RichardS
N/A
But there are two different types of drogue ..... single drogues and series drogues .... both with different design parameters. The two are not interchangeable.
Richard
Deploying a drogue?
- Thread starter Mike k
- Start date
But there are two different types of drogue ..... single drogues and series drogues .... both with different design parameters. The two are not interchangeable.
Richard
dom
Well-Known Member
There are series drogues where many small drag devices are interlinked and non-series ones which utilise a single large device.
Your spade/skeg point is flat wrong: the reason sea anchors are so large is that are designed to functionally stop (i.e. anchor) a boat to the sea. That said, there is inevitably some movement astern, which is why any rudder must be securely locked or it risks being yanked over to its stops and damaged. It is for this reason that parachute anchors must be carefully sized to fit each boat's individual characteristics.
Final point if anyone is interested: para anchors are incredibly time consuming and difficult to retrieve - i.e 2, or 3 hours, possibly more. And if the storm has not blown fully through when the decision is made to set sail again, one must often leave the anchor to the sea.
Edit: I see Richard has beaten be to it!
KellysEye
Well-Known Member
>There are series drogues where many small drag devices are interlinked and non-series ones which utilise a single large device.
If you look at the picture it is not a large drouge so one won't slow the boat down.
>Your spade/skeg point is flat wrong: the reason sea anchors are so large is that are designed to functionally stop (i.e. anchor) a boat to the sea. That said, there is inevitably some movement astern, which is why any rudder must be securely locked or it risks being yanked over to its stops and damaged. It is for this reason that parachute anchors must be carefully sized to fit each boat's individual characteristics.
Parachute anchors are sized to the weight of the boat our 18 foot one was for as steel ketch that weighed 15 tons fully loaded. A parachute anhor in a storm does not hold the boat bows to the wind it will normally be abour 15 degrees off the wind direction so the boat is moving fast enough to break off a spade rudder, if locked itwould be even quicker. For full details of single and drogues and para anchors this is where we bought our para anchor: http://www.paraanchor.com.au/drogues-and-sea-brakes.html In the Para Anchor section is 'Managing Drift'.
If you look at the picture it is not a large drouge so one won't slow the boat down.
>Your spade/skeg point is flat wrong: the reason sea anchors are so large is that are designed to functionally stop (i.e. anchor) a boat to the sea. That said, there is inevitably some movement astern, which is why any rudder must be securely locked or it risks being yanked over to its stops and damaged. It is for this reason that parachute anchors must be carefully sized to fit each boat's individual characteristics.
Parachute anchors are sized to the weight of the boat our 18 foot one was for as steel ketch that weighed 15 tons fully loaded. A parachute anhor in a storm does not hold the boat bows to the wind it will normally be abour 15 degrees off the wind direction so the boat is moving fast enough to break off a spade rudder, if locked itwould be even quicker. For full details of single and drogues and para anchors this is where we bought our para anchor: http://www.paraanchor.com.au/drogues-and-sea-brakes.html In the Para Anchor section is 'Managing Drift'.
RichardS
N/A
I don't get it ..... Stu says it's a flippin' big drogue and you say that it's not large enough.
My view is that at around 2m it's the right size for a single drogue, much too large for a series drogue (one of) and too small/ the wrong design for a sea anchor.
In days gone by sailors trailed lines and towed buckets as drogues .... and the one pictured would be much more effective that either of those.
Richard
bitbaltic
Well-Known Member
Yes it will. It is a completely normal drogue. The cones on the series drogue are just inches across. I have never heard of anyone deploying multiple full-size drogues.
Can't remember the numbers but I have used a drogue (to test it's emergency steering capabilities) and it certainly took an appreciable bit off our boat speed. You would expect that to scale up proportionally if the boat were surfing.
I broadly agree with your comments about being set back on a spade rudder if using a parachute. It is not inevitable that a spade will be damaged but I do think it would be a risk I'd try to avoid. A parachute would not be my first tactic if crossing oceans with a spade-ruddered boat (a JSD would). But then the more I read about survival in heavy weather the more I come to the conclusion that every set of circumstances is unique. Being prepared and carrying appropriate kit (and knowledge) to adapt to the circumstances is key.
thinwater
Well-Known Member
a. I have no idea why Kellyseye posted. A 1500mm drogue would slow the average boat to ~ 4-5 knots and prevent surfing in all but extreme conditions.
b. Yes, multiple 2-3' drogues can be deployed in series, I have been involved in testing, and it has many advantages. The primary vulnerability of a single drogue is that it WILL be pulled out of a steep wave face when loaded past some critical value, dependent on wave steepness, but generally around 5 knots. Having a second drogue 100-200 feet back holds it down and pulls it back into the wave as it passes, getting it back to works in seconds. It also prevents both drogues from being pulled out at the same time. The second drogue also tends to run a little deeper. The pull is more steady, since they are not influenced by passing waves at the same time.The advantage over the JSD is that it is easier to handle and more useful for emergency steering. Total cost is probably similar.
This has been tested in ocean conditions.
c. Drogue resistance is very closely related to total area (single or multi) and speed^2. Design differences don't change that much, although most are much more stable at speed than cone drogues. Those are for drift fishing and costal waters.
