and with racing taking place on course E, chosen for its flatter water. But it is also a course area that is more shifty. Shifty, stronger breeze, this is where INEOS need to demonstrate that they can redress the balance. https://youtu.be/MDYtKNapVdY
