Trailing Warps

[thinwater]

Originally Posted by hpeer

... I wonder under what conditions I would be to deploy a drogue and I would have the guts to work on the aft deck under those conditions.

I did a LOT of drogue testing for some articles, some of it in bad conditions. First drogue a, then recover, then drogue b, then recover, then drogue c.... Nearly all of this was singlehanded. The key to safety is to have a tether attachment point that holds you right at the stern rail and is up high, in my case on the aft edge of the hard top. I fell against the tether untold times, but it never felt dangerous, just tiring.

A jackline tether attachment, secured to a stern cleat is all wrong. Jacklines, for this reason and others, should not, IMO, be secured to mooring cleats, but should end about 4 feet from the ends of the boat. The best answer varies with the boat. But since deploying and recovering drogues is a safety-critical task that will be performed in crappy weather, make sure your tether provides a comfortable, safe brace so that you can used both hands.

[thinwater]

Originally Posted by Snowpetrel

I once chucked about 100 meters of warp out astern after our single element drogue started pulling out of the waves due to having a too short and too strechy line on the drogue and not enough chain.

The extra warp rigged in parallel helped a fair bit and the speed reduction more or less stopped the drogue ripping out. Still it would have been much better if our drogue had been on the end of the 100 meter warp. And ideally on 200 meters of low stretch line.

Even with the drogue and warp we were moving too fast and getting slammed pretty hard at times. It was a very vile night, and I was extremely glad when the wind eased at sunrise.

What type of drogue? At what speed did pulling out of waves become a problem? How long was the rode.

Something you learned but many underappreciate is that when a drogue is on nylon, if it pulls out of a wave it tends to snap forward. Folks have said "the wave threw it forward," but they did not understand what they saw; it was the recoil of nylon. The result is no drogue until the slack is removed. This is why polyester is preferred; reduced recoil.

[Snowpetrel]

Originally Posted by thinwater

What type of drogue? At what speed did pulling out of waves become a problem? How long was the rode.

Something you learned but many underappreciate is that when a drogue is on nylon, if it pulls out of a wave it tends to snap forward. Folks have said "the wave threw it forward," but they did not understand what they saw; it was the recoil of nylon. The result is no drogue until the slack is removed. This is why polyester is preferred; reduced recoil.

Exactly, I will never ever consider using nylon for a drogue again. In our case it was 11mm dynamic climbing rope (typical kernmantle stuff that had been retired from climbing duties), probably 50 meters or so with only a couple of meters of 8mm chain on an old plastic Sea squid (Seabrake HSD 300 copy).

We would have accelerated to 8 or 9 knots when it let go, and then it would slow us to about 4 knots voilently when it caught before being launched airborne again by our giant bungy cord. Very scary stuff.
When we added the 100 or so meters of 20mm 3 strand polyprop in parallel (ie both were out separately) it tamed the speed enough so it stayed in the water.

This was mid way between Hobart and Bluff on a S&S 34. At the time it felt lile we were an awful way away from anywhere.

two warps tangling was a minor concern but it didn't happen. However somehow one of the warps tangled and damaged the fleming windvane. And even with both drag devices we needed to actively steer to keep the drag devices directly upwind.

But I remember seeing the 100 meter warp not even being one wavelength behind us, so that probably made the wavelength something like 120-150 meters, with a speed of 27 knots and a significant wave height around 10 meters or so. It was amazing how quickly the waves built, and I think it might have been an example of dynamic fetch. Certainly it was mighty unpleasant..

[BigBeakie]

Can I ask if anyone has thought of combining the Abbott drogue technique, but use proper drogue devices like perhaps Deltas and then later add a JSD to slide down the warp if sea state deteriorates badly?

It would seem to have the advantage of not needing to retrieve the first drogue before deploying the second, third etc.

I was thinking the first drogue could be on the spin winches when loads are lighter, then could transition to stronger tow points like extra strong bases with shackle eye of stern cleats when seas get bigger/steeper/breaking.

Any thoughts on that from your testing experience Thinwater, or anyone?


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[Suijin]

Originally Posted by hpeer

With our 44’ LOD, 37’LWL, 40,000 lbs displacement. I wonder under what conditions I would be to deploy a drogue and I would have the guts to work on the aft deck under those conditions.

I agree based on personal experience that with your length and displacement, up to force 9 you're best off running bare poles. That is IF you have a wind vane and/or auto pilot to steer, particularly at night. Force 10 is pretty unusual for any sustained period. If I saw that coming that's when I would start preparing to deploy the drogue. Then again, it's really about the sea state more than the actual wind speed. Sustained Force 9 with a longer wave period is generally manageable. Force 10 is almost certainly not.