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bitbaltic
Well-Known Member
Heckler
Well-Known Member
I asked a question! Notice the question mark.I don't get it ..... Stu says it's a flippin' big drogue and you say that it's not large enough.
My view is that at around 2m it's the right size for a single drogue, much too large for a series drogue (one of) and too small/ the wrong design for a sea anchor.
In days gone by sailors trailed lines and towed buckets as drogues .... and the one pictured would be much more effective that either of those.
Richard
Stu
thinwater
Well-Known Member
Unless folks post the post their boat size, this is all guess work, like saying a 35-pound anchor is the right size.
Also, do you want to...
1. stop.
2. slow way down.
3. slow down a little, for easier steering.
4. emergency steering.
5. speed limiting, storm management.
6. entering breaking inlets.
These are all different questions. Personally, for the coastal cruiser (most of us), #4 and #6 are the only ones that makes sense. Obviously, there is some overlap.
Good luck making sense out of vendor sites; since they all have different ideas of what a drogue is "for", their sizing info vs. load is all over the place. A drogue that will generate 5-10% of the ABYC storm anchor load numbers (those are conservative numbers, we'll be going faster than that in the peaks, and we're not trying to stop) at 4 knots is in the bucket, depending on what you want. Too much, and emergency steering is too slow, too little and it will rip out of the waves at high load. One size fits all is... impossible. Anyone who says other wise is selling something.
Also, do you want to...
1. stop.
2. slow way down.
3. slow down a little, for easier steering.
4. emergency steering.
5. speed limiting, storm management.
6. entering breaking inlets.
These are all different questions. Personally, for the coastal cruiser (most of us), #4 and #6 are the only ones that makes sense. Obviously, there is some overlap.
Good luck making sense out of vendor sites; since they all have different ideas of what a drogue is "for", their sizing info vs. load is all over the place. A drogue that will generate 5-10% of the ABYC storm anchor load numbers (those are conservative numbers, we'll be going faster than that in the peaks, and we're not trying to stop) at 4 knots is in the bucket, depending on what you want. Too much, and emergency steering is too slow, too little and it will rip out of the waves at high load. One size fits all is... impossible. Anyone who says other wise is selling something.
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RichardS
N/A
Given that it says in the link that it is 1500 by 2200 that is a flippin big drogue!
I must be losing my grip on reality ..... or my grip on my specs
Richard
PS Just though to add that I'm actually agreeing with you Stu and disagreeing with KellysEye ...... it is a flippin' big drogue but that is what is required for a single drogue.
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VO5
Well-Known Member
I am not going to get embroiled in a silly endless argument like the last time this topic came up.
I will be brief and to the point.
You want first of all to have two secure attachment points on your stern, really reliable cleats.
Then you want to have a Y brace and makes sure the crutch of the Y does not foul your rudder.
Then you want a line that will not coil, one that will track straight of three ships lengths to attach to the Y brace through a thimble.
The towing line should be fitted double ended with thimbles.
To the aft thimble you attach a length of chain with a shackle yo ensure the drogue remains submerged while it it being towed.
Then to the chain you attach your drogue again with a shackle.
All shackles must be moused.
Then the drogue will do its job, by slowing down the boat in bad weather in open water with a following sea.
The object is to keep the stern down, not up.
Think of a surfer surfing very big waves. The bow of the surfboard is kept up.
If the surfboard bow is allowed to dig the consequence is a somersault.
The principle is the same.
The storm will pass over you faster than the progress of your boat.
I have a Seabrake drogue. I am very happy with it and have used it in open water in storm conditions several times with very satisfactory results.
I implore all of you here not to get bamboozled by the series drogue.
It may not be difficult to deploy but a real pain to recover.
In contrast the Seabrake is very easy to deploy and an absolute doddle to recover.
I deploy mine by first letting out half the rig to form a loop in the sea astern and then throw the rest clear in one go.
I recover by using the sheet winch, and finally recovering aboard hand over hand.
A sea anchor is a different beast altogether.
But the beauty is that my Seabrake serves both as a drogue and a sea anchor if needed.
Additionally when rigged at the end of the boom with a chain weight under the drogue and boomed out, in a rolly anchorage it settles the boat like magic.
And it is not cheap, but worth every penny.
I will be brief and to the point.
You want first of all to have two secure attachment points on your stern, really reliable cleats.
Then you want to have a Y brace and makes sure the crutch of the Y does not foul your rudder.
Then you want a line that will not coil, one that will track straight of three ships lengths to attach to the Y brace through a thimble.
The towing line should be fitted double ended with thimbles.
To the aft thimble you attach a length of chain with a shackle yo ensure the drogue remains submerged while it it being towed.
Then to the chain you attach your drogue again with a shackle.
All shackles must be moused.
Then the drogue will do its job, by slowing down the boat in bad weather in open water with a following sea.
The object is to keep the stern down, not up.
Think of a surfer surfing very big waves. The bow of the surfboard is kept up.
If the surfboard bow is allowed to dig the consequence is a somersault.
The principle is the same.
