“Drag devices: Sea anchors & drogues” by Cary Deringer
appearing in the Jan/Feb 2002 issue of Good
Old Boat.

Taking the weather for granted is easy to do on a nice day. Sails are filled with a gentle wind, and the boat heels slightly as it slices through rippling water shimmering beneath a warm sun. On days like these it is hard to imagine that sailing can be a totally different experience when conditions turn rough.

During extremely heavy weather sailors may wish to deploy a drag device, such as a parachute sea anchor or a drogue. To do this, of course, you need to have a drag device aboard before you leave shore. That calls for making a major purchasing decision in preparation for circumstances you hope you never have to face.
 

Depending upon personal preference and boat design, the choice will vary from one sailor to the next. These issues complicate this decision: each device is a specialized piece of gear, each produces a very distinct result when deployed, and storm conditions vary.
 

Some boaters have solved the problem by owning several types of devices. Others feel the need to choose because of issues such as cost, storage space, and the additional weight of the gear on an already heavily loaded cruising boat. For those who must choose between a parachute sea anchor and/or one of the two basic types of drogues, it is helpful to understand some of the basic principles behind these devices.

A quick comparison
A parachute sea anchor is typically deployed off the bow. It will almost stop the boat, allowing only a very slow drift downwind. It is a passive device. It does not demand the continuous attention of the crew. During heavy weather, the sea anchor allows the captain and crew to deal with exhaustion and seasickness, to maintain adequate nourishment, to tend to the boat, and to maintain rational decision-making abilities. To enable a safe landfall, a sea anchor can hold a boat in a favorable position until a heavy fog clears or daylight arrives. It can keep a boat off a lee shore until engine repairs can be made or help arrives. It provides a stable boat from which it is easier to dive, fish, or check your navigation.
 

A drogue, on the other hand, is deployed off the stern. There are two basic types of drogues. The low-drag, speed-limiting drogues are sized to allow the boat to maintain three to six or perhaps even seven knots in conditions where it might otherwise be driven well above hull speed. The slower speed prevents a boat from surfing down wave fronts. With the stern held down, the chance of pitchpoling is reduced. When speed is controlled in this way, yawing is reduced, making it easier to keep the boat from turning beam to the waves. The low-drag speed-limiting drogue is an active device. It makes steering easier, but it does not eliminate the need for the crew to be in the cockpit steering the boat. Most drogues are of this type.
 

The medium-pull drogue is also deployed off the stern, but it brings the boat almost to a stop. Downwind drift will be 1 to 1 1/2 knots in storm conditions, which is not fast enough to steer. The designer of the Jordan Series Drogue recommends that the crew go below and strap themselves in. The medium-pull drogue is a passive device like the parachute anchor.

Parachute sea anchors
Historically, a sea anchor was anything from a leather bucket to a cone-shaped canvas scoop used off the bow to hold the boat in a safe position when faced with heavy wind and waves. Later, commercial fishermen and then sailors began using military surplus parachutes as sea anchors for the same purpose, thereby coining the name parachute sea anchor. These large-diameter devices have evolved over the years and offer much more holding power than their cone-shaped cousins.

Size is an important, and somewhat controversial, issue. A parachute sea anchor must be of an appropriate diameter to prevent the bow from falling off the wind and turning the boat broadside to the seas. Too small, and there may not be enough purchase power to accomplish this task. Some advocate a “when in doubt, go larger” attitude. But an oversized canopy can have its disadvantage, too.

Surviving storms with the aid of drogues and sea anchors
A boat forced aft against an oversized canopy that is “fixed” in the water can present problems. In his book, Heavy Weather Tactics Using Sea Anchors and Drogues, Earl Hinz points out, “The powerful but irregular motion of the sea when resisted by a sea anchor can produce great strains on the sea anchor gear. The dynamic of loading will give all of the problems found in ground anchoring, such as overloading cleats and Samson posts, causing severe chafe on the rode, and occasionally burying the bow in green water.” Larger chutes tend to take up more storage space aboard, cost more, and are often more difficult to deploy and retrieve.

The most frequently expressed concerns regarding the use of parachute sea anchors have to do with the deployment and retrieval process. One danger: when deploying a parachute sea anchor the chute can catch the wind and open up on deck—a common problem with the old military surplus chutes. Another deployment foul-up can occur if lines, either shroud lines or the trip line, become tangled during storage or deployment.

Depending upon the company from which you purchase a parachute sea anchor, the deployment procedure may vary slightly. In general, a parachute sea anchor is dropped off the bow to windward. Some sea anchors come with deployment bags that prevent the parachute from filling with air when being launched. In the absence of such a bag, it is helpful if the chute is wet when it is put over the side. Once deployed, the rod is snubbed to allow the chute to open. Then a sufficient amount of line is payed out. Ideally, both boat and anchor should ride in the same wave phase even though the parachute sea anchor may be several wavelengths away.

