Acquiring A Ready Made Series Drogue

[Dockhead]

Originally Posted by kmacdonald

WOW!!!! Can't believe you said that. Throwing stones while hiding behind "moderator" doesn't garner you respect. Try to stay on subject and task!!!!!!!!!!

Not "stones", but a friendly suggestion to argue less and read more. Word to the wise.

[Davidhoy]

Originally Posted by kmacdonald

Sea buoys don't support that but they are very limited in location. That may be true in isolated locations but aren't reported buy merchant mariners on a regular basis. I'd like to know ESA's definition of rogue wave is.

Here's a link to the MAXWAVE study report - http://www.soest.hawaii.edu/PubServi.../Rosenthal.pdf. I have not read the whole thing yet, but a quick scan was quite intriguing.

-David

[kmacdonald]

Originally Posted by Dockhead

Not "stones", but a friendly suggestion to argue less and read more. Word to the wise.

Yes, friendly suggestions among friends. What was I thinking?

[Dockhead]

Originally Posted by kmacdonald

Yes, friendly suggestions among friends. What was I thinking?

Exactly

[kmacdonald]

OK, so far it's been well established that JSD's are not used in survival conditions and cruisers don't encounter those conditions anymore. Thirty or forty years ago that may not have been the case but with better weather forecasting that has changed. We have seen the dramatic over exaggeration in anchor rode selection as we have in JSD design criteria. It may be time to revisit the recommendations.

[Don C L]

Originally Posted by Dockhead

Indeed! But fatigue is ALWAYS an issue in an ocean storm. It may blow for days at a time. What is manageable with intense effort for some hours, might not be manageable at all, for days.

A full and well organized crew is a huge factor in getting through something like this. The limitations of single handed or double handed sailing very quickly make themselves obvious in a serious ocean blow.

And a drogue may be a life saver exactly for this reason -- you are in conditions which are somewhat mangageable with really active helming, but it wears you down after a certain period of time. Putting the drogue out and putting on the pilot might save you just from the point of view of fatigue.

Actually Shane describes it as unnecessary to employ an AP or vane while the drogue is out, especially the medium pull, since it maintains the boat’s attitude to wind and (hopefully) waves too. The only fly in the ointment is the companionway and main hatch strength, to be sure they can handle the possibility of a solid poop. I heard of someone once who had their main hatch blown off by a wave so now I eye my own with extreme suspicion.

[kmacdonald]

Originally Posted by Davidhoy

Here's a link to the MAXWAVE study report - http://www.soest.hawaii.edu/PubServi.../Rosenthal.pdf. I have not read the whole thing yet, but a quick scan was quite intriguing.

-David

The weather service says: Seas are reported as significant wave height, which is the average of the highest third of the waves. Individual wave heights may be more than twice the significant wave height.

The report cited above calls waves twice the significant wave height "rogue waves". Like I said before, it depends how they define rogue waves whether they exist or not. Gigantic waves are not a problem if they are not breaking.

[Don C L]

I think the official definition of rogue wave much like what one politician said of the term “porn,” I know it when I see it.

[kmacdonald]

Originally Posted by Don C L

I think the official definition of rogue wave much like what one politician said of the term “porn,” I know it when I see it.

Yup. It's like a moving target. Depends on the size of the boat and the eyes of the observer.

[thinwater]

A slight diversion:

A JSD is a multi-element drogue made from many 5" cones. A single element drogue uses a single drogue element of a more stable and stronger design, typically 2-3 feet in diameter. Another option is a drogue that uses 2, 3 or some other number of elements. The JSD is hard to recover and very stable. A single element drogue is much easier to use, typically has less drag (but does not have to--that is a sizing decision), and is unstable over specific loading (pulls out of wave face). A 2-3 element drogue has about the same braking force as a JDS, is much more like a JSD in terms of stability, is more versatile (a single element can be used for emergency steering and slowing down just a little--you can't effectively shorten a JSD for reasons of stability and durability), and is much easy to handle. If the storm builds, you simply add another drogue and play out line (and rig a new bridle). Remember that these are more sophisticated constructions, more stable than the primitive JSD cones.

Starzinger posted something here (post 97).
http://www.cruisersforum.com/forums/...-185292-7.html

I have tested them as well, but not past near gale conditions. That said, I also tested 1/3-scale drogues at what amounted to F10-11 loadings and wave sizes. I tested many styles--they all worked.

However, I've seen very few reports of people trying this. It really does work. As with the JSD, The drogues work as a team to stabilize each other; the increase in stability is more than double. With three elements, it becomes mathematically very much like a JSD. Really, it is a continuum.

I would like to see more people try this approach so that we could learn more about it.

