A question for blue water cruisers

Its also worth looking back at an interesting discussion of series drogues HERE a year ago, starting with an account by Bryan Glover who had used one in anger (though I should warn he has a commercial interest).
 
that report does a thorough job of analysing the drogue, then dismisses the sea anchor in a sentence without evidence!

anecdotal reports claim excellent results for sea anchors in survival conditions though i have read of one case where the crew thought the stretch in the warp made the boat surge forward and yaw about and felt safer without it.
 
A friend set his 16 foot sea anchor, parachute type designed for sea use, off the bow (near Easter Island) off a Hereschoft 48 using 5/8 inch dia nylon.....after a few hours of rest from less than 40 k winds the line was 1/2 its original diameter......
 
It is true that sea anchors and drogues are designed to do very different jobs. One big difference is that a parachute-type sea anchor MUST be big enough to hold the bow to the weather, a small one is not better than nothing - it is worse. In contrast a drogue over the stern can be deployed progressively to keep you under control. For the same reason, you can improvise an effective drogue out of any old rubbish on board, not so a parachute anchor.

To me the biggest difference is that if a parachute is your final safety measure, you must deploy it in good time, before things get so nasty that you dare not round up if you have been running and the loads involved during deployment become lethal.

I have never deployed either in anger so this is only theoretical musing
 
i'd guess a 48 footer displaces in excess of 15 tons. i have a warp larger than that for my 6 tons so it's small wonder his wasn't up to the job! it does point up the fact that the strain imposed by a sea anchor is massive and everything must be up to the job or it's worse than useless.
 
My feeling about drougues was I neither wanted to be pooped by breaking waves over the stern nor have water rushing past my rudder in the 'wrong' direction. It seemed to me that taking breaking waves over the bows was a better option and kinder on the rudder.

Purely annecdotal - I have met several people who in extream conditions deployed their sea anchors and in every case it went from being awful to being not bad at all.
 
[ QUOTE ]
.....water rushing past my rudder in the 'wrong' direction.

[/ QUOTE ]

Don't understand that. With a drogue you are still moving forward.

I see them as two quite different strategies, not just about which way round you want to face.

I certainly agree that in extreme conditions I would rather be tied to a monster parachute and hitting the seas with the bit of the boat designed to do that - the sharp end.

However, given sea room and given 1 or 2 scared people on a boat bouncing around like a mad-thing, I think I would prefer the flexibility and safety of a stern drogue system over the all-or-nothing of the parachute system.

When I also read that the USCG says drogues were also better when deployed (ie regardless of practical issues of deployment), I am convinced.

I can certainly see that the issues to some extent depend on boat design. eg a cat with a cockpit the size of a football pitch might be more vulnerable stern-to than a 'proper' monohul - or maybe not as the cat has also got a flat foredeck the size of a football pitch.
 
Just another point of view for you lot....

If things are that bad, it's likely that you're been clobbered in the dangerous quarter of the low (SE of the low in the northern hemisphere) and if your are bows towards the bad stuff, the storm will pass you sooner rather than later compared to being stern too or running with the wind and the low. So the parachute makes sense to me.

In fact, if you were in the NE quarter of the low and therefore in a l"ighter" winds, you would still be bows to the wind with a parachute resulting in the storm passing sooner than if you were running.

Also haven't tried mine in anger so this is another theory of mine at this juncture.
 
Are you recommending a sea-anchor (drogue) deployed from the bow? It's what I feel intuitively is correct but it seems to be contrary to accepted wisdom. After all the parachute is almost like a brake whereas the sea-anchor should give a more modest drag, so by deploying a sea-anchor one would be making way in the direction of the wind and waves but presenting the bows to the onslaught.

Edit: Furthermore, you could assist with the motor as required to reduce the load on the drogue.

David
 
Yes, I realise that's the accepted wisdom but I though you were suggesting deploying the drogue from the bow; I think I misunderstood you.

On what authority do we accept that drogues shouldn't be deployed from the bow, in place of a parachute? Without doubt it has been done many times and there must be some properly documented reports of the outcome. Sometimes the world goes merrily along down a path of accepted wisdom without question and I am wondering if this is the case here?
 
[ QUOTE ]
On what authority do we accept that drogues shouldn't be deployed from the bow, in place of a parachute? Without doubt it has been done many times and there must be some properly documented reports of the outcome.

[/ QUOTE ]Noel Dilly, the RYA examiner who is something of an expert in this area, told me that if a series drogue is streamed from the bows, it doesn't work so well. Knocked about by the waves, and in the lulls in the troughs, the yacht tends to fore-reach, slackening the drogue line and causing it not to restrain the yacht adequately. It will then follow the natural tendancy of most yachts lying ahull, to start to turn downwind and again be at high risk of broaching. This applies particularly to a high-windage fin-keeled yacht where the risk of forereaching is most acute. Apparently this has been demonstrated in tank tests as well as in practice. For a drogue to work properly, the yacht must be making a little way downwind to keep the tension steady.

To correct a possible earlier misapprehension, when a drogue is deployed there is no active attempt to steer the yacht. The rudder should be lashed centrally, and the crew retire below. The risk of pooping is too high for the crew to stay on deck.

