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Old 30-10-2005, 12:21   #1
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Series drogues

Has anyone any experience with using series drogues (from stern) on cruising catamarans in a storm? Any concerns about large amounts of water in a cocpit (several tons)? What about sliding doors/windows, etc?
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Old 30-10-2005, 12:43   #2
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The US Coast Guard has a little experience (momohull), which they share at:
Drogue Information - Report No. CG-D-20-87
Investigation of The Use of Drogues To Improve The Safety of Sailing Yachts
by U.S. Coast Guard, Groton, CT
http://www.sailrite.com/droguereport.htm
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Old 30-10-2005, 14:15   #3
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More Good data in http://www.seriesdrogue.com/
A cat normally has a much better lifting moment at the stern than a monohull, and the strains on the vessel are lower with a series drogue, than with a parachute anchor. However, if your entrance from the cockpit is flimsy - sliding door etc, then a drogue is probably not the right thing for you.

You are then left only with the parachute anchor. It is vital that you get the right size, cause too small and the boat will be forced back by a big wave, and could damage your rudders or even cause the boat to broach. Make sure you get it set up so that you can rig the lot before the weather gets bad, and lead the rope back to the cockpit, you can then just through the release bag into the water, shut yourself down and go to bed.
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Old 30-10-2005, 16:54   #4
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I would also look at the "Galerider" drogue. Easier to deploy and retrieve than a series but you can't make it yourself

http://hathaways.com/galerider/default.asp
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Old 30-10-2005, 20:03   #5
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Quote:
Jon D once whispered in the wind:
I would also look at the "Galerider" drogue. Easier to deploy and retrieve than a series but you can't make it yourself
Actually, I don't think it would really be that hard to make one yourself (but I've got some experience sewing some of my own gear), you just wouldn't be able to call it a "Galerider." (Of course, it would be nice to have a first-hand look at one in order to reverse-engineer it.) That said, I will probably just buy one already made...

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Old 30-10-2005, 20:32   #6
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May I never need to deploy one, but I think deploying from the bow to keep the boat into the wind is likely to be the least uncomfortable method of riding out a storm. I donít have big sliding doors, but with cats that attempt to be floating patios this would seem even more advisable.

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Old 31-10-2005, 02:28   #7
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The trouble with a single drogue (and also with the parachute anchor) is that you need to veer the right amount of bridle to get the drogue in the correct position in the wave train. If you get this wrong, there is a real danger of the drogue or chute popping out of the water, and causing a massive broach or roll over or at best broken rudder.

The series drogue is designed and sized so that whatever the size of the wave train, a part of the drogue will always be in it.

As to whether the bow or stern is the best place to hang the drogue or anchor, I cant improve on the work in the USCG report so recommend you read it.
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Old 31-10-2005, 05:49   #8
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Bamboo, if your questions reflect your boat (multihull with large patio-door type entrance into the cabin from the cockpit), a series drogue is IMO definitely not for you.

To review the three drag device types, how they are intended to work and their basic physical make-up, I'd encourage you to read Victor Shane's Drag Device Data Base (4th Ed or later). More importantly, it is loaded with documented cases where all the different devices have been deployed, in the real world, on multis and monos of all different sizes.

When this topic is discussed, I get the impression we're all talking about our favorite color; we talk as tho' we're exercising a personal preference for how we want to handle storm seas. Drogues e.g. are discussed by brand rather than by category or intended use. That's why I encourage folks to read DDDB and perhaps Earl Hinz book on this subject. (Oceanography & Seamanship by VanDorn would also be worth the time some selective reading would require). The referral to the USCG study and David Jordan's work is sometimes so absolute and exclusive as to suggest that's all one needs to know. IMO here is at least some of what's missing in this discussion - and in most discussions on this topic - that needs to be considered by Bamboo. I'm using Shane's conceptual terminology...

No-Pull Device - the typical parachute sea anchor, deployed off the bow; a space hog to stow; physically extremely demanding to deploy; very difficult and time consuming to retrieve, and only after seas have significantly moderated (which as we know is subsequent to the winds dropping); intended to restrict boat movement to leeward (the 'anchor' piece); imparting large 'bungee jumping' forces on the boat (the seas will force something to move and the chute is unwilling, so the force of the water as felt by the hull is accommodated by the rode - thus, the sudden surging as tho' at the end of a bungee cord); subject to subsurface currents (a sistership to WHOOSH had to cut hers away after it was caught in a current that took the chute straight down - it was a cold water eddy - depressing the bows into the sea)

Medium Pull Device - the series drogue; deployed off the stern; the heavier the boat, the more difficult stowage becomes (a Tashiba 40 we know has a series drogue bag the same size as their #1 genoa bag; where do you stow something like that, given it will be the least likely used item in the boat?); relatively easy to deploy but difficult to retrieve until conditions moderate; designed to bring the boat to a near-standstill inbetween wave strikes, being pulled thru the water only when the yacht gets struck by a breaking wave, and so subject to significant 'bungee jumping' (Jordan recommends being seated with retraining straps in place, as e.g. what pilot boats and rescue craft use); boat's aft end (transom, aft cabin trunk if a center cockpit design, and/or companionway all need to be physically able to withstand wave loading); number of drogue units critically important when built but the whole device works acceptably with some drogue units coming out of the water due to wave train action, so monitoring usually required only for chafe.

