A Piece of Rope
First of all, if you're going to be a sailor now, you'll have to learn that it is called "line", not "rope".
99 cents buys ten feet of 1/4" braided poly line (which floats) at Harbor Freight, or anywhere else. You never know what you might need it for, always have some on the boat somewhere. And if you're going to be a real mariner, learn to tie a bowline.
A piece of line can be very useful in getting in and out of the boat in tricky places. Just tie the line to the bow handle, and hold it as you climb out. You can then use the line to pull the boat up behind you, or tie it off.
Ten feet is plenty, more than that is just going to make a big tangle.