Use of drogue/parachute anchor on Catamaran

[kmacdonald]

Originally Posted by Steady Hand

What follows is written in a friendly tone of voice, and intended to provide a different point of view to this discussion.

Another few points I would like to make, because a forum like this is usually full of opinions (like mine) from people who have never used an item (e.g. a drogue in a real survival storm where the boat is threatened by breaking waves).

Everyone has an opinion. And if you know sailors like I do, each sailor is always sure they have the made the right or best choices for their boat and the gear they use.

For many years the sailing literature (and by this I mean books that are still in print, read, and recommended by many) has featured suggestions of what to do in a storm, based on traditional methods such as using warps, chains, tires, oil, sea anchors, and parachute drogues, etc.

Anecdotes (like those in the database that has been mentioned) are useful and interesting reading, but I think anecdotes have a weakness that is often overlooked.

Anecdotes about using warps, tires, chains, and such are usually accompanied by statements like "it worked for me."

There is a problem with anecdotes; they are personal observations, NOT rigorous scientific controlled tests and comparisons of gear.

Also, few sailors will experience "survival storms" at sea. And, if they do, it is unlikely they will try testing different forms of drogues, warps, or sea anchors to see which is most effective at that time in breaking waves or that their observations are made with any kind of objectivity. At the time of their use, they will be stressed, worried about their survival, and clinging to hope.

They will just use what they have at hand on their boat at the time. And they may only use that once and never use anything other than that again, if ever again. This is why I think the USCG Test Report and the science behind it is more rational than just anecdotes about towing tires, using a parachute sea anchor, or using oil for a slick, etc.

The USCG Test Report (see link I posted above) is most convincing to me. That is my opinion, and I am sure others will see it differently.
_______________

Finally, this is not to say I don't enjoy reading the opinions and anecdotes of others on this forum or in books. They are always appreciated and usually enjoyed.

But, I like to keep them in perspective, if there are actual scientific or engineering test results that contradict the anecdotes. That is all.

Excellent post.^
Most of the anecdotal opinion needs to be taken with a grain of salt. Often times the physics don't support the incident. Sailors often overestimate (dramatize conditions) wind speed, wave height, and conditions making their observations useless except for good entertainment. I can't remember all the times I've heard people say it's blowing a gale when in fact the wind speed was about 18kts. Waves were towering over the mast when in fact wave height was 2 to 3 feet. Very few of the reported drogue deployments involved survival conditions. They were deployed more for comfort reasons and not survival. In survival conditions (over 60 kt wind) no one could possibly test different devices. We must rely on science to tells us the best course of action and the best device to use. The JSD accomplishes this and the CG report confirms it. To give credibility to n=1 suspect anecdotal "evidence" may not be prudent. Jordan had no financial interest in skewing the analysis or real world testing.

[Fi2010]

Nice story John T.

We know a boat delivery captain who teaches students about speed-limiting, stopping drogues, and the use of para-anchors. His video demonstrates the use of ground tackle as a drogue:

https://www.youtube.com/watch?v=8bZVpDvfimI

[JohnT]

Ah thinwater, quite easy to answer! Both winches on the M&M L40 are at the helm and none each side of the cockpit. It would have been impractical to lead them to the winches. Another reason is the winches cannot handle 22mm. And the last reason is I did not trust the winch fixture integrity - I had one, under load, explode in my face the year before in the Gulf of Lion on an L43. I had also seen one under load, during a test sail in Cape Town, rip out of the GRP deck and nearly take the head off an engineer.

I spread the load on both sides of the boat using both the mid-ships and aft cleats as I truly had no idea of the loads involved. Once the seas calmed and the wind had backed a bit, it was easy for one person to pull the drogue aboard and carry on as normal. My noon to noon run that 24 hour period was –37nm. Oh, and a crew member stayed at the helm (clipped on) the entire period, with myself doing the midnight to 03:00 watch. The boat was under autopilot the entire period with no problems.

As a matter of interest, I have used the same set-up since on 38 foot, 40 foot, 44 foot and 46 foot cats, with it working well on them except the 46 footer was really heavy and the drogue was not as effective as I would have hoped. Anything larger would, in my mind, need a different approach.

As a matter of interest, the video posted at the beginning of this thread of Kenth on the Leopard 39 (which is actually only around 37' 6") in the southern Indian Ocean, he used the standard issued spare anchor line with 8m of chain and an old car tire attached. At the time of the video, the wind had dropped to around 50, gusting just over 60 - it had been up in the 70 knot region.

