Jordan Series Drogue experience

[rgleason]

I see Jim Cate already suggested this! I must have read his post. I think its a good idea.

[rgleason]

Actually it is others including beth and evans

[transmitterdan]

Why not splice a smaller nylon messenger line to the aft end of the drogue? Make it plenty longer than the drogue (say 30%) so that little or no force is applied when the main line stretches under load. After deployment tie the boat end of the messenger to a strong point on the boat. Then when retrieving the drogue you pull on the messenger line and thus retrieve the drogue backwards so the cones are not creating resistance?

When storing the drogue lash the messenger to the drogue every few yards with very small twine. Then it stays neatly with the drogue until deployed but the small lashings can break away if necessary. I don't think the messenger will interfere with the functioning of the cones. If the drogue breaks it will drag behind the boat inverted but remain attached by the messenger. Thus the broken end can be retrieved or one could just cut the messenger and let it go depending on conditions.

I have not tried this but have thought I would do a test of it when I make my own drogue. I plan to do as SWL is thinking. Buy cones and line and assemble it myself.

[UNCIVILIZED]

transmitterdan, given that your boat has a canoe stern, how do you plan to attach a JSD to the boat? As the recommended method seems to be to fabricate a set of chainplates to heavily bolt to a boat's hull at her aft end. Along with adding extra layers of laminate & backing plates to the hull's inside where the chainplates attach. And with a boat with a conventional transom this would nominally be fairly easy to do, barring a tiny IOR type stern. As hulls are pretty commonly slab sided back there.

On some boats (okay, many) it's also wise to add a few heavily glassed in place knees tying the transom to the hull sides in the vicinity of the chainplates. This in addition to reinforcing the hull's skin. As the attachment point for the drogue needs to be able to handle the full weight of the boat. Given that in a worst case scenario, the drogue will repeatedly be preventing the boat from flying off of wave tops, fully airborne at significant speeds.

[carstenb]

Originally Posted by transmitterdan

Why not splice a smaller nylon messenger line to the aft end of the drogue? Make it plenty longer than the drogue (say 30%) so that little or no force is applied when the main line stretches under load. After deployment tie the boat end of the messenger to a strong point on the boat. Then when retrieving the drogue you pull on the messenger line and thus retrieve the drogue backwards so the cones are not creating resistance?

When storing the drogue lash the messenger to the drogue every few yards with very small twine. Then it stays neatly with the drogue until deployed but the small lashings can break away if necessary. I don't think the messenger will interfere with the functioning of the cones. If the drogue breaks it will drag behind the boat inverted but remain attached by the messenger. Thus the broken end can be retrieved or one could just cut the messenger and let it go depending on conditions.

I have not tried this but have thought I would do a test of it when I make my own drogue. I plan to do as SWL is thinking. Buy cones and line and assemble it myself.

Drogues have a tendency to twist when deployed. I suspect your messenger line will end up twisting itself around the main deployment line and eventually around the cones, markedly decreasing the effectivity of the drogue.

Others have tried tying a small fender on a very long messenger line at the end of the drogue. I do not know if that works - the theory is that the fender will stay far behind the drogue and not twist into it, although tying something that floats to the end of the drogue seems self-defeating. you want the drogue to be down in the water and any fender or similar that would float would tend to bring the back end of the drogue up to the surface.

I've never heard of a good solution for this - other than spending the couple of hours necessary to recover the drogue by winching it in

[transmitterdan]

My canoe stern has huge eyes about a foot above the waterline and about 9" inboard on either side of the stern as you view from the rear. Inside the stern there are huge backing plates the spread the load on these eyes across most of the transom and a bit forward but that part doesn't do much. I think the boat could be picked up and held in the air by these 2 eyes. Their main purpose is to support a giant pipe davit for a RIB. But on an ocean passage I remove these and store them in the bilge or in the forepeak with the sails and other gear. We sleep in the center part of the boat on passage as we have good lee cloth berths. And the aft cabin is quite comfortable too so we don't much use the vee berth on passages.

I take your point on twisting. I would not use 3-strand for the drogue. But I guess you are right there is no truly good solution.

[NevisDog]

Originally Posted by mikereed100

... ... Third, and most surprising, was that when we retrieved the drogue in the morning we found that most of the cones had frayed badly, particularly those closest to the boat ... The leading edges were most affected, but the trailing edges were frayed as well. This was after only 2-3 hours of gale force conditions.
... My wife put ours together from a Sailrite kit, which uses lightweight ripstop polyester for the cones without reinforcement. ...

With this warning ringing in my ears, I looked more carefully at what's on offer out there -
- Sailrite US: 2.6 oz nylon cones, no reinforcing = $313 / 100 cone kit.
- Ace Sailmakers US: 6.5 oz dacron, stitched over hem = $700 / 100 cones.
- Ocean Brake UK: 4.2 oz nylon, taped edges = $834 / 100 cones, including rope!
- 'englishseadog' UK: 7.2 oz dacron, taped edges = $442 /100 cones.

Not sure yet but 'englishseadog' may be the eBay title for Neptune's Locker (at least both are in Weymouth, UK). All prices in USD.

Above are the most important differences, though there are others (width of tape used, etc). Note particularly that -
- Sailrite price is for materials kit only - cones are cut to shape but you have to stitch them up yourself. They can supply extra tape if you want to tape the cone edges.
- Ocean Brake price is for the complete series drogue already mounted on the 16mm nylon leader and 14mm nylon tail, ready to deploy: only the bridles (made to size) and weight at the end are extra.
[Of course 100 cones is only for smaller displacement yachts; I'll need about 124 (plus a few spares).]

