Offshore Log: Fit To Be Tied
Musicians practice their scales, wrestlers their grips. No reason why sailors shouldn't go back to the primer once in a while, and review how best to keep a boat secured to something solid.
Tying a boat to a dock and pilings isn’t exactly rocket science, but it's surprising how easy it is to forget some of the basics. Bow and stern lines stop the boat from moving transversely in the slip, while spring lines control fore and aft movement. For a side-tie, a bow line, a stern line, and fore and aft springs will have to do. For a tie-off in the middle of a slip, add a second set of bow and stern lines, but a single set of springs will normally suffice.
Ideally, all the lines should be under slight tension with the boat in a neutral position. This will minimize surging against the lines in rough weather.
Nylon makes the best docklines. It has enough elasticity to stretch under load, reducing shock on cleats and fairleads.
Three-strand nylon 5/8" in diameter will do the job on boats up to about 40 feet. Going to larger diameter line—say, 3/4" on a heavy 40-footer—buys extra margin in the event of chafe, while still giving adequate stretch to absorb shock.
Chafing gear is critical to protect dock lines. Plastic hose is not a good choice, as it will eventually become hard and brittle in sunlight, and is difficult to secure in place. Heavy tubular nylon or polyester canvas is flexible and is easily secured to docklines with a quick seizing.
Avoid tying up with short lines that may not stretch enough to absorb shock. We would recommend a span of at least six feet between boat cleat and dock cleat whenever possible. The longer the span, the more static tension can and should be applied to the line.
Imagine the worst-case scenario when tying up—particularly if you have to leave the boat for a while—with waves washing through the marina, an extreme high tide, and the boat surging against her lines. Look for chafe points, unfair leads, and tenuous tie-ups where lines can jump out of fairleads.
We recently walked through a Florida marina where many boats are left for the hurricane season. We were surprised at how many basic securing errors we found with very little effort.
Out of about 90 boats we examined, only a handful could have been said to be really properly secured for most contingencies. Here are a few of the things we noticed.