I have spent a lot of time wondering if the L44 lost in the southern Indian Ocean (with its 3 crew) at the beginning of last year, after it was hit by cyclone Banzi, would have survived if the crew had rigged a drogue of some fashion. When the upturned hull was found and inspected off Cape Agulhas at the beginning of this year, there was no evidence of any form of drogue being rigged. http://www.dailymaverick.co.za/biggerthantheweather/

[thinwater]

Originally Posted by JohnT

Ah thinwater, quite easy to answer! Both winches on the M&M L40 are at the helm and none each side of the cockpit. It would have been impractical to lead them to the winches. Another reason is the winches cannot handle 22mm. And the last reason is I did not trust the winch fixture integrity - I had one, under load, explode in my face the year before in the Gulf of Lion on an L43. I had also seen one under load, during a test sail in Cape Town, rip out of the GRP deck and nearly take the head off an engineer.

Those are good reasons! I added large backing plates to mine not too long ago. The locations are also better for this purpose, aft and outboard.

I spread the load on both sides of the boat using both the mid-ships and aft cleats as I truly had no idea of the loads involved. Once the seas calmed and the wind had backed a bit, it was easy for one person to pull the drogue aboard and carry on as normal. My noon to noon run that 24 hour period was –37nm. Oh, and a crew member stayed at the helm (clipped on) the entire period, with myself doing the midnight to 03:00 watch. The boat was under autopilot the entire period with no problems.

And easing of steering is another reason, as you imply.

No, I didn't know what the loads were either until I measured them. I seriously doubt they ever get over a few hundred pounds per side with a warp, and the winches should handle over a ton easily (working load) on a boat of that size. With a drogue, the answer is more case-specific, as the load on a 36" drogue will reach a ton at surfing speeds (divided to some extent across 2 bridle legs).

As a matter of interest, I have used the same set-up since on 38 foot, 40 foot, 44 foot and 46 foot cats, with it working well on them except the 46 footer was really heavy and the drogue was not as effective as I would have hoped. Anything larger would, in my mind, need a different approach.

As a matter of interest, the video posted at the beginning of this thread of Kenth on the Leopard 39 (which is actually only around 37' 6") in the southern Indian Ocean, he used the standard issued spare anchor line with 8m of chain and an old car tire attached. At the time of the video, the wind had dropped to around 50, gusting just over 60 - it had been up in the 70 knot region.

I have spent a lot of time wondering if the L44 lost in the southern Indian Ocean (with its 3 crew) at the beginning of last year, after it was hit by cyclone Banzi, would have survived if the crew had rigged a drogue of some fashion. When the upturned hull was found and inspected off Cape Agulhas at the beginning of this year, there was no evidence of any form of drogue being rigged. Bigger Than The Weather

I've deployed drogues in the 40s for test purposes, but never in conditions where I feared for my boat without it. On the other hand, they always calmed the ride, often to the point of boredom (which isn't always a bad thing!).

[Fi2010]

This past year Fiorentino supplied shark drogues to several USCG cutters and an extremely large para-anchor to the new sentinel class cutter at a length of 154 feet. Does this signify a USCG endorsement? Maybe a preference for our equipment, but not an endorsement.

The 1987 USCG report concluded that all of the cone-style drogues and sea anchors that tested against the Jordan series drogue performed equally well in preventing vessel capsize, as long as they were engineered and sized properly. Jordan reiterates this point throughout his report and provides measurements on how much larger a sea anchor needs to be compared to a drogue to successfully prevent capsize.

While Jordan states in the report he has no proprietary interest in the series drogue, he did strongly support the sale of his device through his business relationship with Ace Sailmakers (USA) by encouraging buyers to purchase the Jordan Series Drogue.

Despite his business association, Jordan still admitted that a sea anchor, speed-limiting drogue, and series drogue can do the job if properly sized. We believe, as long as the testing process is easy to understand, all equipment is deployed with the same gear and test parameters, and a reasonable attempt is made to include all pertinent information, then test results have value. That’s the kind of impartial information we always try to provide to sailors.

Originally Posted by kmacdonald

Excellent post.^
Most of the anecdotal opinion needs to be taken with a grain of salt. Often times the physics don't support the incident. Sailors often overestimate (dramatize conditions) wind speed, wave height, and conditions making their observations useless except for good entertainment. I can't remember all the times I've heard people say it's blowing a gale when in fact the wind speed was about 18kts. Waves were towering over the mast when in fact wave height was 2 to 3 feet. Very few of the reported drogue deployments involved survival conditions. They were deployed more for comfort reasons and not survival. In survival conditions (over 60 kt wind) no one could possibly test different devices. We must rely on science to tells us the best course of action and the best device to use. The JSD accomplishes this and the CG report confirms it. To give credibility to n=1 suspect anecdotal "evidence" may not be prudent. Jordan had no financial interest in skewing the analysis or real world testing.

[kmacdonald]

It would be best to read the Coast Guard report yourself. It's quite clear to me what they endorse. http://www.jordanseriesdrogue.com/pd...uardreport.pdf

[jbinbi]

I don't want to take this too ot, I know we are discussing rogues, but on the topic of storm tactics am wondering about heaving to in a cat. Does this ever make sense? And if so , how does one accomplish this in a cat? Triple reef main let out, mostly furled jib backhanded, helm hard over locked by friction screw? Will this hold both rudder? Or reward engine on.

