Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 11-02-2019, 14:02   #16
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: The boat: Cowes (Winter), Above 60N (Summer); me: somewhere in the air!
Boat: Cutter-Rigged Moody 54
Posts: 23,537
Re: Drogue Failures

Quote:
Originally Posted by Adelie View Post
What are G-G boats?

Golden Globe.
__________________

__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 11-02-2019, 14:06   #17
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: The boat: Cowes (Winter), Above 60N (Summer); me: somewhere in the air!
Boat: Cutter-Rigged Moody 54
Posts: 23,537
Re: Drogue Failures

Quote:
Originally Posted by thinwater View Post
. . . Nylon vs. polyester vs. Dyneema is an interesting question. However, Dyneema could not be used on GG boats.



Really??


Count me out of any future GG races then! I am addicted to UHMWP cordage. As far as I can recall, the only polyester cordage left on my boat is a couple of twing control lines, and a mainsail furling line. Even my jib and staysail furling lines are dyneema.
__________________

__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 11-02-2019, 16:04   #18
Registered User
 
oldbilbo's Avatar

Join Date: Sep 2010
Location: Southern England - the 'old', not the 'New'
Boat: Marcon Cutlass 27
Posts: 29
Re: Drogue Failures

Quote:
Originally Posted by thinwater View Post
If you check the strength loss around a bend tables from the rope makers, you will find that the loss is 50% when D=d. The eye splice is a very different case than a rope over a pulley.

There is no error in connection method.

I'm thinking we need to look a little deeper into this.


First, my JSD rode will NOT be 2 or 3 part, but one continuous Dyneema/DynuxDux/UHDPE singlebraid line. I will need to attach a chain-weight at the distal end, but that's not an issue. However, the attachment of this singlebraid to the twin parts of the bridle IS of importance.


I expect to use a pair of suitable professionally-constructed lifting strops, which are cheap, and which have antichafe sleeves on the loops at each end. Those three parts will need to be joined by a very robust D-shackle, which is also quite cheap as part of a dedicated assembly.


The question is how best to attach the proximal end of the singlebraid rode. Does one use a simple eyesplice and pass the shacklepin through the loop? Does one better use a cow hitch around the shacklepin? Or does one best use a manufactured 'hard eye' with the shacklepin passing through this, as shown in the attached pic from Colligo Marine?






I can't speak definitively for Colligo, or for rope manufacturers such as Marlow, but it is my understanding they all recommend the use of an appropriate-size hard eye for best strength in high loadings.


Perhaps there's some comparative data showing the ultimate strength of spliced assemblies, with and without a hard eye.
oldbilbo is offline   Reply With Quote
Old 11-02-2019, 16:11   #19
Registered User

Join Date: Jun 2010
Location: Easton, MD
Boat: Catalina 22 Capri, 15' Catboat, Bristol 35.5
Posts: 2,216
Re: Drogue Failures

thinnwater, if you were to make a Jordan Series Drogue would you use dyneema?
kmacdonald is offline   Reply With Quote
Old 12-02-2019, 07:33   #20
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: The boat: Cowes (Winter), Above 60N (Summer); me: somewhere in the air!
Boat: Cutter-Rigged Moody 54
Posts: 23,537
Re: Drogue Failures

Quote:
Originally Posted by oldbilbo View Post
I'm thinking we need to look a little deeper into this.


First, my JSD rode will NOT be 2 or 3 part, but one continuous Dyneema/DynuxDux/UHDPE singlebraid line. I will need to attach a chain-weight at the distal end, but that's not an issue. . .



Why would you do that? You can taper the sections gradually, and this has a significant advantage in weight and cost. The connection is trivial, with single braid dyneema -- make eyesplices at every end of every section, and lead each tail through each eye. This is not like a cow hitch as the loops fit over each other with a milder bend. And in any case, the reserve of strength is quite enough to deal with this.


Alternatively, you can splice dyneema sections of different diameters together. But there are a lot of advantages to just looping eye splices through each other -- you can take the drogue apart to work on it, and you might want to use just one section of it for something like, for example, a steering drogue, in case of steering failure.



Quote:
Originally Posted by oldbilbo View Post
. . . However, the attachment of this singlebraid to the twin parts of the bridle IS of importance.


I expect to use a pair of suitable professionally-constructed lifting strops, which are cheap, and which have antichafe sleeves on the loops at each end. Those three parts will need to be joined by a very robust D-shackle, which is also quite cheap as part of a dedicated assembly.


The question is how best to attach the proximal end of the singlebraid rode. Does one use a simple eyesplice and pass the shacklepin through the loop? Does one better use a cow hitch around the shacklepin? Or does one best use a manufactured 'hard eye' with the shacklepin passing through this, as shown in the attached pic from Colligo Marine?


