Once you are comfortable with tacking, gybing, sailing closed hauled, reaching and running it is time to combine these skills and sail courses. The triangle course is the first to be tackled.
A Triangle course has 3 marks (buoys):
Traditionally a boat will start the triangle course heading towards the the windward mark. The marks would be rounded to port i.e.. the port side of the sailboat passes by the marks.
Starting at the leeward mark the boat will sail close hauled towards the windward mark into the wind. The boat will need to tack from closed hauled (sails in tight) on starboard to close hauled on port to beat (a series of close hauled tacks to sail in to the wind) it's way up the course. When planning the the approach to the mark it is best to ensure the final tack is on starboard. A boat on starboard has rights of way over a boat on port so this reduces the risk of having to make any last minute alterations to the course near the mark.
The mark should be rounded as close to the buoy as possible but not so close as to touch. Once the mark has been rounded the boat will shift from a beat to a reach. The helm needs to trim (adjust) the mainsail so as it is at an angle of about 45 degrees to the boat and sail straight for the gybe mark. In a two handed boat the crew will also need to let the jib out similarly and at the the same time.
As the boat approaches the gybe mark the helm will prepare to gybe, checking the area is clear and preparing the crew (in a two handed boat). The boat will pass the mark to port and gybe around the buoy. Once gybed the boat will again be on a reach but this time on a port tack. The helm will sail towards the leeward mark. Some small adjustments of the sails might be required but they should remain at about 45 degrees to the boat.
As the boat approaches the leeward mark the helm will ready to round the mark to port. As the boat passes the mark the helm and crew will need to pull in the sails and set of on a close hauled course again.
That is it, the boat has sailed a triangle course. Repeat the above for as many laps of the course as required.