Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 24-04-2019, 23:00   #106
Moderator
 
Seaworthy Lass's Avatar

Cruisers Forum Supporter

Join Date: Oct 2008
Boat: KM Yachtbuilder’s Bestevaer 49
Posts: 13,766
Re: Stealth mode - New Generation Ropes

Dockhead (and everyone else contemplating making a drogue with a bridle or who has made one). Your discussion on cow hitches has made me start thinking (always dangerous ).

I was also going to simply cow hitch the individual legs of the bridle to the eye on the leader, as you did, but thinking about it, this is a REALLY, REALLY bad idea.

The reason for this that when load is applied equally to the two legs of the bridle, they will slide until the eye of the leader takes the shape of an equilateral triangle. This will place a huge tearing force at the base of the eye of the leader and I think the bridle would be very likely to fail at the insertion point of the buried portion of the eye.

WARNING: My advice is only given as an enthusiastic amateur, and failure of the bridle could have a catastrophic effect, so seek advice from the experts.

I will now splice in a continuous loop to the junction point of the three legs on the bridle using the same diameter rope being used for the bridle.
Technique I will use:
Thread the three eyes onto the loop (plus chafe protection) before splicing.
Use the full amount of bury required (72 x).
Follow the weave around and make sure the line is not twisted.
Stitch the junction using HMWPE braid the same thickness as one strand of the line on the bridle.
Follow Samson’s lockstitching directions exactly, taking care not to pierce the strands of the outer portion (if you wriggle the needle a bit you should be able to slide around the strands in that portion as well).

The legs of the bridle will slide around the loop, so chafe protection would be sensible on the loop and all three eyes attached to the loop.

Cow hitching the three eyes onto the loop may actually be better. I don’t know. The reason it may be better is one Thinwater mentioned earlier - under load the cow hitch will lock tightly and will be less likely to slide around.
Because I don’t know, I don’t want to risk it.

SCRAP THAT. Cow hitching is a bad idea.
When one bridle is taking the load the cow hitch will slide around the loop to a point opposite the loop, so continual rapid movement will be occuring as the load alters from one leg to the other to both. Another point of failure, in this instance due to chafe.

A huge SS ring at the junction instead of a spliced in loop would work in a similar manner to the loop of UHMWPE. Apart from the strength requirement, the diameter needs to be at least same as that of the legs of the bridle and leader to avoid losing strength as the eye bends around the ring.

SWL
__________________

__________________
Unveiling Bullseye strops for low friction rings
"To me the simple act of tying a knot is an adventure in unlimited space." Clifford Ashley
"The cure for anything is salt water: sweat, tears or the sea." Isak Dinesen
Seaworthy Lass is offline   Reply With Quote
Old 24-04-2019, 23:08   #107
Moderator
 
Seaworthy Lass's Avatar

Cruisers Forum Supporter

Join Date: Oct 2008
Boat: KM Yachtbuilder’s Bestevaer 49
Posts: 13,766
Re: Stealth mode - New Generation Ropes

I see Peter from Timm Ropes is viewing the thread.

Peter, welcome to the forum. Advice here from the experts would be invaluable. What do you suggest is the best method of securing the eye splices of the two legs of the bridle to the eye splice of the leader of the drogue?

SWL
__________________

__________________
Unveiling Bullseye strops for low friction rings
"To me the simple act of tying a knot is an adventure in unlimited space." Clifford Ashley
"The cure for anything is salt water: sweat, tears or the sea." Isak Dinesen
Seaworthy Lass is offline   Reply With Quote
Old 25-04-2019, 00:57   #108
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 24,535
Re: Stealth mode - New Generation Ropes

Quote:
Originally Posted by Seaworthy Lass View Post
Dockhead (and everyone else contemplating making a drogue with a bridle or who has made one). Your discussion on cow hitches has made me start thinking (always dangerous ).

