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Internation Regulations for the Prevention of Collisions at Sea 
Rule 12 - sailing Vessels 
  
When two sailing vessels approach so as to risk collision one 
shall give way as follows: 
– with each having wind on opposite sides, boat with wind on port side 
keeps clear. 
– with wind on same side, boat to windward keeps clear. 
– with wind on port side and unable to determine if a vessel to windward 
has wind on port or starboard side then shall keep clear. 
  
Windward side deemed to be the opposite side from which the 
mainsail is carried or in a square rigger the opposite side from 
which the largest fore & aft sail is carried. 
  
  
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