I can't speak definitively for Colligo, or for rope manufacturers such as Marlow, but it is my understanding they all recommend the use of an appropriate-size hard eye for best strength in high loadings.


Perhaps there's some comparative data showing the ultimate strength of spliced assemblies, with and without a hard eye.

Why would you cow hitch it? This increases the acuity of the bend. Just make an eye splice and pass the pin through it.



Pay attention to bend radius. If the pin is equal to the diameter of the rope, and the pin is quite smooth, then you should be ok. Bend radius of 1:1 in dyneema apparently results in a slight reduction of strength; if you can go 1:1.5 then this disappears, but again, the reserve of strength should be plenty adequate to cover this. But testing shows 1:1 gives 94% of line strength which ought to be quite enough.



It's discussed here: bend radius with larger diameter dyneema - Gear Anarchy - Sailing Anarchy Forums


Evans Starzinger is a great expert on these subjects.


Evans does not use thimbles with single braid dyneema, but you might consider if there is any risk of chafing. Your shackle pins need to be mirror smooth.


I have large loops spliced in all of my drogue sections, and I am using my stern cleats (verified by the designer to be strong enough) and fairleads with chafe sleeves. The bend radius around the massive cleats is, obviously, fine.




P.S. When you make your eyesplices, pay attention to throat angle. Too small, too tight eyes, reduce strength. Also discussed in the linked article.
__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 12-02-2019, 08:30   #21
Registered User

Join Date: Jun 2010
Location: Easton, MD
Boat: Catalina 22 Capri, 15' Catboat, Bristol 35.5
Posts: 2,216
Re: Drogue Failures

I like my idea of multiple sections so they can be switched between uses to even wear on cones. Dockhaeds suggestion of using multiple sections so the number of sections used can be varied for the situation, ie emergency steering. Dyneema dramatically reduces size and weight and increases abrasion resistance. Can also increase strength without adding a lot more size and weight.
kmacdonald is offline   Reply With Quote
Old 12-02-2019, 08:53   #22
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: The boat: Cowes (Winter), Above 60N (Summer); me: somewhere in the air!
Boat: Cutter-Rigged Moody 54
Posts: 23,537
Re: Drogue Failures

Quote:
Originally Posted by kmacdonald View Post
I like my idea of multiple sections so they can be switched between uses to even wear on cones. Dockhaeds suggestion of using multiple sections so the number of sections used can be varied for the situation, ie emergency steering. Dyneema dramatically reduces size and weight and increases abrasion resistance. Can also increase strength without adding a lot more size and weight.

It's not my idea or suggestion to use different sections of different diameters -- it's the original Don Jordan design.


As to using single braid UHMWP instead of other cordage -- the advantages are many:


1. Great increase in resistance to chafing.
2. Much lighter for given strength -- ease of handling can be a life or death matter in a storm.
3. Much easier to splice.
4. Very little stretch so less surging on wave faces (and you don't need stretch for shock absorption -- the cones slipping in the water provide that)
5. Very little stretch so no degradation of strength from cyclical loading.

6. Doesn't absorb water so much easier to recover.
7. Much more compact so much easier to store.



Single braid dyneema is not dramatically more expensive than quality poly or nylon, when you compare strength for strength.


For me, it's a no-brainer.
__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 04-03-2019, 08:36   #23
Registered User
 
deluxe68's Avatar

Join Date: Apr 2009
Location: Arizona/Rhode Island
Boat: Swan 432
Posts: 771
Re: Drogue Failures

Did Galerider go out of business? I was planning on buying one this year, now I am looking into the Fiorentino Shark. Any unbiased reviews on this brand?
deluxe68 is offline   Reply With Quote
Old 05-03-2019, 12:20   #24
Registered User
 
oldbilbo's Avatar

Join Date: Sep 2010
Location: Southern England - the 'old', not the 'New'
Boat: Marcon Cutlass 27
Posts: 29
Re: Drogue Failures

Quote:
Originally Posted by Dockhead View Post
You can taper the sections gradually, and this has a significant advantage in weight and cost. The connection is trivial, with single braid dyneema -- make eyesplices at every end of every section, and lead each tail through each eye
It's my practice to ask WHY. We don't know WHY Jordan picked multiple sections, when he sought simply to 'prove the concept' back in the 70s. It could have been as simple as what he had to hand at the time.


As for the connection being 'trivial' - spliced eye looped through eye - that's an 'assertion'. An opinion, unsupported.



We know something broke on Susie Goodall's JSD and we don't know what. Photographs show 2 sections of different diameters, and perhaps completely different rope construction, joined in paired eye splices. Within that setup there was certainly no D/d.... instead, it was clear to me that was d/D in some significant regard for one of the lines.



