Originally posted October 2021
While many of the fastest sailboats on the planet are now ‘officially’ monohulls, they can only achieve this with projecting foils, which to my way of thinking is like ‘a trimaran on steroids’. In fact, I fantasize that IF our civilization had somehow started boating with monos-on-foils, that sailors and designers would be slowly taming them over time to be more broadly useful, finally replacing their speed-dependent foils with far more versatile floats or amas … et voila, a trimaran would be born!
But as we know, that’s not the way it happened ;) Instead of using ‘buoyancy pods’, these monohulls now use carbon-fiber foils to provide the stability needed to resist heeling from their tall, efficient rigs … so let’s compare these two types for a second.
‘Real’ trimarans with buoyant amas provide an automatic increase in ‘resistance-to-heeling’ as an ama is depressed into the water, but as the displacement stays almost the same (the heeling force does briefly add a little extra displacement), the main hull lifts out as the amas are pressed in, so overall resistance is not seriously increased. The great thing is that trimaran ama buoyancy is always there … and works as a function of heel. and having little relationship to speed they are effective 100% of the time … be it windy or dead calm.
By comparison, these new AC75’s are composed of monohulls (that no longer even have a keel), having lifting foils whose ability to function is totally tied to the speed they are driven through the water, so at very low speeds they are just adding drag unless fully lifted out, and then, most of their stability must now come from the beam of the main hull**. Unlike ama buoyancy, foil lift and the stability they can provide, is not automatic and not 'always there'. (to be fair, the foils ARE slightly weighted, so when BOTH are deployed fully down, they would provide a little added stability to the hull, but only with significant added draft).
So while conventional trimarans can have a very slim main hull, a mono with foils and no ballasted keel, really cannot.
If the weather in which these foiled monos sail (or race) is limited (as for the AC75 America’s Cup boats) then no keels are required, but if such boats are subjected to all weather conditions (as for the IMOCA 60 Vendee-Globe ocean racers), then typically a transversally-inclining keel with a heavy lead pod at the bottom, is needed. This adds weight of course and to the hull also, so they will only be ‘semi-foilers’. This technical difference contributes to the fact that while the AC75’s may be pushing over 50kts at times, the fastest IMOCA-60 boats will probably be limited to around 35 and more often around 25k when really at sea.
Still incredible speeds though … but both boat types are now almost totally dependent on their hi-tech carbon fiber foils that stick out and for open water racing, these will be vulnerable to damage or even destruction by collision. This will particularly affect the faster foiled IMOCA-60 boats racing around the globe (starting very soon), as unlike the conditions for the America’s Cup, the huge expanse of ocean that needs to be sailed both day and night, is totally un-screened or surveyed for UFO’s … ‘unidentified floating objects’. (Note that a fair percentage of the IMOCA boats will still be 'more conventional keel boats' and sailing without foils).
So unlike the conventional, slower trimaran with buoyant amas, one can expect some rather violent collision damage for a few unlucky IMOCA-60 foil-assisted boats and some capsizes by the AC75 boats, to add to their ‘quiver of capabilities’. Who and What survives remains to be seen, but these boats are not for the ‘risk adverse’ or faint-of heart. Even if their rapid motion-accelerations can be tolerated and managed, noise levels inside these carbon-fiber ‘drums’ can be horrific and more than one skipper has said; ‘perhaps the most critical piece of equipment on board is now noise-cancelling headphones!’
So there’s my Intro. Having now justified these boats as ‘quasi-tris’ (tongue-in-cheek), and having been denied all chance to sail and collect new cruise material this season by a COVID border closure, I now have ‘the little excuse’ I needed to switch gears and introduce the amazing upcoming races.
The VENDEE-GLOBE. On Nov 8th, the largest fleet ever (33 boats registered to start) for the non-stop, unassisted, 24,000 mile circumnavigation “Vendee-Globe” race starts in La Roche-sur-Yon, France with the IMOCA-60ft foiling monos leading the charge, all sailed single-handed. The course takes them south down the Atlantic to Cape of Good Hope, then around the globe at this southern latitude across the huge and challenging Indian and Pacific Oceans, to round the notorious Cape Horn and then head back north to France. Not all men either, with a record six females (ages 29-51) also taking on this epic battle against the powerful elements of nature and self reliance. Three have top level sponsors including 46 year old British-born Samantha (‘Sam’) Davies sailing ‘Initiatives-coeur’, and Sam already has a formidable biography as does 51 year old, Miranda Merron Just check out their achievements on WIKI.
No doubt that SailingScuttlebutt.com will stay on top of the daily news if you wish to follow it. First boat is likely to finish around Jan 20-25th 2021 if things go well. Most sailors are now hoping for someone other than the French to finally win this top event for the first time (good for the sport) and UK’s Alex Thomson on Hugo Boss is a top prospect, having been very close twice before. (see pic above). But Charal driven by Jeremie Beyou is a French favourite as is Armel Tripon on his breakthrough design L’Occitane that also looks like a real challenger. Many of these new IMOCA boats have full scow-bows rather like the first generation of AC75 boats, with more bow buoyancy than those with finer skiff bows, raising the Question: Should you cut through or bounce over at this speed ? L’Occitane certainly looks very light and eager to fly. Her canted keel is also very visible here too.