Sea anchor retrieval
Deploying the parachute sea anchor is only half of the procedure. Retrieving it successfully is the other half. A trip line can make the retrieval process easier. The next choice is whether to use a full or partial trip line. Full trip lines extend from the apex of the chute all the way back to the boat; partial trip lines run to retrieval floats.

If a partial trip line is used, retrieval involves motoring slowly up to the float while the main anchor rode is taken in gradually. A boathook can be used to snag the trip line, which is then pulled in, followed by the parachute sea anchor and the remaining rode. Maintaining tension in the rode as you power up to the retrieval float and timing your moves with ocean waves or swells are the keys to successfully bringing the parachute sea anchor onboard.

If the rode is allowed to go slack before the trip line is activated, the canopy can change positions in the water. This scenario would be similar to having a large-diameter bucket hanging from the bow beneath the water surface. With the bow weighted, it is unable to rise up over oncoming waves and instead causes the bow to be pulled down. Retrieval of the parachute sea anchor from this position is more difficult, especially without a trip line. Smaller parachute sea anchors can be simply brought in by hooking a shroud with a boathook and dumping the chute by pulling on it.

Controversial matter
Another concern about using parachute sea anchors is whether they will always hold the bow of a boat upwind. This is a controversial matter. Left to its own devices with no drag device, a modern monohull will normally lie ahull, meaning beam to the wind. This is caused at least in part by the center of aerodynamic drag (force of the wind) being forward of the center of hydrodynamic drag (force of the water acting on the hull). This is particularly true if the boat is not carrying sail. The sea anchor must overcome this natural tendency and pull the bow into the wind.

In his book, Drag Device Data Base, Victor Shane has collected the experiences of sailors using parachute anchors and other drag devices in heavy weather. His finding strongly indicate that multihulls (using bridles) are held head to wind, and yaw is minimal. The picture concerning monohulls is less clear. Some boats did very well; others did less well. There were not enough cases reported to show clear trends, but it seems that schooners and yawls did better than sloops and cutters, and fin-keeled boat did better than full-keeled boats. It also seems that there was less yaw as the wind speed increased. These “trends” are vague, however. Lin and Larry Pardey, for example, are quite satisfied with the performance of their full-keeled cutter when using a parachute anchor. They also use a special bridle arrangement which is intended to hold the bow as much as 50 degrees off the wind. California-based manufacturer Fiorentino’s sea anchor sales literature suggest a similar arrangement.

Recommendations on rode thickness and length vary among the different manufacturers, but nylon is the material of choice because of its elasticity. The loads on a parachute sea anchor rode may be equal to the displacement of the boat in storm conditions. The rode is one accessory that can serve double-duty elsewhere, such as for use with ground tackle. However, using it for other purposes reduces its strength due to simple wear and tear. It may be better to have such gear specifically assigned for use solely with the parachute sea anchor if space and budget permit.

There are a few other issues to address when using a parachute sea anchor system. Lashing the tiller with a semi-flexible lashing such as a heavy shock cord, for example, reduces the chances of rudder damage when sever waves force the boat astern. Chafe is likely to be the most serious problem encountered when using any drag device. It deserves advanced planning. Once the sea anchor is deployed in storm conditions, the load on the rode will make adding chafing difficult, and the bow will not be an easy place to work. Depending upon conditions and boat design, a riding sail aft may be needed to reduce the amount of yaw that might be encountered.

Drogues
While a monohull’s “natural” tendency is to lie ahull, in most cases it is quite easy to get these boats to be fairly stable sailing dead downwind under bare poles. Drogues take advantage of this natural stability. There are both unitary and series drogues. A unitary drogue is deployed as a single drag device attached at the end of a length of rode. A series drogue utilizes smaller drag devices, such as cones, all of which are attached along a length of rode.

Unitary drogues
Most drogues are unitary drogues, and most unitary drogues are intended to reduce a boat’s speed to a safe and manageable level while allowing for a fair amount of directional control by the helmsman. Keeping the boat below hull speed can prevent surfing down large wave fronts and punching the bow into the back of the next wave in the trough. These drogues are referred to as speed-limiting or low-drag drogues to contrast them with medium-drag drogues (like the Jordan Series Drogue which is designed to virtually stop the boat). These drogues require active participation from the crew, but allow the helmsman greater control and ease of steering. In situations where it is desirable to keep moving to reach shelter, or to maneuver to a more favorable part of the weather system, these devices are preferable. However, the same low drag that grants more steering control can also make the boat more vulnerable to capsizing, broaching, or pitchpoling in a “once-in-a-lifetime storm.”