[DumnMad]

Originally Posted by NevisDog

With this warning ringing in my ears, I looked more carefully at what's on offer out there -
- Sailrite US: 2.6 oz nylon cones, no reinforcing = $313 / 100 cone kit.
- Ace Sailmakers US: 6.5 oz dacron, stitched over hem = $700 / 100 cones.
- Ocean Brake UK: 4.2 oz nylon, taped edges = $834 / 100 cones, including rope!
- 'englishseadog' UK: 7.2 oz dacron, taped edges = $442 /100 cones.

Not sure yet but 'englishseadog' may be the eBay title for Neptune's Locker (at least both are in Weymouth, UK). All prices in USD.

Above are the most important differences, though there are others (width of tape used, etc). Note particularly that -
- Sailrite price is for materials kit only - cones are cut to shape but you have to stitch them up yourself. They can supply extra tape if you want to tape the cone edges.
- Ocean Brake price is for the complete series drogue already mounted on the 16mm nylon leader and 14mm nylon tail, ready to deploy: only the bridles (made to size) and weight at the end are extra.
[Of course 100 cones is only for smaller displacement yachts; I'll need about 124 (plus a few spares).]

Mike said he had a nylon rode - that stretch meant the cones nearest the boat were taking maximum surge speed while the ones further back were more gradually coming under load. Boat rises to the top of the wave, is thrown forward by wind and water then slows as the drogue comes into effect.
He said he would change to Dyneema Less stress on the cones if the boat is held back sooner.

[CarinaPDX]

I thought the choice of nylon odd. IIRC Donald Jordan called for low-stretch materials. The greater stretch would reduce the immediate slowing effect, and crucially increase heating within the rope potentially leading to eventual failure (the cyclic loading/unloading can create a lot of heat in a stretchy material). OTOH there is less impact loading, but that isn't much of a problem due to the distributed design. I would stick with Jordan's original recommendation, unless someone wanted to do an engineering analysis on the system including heating effects for different materials.

Greg

[sailormed]

Being water cooled I wouldn't worry much about the stretch heating effect.

[DefinitelyMe]

Wonderful post, thanks very much.

We lay to a single cone drogue in a force nine in the North Atlantic ten years ago that lasted for about 36 hours. Waves were ten metres. In that case, the nylon rodes (we had two rodes each led to one of the cockpit primaries) were indispensable I feel, however I can see the logic of your decision to replace with dyneema. Perhaps. My concern would be when the waves get bigger than the ones you experienced - we were getting picked up and thrown by some of them. The load exerted on the boat by the waves themselves was erratic, and would still be erratic with a series drogue I think. What we really need is shock absorption coupled with some form of rebound damping. Any ideas for that anyone?

[DumnMad]

Originally Posted by DefinitelyMe

Wonderful post, thanks very much.

We lay to a single cone drogue in a force nine in the North Atlantic ten years ago that lasted for about 36 hours. Waves were ten metres. In that case, the nylon rodes (we had two rodes each led to one of the cockpit primaries) were indispensable I feel, however I can see the logic of your decision to replace with dyneema. Perhaps. My concern would be when the waves get bigger than the ones you experienced - we were getting picked up and thrown by some of them. The load exerted on the boat by the waves themselves was erratic, and would still be erratic with a series drogue I think. What we really need is shock absorption coupled with some form of rebound damping. Any ideas for that anyone?

Nylon shock absorbtion is needed for a parachute which has a large resistance even at low speeds but the small cones absorb impact by having low resistance at low speeds but increasing with the square of velocity to counter surfing.

[Pauls]

Anyone who wants to build a Jordan Series Drogue should read what Dan Jordan said about how to build them. This is the guy who did the testing, developed the concept and quantified loads and design factors. His full report, published by the Coast Guard, gives the design details on series drogues. Here is the link: http://www.jordanseriesdrogue.com/pd...uardreport.pdf

Jordan recommends double braid nylon. And he includes a chart showing increased loads as the rode becomes stiffer.

For those advocating using dyneema as a rode, you are reducing load on the cones nearest the boat at the expense of increasing shock loads on the hull attachment points and the rode itself. Which is most important to you? I'd rather build the cones a little heavier and reduce the loads on the hull attachment, personally.

[DumnMad]

Originally Posted by Pauls

Anyone who wants to build a Jordan Series Drogue should read what Dan Jordan said about how to build them. This is the guy who did the testing, developed the concept and quantified loads and design factors. His full report, published by the Coast Guard, gives the design details on series drogues. Here is the link: http://www.jordanseriesdrogue.com/pd...uardreport.pdf

Jordan recommends double braid nylon. And he includes a chart showing increased loads as the rode becomes stiffer.

For those advocating using dyneema as a rode, you are reducing load on the cones nearest the boat at the expense of increasing shock loads on the hull attachment points and the rode itself. Which is most important to you? I'd rather build the cones a little heavier and reduce the loads on the hull attachment, personally.

Dyneema wasn't available in those days

[NevisDog]

Originally Posted by DumnMad

Dyneema wasn't available in those days

The reference to preferring less stretch in the towline in the USCG/Don Jordan report states (p.52 para 2) (in reference to a single drogue) "Actually the model tests show that a highly elastic line is very undesirable because the boat may be capsized before the load builds up."
Fig 24C then shows a 300% increase in towline stiffness results in only a 20% increase in (maximum) drogue load (again based on a single drogue).

I would guess that the series drogue would produce an even smaller increase in maximum load due to reduced stretch in the line (since resistance is spread along the line, rather than applied at the line end), making Dyneema a viable, perhaps even a preferable option. Makes me wonder why nylon was used throughout the tests, instead of say polyester?