Tie in 3 or 4 places crosswise and 1 or 2 places lengthwise (twist the string around itself 3 times instead of just once before you pull it tight, so it won't loosen as soon as you let go).
This is one of my favorite cases of the session: Fane Lozman, a former Marine pilot with a habit of getting crosswise with local officials (he got four of them removed from office when he lived in another city) fought the City of Riviera Beach over a multibillion-dollar development project as well as his right to continue leasing a slip for his 60-foot floating home.