I won't blindly accept that form of connection is trivial until/unless there is data. Until then, it is suspect.


I'm grateful for the above references, which help my understanding of known work/tests. I've also looked at the weight differences ( kg/100m ) of representative UHMWP ( ? ) cordage here : http://www.hampidjan.is/Media/dynice...read-press.pdf
In the sizes relevant to the 'small sailboats' we're discussing, the weight difference between 10mm and 8mm/100 metres is 4kg. And 50 metres, only 2kg. Now THAT is trivial. I'll concede on cost, and using the gear for sundry other tasks..... but wonder about all those fabric cones remaining attached!


Certainly, taking steps to reduce abrasion of a Dyneema/SK75-99 loop around a( slightly? ) rusty shackle pin makes sense. It would be easy to slip a section of abrasion-resistant sleeving onto the spliced loops, during construction. It would also be easy to 'sleeve' the shackle pin in a non-rusting smooth tubing, at a cost of pennies, while improving the D/d factor a bit. This kit is 'dedicated safety gear' to me, and I'd certainly spray the shackles with a zinc-rich paint.



Asking questions - quietly challenging assumptions - contributes to keeping me healthy. It's grown into a habit....




Oh, and gently amused to read of the enthusiasm for classic English sports cars e.g the Austin-Healey.... and the reference to iconic engineer/designer Colin Chapman.
oldbilbo is offline   Reply With Quote
Old 05-03-2019, 12:52   #25
Registered User

Join Date: Jun 2010
Location: Easton, MD
Boat: Catalina 22 Capri, 15' Catboat, Bristol 35.5
Posts: 2,216
Re: Drogue Failures

I've always questioned the eye to eye attachment method. Maybe Thinwater could give us his opinion on it.
kmacdonald is offline   Reply With Quote
Old 05-03-2019, 14:07   #26
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: The boat: Cowes (Winter), Above 60N (Summer); me: somewhere in the air!
Boat: Cutter-Rigged Moody 54
Posts: 23,537
Re: Drogue Failures

Quote:
Originally Posted by oldbilbo View Post
It's my practice to ask WHY. We don't know WHY Jordan picked multiple sections, when he sought simply to 'prove the concept' back in the 70s. It could have been as simple as what he had to hand at the time.


As for the connection being 'trivial' - spliced eye looped through eye - that's an 'assertion'. An opinion, unsupported.

Why are you arguing? No one said you can't ask why, and no one called any opinion anything but that. I don't understand the vehemence of this.




Quote:
Originally Posted by oldbilbo View Post
We know something broke on Susie Goodall's JSD and we don't know what. Photographs show 2 sections of different diameters, and perhaps completely different rope construction, joined in paired eye splices. Within that setup there was certainly no D/d.... instead, it was clear to me that was d/D in some significant regard for one of the lines.



I won't blindly accept that form of connection is trivial until/unless there is data. Until then, it is suspect.

Well, get some data then. No one is asking you to believe anything. Suspect whatever you like, and by all means, build your own drogue, however you like and feel best about.


Samson Ropes state that this kind of connection is about 85% as strong as the cordage, with ropes of usual size. Samson Ropes User Manual, p. 33. https://samsonrope.com/catalog/rope-users-manual/.


That would be plenty strong for my use, but I guess that the real strength of such a connection is much more than that. A well done eye splice is as strong as the cordage (see testing here: https://www.chicagoyachtrigging.com/...v=f0aa03aaca95). And a loop of dyneema will be within a few percentage as strong as the cordage from a bend radius slightly greater than the diameter of the cordage (for example, E. Starzinger's testing; see Post 44 here: bend radius with larger diameter dyneema - Gear Anarchy - Sailing Anarchy Forums).


Joined eyes achieve something more than 2x bend radius because the loop of each piece of rope bends around TWO sections of the other rope. Further improving the bend radius is the angle at which the loops meet each other. You can look at joined eyes and see that this is strong. For joining a smaller section of rope with a bigger one, you care only about achieving approximately the strength of the smaller one, and since this is going around two pieces of larger diameter rope, then you have a lot of reserve. So joined eyes of different size cordage should be easily equal to the strength of the smaller cordage, which would mean no loss of strength in the system.



You are welcome to your own conclusions, however, and there are certainly other ways to do it. If you don't care about taking the sections apart later, you can simply splice them together, which is plenty strong and smooth and elegant. I personally prefer to be able to take apart and use a smaller section alone, in case I want less power, for example if an emergency steering drogue is needed. YMMV.