As mentioned one of the primary benefits of a drogue is keeping the boat lined up with the waves. But deploying (and retrieving) a drogue has it's dangers and complications and should not be done without due consideration. Let the boat run with the waves until you're of the opinion that you're headed towards the threshold where it is no longer safe to do so.

[thinwater]

Originally Posted by BigBeakie

Can I ask if anyone has thought of combining the Abbott drogue technique, but use proper drogue devices like perhaps Deltas and then later add a JSD to slide down the warp if sea state deteriorates badly?

It would seem to have the advantage of not needing to retrieve the first drogue before deploying the second, third etc.

I was thinking the first drogue could be on the spin winches when loads are lighter, then could transition to stronger tow points like extra strong bases with shackle eye of stern cleats when seas get bigger/steeper/breaking.

Any thoughts on that from your testing experience Thinwater, or anyone?


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There are several reasons you would not do that.

First, recovering warps is not difficult. They don't generate that much drag and you can just winch them in. You should not be waiting to do this untill survival conditions.

Second, the warps, if long enough, could easily foul the "propper" drogue during deployment. Then you would be in a terrible pickle.

Third, the warp becomes a long bridle, and with any yawing at all, will be loaded on one leg at a time. This causes fatigue and chafe.

Fourth, and most importantly, the "proper drogue" would be free to slide from side-to-side on the warp (which is now the bridle). This reduces or even eliminates its ability to control yaw (I have tested this sort of floating bridle) and risks fatal chafe.

So you really want to pull the warps in before deploying something different. That this is easy is their greatest virtue.

What you really want to do--and I repeat this often--is go out in near-gale conditions and test your gear. Every boat is different, gear varies, and you will learn things about deployment, rigging, and recovery that you won't find in a forum.

[BigBeakie]

Originally Posted by thinwater

There are several reasons you would not do that.

First, recovering warps is not difficult. They don't generate that much drag and you can just winch them in. You should not be waiting to do this untill survival conditions.

Second, the warps, if long enough, could easily foul the "propper" drogue during deployment. Then you would be in a terrible pickle.

Third, the warp becomes a long bridle, and with any yawing at all, will be loaded on one leg at a time. This causes fatigue and chafe.

Fourth, and most importantly, the "proper drogue" would be free to slide from side-to-side on the warp (which is now the bridle). This reduces or even eliminates its ability to control yaw (I have tested this sort of floating bridle) and risks fatal chafe.

So you really want to pull the warps in before deploying something different. That this is easy is their greatest virtue.

What you really want to do--and I repeat this often--is go out in near-gale conditions and test your gear. Every boat is different, gear varies, and you will learn things about deployment, rigging, and recovery that you won't find in a forum.

Thanks Thinwater, for those points.

Some of these points we'd thought about, such as the length of warp & risk of tangling. If a warp is too long, it seems to me it would at some point collapse on itself as the water pressure is not great enough to keep it "open' in a U shape and it would be like dragging a single line, ie useless.

We had thought we'd put the drogues, on their own lines of dyneema with a a low friction ring, down the warp end, and that might address chafe.

But your point that we'd lose the straight tracking advantage of a drogue attached to a fixed point of correctly sized bridle, is a good one. Larger cats track pretty straight when going down waves though, and if the boat speed is managed by the drogue to safe levels ( below surfing speeds), I was thinking the yawing could be controlled well enough.

But you're right, I haven't tried it yet, but we certainly will when we launch the new cat. I am surprised by the number of people who say they have a drogue or parachute anchor in a locker somewhere, but have never actually tried it when it's a bit rough, for practice. Everything has a learning curve, and finding the lessons during a storm could be too "exciting".

[Franziska]

Practical question on the Abbott Drogue mentioned here earlier in this thread.

How do you slide the hose on when the rope is attached on both ends and very heavily under load?

I could see a problem doing this as the moment you take one end of the winch you'd need to hold the full load for the few moments it takes to slide the hose past the winch.

One option I can see is to slide several hose sections onto the rope before the rope gets deployed and keep those sections "onboard".
Once you need to slide something down, you just launch it.
Second question is how do you tie the part you want to slide down onto the hose without constricting it to much and with this preventing it from sliding?

We carry a very long and strong rope and car tire with us for this.

[BigBeakie]

Originally Posted by Franziska

Practical question on the Abbott Drogue mentioned here earlier in this thread.