Sent from my KFTBWI using Cruisers Sailing Forum mobile app

[kmacdonald]

I don't know about cats but I would never heave to in survival conditions in a monohull. Might be OK in a gale if you got tired of sailing.

[StuM]

Originally Posted by kmacdonald

I don't know about cats but I would never heave to in survival conditions in a monohull. Might be OK in a gale if you got tired of sailing.

Where did you read that opinion?

[kmacdonald]

Originally Posted by StuM

Where did you read that opinion?

Why? You don't still believe in heaving to in storm conditions do you?

[Fi2010]

The USCG’s official position is they do not endorse any of the drogues or sea anchors in the nearly 30 year old report. An e-mail from the office of Design and Engineering Standard Lifesaving and Fire Safety Division of the USCG clarifies their role in Jordan’s test as supportive.

“In general, the Coast Guard does not endorse products and findings in test reports are presented as the opinions of the researchers and not necessarily the opinion of the Coast Guard….The R&D Center was in charge of the project with the assistance of Mr. Donald Jordan as a consulting engineer involved with formulation of test parameters, test methods, data acquisition, evaluation of results, and writing the report. The Coast Guard provided a convenient, low-cost test platform…”

Throughout the report, its author, Jordan, makes it clear that every drag device, the cone-drogue and sea anchor and the series drogue performed the same when they were properly sized. Although Jordan favors his product in the final conclusion of the report, he still mentions that everything works if it’s “properly engineered.”
Here are just a couple of quotes from Jordan that further support the “properly engineered” statement in Jordon’s final conclusion:

“The overall conclusion of this early testing was that a properly designed drogue could prevent capsize.”

“It was found that for a small sailing yacht with a displacement of 7500 lbs. a cone or parachute drogue with a diameter of 4 feet or an equivalent series drogue would generally prevent capsize even when the model was struck by a very large breaking wave.”

“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 sea anchor deployed from the bow would have to be much larger, 2 or 3 times the diameter of a stern drogue, in order to hold the bow into the wind and sea.”

Originally Posted by kmacdonald

It would be best to read the Coast Guard report yourself. It's quite clear to me what they endorse. http://www.jordanseriesdrogue.com/pd...uardreport.pdf

[kmacdonald]

Originally Posted by Fiorentino

This past year Fiorentino supplied shark drogues to several USCG cutters and an extremely large para-anchor to the new sentinel class cutter at a length of 154 feet. Does this signify a USCG endorsement? Maybe a preference for our equipment, but not an endorsement.


No it doesn't. They don't endorse.

[Fi2010]

Correct. The USCG does not endorse product, maybe a preference for our equipment, but not an endorsement.

Originally Posted by kmacdonald

No it doesn't. They don't endorse.

[kmacdonald]

First off, Donald Jordan was not the author of the CG report. He was clearly listed as the consulting engineer.

Since you are so keen on quoting the report, I will add a few of other quotes in the report.

1) The contents of this report reflect the views of the Coast Guard Research and Development Center, which is responsible for the facts and accuracy of data presented. This report does not constitute a standard, specification, or regulation.

2)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.

3) The series drogue offers the following desirable features:

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.
It is almost impossible to foul it or entangle it enough to make the drogue ineffective.
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.
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.
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.
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.
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.

4) After observing the various drogues in the water channel, it was apparent that a cone or a small parachute drogue will collapse when the towline goes slack, as will occur each time the boat passes through the trough of a large storm wave. This behaviour results from the fact that the mass of water in the wake behind the drogue continues to move forward after the towline force has dropped to zero. This wake can collapse and even tumble the drogue.

There is a long history of drogue failures under storm conditions. It is probable that the alternative filling and collapsing is a major cause of these failures. In a single storm, a drogue can be subjected to as many as 10,000 cycles.

[thinwater]

Originally Posted by Fiorentino

This past year Fiorentino supplied shark drogues to several USCG cutters and an extremely large para-anchor to the new sentinel class cutter at a length of 154 feet. Does this signify a USCG endorsement? Maybe a preference for our equipment, but not an endorsement. 

I take three things from this:

1. Prima facie evidence that drogues and chutes scale up across very large factors (353 tons displacement).

2. Fiorentino can build some strong stuff.

3. A number of very well known and respected sailors, including Skip Novak, have stated that they do not believe drogues make sense on boats over about 65 feet. The forces become too great and safety is better served by other tactics. Sailboats are also very different in sea keeping abilities and needs than powerboats. I don't have experience in such boats, so I will not comment, but there seems to be a large difference of opinion.

Interesting. The question I have is the intended use. I'm guessing it is somewhat different.