The series drogue has been called “the sailor’s airbag,” because, similar to the airbags in your car, it is a device that could save your life, but one that you hope you never actually need. A series drogue is a sea anchor that is used during storms to prevent capsize in the event of a large breaking wave and to improve the motion of the boat and reduce drift. In this blog post, we’re going to discuss the history of the series drogue, what it is, and how it’s used.
What Is a Series Drogue?
A drogue is a sea anchor that is launched from the stern of the ship as opposed to the bow. A conventional drogue or sea anchor is usually shaped like a cone or a parachute and is very large. The series drogue, as the name implies, is, rather, a series of cones that work together to create constant drag in the water.
The series drogue is launched from the stern from a two-legged bridle. When in the water, a series drogue looks like a parade of jellyfish in single file, but really it’s a series of 100 or more 5-inch-diameter nylon cones that are attached every 20 inches along a large rope. A 15-25 lb. anchor is attached to the end of the line to keep the drogue securely in the water. The exact number of cones and the length of line varies from boat to boat and are based on the displacement of the vessel.
The series drogue design of a long lead line, multiple cones and a weighted tail ensures that there are always cones in the water, filling and grabbing hold to keep the boat properly positioned for the next wave strike. It offers the best capsize protection in breaking waves. In simulated fatigue testing, the series drogue was subjected to 15,000 cycles (the equivalent of a giant hurricane) without a failure.
A Bit of Series Drogue History
The series drogue was conceived by Don Jordan an aeronautical engineer and sailor, in conjunction with the U.S. Coast Guard. Jordan was inspired by the 1979 Fastnet Race Disaster, in which 15 lives were lost and 24 boats were either sunk or abandoned. Working off initial research and engineering data from the Fastnet Disaster and the 1998 Sydney- Hobart race (which also ended tragically with five ships sunk and six sailors dead), Jordan and researchers at the Coast Guard built scale models of yachts that were tested rigorously with various storm anchor set-ups. The team even tested full-scale at the Coast Guard’s motor lifeboat testing facility where boats were subjected to breaking waves formed on the Columbia River Bar, between Oregon and Washington.
From these studies, the series drogue was created. Together with the Coast Guard, Jordan published the results of their testing in a report. The team also outlined standards for series drogue creation and recommended sizes based on boat displacement.
How to Use a Series Drogue
To deploy the drogue, first attach the bridle. A series drogue attaches to the stern of the ship at two points via its “Y” shaped bridle. Attach the bridle to either: the furthest aft and outboard corners of a monohull, the furthest aft or forward and outboard corners of a catamaran or trimaran, or a fitting of adequate strength with a secondary attachment to distribute the load to the hull structure.
Next, attach the anchor to the drogue end. Using a lazarette or a secured drogue deployment bag, slip the anchor overboard to pay out the drogue. Once the drogue is set, the cones will fill and begin to produce drag. Steerage will be locked, so the rudder should be locked amidship and the crew and helmsman should go below.
Retrieve the series drogue hand over hand or use a winch. The drogue cones will collapse around a winch without damage. To reduce the load on the drogue for retrieval, head into the seas so that the drogue’s velocity relative to the water is zero.
Do you have any experience with drogues? Have you ever made one or used one? Share your stories, ideas and opinions with us in the comments!