[Dockhead]

Originally Posted by thinwater

A slight diversion:

A JSD is a multi-element drogue made from many 5" cones. A single element drogue uses a single drogue element of a more stable and stronger design, typically 2-3 feet in diameter. Another option is a drogue that uses 2, 3 or some other number of elements. The JSD is hard to recover and very stable. A single element drogue is much easier to use, typically has less drag (but does not have to--that is a sizing decision), and is unstable over specific loading (pulls out of wave face). A 2-3 element drogue has about the same braking force as a JDS, is much more like a JSD in terms of stability, is more versatile (a single element can be used for emergency steering and slowing down just a little--you can't effectively shorten a JSD for reasons of stability and durability), and is much easy to handle. If the storm builds, you simply add another drogue and play out line (and rig a new bridle). Remember that these are more sophisticated constructions, more stable than the primitive JSD cones.

Starzinger posted something here (post 97).
http://www.cruisersforum.com/forums/...-185292-7.html

I have tested them as well, but not past near gale conditions. That said, I also tested 1/3-scale drogues at what amounted to F10-11 loadings and wave sizes. I tested many styles--they all worked.

However, I've seen very few reports of people trying this. It really does work. As with the JSD, The drogues work as a team to stabilize each other; the increase in stability is more than double. With three elements, it becomes mathematically very much like a JSD. Really, it is a continuum.

I would like to see more people try this approach so that we could learn more about it.

I think one of the issues which is supposed to be addressed by the JSD is matching the drag system to the wavelength of the seas. If you have the drag spread out over a long distance, this is supposed to reduce the risk of a mismatch, which is what causes parachute sea anchors, for example, to pop out of a wave face, a potentially very dangerous situation.

Maybe spreading it out over at four or five devices would solve this; I don't know.

[Snowpetrel]

^^ The multielement drogue concept is very appealing. I like the way it would enable an easy transition from a steering drogue (1 element) to a speed limiting drogue (2 elements) and to a survival drogue (3 elements) and back as the wind eases.

Much easier to build and store as well. Fatty Goodlander talks about a similar idea in his excellant book "storm proofing your boat". Bob and Nancy Griffith used a similar system on Awanee using multiple car tyres when they circumnavigated antarctica in the 70's, and back in the 30's Jonny Wray survived a Hurricane by trailing his gaff, boom, mainsail and a heap of other stuff after being rolled and badly damaged. So it would seem like it has been well tested over the years. From what I recall Evans uses a similar system.

It would be interesting to nut out how it would best be handled while under load. Each element would have to be very strong. I have two solid plastic original seabrake drogues that would form a good basis for a mulitielement system.

[Snowpetrel]

Originally Posted by Don C L

I think the official definition of rogue wave much like what one politician said of the term “porn,” I know it when I see it.

Offically it's twice the significant wave height.

Rogue waves have been part of sailors lore for centuries, only recently has the sceince around them started to emerge.

I have seen three that were definate rogues. The one in the video I linked to above was not a rogue, being only about 1.8x the significant wave height.

[thinwater]

Originally Posted by Dockhead

I think one of the issues which is supposed to be addressed by the JSD is matching the drag system to the wavelength of the seas. If you have the drag spread out over a long distance, this is supposed to reduce the risk of a mismatch, which is what causes parachute sea anchors, for example, to pop out of a wave face, a potentially very dangerous situation.

Maybe spreading it out over at four or five devices would solve this; I don't know.

In practice, 2 is enough, since even a single drogue only rarely comes out. Two makes this very, very unlikely, plus the load on each element is 1/2, reducing the probability farther (they only come out when overloaded). Yes, that is exactly the problem you are trying to solve.

I tested using Seabrake, Delta Drogue, and Gale Rider. A Shark would also be very good. As Evan pointed out, the Delta needs to have a grommet added for the pass-through (not structural). The others are adaptable as-is (Shark has pendant, Gale Rider has the grommet, Seabrake has a pass-through).

The transition feature is nice. It can also be used to reduce drag at the end of a storm; just winch one in.

I also have a bias towards having a steering drogue, having jammed a rudder once. MANY boats are abandoned in moderate weather when they loose steering, and this is sad. It's simple to rig a drogue to steer... if you have one... and a JSD tail doesn't really work. The JSD is actually incredibly unstable when shortened, one of the reasons Jordan was emphatic about using enough cones. A JSD makes a crappy speed limiting drogue. I've tried it and it is basically dangerous.

[conachair]

Originally Posted by Snowpetrel

Offically it's twice the significant wave height.

Rogue waves have been part of sailors lore for centuries, only recently has the sceince around them started to emerge.

I have seen three that were definate rogues. The one in the video I linked to above was not a rogue, being only about 1.8x the significant wave height.

The science ever digs deeper, non linear physics seems to be favoured ..
https://www.sciencedaily.com/release...1013095756.htm

Interestingly similar nonlinear waves have been studied in optics and Bose-Einstein condensates.

https://www.nature.com/articles/srep20785

Funny but no hits on Google scholar about rogue waves being a figment of wild imaginations