6.5 Types of Drogues
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        The two conventional drogue configurations are the cone drogue and the parachute drogue. Both types have been used successfully in a variety of applications. A third type of drogue called a series drogue has been developed as part of this investigation. The series drogue is intended to provide near optimum performance under storm conditions and to avoid some of the problems encountered with cone and parachute drogue.

        The series drogue offers the following desirable features:

  1. If pre-rigged and coiled down into lazeret, the drogue is simple and safe to deploy under difficult storm conditions. The boat, under bare poles, will be either running off lying ahull. The anchor can be slipped over the stern and the line payed out. The drogue will build up load gradually as it feeds our.
  2. It is almost impossible to foul it or entangle it enough to make the drogue ineffective.
  3. The drogue ride-s beneath the waves and is not affected by the following sea even f a wave should break in the vicinity. There are cases on record where a cone drogue has been pulled out of the face of a following wave, and even instances where the drogue has been catapulted ahead of the boat. It is difficult to weight a cone or parachute drogue so that it will ride at a sufficient depth to avoid the wave motion. As discussed previously in this report, a weight causes the drogue to collapse when the towline goes slack.
  4. When the boat is in the trough of a large wave, the towline tends to go slack thus permitting the boat to yaw. With the series drogue, the anchor sinks pulling the drogue backwards and taking some of the unwanted slack out of the towline.
  5. When a breaking wave strikes, the drogue must catch the boat quickly to prevent a broach. The series drogue, since some of the cones are near the boat where towline stretch is low, will build up load faster than a conventional cone or chute at the end of the towline. A computer study shows that two seconds after wave strike, the series drogue will develop 40% more load than an equivalent cone or chute. Similarly, if the breaking wave strikes at an angle to the towline rather than directly astern, the series drogue will build up load much faster than the conventional types.
  6. The series drogue is durable as demonstrated by the testing described in this report. The load on each individual element is low. No single failure can make the drogue ineffective.
  7. The series drogue can double in function as a spare anchor line and can use the boat's regular anchor as a weight. All 90 cones weigh only four pounds.

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