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Old 28-03-2011, 13:36   #16
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

I would suggest that in survival conditions, the choice between a series drogue and a sea-anchor is decidedly not a no-brainer, especially in the case of a multihull. Herewith some positives for the series drogue:

1. It is easier to deploy a series drogue off the stern downwind, than to have to carry a heavy sea-anchor/rode forward in life-threatining conditions and deploy it into the wind, likely with waves breaking over the bow.
2. To be effective, a sea-anchor should be kept in roughly the same relative position on the wave train as the boat (if not, it will tend to collapse and then re-engage suddenly, putting huge strain on the attachment points). Accordingly, the length of the rode may (and in changing conditions will) have to be adjusted from time to time. The series drogue, however, is intended to be deployed full length and left in that state.
3. The series drogue will slow the boat to a speed (approximately 1.5 knots) where it cannot pitchpole. It is also a passive device which does not require the boat to be steered.
4. Broaching is not a significant risk in a catamaran because their are two hulls and, what minimal heeling occurs will not reduce the 'bite' of the keels/boards/rudders. Furthermore, the virtually constant tension of a series drogue set off a bridle at the stern will make a broach a virtual impossibility.
5. The USCG study found the series drogue to be the most effective tool in coping with large breaking waves.
6. While in theory a sea-anchor will keep the boat absolutely anchored to one spot, in reality there will often be some movement backwards; indeed, if the anchor is not properly deployed, it is (as already mentioned) especially prone to a collapse. This can lead to sudden acceleration backwards with the potential to damage steering gear before the anchor 'resets'.

Please take note that the above comments apply only to a series-drogue. Furthermore, take note that they assume that one is in a position (or has put themselves in the position) to have the required sea room when the storm reaches survival mode. If not and one is being driven towards a lee shore, then the sea anchor is the only choice.

IMO a non-series drogue can and should be used only when conditions are not at, or approaching survival conditions. The object is then to run with the storm, reducing the relative effects of the wind and waves through forward motion, while reducing speed so as to reduce the risk of pitchpoling/broaching in a rogue wave.

Brad
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Old 28-03-2011, 14:23   #17
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

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If you are anticipating oceanic travel, I would carry both a sea anchor and a drogue, for they are fundamentally different approaches to life and vessel preservation in heavy weather. I
That's probably not realistic for most of us - both financially and in terms of storage. For me I am convinced by the Pardeys and others that heaving to with a Sea Anchor will get you through about anything. The drogue will slow you down and prevent pitchpoling and probably a broach, but I would rather "Stop" and let the storms pass.
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Old 28-03-2011, 14:47   #18
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

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Originally Posted by Southern Star View Post
I would suggest that in survival conditions, the choice between a series drogue and a sea-anchor is decidedly not a no-brainer, especially in the case of a multihull. Herewith some positives for the series drogue:

1. It is easier to deploy a series drogue off the stern downwind, than to have to carry a heavy sea-anchor/rode forward in life-threatining conditions and deploy it into the wind, likely with waves breaking over the bow.
2. To be effective, a sea-anchor should be kept in roughly the same relative position on the wave train as the boat (if not, it will tend to collapse and then re-engage suddenly, putting huge strain on the attachment points). Accordingly, the length of the rode may (and in changing conditions will) have to be adjusted from time to time. The series drogue, however, is intended to be deployed full length and left in that state.
1. A para anchor can be set up pre-departure so it can easily be deployed from the cockpit.

2. You point 2 is a myth. With correctly sized rode, no adjustment is needed. Sea Surface Anchors. Para-Anchors Australia Pty. Ltd.
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Old 28-03-2011, 14:48   #19
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

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That's probably not realistic for most of us - both financially and in terms of storage. For me I am convinced by the Pardeys and others that heaving to with a Sea Anchor will get you through about anything. The drogue will slow you down and prevent pitchpoling and probably a broach, but I would rather "Stop" and let the storms pass.
Fair enough. Boats that can reliably heave to might not need to resort to a sea anchor, but that's a big "if".

Financially, you can make a JSD for not very much money if you can sew, and I imagine a "never deployed" sea anchor is available in various ports from sailors who are swallowing the anchor after owning three different crimpers, etc.

Me, I would rather stop as well, but there are times and reasons, like being blown "out" of the storm due to be on the safer side of the system and it's the way you were going, anyway, in which a "run, but not too fast" strategy is the way to go, rather than staying put and then dealing with a day of near-windless slop and confusion. And that's just the galley.

