sail-world.com -- Rod Davis: Rethinking the Current Tactics
Rod Davis: Rethinking the Current Tactics
Sun, 26 Aug 2012
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.
Burke Marine
Burke Marine, suppliers of international quality marine clothing and equipment, was founded by Martin Burke on the shores of Sydney Harbour in 1971. Visit our website for your nearest stockist. [More info]
http://www.burkemarine.com.au
Ensign Ship Brokers
Ensign Ship Brokers was established in 1980 and has spent the last 28 years expanding our marine knowledge and developing our reputation! We strive to provide the very best service! [More info]
http://www.ensignbrokers.com.au/
GME Standard Communications Pty Ltd
Leaders in communications and navigation. Their goal has always been to make products whose innovation, convenience and peace of mind can help improve the lives of their customers. [More info]
http://www.gme.net.au
Hamilton Island Luxury Accommodation
Full range of private apartments, villas and houses on Hamilton Island. 1, 2, 3, 4, and 6 bedroom options available. All include buggy and island airport or marina transfers. [More info]
http://www.whitsundayholidays.com.au
Multihull Solutions
Multihull Solutions is Australia and New Zealand’s premier offshore and cruising catamaran and trimaran specialist, offering sales and servicing of the world’s finest multihull brands.
[More info]
http://www.multihullsolutions.com.au
Navionics Australia
Navionics is proud of its superb cartographic database comprising more than 25,000 charts and port plans; the largest privately owned database of its kind, the only one using full seamless technology [More info]
http://www.navionics.com.au
OziOpti
OziOpti is all about 'getting kids in boats' and the Australian company supporting the introduction to of the world’s most popular junior sailing yacht, the 'International Optimist Dinghy' [More info]
http://www.oziopti.com.au
Performance Sailcraft Australia (Asia Pacific)
Laser builder Performance Sailcraft Australia has taken on the successful RS Sailboat range from Britain, and is now licensed to build and distribute all of the RS range in the Asia Pacific region. [More info]
http://www.lasersailing.com.au
Sanctuary Cove International Boat Show
2013 Sanctuary Cove International Boat Show is Australasia's most significant marine lifestyle event. We look forward to welcoming you to the 25th annual event. [More info]
http://www.sanctuarycoveboatshow.com.au/
Sealink Magnetic Island Race Week
Entries for the fourth annual Sealink Magnetic Island Race Week have opened! 4 days of racing, 5 days of fun – that is what you can look forward to from 3-7 September at Magnetic Island. [More info]
http://www.magneticislandraceweek.com.au
Ullman Sails
For over 45 years, Ullman Sails has been devoted to helping our customers reach their sailing goals. [More info]
http://www.ullmansails.com
VicSail Sydney
Vicsail Sydney Pty Ltd, launched into the Australian sailing fraternity in 1983 and has been sailing strong ever since. At Vicsail, “We Sail the Boats We Sell”. [More info]
http://www.vicsailsydney.com.au