Low-Pull Device - the Galerider is one such device; deployed off the stern; smaller size and weight makes stowage less of an issue; not intended to prevent drift to leeward, but rather designed to be used underway (very compatiable with windvanes & a/p's); rode length adjustment appears more critical to effectiveness, so this may need monitoring & adjustment; more easily retrieved in higher winds/seas that the other devices; a variety of functionally similar products (of different designs) available on the market

IME most full-time cruising boats are sailed by short-handed crews, and a majority of those crews consist of middle-aged and older men & women. When it comes times to move from theory to practice WRT choosing a drag device, I would think we should start there. The physical capabilities of the crew will determine what can be unstowed and deployed (and hopefully retrieved) effectively, which in turn will mean its use is more likely, and in addition how well a watch is kept and rode monitored & adjusted as necessary when deployed. From there, consideration of the boat's design, structural integrity and deck hardware could be considered...and finally, the kinds of waters in which the cruising is to be done, as that will shape the kinds of conditions when a device will be deployed. IMO it's at that point when you can begin picking your favorite color... <g>

Jack
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Old 31-10-2005, 07:15   #9
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Low-pull devices are only acceptable if you have the sea-room. Even the series drogue allows a 1.5 - 2 knt forward movement.
The parachute is the only one that promises to basically hold you in position on the water, and thus go merely where the current is going.
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Old 07-11-2005, 00:05   #10
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Let me just pipe in here - as I have some very recent experience with using a drogue in typhoon conditions in the South China Sea. My recommendation is: get one. I can't say one version is better than the other, but my Delta-style drogue made a big difference and was well worth having aboard.
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Old 07-11-2005, 05:54   #11
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Sam, yours is the kind of experience we all can learn from. I'm somewhat familiar with the Delta (a medium-pull device) but would very much welcome hearing what you learned when using yours recently. Please share with us the details of its rigging and deployment, how it affected vessel performance, could you rely on the windvane or a/p to steer when it was deployed, and at what point you were able to retrieve it.

Many thanks!

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Old 30-11-2005, 21:20   #12
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I think I read somwhere that a catamaran on a sea anchor may allow the boat to back-flip. As the wave begins to go under the boat and the line stretches the boat will bungee forward to the next wave and then the line goes slack - slack enough, perhaps, for the next wave to overturn the boat. Maybe Dashew or??
Or was I dreaming.
I would love to hear any first hand datamaran experience in heavy weather.

Regards,

Bill
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Old 01-12-2005, 04:33   #13
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As has been said earlier the Drag Device Database has a wealth of knowledge and experience:
(DRAG DEVICE DATA BASE, Shane, Victor, PAI, 1990, ISBN 1-878832-01-8)

Just to quote one:

File S/C-8 || CATAMARAN, KELSALL DESIGN, "CATHERINE ESTELLE", 36' X 20' X 5 TONS, USED AN 18-FT. DIAMETER PARA-TECH SEA ANCHOR IN A 985 MILLIBAR STORM IN THE GULF OF ALASKA WITH WINDS OF 70 KNOTS AND SEAS OF 40 FEET. THE SKIPPERS COMMENTS: "The sea anchor definitely saved the boat and I'm sure our lives. It operated flawlessly on those 2 days and the other 3 days during the other 2 gales.... We did what should have been done and came through a very violent storm and survived with no damage. Thank you again for everything."
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Old 01-12-2005, 05:04   #14
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Remember, the DDDB is a commercial site, selling Para-Anchors and their Book. Nonetheless, they offer some good information.

Drag Device Data Base (DDDB): http://www.dddb.com/
Includes some free online information, including:
Para-Anchor Setup: http://www.dddb.com/setup.html
Wave Particle Rotation: http://www.dddb.com/rotation.html
Catamaran Bridle Advisory: http://www.dddb.com/bridle.html

And miscellaneous infoí at (scroll through the whole page): http://www.dddb.com/news.html
~ GROUP SYMMETRY AND DISASTERS AT SEA: There comes a time when every fiber in a seaman's body seems to be urging him to change course, or break away, or heave-to...
~ NYLON 3-STRAND: The use of 3-strand rope for tether or towline is now discouraged...
~ AVOIDING HIGHLY LOCALIZED BOUNDARY CONDITIONS: If the choice were between deploying a sea anchor in shallow water, say, over the Cortez Bank, or in deep water only 10 miles away, which would you choose?...

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