Certainly, multihulls seem to favour running before the storm (angled away, presumably!). I don't recall too many reports of them hanging from sea anchors.
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Old 28-03-2011, 15:03   #20
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

I posted a bunch of web data and some test data comparing most common chute and drogue types:

Sail Delmarva: Drogue and Parachute Sea Anchor Testing: A Summary for Small to Medium Cruising Catamarans

Also posted are some opinions regarding my personal boat, because that was my interst. Still, there is a lot of data and a number of links at the bottom. One CLEAR conclusion was that comparing a tire to a JSD is like comparing dental floss to chain.

It does seem obvious, after looking at the data, that used tires, chains, and other battle field expedients are very poor substitutes, and I hope few people assume they will just "figure something out." The loads involved are huge and the stakes are high.
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Old 28-03-2011, 15:12   #21
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

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Originally Posted by PamlicoTraveler View Post
I am convinced by the Pardeys . . . . I would rather "Stop" and let the storms pass.
Actually, the pardey technique is NOT to stop the boat, but to set it up so it will slide slowly square to the waves. They recommend a much smaller para-anchor than the standard mfg recommendations (and theirs is made from porous cloth rather than the more typical watertight cloth). They suggest this 'sliding' approach for two reasons: (1) to create a 'slick' upwind to break the waves and (2) to reduce the shock loads.

So, in fact if you follow the pardey recommended technique (and para-anchor sizing) you end up going downwind roughly the same speed (or perhaps 1/2kt slower) as a series drogue.

Even the conventional non-pardey 'over the bow with big para-anchor' technique does NOT stop you. At para-anchor in the water is not fixed like a steel anchor in the bottom is. You will drift backwards. How fast depends on the specific conditions and para-anchor, but the drift is generally somewhere in the .5 - 1.5kt range (excluding any current).

Back to the OP question . . . In fact empirical experience and tank testing shows that multi-hulls tend to be VERY resistant to wave capsize but more vulnerable to wind capsize. This means that on a multi-hull if you simply drop all sails and lie ahull you are quite safe unto very extreme conditions - lying a-hull is a very bad technique for most monos but multis don't have keels to trip over (if the boards are up) and will slide sideways rather than the mono-hull "roll over the keel" and they tend to have much bigger beam than monos.

But if you get to some sort of extreme condition where lying ahull does not feel right, then it can be argued that running (which reduces apparent wind) just slowly enough (drogue as necessary) to prevent bows digging in the wave trough, will reduce the most critical risk - better than para-anchor which does not reduce the apparent wind. But either technique properly executed will work and which is best depends on the conditions (eg don't use a para-anchor in the gulf stream or English channel and don't use a drogue on a lee shore)
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Old 28-03-2011, 15:22   #22
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

Running at 1 - 1 1/2 knots isn't really going to make much difference to apparent wind speed though.
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Old 28-03-2011, 15:23   #23
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

Yes, I've read that USCG report. As mentioned above, the para rig should be readied and launched from the cockpit. It also should be rigged with a second line and snatch block, pre-set for length and cleated at the cockpit to bring the center of purchase off the bow. This sets the boat at an angle to the sea and reduces any tendency to tack through the wind which has been a problem when setting sea anchors. If I had a cat, would certainly have a drogue, harnessed between hulls as it would be another way to deal with heavy weather. (Didn't a cat just flip from an improperly set para?) Cannot see any reason to set the wrong end of a monohull to the sea in any kind of dangerous breaking sea. Have had waves break over cockpit in normal sailing conditions and would not like to see large breaking waves attempting to dislodge the main hatch and flood the cockpit repeatedly. Although latched down tight, I would not want to depend on the many hatches in the cockpit area should blue water crash over them with full force. The force of water is awesome and scary. Monohulls are designed to shed blue water coming over the bow.
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Old 28-03-2011, 15:27   #24
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

Now, thats more like it ;-) Good discussion!

Well, short word on my sailing background, to put the question into perspective.

I've sailed and owned boats like the International 10mē Canoe, Hobies Cats sailed more than 12000nm (twelvethousand) with an open bridgedeck 8m racing catamaran (the latter was 9 month in the Med & to a large extent single-handed).

My next sailing project is going further, crossing some big oceans on the way...

So now to the reason why I am asking (and please do not get to much hung up on the wording, as my native is not English), I know that a parachute anchor is for keeping a boat in a biiiiiiiigg storm almost in one location (currents ommitted). This is what I would try to do in a survival scenario.

So yes, logically I'd choose the parachute anchor (prerigged & ready to deploy from the central hull & with a bridle to the amas). Still, naturally there is some "slipping" of the boat and anchor no matter how large the parachute is (both are not attached to the ground!!).

No here the primary question, could the same (almost stationary with some "slipping") be not achieved with an oversized series "drogue" if deployed over the bow?

The advantages seem to me, higher level of redundancy (lots of small cones with lower loads).
As the load rises, steady and fall over a long rope, I'd anticipate a more even load than with one big canopy, which could partially collapse and than excert a huge "jank" when coming back in shape.

Of course I would try running off first, trailing warps & the like, but if that does not work anymore I'd resort to a kind of sea anchor...

Any more thoughts?


Thanks for the lively discussion,

Franziska
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Old 28-03-2011, 15:41   #25
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

A drogue will allow faster "slippage" - possibly fast enough to damage your rudders.
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Old 28-03-2011, 15:46   #26
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

That's a good question Franzisca. Have never heard much about using a drogue from the bow. They are supposed to be very difficult to get back on board but if buoyed at the end, should be retrievable the same way as a sea anchor. Maybe they do not have enough "give" ?? A sea anchor, properly sized WILL slip enough to avoid ripping cleats out. Has anyone here actually tried it or heard of it being tried?
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Old 28-03-2011, 15:52   #27
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

Running off on many cats is a viable option up to a point, but I don't think you would want to tether most of today's cats by the stern to a drogue device, Jordan or otherwise, because of the huge cockpit and very vulnerable aft doors on many. There is at least one cat, I believe it was a Pearson Lagoon, that was sunk due to being pooped from astern--at least that was the speculation at the time. In any case, I have run off using a small chute in a small cat (32 feet) in an offshore force 9, and I was very happy that the cockpit had a huge hole in it for the outboard engine, which allowed water to drain very fast, and the aft part of the cabin was very strong. The door was small (required squeezing through) and constructed of mostly solid ply over 1-inch thick. There were points during the gale when we took breaking seas right over the boat that hit as far as the first reef point up on the sail, measure to be around 10 feet over the water. I think under those conditions it is better in a cat to present your bows to the seas, which requires a large parachute sea anchor.
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Old 28-03-2011, 16:05   #28
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

We have monohull and a Jordan series drogue, which we have never deployed and hope we never will. I have read enough about them, though, to be convinced of their efficacy for our little boat. I have heaved to many times without deploying a device.

If I had a multihull, no question I would have a bow-deployed chute, based mostly on the experiences of friends with multihulls. It is simply the best way for a multihull to properly heave to, or so I am told.
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Old 28-03-2011, 16:13   #29
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

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OK - at risk of sounding EXTREMELY STUPID - how come!! I can obviously see the problems with retreval and storage as well as a number of other logistical challanges, but the strength of your reply makes me wonder what else I may be missing
It is better to ask a question even if anybody could label it stupid than not ask one and do a stupid thing because of not asking.

Like maybe a tire or chain are not quite good - you want steady pull, not something that maybe stops you when you are going slow so you lose way and steerage then flops sidewards giving negligible drag when you need it most. That would be a tire.

Then chain may give too little drag. How much chain would you tow? And would it not rather sink pushing your stern (bow, have your pick) under the onrolling roller?

There must be a reason why someone invented toys like the parachute and the JSD. We do not jump out of a plane with a length of a chain round our neck either, do we.

My two.

b.
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Old 28-03-2011, 16:16   #30
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Re: Parachute anchor vs series drogue vs tires, any thoughts?

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Originally Posted by Southern Star View Post
IMO a non-series drogue can and should be used only when conditions are not at, or approaching survival conditions. The object is then to run with the storm, reducing the relative effects of the wind and waves through forward motion, while reducing speed so as to reduce the risk of pitchpoling/broaching in a rogue wave.
One other use for a conventional drogue could be to assist the boat in the process of heaving to. Fin-keel boats have a difficult time heaving to in some situations because they want to point too high to stall effectively. Additionally, a drogue can be used to help keep the boat from accelerating down the back side of a swell that has just passed, which will assist considerably with heaving to.

That said, I would agree with Brad that I'd much rather run with a storm whenever possible. For that reason we keep a drogue on board but don't even own a sea anchor.
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