Sea bird deterrent for boats and navigation aids

A boat comprising

• a boat shell,
• a deck on said shell providing surfaces to support people,
• a top at an elevation above said deck,
• at least two posts extending upward from said top, and
• at least one line between said posts at an elevation above said top to prevent sea birds from landing on said top, said elevation being greater than about 5" and less than about 20",
• wherein there are four said posts generally along the perimeter of said top, and said lines go generally along the perimeter of said top between posts, said lines along said perimeter defining a region having more than about 3' between said lines, said region having a generally square area, said lines being at two elevations,
• wherein there is an additional line bisecting the region within the perimeter such that there is a space of no more than about 3' between lines.