No. The bo'sun is only responsible for the rigging while in port, when it's all rolled up tight against the yardarms. He is in charge of the supplies, the longboats, ensuring the deck is clean and things in their place, the anchor, running the flag up the pole and other minor issues.

The master of sail is responsible for the angle of the jib, spanker, foremast, mainmast and mizzenmast. Generally, if I remember correctly, it has been ages since I did my reading, the jib and spanker are used to bounce wind into the other masts. See, if the wind is coming from directly behind the boat only one set of sails would fill with wind and block the others. By angling the vessel several degrees to port or starboard they could catch more wind, and through the use of the taut jib and spanker, bounce wind into the other sails.

It's a lot of work and requires a great deal of concentration. Every time the wind shifts you need to send sailors scurrying like ants to adjust every aspect of the sails. He or she can't do much else and maintain optimum speed.