(To keep this circumnavigation in perspective, these are IMOCA yachts limited to 60ft. Meanwhile the ‘ultimate’, unlimited ‘Race around the Globe’ is a timed event for the Jules Verne Trophy, awarded (if pre-registered) to the fastest trip around the globe, with no size limit or detailed rules for the boat. The current holder is a 31.5m (103ft) trimaran, then named IDEC SPORT, that was originally built (by Multiplast, FR) back in 2006 and had been updated and renamed several times since. In 2017, she won the Trophy, skippered by Francis Joyon (with a crew of 10) in the unbelievable time of 40.98 days with an ’average’ speed over those 40+ days of well over 20kts! She has a beam of 22.5m (74ft) and carries a sail area of nearly 9000 sqft on a mast of 41m (135ft). She weighs just 40,000 lbs and has a daggerboard extending down to 5.7m (18.7ft). Back in 1993, a catamaran was the first boat to break the 80-day mark and since then, the best time for a 120ft maxi-catamaran to date is about 50.7 days. Attempts to break this record are made roughly every 5 years so we may read about another attempt soon).
But what about the 36th AMERICA's CUP coming up early 2021? This is the oldest trophy in international sport and dates back to 1851 when ‘America’, a 100ft schooner from NY City, beat all the British boats available, around the Isle of Wight in the UK ... home of my teenage sailing grounds. Read more here if interested: WIKI on the America's_Cup.
In comparison to the ocean-going IMOCA-60 boats, the new AC75's are not needing the main hull to handle rough water but mainly need it to get up as early as possible on their foils. So there has been quite some research into how the main hull bow shape (and its bow wave) can/may affect the performance of the foils, as the earliest possible lift-off will most likely result in the fastest boat overall. The newest (2nd) boat from each team should help to show what their research has revealed. Fuller sections and flare can save a boat from nose diving too ... see the US boat #2 'Reliant' on its first sail !
After no less than 11 teams first issued a challenge to the cup holder New Zealand, the final boat design requirements (with associated cost and time required) really thinned things out over the last couple of years, bringing it finally down to just 4 teams, but as these are all highly competent there's clearly no loss of quality or competition for this event. In fact, this could perhaps be the most spectacular event ‘the Auld Mug’ has ever created!
As most sailors will know by now, the final cup races are sailed as ‘one-on-one match races’ between the current cup holder (Team Emirates - NZ) and the winner of an earlier two-week series between the Challengers, called the Prada Cup. Each team is allowed to build 2 boats, so after several months testing and learning from the first one, the 2nd boat is typically a little faster. (Note the unique scow-like hull shape of Italy’s 2nd boat). This time, the 3 Challengers who made it this far, are from the USA, Italy and Great Britain with their teams called American Magic, Luna Rossa and Ineos (UK). These 3 will race it out in Round-Robins for the Prada Cup, between Jan 15th and Feb 24th 2021.
The final America’s Cup series between NZ and the Prada Cup winner, will run from March 6th to March 21st but could finish earlier if one boat is winning most of the races. As it’s a best of 13, the first team to get 7 wins will take The Cup.
Skippers for the boats can always change, but as per October 2020, they will be as follows:
American Magic: Terry Hutchinson (skip) and Dean Barker (helmsman)
(Terry was the tactician when the US finally rallied to win the 2013 America’s Cup in San Francisco, 9 races to 8).
Team UK-Ineos: Ben Ainslie
Luna Rossa: Max Sirena (GM) and Jimmy Spithill
DEFENDER: Emirates Team New Zealand: …. Glenn Ashby
Should be a really exciting event with lots of wild video hitting the web for 2 months in early 2021. So tune in!
**I should mention that the foils on these boats are themselves weighted, so when both are fully lowered, this does add something to the boats stability. The lifted weather foil also adds stability. The original hope was that this would allow them to be self-righting but this had not apparently been achieved to date, though its close. It is amazing though, that even 3 years ago when the new boat concept was first announced, a short video really gave quite a realistic view of what we might soon see in 2021… even if the foils make a little more water disturbance in real life ;) Here it is: https://youtu.be/rx2qG_YMrDs
I should also mention the unique new rig. Gone are the efficient rigid wing-sails that only rarely survive a capsize, but mainly because they offered no practical flow-down to practical pleasure yachts. The soft double-sail has surfaced again, after L.F.Herreshoff first suggested this, way back in the 1920's. See here: Mast-Rig Options.
With the races not due to start before 4pm Auckland time, the time for ‘live news’ in various places will start at: 3am in the UK; 4am in Italy and 10pm in Eastern USA.
Video clips should be available free (to 225 countries!) on www.americascup.com with the NZ organization aiming to make this ‘the most accessible and exciting America’s Cup in its history’.
