LONDON, England (CNN) -- Editor's note: Watch MainSail on CNN International at the following times: Thursday 16th April at 1230 GMT; Saturday 18th April at 0700 and 1730 GMT; Sunday 19th April at 0300 and 0730 GMT; Monday 20th April at 0300 GMT.

CNN's MainSail anchor Shirley Robertson has won two Olympic gold medals in an extremely successful sailing career, but, she has never climbed to the top of a huge mast.

Tall task: MainSail host Shirley Robertson takes on the world's biggest aluminium mast

Until now, that is.

On this month's MainSail programme, Shirley reaches the top of the tallest aluminium mast in the world - aboard the 56 meter Perini Navi vessel, Salute.

The mast reaches a remarkable 250 feet (76 meters) into the air, and even with a small swell and light breeze, the top of the mast can swing through as much as ten meters -- five meters each side -- of its center point.

Going up the mast is a dangerous job, but it is also a common necessity on any large yacht -- whether it be to check the rigging or complete a repair.

Shirley has to wear all of the appropriate safety equipment for the climb -- which she has to do alone. Fortunately for Shirley, she doesn't have a big fear of heights and she receives some expert instruction, too.

Watch Shirley climb the mast »  You can also watch the full MainSail show and catch up with the latest news and features on the MainSail homepage.
What has Robertson never climbed before today? What did CNN's Shirley Robertson accomplish at the Olympics? What is she doing with the 250 foot mast?
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