The storm will pass over you faster than the progress of your boat.
I have a Seabrake drogue. I am very happy with it and have used it in open water in storm conditions several times with very satisfactory results.
I implore all of you here not to get bamboozled by the series drogue.
It may not be difficult to deploy but a real pain to recover.
In contrast the Seabrake is very easy to deploy and an absolute doddle to recover.
I deploy mine by first letting out half the rig to form a loop in the sea astern and then throw the rest clear in one go.
I recover by using the sheet winch, and finally recovering aboard hand over hand.
A sea anchor is a different beast altogether.
But the beauty is that my Seabrake serves both as a drogue and a sea anchor if needed.
Additionally when rigged at the end of the boom with a chain weight under the drogue and boomed out, in a rolly anchorage it settles the boat like magic.
And it is not cheap, but worth every penny.
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Mad Pad
Well-Known Member
I will be briefer..I hope.
1/Drogue
A device to slow you down in a following sea,mainly to stop you being pitch poled or broaching due to excessive speed surfing down a wave.
A drogue can be anything trailed from the yacht...purpose made,a long rope,a short rope with any old crap tied to it ie floor boards buckets,unwanted crew.
2/Sea Anchor
Luckily have only had to cope with 60 knot + winds a few times close to land.
Even when close (100 nm ) to shore my solution was to set the storm jib (normally 50 sq ft on a 35" yacht) back the rudder and heave to.
I think we lost less sea room than employing a sea anchor.
Best Mad Pad
1/Drogue
A device to slow you down in a following sea,mainly to stop you being pitch poled or broaching due to excessive speed surfing down a wave.
A drogue can be anything trailed from the yacht...purpose made,a long rope,a short rope with any old crap tied to it ie floor boards buckets,unwanted crew.
2/Sea Anchor
Luckily have only had to cope with 60 knot + winds a few times close to land.
Even when close (100 nm ) to shore my solution was to set the storm jib (normally 50 sq ft on a 35" yacht) back the rudder and heave to.
I think we lost less sea room than employing a sea anchor.
Best Mad Pad
VO5
Well-Known Member
No. Not exactly.
A drogue is not just a device used in heavy weather sailing just to slow down a boat.
Additionally it has to track straight and to provide directional stability.
And additionally, its function is to keep the stern DOWN so that the boat rides down the wave BOW UP and not BOW DOWN which is the precursor to pitchpoling or being rolled over as a consequence of directional stability not being preserved in critical following sea situations.
And additionally, it should not spin, because if it does the tow line becomes coruscated and behaves like a rubber band which must be avoided.
And additionally and finally, it must remain submerged throughout at an angle astern that guarantees effective bite. Too much weight increases the angle and diminishes the effect of bite, and that, will cause the stern to wander, which is not a good idea. And too little bite will cause the drogue to surface intermittently, again, not good. Not good at all.
Mike k
Well-Known Member
thanks for all the contributions- you have clarified its a sea anchor I need , deployed off the bow with a Y arrangement to cleats and a 60feet rode with anchor chain to the sea anchor. That should slow down the movement of the boat in a tidal flow. Its a 26ft motorboat weighing about 3 tonnes. Many thanks for the explanations. If that doesn't work its a call to the coastguard as Bigwow suggests.
NormanS
Well-Known Member
I think you have been led astray. You say you want the boat to be stopped in an 8 knot current. No sea anchor or drogue is going to do that for you.
RichardS
N/A
Although not led astray by any of the previous posts on this thread. As far as I can recall, every poster has been clear that Mike's idea will not work.
Richard
bigwow
Well-Known Member
Where you sail you can ring Mersey Fire and Rescue direct, their jet driven rib will get to you before you've finished the call:encouragement:
Neil_Y
Well-Known Member
I would seriously think that for Mike's situation an anchor on a long anchor rope would still be the best emergency action to take, maybe set it up so you can use it more easily. You can happily anchor anywhere between the UK and Holland or Denmark or in the Channel with 100m of anchor rode. From a search and rescue point of view you will not be moving where as if you deploy the drogue you'll drift with the tide or current. If you are close to the shore or shallows and close for me would be 5nm then anchor is the only option. Unless it's a raging gale with swell a relatively small anchor will hold you in an 8knt current. So maybe get a smaller anchor with a small length of chain and a long rope you can deploy from the back of the boat in an emergency, that would be my approach. Just lead the rope to the front of the boat but have it ready to deploy.
Kukri
Well-Known Member
Very good summary. I have emphasised it should not spin because THEY ALL DO SPIN if towed on a conventional three strand warp - the spinning is just a way of shedding load by extending the warp, and there is nothing to stop a drogue from spinning.
So you need to have a multiplait warp and you then have to think carefully about whether you want this to be nylon (will stretch - may not be what you want) or Dacron/Terylene (will not stretch much - may transmit shock loads to the attachment points on the boat)..
LadyInBed
Well-Known Member
No, a Sea Anchor is NOT what you need for the job you actually want to do.
See my PS in post 19 http://www.ybw.com/forums/showthread.php?469368-Deploying-a-drogue&p=5910475#post5910475
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