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 does n'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 .
CNN 's MainSail host Shirley Robertson is a double Olympic gold medalist . Robertson has never climbed a big mast before this . Comment: