Drogues and paras

C

ChrisE

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I've started here because, it was such a long climb into the other thread.

As I said in my earlier post these things are for survival conditions when ocean cruising and the mentality you adopt for a long passage is different. You set the boat up for the worst possible conditions and then pray they don't happen. We sail with our storm jib in its bag hanked on the detachable inner ready to haul up and the drogue ready to go. We have a Rival 38 which can be anchored by its bum without compromising its integrity and if you've seen the USCG film of this you'll see why its the best bet. I wouldn't be so sure in wide bummed speed machine.

I'm also thinking of adding a para to my armoury, the argument being that if the wind is coming from aft then out with the drogue, from the forward then use the para. Charles made a point about having to readjust the drogue to the considitions and I've read the Pardey's on this. All I can say is that from what I've heard most don't they just shackle lots of string (150 m) onto a firm point at the front and throw the whole lot out. Getting them back is not so difficult, I'm told providing you have enough HP to motor up to the drogue and collect the line en route. I've no personal experience of deployment or recovery but I'm convinced by the arguments.

I just pray to God that I never have to use them

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Let's separate out drogues from para-anchors.

Drogues have proven value in any number of conditions and all RNLI boats carry them.

The para-anchor, from all accounts from those who have used them in anger, works well with conventional long-keel designs - the Rival, with longish keel and separate rudder on skeg is probably one of those.

All those, of whom I'm aware, who have deployed a para-anchor over the bow, using a bridle to control attitude; when it acts as the ultimate sea-anchor.
IMHO trailing it would be suicidal, the probability of pooping far too great and the loss of control dangerous.

For my money heaving to will have nearly the same effect and can be used effectively at far lower wind speeds and far more often than those which justify a para-anchor.
The para-anchor is an alternative to running off, presenting the most seaworthy part of the boat to the wave trains - at some risk to the rudder - and allowing the crew to rest.
After all in survival conditions it's not the boat which is the critical weak link, it's the crew.
My contention is that overall it makes demands on the crew which are insufficiently offset by the benefits.


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I'd agree about heaving to in most conditons. I'm specifically referring to survival condintions ie big, breaking waves or when boatspeed and conditions indicatee that a pitchpole is on the cards and running off becomes risky.

First a couple of corrections, I meant para when I referred to adjusting and I should have said series drogues when referring to drogues. A series drogue is designed be deployed from the stern on a bridle and is designed to let the boat look after itself. I've heard Noel Dilley talking about his experience of deploying one in the Gulf Stream in some awful stuff and by his reckoning they work very effectively, hence why he, and I, have one.

As I said at the beginning of this, I hope this remains a theoretical debate.

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I once came across a detailed US coast guard research project into the subject of small boat survival in bad weather. unfortunately i have mislaid my copy, but you will no doubt find it on their site.
their conclusion seemed to be (from memory) that the only method which worked reliably was a drogue (series) from the stern. i seem to remember that the strength of deck fittings was a major issue with para type anchors.
size of boat was the major factor - design less so.


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Re:As I stated below

I've been involved in some testing of some pretty Heath Robinson drogues and sea anchors.

Even in quite moderate conditions the only thing they do is control your angle to the seas and speed of drift. The only reason your using it is to try to improve conditions onboard for the crew. The yacht will most likely lie ahull without such a thing but the ride will be hideous. The only way you find your best angle is by trying one and then adjusting it in use. Perfectly head on is quite horrible as you slew around all over the place and roll like hell.

The guy who's project it was had the following concerns.

Strength of anchor point. After all if it puts a hole in the boat it wasn't great safety equipment. This means that the most important consideration is that the resistance provided by the device must be appropriate to the boat size and weight. This is a complex variable so buying suitable kit of the shelf is not that easy.

Timing your deployment and recovery presents a tricky judgement call. You have to make a decision to stop sailing in time to deploy the gadget in safety. You are likely to be making your recovery attempt in quite large seas while you and your crew are pretty tired & beat up. It is a physical challenge to recover a drogue in a seaway. Motoring up to it presents it's own challenges as anyone who has motored into a head sea knows and makes the foredeck a difficult place to operate. The amount of rope in the water does present a threat to the boat during the recovery procedure. We found it quite difficult in Christchurch bay in a F6 and we were using a 21ft RIB.

Other considerations that I came up with.

There is a school of thought that says that a yacht is more stable secured from the stern. This would certainly give a better working area for recovery, I prefer working a cockpit full of breaking waves than a foredeck. This address's a bugbear I had with the deployment from the bow. If you use your anchor cleat and your line brakes or jumps out of the roller or fairlead, I believe that you could loose your forestay.

You must be able to fix your rudder firmly as your boat will at times be going backwards which will break your steering as fast as anything.


Now this wasn't a CG project, it was just some marine engineering students with a small grant, looking at the problem. I came to the conclusion that sailing yachts could do as well without using drogues but if I did use one I'd deploy it over the stern, from one quarter. Motor boats might get more out of using a drogue from the bow.


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In a book - title lost - written by a seasoned delivery skipper (mainly seemed to be in Irish/Celtic Sea) - he observed that using a Para/drogue with long keeled boats did not work.
He had streamed an some device, attached from the bow at one end & back to a cockpit winch at the other-attempting to adjust the attitude. The long keeled yacht then proceeded to 'sail' barepoled-due only to its keelarea- upwind & over the device. These things will obviously work best only when the vessel is drifting away from them creating some pull to anchor the drift against.
I have myself experienced this keel effect, 'sailing' over the bouy I was attached to - against a strong tide off Cowes.

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Trouble is...

... that the vast majority of us have no experience of using either device (at least not in the conditions where they really win their spurs) both of which very much come into the last-chance-saloon category. So we are not qualified to comment.

Then there are those who have used one or the other and have survived to tell the story and are consequently evangelists for their saviour, be it para or drogue.

And there are those who have used them and not survived, who understandably have little to say on the demerits of their choice.

Conclusion: confusion.



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Re: Trouble is...

I'd agree, we plumped for a SD on the basis of listening to Noel Dilley's lecture on the subject to the Cruising Association.

The one thing I am sure of is that unless you have a large strong crew, as with the RTW races, then you have to have a method that allows the skipper and crew respite from the storm. We've all read Motissier et al and hand steering down wopping great waves but I'm not in that heroic category, I'd just want a chance to change my brown trousers after the storm had passed.

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Re: Trouble is...

Well, it's an aye to Ken's points, a question to CR in that I understood from HW that the rudder, esp the modern spade, no skeg, rudder, which was at greatest risk from following seas?

I heard ND at the CA, a few weeks back - a really splendid professional lecture (but then, he was referred to as Prof, so presumably is a pro). I hesitated to ask what his actual experiences of these conditions were. He has presumably been out in more severe conditions, but, re:Ken's note above - I cannot conceive that, given a system which has worked for me in the past, I would, as an academic exercise, try the opposite! He favours the series drogue, how much has he tried a PA? This is not criticising what he says, just wondering.

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Re: Trouble is...

Noel Dilley wrote up his expereiences of being stuck in heavy weather in the Gulf Stream off the US coast, hanging on a SD until the line broke when life became more interesting. It was in YM some years ago. He is a professor of medicine. Like other posters have said you have to secure your rudder amidships or risk losing it. As I said in my earlier post, I'm not sure that this is the method for widebummed, spade ruddered jetships but then they'd probably have the speed to get out of the way of the weather.

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Re: Trouble is...

To keep this short - I'll just say that people seem to ignore the fact that short handed crews cannot work continiously hour after hour in storm conditions. It makes sense to develope and practice a passive storm management approach. You need not use it immediately - but there will come a point in time (tiredness or lee shore) where it is time to stop running. This is where heaving-to and (optional) PA's come into thier own, why are poeple so convinced that this is a bad strategy? If it doesn't work for a specific boat ask not what is wrong with the method but what is wrong with the boat ... Just my opinion mind you.

Jeff.

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Re: Trouble is...

Agree entirely.

With a fully fit racing crew we were able to negotiate f9+, gusts up to 50kt, both upwind and downwind: three persons were able to steer, but could hardly manage more than one two hours each.
Now with the same boat and being just a couple to handle her, call it age but I am almost sure we would not be able to keep it going under those conditions for more than a couple of hours in total. The boat would be able, the crew is the limit.

For this very reason I think there is a huge opportunity space available for a passive approach, trouble is which one..

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Re: paras from the stern

surely the type of boat is relevant. A double ender with low cockpit volume would not be at risk the same as a wide stern, high volume cockpit.
I am interested in this as I have a Prout Catamaran with a similar hull shape front and back. The cockpit is quiet high volume but has a 3 inch diameter drain. The rear of the boat has no large windows so maybe a PA on the stern is not such a bad idea?
Not sure there is a loss of control issue as speed under parachute is likely to be less than 1 knot without tidal influence. Anybody any views?

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