If this repair is to your "new" Sunfish, is it damage that will require cutting out the damaged section?
For a proper repair, any perforation of the hull or cracks leading away from the immediate area would require cutting out the affected hull section—
however small. This could actually be to some advantage, if the Sunfish needs the typical "drying-out".
(Usually done on hulls weighing over 134 pounds, and best accomplished during the long months of Winter).

But the next five weeks will be the
best weeks for Winnipesaukee sailing!

(Especially for
learning to sail).
With only a few weeks left to summer—and the arrival of prolonged days of high winds and cooler waters—a duct-taped repair should get you through to October.
(Even taped below the waterline—I'm serious!)