In addition, with a single drag device at the end of a long rode, the boat is more susceptible to large waves that approach from an angle. In order for a boat to get assistance from the drogue, it must position itself by swinging at the end of the long rode. The time it takes to do this can be crucial, and failure can result in a wave hitting the boat broadside.

Series Drogue
Series drogues were invented and developed by Donald Jordan. These drogues are deployed off the stern but, like the bow-deployed parachute sea anchor, they are intended to almost stop the boat. In this manner, the stern of the boat faces toward the wind and waves. The advantage of this is that the boat is much more stable pointing and sailing slowly downwind. There is less tendency to yaw because the mast and other high wind-drag items are downwind of the keel and rudder which are the high water-drag items.

A properly sized series drogue will keep the boat speed down to 1 to 1 ½ knots in storm conditions, so it does not require the crew to steer. In this attitude if the boat is struck by a large breaking wave, which is the most dangerous threat to a boat in heavy weather, the boat will be briefly accelerated up to wave speed, and then as the wave passes it will be dragged back by the series drogue. Unlike the sea anchor, the series drogue is intended to control the loads on the rode, fittings, and attachment points by allowing the breaking wave to accelerate the boat. It is not intended to have enough drag to resist this large and rapidly developed force. It does have enough drag to quickly bring the boat speed back down after the breaking wave passes. It will prevent the boat from being thrown into the trough. Donald Jordan asserts that a breaking wave will not damage a boat by striking it but can damage it by throwing it into the trough. The Jordan Series Drogue typically is made up of more than 100 small fabric cones. These smaller drag devices are located all along the length of the rode. Therefore, if half the cones are inactive within the slack portion of a wave, the other half are still capable of maintaining a hold on the boat. Also, if a large wave is approaching from an angle off the stern, the drag devices closer to the boat, where the rode elasticity is low, will create a load much faster than if a unitary drogue were being towed at the end of a long rode. The drogue is weighted by chain at the end, which makes it function below the wave action and keeps a constant tension on the rode.

High stress
Because of the way the Jordan Series Drogue works, the stern will be struck by breaking waves. This is a controversial aspect of the device. Critics assert that the transom, cabin trunk, and drop boards must be capable of taking the full impact of breaking waves and that the impact will be severe. Donald Jordan contends that experience with his drogues has proven that this is not a problem. In any case, the cockpit should be able to drain water quickly, and all drogue attachments should be well backed up to help spread the loads imposed upon the gear. In addition, it is not intended that the crew be in the cockpit when the drogue is in use. The speed will be kept too low to allow the boat to be steered, and the crew should go below.

Deployment of any drogue generally takes place over the stern. The whole assembly should be carefully checked to ensure knots are properly tied, shackles are safety wired, the bitter end is attached to the boat, and the system is free of tangles with itself as well as parts of the boat and crew.

When the boat is in the trough of a wave, its speed is at its minimum. This is the time to deploy the drogue. In the case of unitary drogues, a portion of the rode nearest the boat is deployed first. As the boat moves forward, the water will pull the rode along in a bight. More of the rode is paid out until the drogue itself is reached. The device, previously laid out and checked for tangles, is then released. The series drogue has a length of anchor chain at the end to keep it below the surface. This is dropped into the water, and the drag from the chain is allowed to pull the rest of the drogue overboard. The series drogue is intended to be permanently attached to a bridle on the transom and ready for deployment at any time.

Unitary drogues can also use an adjustable bridle setup. The main rode is led off to one side of the transom and secured to a strong cleat or reinforced attachment point, preferably forward of the rudder post to improve steering. A snatch block with a pendant line tied to it is then snatched onto the main rode. The pendant line is run off the other side and led to a winch for adjustment. This system allows the crew to position the boat’s stern to oncoming waves, exposing, for example, only the quarter portion of a flat transom to the full impact of a breaking wave.

Retrieval of the drogue must be done carefully due to the forcefull drag produced by the device in the water. On a sailboat, winches can be used to haul in the main rode once the pendant line is released. When operating under power, the rode can be taken to the bow and brought in as the boat motors back to the drogue.

Summary
Once you have made a decision to purchase a parachute sea anchor or drogue, take the time to research all available options.

“Silver-bullet storm tactics” are hard to come by because of the variety found in weather conditions, boat designs, personal preferences, and crew capabilities. There are other tactics to employ in heavy weather, such as running under bare poles and heaving-to. Using a drag device requires prior planning since the equipment must be aboard. If it is to be effective it must be ready for deployment, and you must be comfortable using it. If you equip your boat with drag devices, practice deploying them in moderate conditions. Get familiar with the components. Make sure all crew members know the procedure and their responsibilities.
 

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