I was also going to simply cow hitch the individual legs of the bridle to the eye on the leader, as you did, but thinking about it, this is a REALLY, REALLY bad idea.

The reason for this that when load is applied equally to the two legs of the bridle, they will slide until the eye of the leader takes the shape of an equilateral triangle. This will place a huge tearing force at the base of the eye of the leader and I think the bridle would be very likely to fail at the insertion point of the buried portion of the eye.

WARNING: My advice is only given as an enthusiastic amateur, and failure of the bridle could have a catastrophic effect, so seek advice from the experts.

I will now splice in a continuous loop to the junction point of the three legs on the bridle using the same diameter rope being used for the bridle.
Technique I will use:
Thread the three eyes onto the loop (plus chafe protection) before splicing.
Use the full amount of bury required (72 x).
Follow the weave around and make sure the line is not twisted.
Stitch the junction using HMWPE braid the same thickness as one strand of the line on the bridle.
Follow Samson’s lockstitching directions exactly, taking care not to pierce the strands of the outer portion (if you wriggle the needle a bit you should be able to slide around the strands in that portion as well).

The legs of the bridle will slide around the loop, so chafe protection would be sensible on the loop and all three eyes attached to the loop.

Cow hitching the three eyes onto the loop may actually be better. I don’t know. The reason it may be better is one Thinwater mentioned earlier - under load the cow hitch will lock tightly and will be less likely to slide around.
Because I don’t know, I don’t want to risk it.

SCRAP THAT. Cow hitching is a bad idea.
When one bridle is taking the load the cow hitch will slide around the loop to a point opposite the loop, so continual rapid movement will be occuring as the load alters from one leg to the other to both. Another point of failure, in this instance due to chafe.

A huge SS ring at the junction instead of a spliced in loop would work in a similar manner to the loop of UHMWPE. Apart from the strength requirement, the diameter needs to be at least same as that of the legs of the bridle and leader to avoid losing strength as the eye bends around the ring.

SWL
My bridles and first section are 14mm Acera, so what diameter metal ring would I need to have a reasonable bend radius? I don't know if I like this.

How about simply splicing the two bridle eyes through each, so that they don't pull apart? Then all the forces on all three legs of this connection, will be exerted straight?

And actually just splicing all three eyes together, so that the loops capture each other? Et voila, no cow hitches, no pulling any eye apart.
__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 25-04-2019, 01:19   #109
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 24,535
Re: Stealth mode - New Generation Ropes

Quote:
Originally Posted by Seaworthy Lass View Post
I see Peter from Timm Ropes is viewing the thread.

Peter, welcome to the forum. Advice here from the experts would be invaluable. What do you suggest is the best method of securing the eye splices of the two legs of the bridle to the eye splice of the leader of the drogue?

SWL

I'd like to second the warm welcome to Peter from Timm Ropes!


I know your marketing is not oriented to the leisure marine market, but as a pleased user of your Acera Amundsen ropes, I have to say -- you should be selling into this market! You have an excellent product which would enjoy a great success in our market.
__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 25-04-2019, 01:29   #110
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 24,535
Re: Stealth mode - New Generation Ropes

Quote:
Originally Posted by Seaworthy Lass View Post
.. .
A huge SS ring at the junction instead of a spliced in loop would work in a similar manner to the loop of UHMWPE. Apart from the strength requirement, the diameter needs to be at least same as that of the legs of the bridle and leader to avoid losing strength as the eye bends around the ring.. .

A 14mm SS ring? Hmmm.


How about just going back to the classical configuration used with old fashioned cordage, and use a shackle?


Put thimbles in all 3 eyes.


Maybe that's best of all.



You are right to focus on chafe. That's really the enemy here, isn't it?




Edit: I did find 14mm SS rings, on about the 10th Google page (after 9 pages of penis rings), here: http://www.baselinemarine.com/shopdi...d=57&cat=Rings. 15.5 tonnes of breaking force, less than 14mm Acera, but probably strong enough. I guess you could double the ring.