Quote:
Originally Posted by oldbilbo View Post
I'm grateful for the above references, which help my understanding of known work/tests. I've also looked at the weight differences ( kg/100m ) of representative UHMWP ( ? ) cordage here : http://www.hampidjan.is/Media/dynice...read-press.pdf
In the sizes relevant to the 'small sailboats' we're discussing, the weight difference between 10mm and 8mm/100 metres is 4kg. And 50 metres, only 2kg. Now THAT is trivial. . ..

The bridles and first section of my own drogue are 14mm 12-strand. The sections taper from there to 8mm. The drogue is a couple hundred meters long. Whether 10-15kg of weight and a lot of bulk are "trivial" to you or not, is a matter of your own judgement. For a device which has to be handled and deployed possibly in extreme conditions, this is not at all trivial to me. YMMV.
__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 05-03-2019, 15:21   #27
Registered User
 
oldbilbo's Avatar

Join Date: Sep 2010
Location: Southern England - the 'old', not the 'New'
Boat: Marcon Cutlass 27
Posts: 29
Re: Drogue Failures

[QUOTE=Dockhead;2840909] I don't understand the vehemence of this.[quote]


No vehemence. It is simple refutation of largely unsupported opinion based on assumed 'non sequiturs'. Show me the links to the data. I'll draw my own conclusions. If they differ from yours, that's showbiz.


And perhaps what is not understood is that emotion in social media posts - such as vehemence - does not communicate well, if at all, from a keyboard. That is imagined, then erroneously projected into the text. Some might call the application of scepticism in the absence of acceptable data to be an example of 'peer review'......



Quote:
And a loop of dyneema will be within a few percentage as strong as the cordage from a bend radius slightly greater than the diameter of the cordage (for example, E. Starzinger's testing; see Post 44 here: bend radius with larger diameter dyneema - Gear Anarchy - Sailing Anarchy Forums).
I'm pleased to accept that.



Quote:
So joined eyes of different size cordage should be easily equal to the strength of the smaller cordage, which would mean no loss of strength in the system.
That is a supposition, a jump too far, a 'non sequitur'. It does not necessarily follow. Show me the experimental data.



As for your recommendation elsewhere of long splicing a thin cord into a thicker one, again presuming no significant losses of strength, I have found no data to support that claim, so I label it 'specious'. Further, am I supposed to assume from your recommendation that one could expect MY long splices of such cordage to achieve close to 100% of that a very skilled operative? Or just enough%....? Or what?



Trust in one's rigger/trader? Just a week or three back, while in the rigging shop of a noted supplier, I watched a new recruit do a simple tucked splice. Now I do not claim any especial skills, but I have made a handful of such splices myself along the way, and so I asked the young fellow - politely - how long he'd been there. "Oh, almost three weeks," he told me. "I worked on my father's farm before that."



I do know the old aphorism 'Different ships, different long splices' and its meanings in a different metaphor. But I'd have been reluctant to have paid top dollar for that work....


How much do we take on blind trust, and how much do we take on inspection?
oldbilbo is offline   Reply With Quote
Old 05-03-2019, 17:45   #28
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Location: Bellingham
Boat: Outbound 44
Posts: 6,711
Re: Drogue Failures

Dockhead
I'm not clear what your loop attachment is for the multiple sections of the drogue. Are these large loops where you pass the other tail and all the cones through the loop? How is this different than a cow hitch?
Paul L is offline   Reply With Quote
Old 06-03-2019, 00:45   #29
Registered User
 
oldbilbo's Avatar

Join Date: Sep 2010
Location: Southern England - the 'old', not the 'New'
Boat: Marcon Cutlass 27
Posts: 29
Re: Drogue Failures

For what it's worth, here is a pic of such a connection, from a commercially-made JSD. It may help our discussion.....


oldbilbo is offline   Reply With Quote
Old 06-03-2019, 01:31   #30
Registered User
 
oldbilbo's Avatar

Join Date: Sep 2010
Location: Southern England - the 'old', not the 'New'
Boat: Marcon Cutlass 27
Posts: 29
Re: Drogue Failures

Here's something else which popped up on a Pinterest page....




I like the creativity....
__________________

oldbilbo is offline   Reply With Quote
Reply

Tags
drogue

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hurth / ZF M15A Transmission Failures tomj Propellers & Drive Systems 138 06-05-2016 04:05
Maine Passage - Successes and failures, Moving On... skipgundlach General Sailing Forum 2 20-08-2008 08:20
Warning: Pre-1994 Crewfit PFD failures hellosailor Health, Safety & Related Gear 0 12-07-2006 18:41
Bilge Pump Failures ? GordMay The Sailor's Confessional 6 14-08-2003 01:23
Equipment Failures GordMay Construction, Maintenance & Refit 2 31-03-2003 16:47



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:20.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.