Futtock shrouds are lines attached from the outer edge of the top to a point lower down on the mast to support the top and keep it square to the mast. After climbing the main shrouds by the ratlines, the climber then transfers to the futtock shrouds to the top. The top has a hole, called the lubber's hole for accessing the top, but, is disdained by experienced sailors as 'for lubbers'.
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