Part of the problem that you experienced comes from the physics of sails and a sail boat. The force that the wind provides to the sail is focused on a point of the sail called the Center of Effort, or CE for short. Here is a pic (not mine - used without permission - from paddlin.com - I acknowledge rights to whomever posted it) that illustrates the point well;
On a boat, like yours, with a Jib and a Main, the two centers of effort should work together to bring the CE near the center of the boat. Trimming the sails so that the CE allows the boat to sail on a particular heading is called balance. Here is another pic (same disclaimers - this from answers.com) that shows how the two combine;
... and a great image of "balance" here (from catamaranvega.com);
So, with you only flying the jib, you had the center of effort too far forward to allow the boat to head more closely to the wind (called pointing). Think of a windsurfer where you hold the sail toward the bow of the board; what happens?... That's right, the boat sails down wind.
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