File D/C-3, obtained from Thomas W. Kintz, Groton, CT. - Vessel name Sundsvalla, hailing port East Lyme, MA, Snowgoose catamaran designed by the Prout brothers, LOA 34' x Beam 15' 8" x Draft 3' x 5.5 Tons - Drogue: 9-ft. diameter BUORD on 350' x 3/4" nylon three strand tether, with bridle arms of 45' each and 1/2" galvanized swivel - Deployed in a gale about 60 miles west of Cape Finisterre, Spain, with winds of 40-45 knots and seas of 20-25 ft. - Vessel's stern yawed up to 90° off to each side - Drogue was eventually tumbled and rendered useless - Drift was about 30 nm during 18 hours of deployment.
Sundsvalla crossed the Atlantic in August 1987. On her way down the Iberian Peninsula she ran into a northeasterly gale about sixty miles west of Cape Finisterre. She used the same parachute drogue used by Echo in the previous file (D/C-2). The behavior of Echo was satisfactory. The behavior of Sundsvalla was anything but satisfactory. She would not lie to the relatively large drogue by herself. She had to be steered manually down the steep wave faces. And she kept doing the same thing that Galliard did in file D/T-2, i.e., surge forward and then snap back on the elastic rode. Later on, when the line had temporarily gone slack, a breaking wave threw the drogue and tangled it around itself.
What was the big difference between Echo and Sundsvalla? Sundsvalla has her mast stepped aft (most Prouts catamarans do). Any sailboat with her mast stepped aft will behave relatively well when using a sea anchor off the bow, but relatively poorly when using a drogue off the stern. The opposite is also true, of course: any sailboat with her mast stepped well forward - cat-rigged - will behave relatively poorly when using a sea anchor off the bow and relatively well when using a drogue off the stern. Transcript:
Echo (previous file) behaved quite well with a 9-ft. BUORD off the stern. Sundsvalla did not. Sundsvalla has her mast stepped aft, as do many Prout catamarans.
On passage from the south coast of England to Bayona, Spain. Encountered "dry" gale from the northeast. Sailed in rising wind/seas all day under staysail alone. Near dusk, wind rose to Force 9 and occasional seas began to break. Took down all sail and deployed BUORD off stern. No problem with deployment, but vessel would not lie to the parachute by itself - it had to be steered. Line would go slack periodically. Could not keep bows pointed downwind all the time. Finally, a breaking wave caught the drogue and tangled it around itself. We left it deployed, but effectively lay a-hull all night and into the next day. Took several breaking waves over the boat - not recommended! Recovered BUORD after gale subsided and continued to Bayena.
PROBLEM: The Prout Snowgoose 34 catamaran has the mast stepped way aft. I believe that this is what caused our problem. The center of effort of the boat's aerodynamic drag was so far aft that it would yaw from side to side. This allowed the tether to go slack and ultimately tangle.
SOLUTION? The next time on a vessel of this type, I would use a storm jib hanked onto the forestay and sheeted athwartships. I believe that this would keep the bows pointed downwind by moving the center of effort forward. This would allow the helm to be untended and the tether to remain taut. Although I haven't tried it, a large para-anchor deployed from the bow should work very well because the aft mast position would increase yaw stability. [Note that a large diameter para-anchor did work well off the bow of the Prout Snowgoose, Rhayader, in File S/C-3.]
File D/C-2, obtained from John Kettlewell, Middle Grove, NY. - Vessel name Echo, catamaran, designed by Mark Louis Rifflart, LOA 31' 6" x Beam 16' x Draft 2' 8" x 4 Tons - Drogue: 9-Ft. diameter BUORD on 400' x 1/2" nylon three strand tether, with bridle arms of 25' each and 1/2" galvanized swivel - Deployed in a gale in deep water about 400 miles SW of Bermuda with winds of 40-50 knots and seas of 18-25 ft. - Vessel's stern yawed 10° - Drift was estimated to be about 30 nm during 20 hours of deployment.
Echo was en route to San Juan, Puerto Rico, from Beaufort, NC., when she ran into a gale. Her owner John Kettlewell is a marine consultant with a good deal of cruising experience. He has written numerous articles and was acquisitions editor for International Marine Publications for a while. (See also his article entitled, Rough Passage To San Juan appearing in the November/December 1991 issue of Multihulls Magazine).
