"Without a skeg a skiff is vicious to row. A skegless skiff wanders about, drifts with the wind, and quickly exhausts the already infuriated rower. A good skeg reaches perhaps six inches below the bottom of the skiff, and as a fixed rudder (or aftermost part of an otherwise nonexistent keel) directs the boat in a straight line.
Of course, a skeg adds draft to a skiff. Add a nice deep skeg to a skiff and it draws a half foot more water, and runs aground that much more frequently. Moreover, a skeg cants a grounded skiff, and if the skiff grounds on rocks or hard sand, the skeg often twists, then splits, and becomes flotsam. To skeg or not to skeg bedevils those who wish to 'skiff' the marshes - to use a verb Shakespeare used, although infrequently - and often the unwise forego skegs."