Drogue - Series Drogue

Series Drogue

Retired aeronautical engineer Don Jordan tested what is now known as the series drogue, originally conceived and patented by E.J. Pagan and later patented by Sidelnikov in 1975; however, before his tests, numerous mariners had experimented with pulling several large drogues in series. Like Sidelnikov, Jordan expanded upon this idea, and affixed a large number of small parachute drogues to a nylon rope with a weight at the end. The large number of smaller drogues results in there always being a drag force on the line; it does not have to be adjusted to be in phase with the waves as the drag is spread out over many waves. Because the drogue line is prevented from becoming slack there is no jerking or snapping of high loads on the line. This prevention reduces damage to deck fittings and reduces the chance of breakage. The number of small parachutes, the length and thickness of the line, and the size of the end weight are all matched to the displacement of the boat. Another key design feature is the V-bridle. The two attachments should be made at the outer corners of the transom with the lengths of the two bridle lines being 2.5 times the width between the attachment points. According to Jordon, special reinforcement is required for the bridle attachment since Jordon projects that forces of 7,000 lb. to 27,000 lb. and even higher can occur with a breaking wave strike. With this deployment no steering of any kind is needed.

The series drogue does not have to be adjusted during a storm. Neither do other storm drogues if they are fully deployed and they adhere to the constant rode tension theory. As sea conditions requiring a drogue are usually hazardous to be on deck, it’s usually smart to fully deploy all of the rode associated with a storm drogue. Also, the series drogue can be deployed safely with one hand from the cockpit as can any other storm drogue. Recovering a series drogue before the storm abates takes effort, but the process is safe and straightforward. It can be winched in on sheet winches if the cones are small enough to travel around the winch drum without jamming. The series drogue is currently made by three manufacturers, one in Australia, one in the United States and one in the United Kingdom. Any sailmaker can make one and you can make one yourself, though it is a tedious job.