Incidentally I don't know how many people here have actually been in open ocean in a storm in a small yacht, but from my one experience nothing, but nothing, would have persuaded me to crawl to the bows while the boat was being held upwind in order to deploy a sea-anchor or a drogue. Its simply beyond my capabilities, and I could not consider any device that relied on this being done. Others may be more brave than I - or maybe hope to get the job done before the really bad stuff hits them.
 
i saw a smart arrangement on a cat making a transatlantic passage- the bridle for the parachute was attached at the bows then led aft outside the stanchions to the cockpit area. it was secured with cable ties. to deploy the anchor you attach the warp and other bits to the bridle and chuck it all over from the cockpit. as the chute deploys and the load comes on, the cable ties break
 
I agree there is nothing that would make me crawl around the decks in a storm! However the parachute sea anchor is really launched from the cockpit - it comes in two bags - 1 with the parachute and the other with nylon warp.. You just throw them in to windward.. Or so it says on the label.

On the 3 occasions when I have got the whole thing set up (but did not launch) it was after the 3rd reef had gone in and the situation was deteriorating - I took the shackle forward and attached it to the bar across the CQR... went back to the cockpit and watched the wind gauge... Each time conditions moderated shortly after or did not deteriorate more...
 
After reading your post, I dug out a book (as yet unread but looks promising) that I bought at the Boat Show called "How to Cope with Storms" by von Hafting published by Adlard Coles and he states categorically that the drogue must not be trailed astern or the cleats will be broken off and then goes on to explain how to use it from the bow (in the same way that a parachute is intended to be used though he does not discuss parachutes, only drogues that "look like a windsock"). He makes the point that it takes a good deal of time to get the warp length correct and talks about means of doing that.

Please understand that I am not expressing a personal opinion on this - I have never experienced heavy weather in the accepted meaning of the word - but I am trying to think through what we would do if the need arose, where my kit is stowed, how to put it together, etc., because if I can't sort this out in the comfort of my marina berth I am not going to be able to do it at sea!
 
Your references are no longer up-to-date. It would be a foolish man who streamed a single drogue over the bow. The boat would inevitably make considerable stern way, and in a bad storm I would place a large bet on loss of the rudder. A series drogue is designed with lots of little drogues in order to make sure that a good part of the line is in the exact correct spot in the wave train. It is obvious that the stress of this device is far more than the average cleat is designed for, proper bespoke fixings designed for the load would be an essential part of the kit along with appropriate connections that are chaff free.

If money and stowage were no problem, I would have both, as it is I cant afford either, but the series drogue is a lot cheaper to buy and takes up less space to stow, so that is my priority.
 
Absolutely I don't think there will be any argumnent that the realisation of the effectiveness of BIG ENOUGH drogues from the stern or 'parachutes' from the bow have transformed heavty weather tactics in small boats.

Old stuff talks about lying ahull which in most modern boats would be suicidal in extreme condition. Or farting about with little 'sea anchors' which from the bow are only marginal improvements on parachutes or from the stern are totally inadequate drogues.
 
[ QUOTE ]
I dug out a book (as yet unread but looks promising) that I bought at the Boat Show called "How to Cope with Storms" by von Hafting published by Adlard Coles and he states categorically that the drogue must not be trailed astern or the cleats will be broken off.

[/ QUOTE ]Interesting. Von Haeften is well respected and the book is not that old. But I'm surprised by the advice about the cleats. The USCG tests seem to imply that the maximum loads imposed by a 90-cone series drogue in their tests were large but not collosal. For example, if the yacht were moving downwind at 4 knots= 6.7 ft/sec, quite a rate trailing a full-sized drogue even in a storm, figure 19 (below) in the USCG report suggests a maximum load of around 500 lbs. All my cleats are designed to take a load of 5 tons (half the weight of the yacht, which at one time was a standard design criterion), so I think they should cope. In any case, the method of deployment is by with bridle to both aft cleats, finally made off at the main winches to assist recovery if necessary, so the load is shared.


drogue_figure_19.gif
 
[ QUOTE ]
Interesting. Von Haeften is well respected and the book is not that old. But I'm surprised by the advice about the cleats.

[/ QUOTE ]I got this wrong - my apologies.

What von Haeften says under the section on towing warps is "A sea anchor should never be towed astern to slow the yacht. The boat would come to a near standstill and every breaker would hit the stern with its full force. The value of a sea anchor is in maintaining an offing, a tactic which we discuss a little further on."

Then, in the section under "Lying to a sea anchor" he says "The holding power of the drogue or sea anchor increases with the square of the drift speed. Deployed when under way at full speed it would tear off any cleat". He does then go on to describe how to deploy a sea anchor from the bow - not a parachute.

Sorry to have caused the misunderstanding - I had skimmed through rather too quickly - I hope it is now clear. By the way, the mistake that I made in spelling von Haeften's name was entirely due to my spell checker! /forums/images/graemlins/smile.gif

David
 
You must log in or register to reply here.

Share this page

Top