Echo ran downwind for a while until it became unsafe to do so. She lay a-hull for a short period thereafter and Kettlewell deemed that just as unsafe - the occasional breaker would knock the bow off and she would surf sideways out of control.
He then deployed a 9-ft. BUORD parachute off the bow, his wife Leslie assisting. The 400 feet of line smoked out so quickly that they were barely able to cleat it before it reached the end. The 9-ft. diameter Naval Ordnance parachute (porous canopy) did not produce enough drag to keep the bows pointed into the seas - they were yawing up to 90° off to each side. So Kettlewell decided to switch ends and use it as a drogue off the stern instead.
This accomplished, the parachute then kept the stern pointed into the seas in a satisfactory way, with no further steering required. The crew was able to go down below and get some rest on the floor of the saloon area. Transcript:
In general we were very pleased with the performance of the drogue. As I stated previously we could not lie bow into the wind with this size chute. I wonder if we had removed our roller furling jib we could have laid bow to.... In any case I'm sure I would now prefer to run before the seas on this boat. Our cockpit is well protected with a strong door and great drainage due to the motorwell for the outboard. I think it is useful to give with the punches of the waves. We even raised our rudders to take the strain off of them from wave hits.... With a bridle to each stern the drogue held us straight on to the sea and we did not have to steer.
I am very wary of using a trip line as I find storms tend to make amazing tangles of even the simplest rigs. On the other hand, if something were to disable the chute suddenly, it would be very difficult to get it in and untangled during the height of a storm. However, even though it was extremely tiring and difficult to retrieve I still would not rig a trip line. We had some success using the motor to slowly power up to the drogue.
We had no problems with the line kinking or chafing. I used two 5/8" braided bridle lines led through clear PVC water tubing. Our rode consisted of 2 x 200' lengths of 1/2" nylon connected by a large shackle in the middle. I feel your length recommendations (i.e., LOA x 10) may be a bit short. I was certainly happy I had 400' of rode!
File D/M-6A, obtained from Gary Danielson, St. Clair Shores, MI. - Vessel name Moon Boots, hailing port Detroit, monohull, designed by Bruce King, LOA 24' 8" x LWL 20' 10" x Beam 8' x Draft 4' (27" keel up) x 3 Tons - TESTS OF: 9-Ft. Diameter BUORD, 30" Galerider, Jordan Series Drogue - Deployed for evaluation purposes during passage of frontal trough in shallow water (9 fathoms) on Lake Huron with winds of 25 knots and seas of 6-8 ft.
Prior to sailing his Ericson 25 across the Atlantic Gary Danielson tried out three different drag-device concepts: A 9-ft. diameter BUORD parachute off the bow, a 30-inch Galerider drogue off the stern, and a Jordan series drogue off the stern (88 x 5-inch diameter cones spliced into 300 ft. of braided 1/2" nylon towline at 20" intervals, with a 15 lb. mushroom anchor at the very end to keep the array well-submerged).
To make his investigation as reliable as possible Danielson did all of the testing on a single day, in constant conditions. The crew for this evaluation was along solely to take measurements and record data. The tests were conducted in November 1988 on Lake Huron. On the day of the tests the sustained wind speed varied between 20 and 25 knots with gusts of 30 knots. The waves varied between 6 and 8 feet.
One of Danielson's preconditions was that the swing keel be up and out of harm's way on this particular boat. With the keel raised he found that the 9-ft. BUORD parachute would not pull the bow of Moon Boots into the seas in a satisfactory manner. It yawed up to 50° off to each side. This is not too different from the experience of Harley Sachs in file S/M-11, where the bow of Gamesmanship yawed 30-45° off to each side when the keel was retracted, but only 10° when it was lowered. Transcript:
Sea Anchor: A 9 foot sea anchor was deployed over the bow attached to 300 feet of 3/8" braided nylon rode. The centerboard and rudder were both raised and all sails were lowered for this test. The sea anchor was very easy to deploy and there was no shock to it when it grabbed hold of the boat. It did an extremely good job of keeping the boat in place as sternward drift through the water ranged from .25-.75 knots. The problem was that the boat was yawing through an arc which totaled almost 100 degrees (putting the bow of the boat almost 50 degrees off the wave). It was yawing very slowly from side to side so that there were lengthy periods (60 seconds) where the bow of the boat was as much as 50 degrees from the wave direction.
