Please select your home edition
Edition
Predictwind - Iridium

Rod Davis- Rethinking the Current Tactics

by Rod Davis on 26 Aug 2012
Ben Ainslie Racing heads for the shore - out of the current, maybe - but not the place to be. Jon Nash / J.P.Morgan BAR

Professional sailing coach, Olympic Gold and Silver medalist and long time America's Cup crew and skipper, Rod Davis gives his insights on the effect of current on catamarans, and the new tactics, in San Francisco.

We are always learning in this new Cat world.

You have to think a bit more laterally when comes to racing high-speed boats like cats, particularly in current. Be it San Francisco’s America’s Cup course, or anywhere else that you try to play the current.

A few quick facts: In your 50 foot mono hull, you sail up wind at say 8 knots. If the current is 2 knots that means current is about 25% of total speed. The new Cats will sail up wind at, about 18 knots, a 2 knot the current is about 10% of the boat speed.

That is two and half times different, and is a very big deal.

When you play the shore short by tacking into the shallow water where the current is weaker, you can make big gains in your monohull. The wind shifts are a secondary consideration to getting that 25% boost in performance.

With the cat it is only 10%, so balance between current and shifts enters a different equation. On top of that, a monohull loses about a boat length in a tack.

A good tack in the cat costs you four boat lengths in smooth water, and more in waves. That's a big part of the new cat equation too. You can’t afford to short tack up shore.

The easy conclusion - no short tacking up a shore for current.

Ahhhhh, not so fast. You don’t abandon the current all together; just the current has a factor, given the new situation we are in at San Francisco sailing catamarans.

There is a mind twister: Downwind in some conditions at cat will go two knots faster with just a knot more wind speed. So, in those conditions, you would sail out into adverse current of a knot, increasing the winds speed by a knot, and boat speed by two knots, to get to the finish faster........

That's something you never purposely do in a normal boat.

Strange but true. Still learning.

Rod


Selden 660x82C-TechRS Sailing 660x82

Related Articles

America's Cup - Dalton opens up on boat and options for next Cup
The Protocol for the 36th America's Cup will take place in Auckland on the morning of the 29th September Italian media are reporting that the announcement of the Protocol for the 36th America's Cup will take place in Auckland on the morning of the 29th September. Dalton confirmed the details of the yacht will be revealed two months later on November 30, but would not say if it will be a foiling monohull as speculated in the media.
Posted on 18 Sep
Pulling G’s with Beneteau – Pt II
Just a little while ago we pulled some Gs with Beneteau’s Mr Product, aka G3. Just a little while ago we pulled some Gs with Beneteau’s Mr Product, aka G3. You can go back and read Part One of the story of Gianguido Girotti, as and when you may like. However, for now we’ll push on with the incredible semi-foiler Figaro 3, and the new Oceanis 51.1, along with what they represent for the brand as a whole. It is a very interesting tale, especially as Beneteau...
Posted on 31 Aug
JATO ignited as SuperFoiler prepares for take off (Pt II)
When we left SuperFoiler last time, the JATO rockets had been lit, and we were rapidly approaching the time for rotation When we left SuperFoiler last time, the JATO rockets had been lit, and we were rapidly approaching the time for rotation (lift off). You can catch up with Part One of SuperFoiler and the JATO rockets, but for now we get to talk speed, the crew on board, and finally the commercialisation of it all. Buckle up!
Posted on 28 Aug
Pulling G’s with Beneteau – Pt I
In a car, just the one G will have you straining at your seatbelt. In a car, just the one G will have you straining at your seatbelt. Over nine (+ve) in an aircraft, and without a G-suit, you will be unconscious. So at three G’s, and pulling no punches with them either, we not only enjoyed our opportunity to sit with Gianguido Girotti (G3), we got to learn a lot as well!
Posted on 23 Aug
JATO ignited as SuperFoiler prepares for take off (Pt I)
When small military transports have to take off from impossibly short runways with a belly full of cargo When small military transports have to take off from impossibly short runways with a belly full of cargo akin to Mr. Creosote, they reach for the JATO bottles. Aircraft like C-7 Caribous and LC130 Hercules strap rockets, yes rockets, to the underside of their wings to gain valuable extra thrust, which surely helps keep the pilots' heart rates below the red line.
Posted on 22 Aug
A Q&A with the RORC’s Nick Elliott about the 2017 Rolex Fastnet Race
I caught up with Nick Elliott, RORC Racing Manager, via email, to learn more about the world-famous Rolex Fastnet Race. When one stops to consider the world’s best ocean races, the Royal Offshore Racing Club’s Rolex Fastnet Race, which starts on Sunday, August 6, 2017, is never far from mind. I caught up with Nick Elliott, RORC Racing Manager, via email to learn more about the race’s history and evolution, its challenges, and the amount of work that goes into pulling off this world-famous regatta.
Posted on 1 Aug
Ian Walker - Musto Ambassador on the Volvo Ocean Race, America's Cup
Ian Walker on his Volvo Ocean Race win, why food and clothing are so important offshore, his views on the America's Cup We speak to Musto ambassador Ian Walker about his Volvo Ocean Race win, why food and clothing are so important offshore, his views on the America's Cup, his new desk job, sailing for fun, and 20 years of the John Merricks Sailing Trust.
Posted on 23 Jul
Black Jack Yachting. Bigger boat. Bigger team. Even bigger performance
Throughout the iterations of maxis called Black Jack, a strong, consistent and talented team has been their focus Throughout the iterations of maxis called Black Jack, a strong, consistent and talented team has been their focus. Some were sail makers, like Skipper Mark Bradford and also Vaughan Prentice from North Sails’ Brisbane loft. Others were riggers, such as Bruce Clarke, and there are even boat builders, like Gary van Lunteren, as well as Ash Deeks.
Posted on 20 Jul
Gladwell's Line - America's Cup returns to its new home and thinking
Emirates Team New Zealand's win in the 35th America's Cup ends 17-years of wandering in the AC wilderness Emirates Team New Zealand's win in the 35th America's Cup ends 17-years of wandering in the AC wilderness and will open a new era of America's Cup, New Zealand and World Sailing. A rookie crew won the most prestigious trophy in sailing, and one of the most difficult to win in any sport.
Posted on 29 Jun
SuperFoilers Are Go!
SuperFoilers represent many things. Whilst those components are disparate and virtually from different planets SuperFoilers represent many things. Whilst those components are disparate and virtually from different planets in the great scheme of things, they come together in the one form as harmoniously as a Rolls Royce, and also deliver intense energy way past the sum of their parts, just like some amazing band.
Posted on 28 Jun