How do you slide the hose on when the rope is attached on both ends and very heavily under load?

I could see a problem doing this as the moment you take one end of the winch you'd need to hold the full load for the few moments it takes to slide the hose past the winch.

One option I can see is to slide several hose sections onto the rope before the rope gets deployed and keep those sections "onboard".
Once you need to slide something down, you just launch it.
Second question is how do you tie the part you want to slide down onto the hose without constricting it to much and with this preventing it from sliding?

We carry a very long and strong rope and car tire with us for this.

I stress again, I haven't tried any of this yet, so this is just a thought exercise at this point, but this is what we imagine:

Your idea if keeping some tubes already loaded on the warp at the ready in the cockpit is good. We thought we'd do the same with some beefy low friction rings and then soft shackle the drogue rode thimbled eye to the ring, to try to avoid chafe. We thought the tube/hose would chafe the warp,and yes, how do you attach the drogue rode to it strong enough?

Or you could use another winch to take the load off the warp with a line and a hitch on the warp long enough to unwrap the winch, load the tube or friction ring, reload the winch and untie the hitch, then launch the additional drogue down the warp.

Keep the ideas coming....

[Franziska]

Regarding the chafe prevention, a section of beefy Dyneema in the center of the loop would help.
Still that would mean always adjusting from both sides.

[Franziska]

One way to connect.
We have prepped this to rig the parachute anchor, as Dyneema is very chafe resistant.

The plan is to put the Dyneema on the bow cleat, wrap it (inside a fire hose) once around the fwd beam and than have the connection away from any chafe point on the boat.
This happens to both bows and forms the bridle.
Our aft beam is accessible so we can wrap the Dyneema directly around it.

Still the Dyneema to warp center connector could perhaps be done in a similar way with a tight fire hose on top.

[arsenelupiga]

Originally Posted by Franziska

One way to connect.
We have prepped this to rig the parachute anchor, as Dyneema is very chafe resistant.

The plan is to put the Dyneema on the bow cleat, wrap it (inside a fire hose) once around the fwd beam and than have the connection away from any chafe point on the boat.
This happens to both bows and forms the bridle.
Our aft beam is accessible so we can wrap the Dyneema directly around it.

Still the Dyneema to warp center connector could perhaps be done in a similar way with a tight fire hose on top.
Attachment 168429

link does not look right, you lose 50 % strength on each rope just like that. larger diameter metal shackle in between should do better.

If that not possible at least 'reef knot like' link should be somewhat better. You want to have rope turn radius as large as you can. It will break where radius is the smallest.

Or maybe fatter soft shackle.

[StuM]

Originally Posted by arsenelupiga

link does not look right, you lose 50 % strength on each rope just like that. larger diameter metal shackle in between should do better.

Why do you think you lose 50% strength on each rope? Larksheads are generally reckoned to weaken a line by about 20-25%.

And look at the load distribution on a loop. you have two legs taking the strain so theoretically, you have double the breaking strain

Knots such as bowlines don't usually break in the loop, they break at the knot.

If that not possible at least 'reef knot like' link should be somewhat better. You want to have rope turn radius as large as you can. It will break where radius is the smallest.

Aaaaaaaaahhhhhhh! Anything like a reef knot is bad in this situation for so many reasons!

[arsenelupiga]

Originally Posted by StuM

Why do you think you lose 50% strength on each rope? Larksheads are generally reckoned to weaken a line by about 20-25%.

And look at the load distribution on a loop. you have two legs taking the strain so theoretically, you have double the breaking strain

Knots such as bowlines don't usually break in the loop, they break at the knot.

Aaaaaaaaahhhhhhh! Anything like a reef knot is bad in this situation for so many reasons!

looking at my dyneema strength chart, if part of circle has radius 1 or less thickness of rope, strength is 50%. In this link smallest circle is where dyneema surrounds itself - that part of circle is sharpest (although very small angle change) and would be breaking point.

Presume white rope has similar characteristics.

I have done some in depth studies when implementing dyneema steering cables. Too quick one introduces weakness if not very careful.

[Franziska]

Actually the white one is 18mm Nylon, the grey one is 14mm Dyneema.

The sole reason for the Dyneema feeder is its very high chafe resistance.
It's a lot stronger than the 18mm Nylon warp.

We wanted to eliminate metal to rope contact as far as reasonably possible.
Only area where Dyneema goes onto metal is at the loop over the smooth bow cleat.
The rest of the Dyneema and few feet of the Nylon are inside an extra thick firehose.

They wrap once around the fwd beam before going overboard and forming the bridle.