Also check out: www.sailingscuttlebutt.com coming out of California, plus BBC Sport at www.bbc.com.uk as well as www.sail-world.com and the Herald (sports) from New Zealand: www.nzherald.co.nz A program out of Amsterdam hosted by Florian Rooz, is also gaining popularity and can be found at www.seawolvesTV.com
Originally, there was supposed to be 3 World Series races with these AC75’s in 3 locations .. Cagliari, Sardinia (April 2020) ; Portsmouth, UK (June 2020) and Auckland, NZ (Dec 2020) plus a major Youth AC Competition in Feb-March 2021, but everything other than the last World Series event in Auckland had to be cancelled due to COVID.
But enjoy what you can … this should REALLY be impressive !
More on the 2021 America’s Cup, the boats & the Rules can be found in this earlier article: America’s Cup 2021.
mike Oct. 2020.
Hi guys …had a few emails asking, what’s my take on the America's Cup to date ?
The fact is, I have no more info than what we are shown on YouTube and you can be pretty sure that all the teams are now keeping things to themselves other that what is obvious on the water, but here are some personal thoughts for what they are worth.
First, the speed and maneuverability of these boats is truly amazing me .. (over 3 times wind speed downwind !! .. are you kidding me ??), and the resulting stability and vertical posture of these boats on just two foils that are on a severe diagonal with the boats direction, is an amazing display of what computers can, and will, do in the future for sailing. But I cringe at the thought of 3 or 4 such boats like this ever racing together, as if any of those outstretched foils ever get entangled, this could be a massacre … and with a boat on each side of you, where do you go at 30 kts to avoid something like that? Unthinkable.
Re the comparison of teams, I do see small differences in the fullness of sail shapes, though these 3Di sails all appear incredibly beautiful and efficient. Although it's very hush-hush, we are learning that between the two plies of these new sails, there could be a network of pistons and cables (computer controlled) that can rapidly change sail fullness, so that there's more fullness (hence more slow speed power) to help get the boat foil-born, but then with the ability to rapidly become much flatter at the suddenly higher foiling speed. That's a game-changer if so.
As far as the hulls are concerned, its more a matter of how aero-efficient they are than anything else, as from what we have now seen .. a hull that drops down, loses about 1 minute and that’s nearly ½ mile at the speed they are averaging, so you’re not going to win a race if you drop down anywhere, unless the other team does the same. Perhaps the deep center ’keel’ of the UK boat has too much surface, but once the boat is up, it seems to have a competitive speed. One has the impression that at least initially, their equipment seems less reliable and the pressure on them could well be upsetting the essential ‘team spirit’.
But as an ex-Brit myself, I am of course disappointed with their results so far, and see it as a collection of several things, not the least of which is now an almost intolerable pressure to do the impossible in a very short time, to save face for their sponsors and national pride. Regardless, someone has to be last and that team as a whole will not be happy.
But it’s not over yet. One area that I am secretly praying will be addressed with new hardware coming at the last moment from the UK, is their main foils. I personally see no justifiable reason for a reverse dihedral on such a foil…it just gives up that last essential % of lift. Just as for plane wings, some positive dihedral might even be justified, but for me, being as they are clearly able to sail quite vertical, a dead straight wing must surely give the most direct lift and as ’getting up & staying up’ is THE most important factor for this competition, why compromise on that? So far, despite being allowed 6 foils (or 3 pairs?) each, the only boat I've seen with a nearly straight wing is the NZ one! (see photo at right). The camber of that foil is hard to assess in the videos we see, but more camber will give more slow speed lift, but result in less speed at the top end ... so there is the design dilemma. Are the British foils presently 'too fast' (too thin) and therefore offering less initial lift ?
One thing that more conventional fast boats can take from what we are seeing, is the confirmation that trimming the traveler is THE way to go for the best mainsail performance. This is very noticeable on several videos and I predict that this will place a demand on equipment suppliers to improve their present travelers so that they operate even better under load. 'Playing the traveller' is presently not always so easy, and it's highly unlikely that 'twin-ply sails packed inside with individual batten control systems' are going to become standard on any boat you or I will get to sail. (At least all my boats have wide tracks ;)
The choice of foresail also seems pretty critical, not just because of a wide range of sail area, but also for the different slot effect that's apparent with the rotating twin-ply main.
Another very significant thing that I expect to feed into the up-coming races is the wind force. In that part of the world, they are getting deeper into summer and as we all know, with heat, the winds generally get lighter requiring slightly fuller sails for more drive and the maximum lift from the foils. The Challenger who wins the Prada Cup, will probably need to make some last moment changes, as racing in February could well be different from racing in March for the actual America Cup …and you can be sure that Emirates NZ are now focused totally on March conditions, whereas the Challengers first have to win in February before they can even get a shot at NZ. This puts the odds on NZ successfully defending The Cup, unless, either the wind changes or there’s an equipment failure. But both or either are certainly far from impossible.
But what a spectacle we are now able to see, in ways previously unimaginable .. .. both with the America Cup and the Vendee Globe. Enjoy ! Will be over all too soon
"New articles, comments and references will be added periodically as new questions are answered and other info comes in relative to this subject, so you're invited to revisit and participate." —webmaster