I think you may see that the sharks are using a different base than what you have. Grease will help(an appropriate silicone spray). I know the one shark that i saw that had a split base had a half dollar on it- part for superstitious good luck, and part to help the mast rotate.

The biggest thing to make a shark go fast is new sails. It puts even the older boats up close to the new ones.
Second, check your boards and make sure they are smooth, as well as the rudders. Measure the rudders on the leading edge and trailing edge to be sure they are parallel.
The gaskets underneath need to be in good shape. If they are loose or sloppy, that means drag
Do anything to get excess weight off the boat. The class weight is 450lbs. Fiberglass boats are going to be heavier, but can still be competitive. The flotation foam put in some sharks is notorious for absorbing water over time.

Have fun in Put-in Bay!
Rob