Since the boat spent so much of its time not being bow-on to the waves it rolled quite heavily (in excess of 20 degrees) and relatively quickly. Had the conditions been more severe, this could have proved to have been dangerous. The rode was then shortened to 150 feet of scope to see what effect that would have on the yawing of the boat. Repeated measurements showed no substantial variation in yaw even with the shortened scope. The sea anchor was very difficult to retrieve as Moon Boots has no anchor windlass on the foredeck and as no trip line had been attached to the sea anchor.
A BUORD is a porous small parachute issued by the Bureau of Ordnance
Galerider: The next item tested was the Galerider drogue. This was set from the stern utilizing a 30 foot 1/2" braided tether which was connected to each of the stern quarters of the boat and then attached to a 150 foot 3/8" braided nylon rode. Initially the Galerider was utilized with no sail up, the centerboard and rudder both retracted. The Galerider drogue had a steady and constant pull and did not jerk when it was deployed... it held the boat to a total yaw of 10° (5° per side). The boat rolled (vertically) no more than 10-12° to a side. As well, it rolled much more slowly than it did with the sea anchor out. The Galerider was running below the surface, but only by about 5 feet. Therefore, in heavier conditions it may be somewhat more susceptible to surface wave action. It did not pull the stern down much at all and gave the boat, overall, a very nice ride.
Next, the rudder was lowered and allowed to swing free and the centerboard was lowered while the Galerider was still out. It was noted that the boat then yawed through a total of about 70° (35° per side). The boat still rolled very little and did so slowly. Next, a small jib sail was raised to see how the boat sailed with the Galerider out. The boat could be sailed through a total arc of 90° (45° per side). The boat speed ranged from 2.5 to 4 knots. There was no tendency whatsoever for the boat to surf and, of course, at these speeds it was very responsive to the helm. The Galerider was particularly easy to retrieve as the rode with which it had been deployed was wrapped around a cockpit winch and winched back aboard.
Series Drogue: The Jordan style series drogue was then deployed over the stern using the bridle to each of the quarters of the boat and attached to the 300 ft. rode (with cones)... the centerboard was up, the rudder was up and all sails were lowered for this test. This drogue was easy to deploy and caused no shock loading when it began to take effect. The Jordan style drogue appeared to sink very deeply into the water and, in fact, created a substantial downward as well as rearward pull on the boat. Consequently a number of waves washed in over the transom of the boat while the Jordan drogue was deployed. The Jordan drogue slowed the boat so that the average speed was between 0 and .25 knots.... The boat yawed a total of 10° (5° per side). The boat rolled very little, only 10-12° per side, and did so slowly. The series drogue was easier to retrieve than the sea anchor (without any trip line) but more difficult than the Galerider. It was easier than the sea anchor because every few feet of rode that were retrieved resulted in one less cone being in the water to create drag and therefore the drag continued to be reduced as the rode was brought in. The difficulty with retrieving the Jordan style drogue is that it cannot be retrieved utilizing winches because the cones get tangled up when a winch is used so that retrieval can only be done by hand....
The Jordan Series Drogue consists of dozens of tiny cones spliced into the long rode
CONCLUSIONS: In the moderate conditions of the test the Galerider was definitely the best product of those which were tested. Its advantages are its small storage space, its ease of deployment and retrieval.... It has the additional benefit of having enough drag that the boat can be actively sailed, but will not surf, should you find the wind blowing in a favorable direction. It would be useful if repairs were needed since it stops the boat from rolling. The Galerider is also good in that it does not seem to pull the cockpit down (which would make it vulnerable to breaking waves). The concerns that I have are that it may not ride deep enough to avoid wave action in heavy weather (resulting in a possible loss of drag) and it is possible that it may not offer enough drag in the ultimate storm to pull the stern into a serious breaking wave....
The Jordan style drogue would be helpful to keep the boat from rolling while some repairs were made and is the best at keeping the boat in a stationary position if drift were undesirable. It also was the best at keeping the stern directly into the waves and at exerting a constant pull. Finally, I am confident that its design of multiple cones coupled with its deep riding nature would ensure that no matter what the wave situation it would never be caught in wave disturbance and lose any appreciable amount of drag. The disadvantage was that it rode too deep and exerted too much downward force on the stern of the boat. However, I will be putting a smaller weight on the end in an effort to reduce the downward pull.
D/C-3
