Harken Derm

Modern Race Navigation: Expedition Software in Action

Published on April 28th, 2014

Will Oxley is well known internationally as an offshore racing navigator; on Camper ETNZ in the last VOR race and more recently, in U.S. waters as navigator onboard the multihull Lending Club, taking line honours in the 2013 Transpac race.

Will decided to share his knowledge with other sailors, recently publishing an ebook entitled Modern Race Navigation: Expedition Software in Action. The book has received excellent reviews and is available from Amazon. Here are some text excerpts from Chapter 7 Short Course Racing: preparation and execution to whet your appetite.


During the Race
A key function for the navigator is to paint a picture of where the yacht is located on the race track relative to the next mark. The picture needs to be clear and concise. When racing up or downwind, positioning is best illustrated by providing estimated times on each tack (or gybe) to the next mark.

At the start of a beat there might be 8 minutes predicted sailing on starboard and 8 minutes on port tack. Agree with the crew how this will be communicated. The suggestion is to say “8 and 8” or “8 minutes each way. “ This tells the crew you are in the middle of the race track with 16 minutes to the top mark and 8 minutes to the layline. Always say the tack you are on first.

A well drilled team will plan their jobs prior to a mark rounding, based on time to the mark. Provide regular estimates of time and distance on the final approach to the mark.

When you are approaching a mark, information on the next leg of the course should be provided to help with sail selection and tactics. Prior to the mark rounding decision making, advise the times for each tack or gybe and the expected wind range on the next leg.

Much is made of the final layline call. Accurate calls rely on a good knowledge of your tacking angles in different wind strengths, expected wind direction and strength changes, tidal considerations and a fair chunk of luck! If any of these is out then it’s easy to mess up the lay. Keep some eyes out of the boat for a potential gust or shift between you and the mark and look at the progress of other yachts. Course Over Ground (COG) rather than heading, is the relevant number when trying to lay a mark.

Reaching Legs
Reaching legs can often be mistakenly regarded as easy as there are no tacks or gybes. The reality is somewhat more complex. Even in a short jib reach it is important to monitor the heading vs. COG and, when going straight to the mark is the best tactical option, ensure that the average COG matches the bearing to the mark. Inform the crew of the difference between Heading and COG and get the helm to steer a course that produces the desired COG.

Correct sail selection is critical on a reaching leg and so a comprehensive understanding of the boat polar along with the sail chart is needed. Estimate the TWA and AWA for a reaching leg and decide ahead of time what sails are needed. If you are expecting the wind direction to free up as you sail the leg then setting the spinnaker early is often the best move. As always, the most important thing is for the navigator to be thinking ahead and informing the crew of the conditions expected to be encountered so that the sails are ready when needed.

Click here to learn more about Will Oxley’s ebook. Amazon provides ‘Free Reading Apps‘ to allow Kindle books to be read on smartphones, tablets and computers.

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