The good thing about a ring is that there are no sharp edges anywhere.


Now here's something else to think about -- do we need a swivel on these drogues? I have heard someone (third hand) tell about his drogue spinning and twisting up. It would not be hard to introduce a big anchor swivel into the system at this point.
__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 25-04-2019, 01:49   #111
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 24,535
Re: Stealth mode - New Generation Ropes

For lifting, they sometimes use what is called a "master link", for this kind of connection. It looks like this:


Click image for larger version

Name:	Capture.jpg
Views:	69
Size:	228.8 KB
ID:	190768




https://www.thecrosbygroup.com/catal...nk-assemblies/
__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 25-04-2019, 01:50   #112
Registered User

Join Date: Aug 2016
Posts: 20
Re: Stealth mode - New Generation Ropes

Quote:
Originally Posted by Dockhead View Post
Put thimbles in all 3 eyes.

I'd use a spreader plate with 3 thimbles.



https://www.riggingandhardware.com/c...le-plates.aspx
N1774 is offline   Reply With Quote
Old 25-04-2019, 02:50   #113
Moderator
 
Seaworthy Lass's Avatar

Cruisers Forum Supporter

Join Date: Oct 2008
Boat: KM Yachtbuilder’s Bestevaer 49
Posts: 13,766
Re: Stealth mode - New Generation Ropes

Quote:
Originally Posted by Dockhead View Post
A 14mm SS ring? Hmmm.


How about just going back to the classical configuration used with old fashioned cordage, and use a shackle?


Put thimbles in all 3 eyes.


Maybe that's best of all.



You are right to focus on chafe. That's really the enemy here, isn't it?




Edit: I did find 14mm SS rings, on about the 10th Google page (after 9 pages of penis rings), here: Baseline Marine Products Ltd - Rings. 15.5 tonnes of breaking force, less than 14mm Acera, but probably strong enough. I guess you could double the ring.


The good thing about a ring is that there are no sharp edges anywhere.


Now here's something else to think about -- do we need a swivel on these drogues? I have heard someone (third hand) tell about his drogue spinning and twisting up. It would not be hard to introduce a big anchor swivel into the system at this point.
I am out of my depth here, but chafe with thimbles would worry me. The drogue is going to be yanked around centred on this point. I would personally far prefer to use a soft loop, as I described earlier. I can see no drawbacks with this if a dyneema sleeve was added for chafe protection.

I am not at the stage of constructing the bridle, so I will wait to get some feedback from those with more expertise. I am surprised the drogue manufacturer contributing to this thread has not chimed in with advice on how they are solving this problem (instead of placing one long advertisement on how wonderful their drogue is ).

SWL
__________________
Unveiling Bullseye strops for low friction rings
"To me the simple act of tying a knot is an adventure in unlimited space." Clifford Ashley
"The cure for anything is salt water: sweat, tears or the sea." Isak Dinesen
Seaworthy Lass is offline   Reply With Quote
Old 25-04-2019, 02:59   #114
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 24,535
Re: Stealth mode - New Generation Ropes

Quote:
Originally Posted by Seaworthy Lass View Post
I am out of my depth here, but chafe with thimbles would worry me. The drogue is going to be yanked around centred on this point. I would personally far prefer to use a soft loop, as I described earlier. I can see no drawbacks with this if a dyneema sleeve was added for chafe protection.

I am not at the stage of constructing the bridle, so I will wait to get some feedback from those with more expertise. I am surprised the drogue manufacturer contributing to this thread has not chimed in with advice on how they are solving this problem (instead of placing one long advertisement on how wonderful their drogue is ).

SWL

I've had ropes slip off thimbles, and it's not pretty. So maybe there is something in it after all -- chafe-protected soft eyes on a heavy stainless ring.


Or what did you think about my idea of simply splicing all the loops together?
__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 25-04-2019, 04:21   #115
Registered User

Join Date: Apr 2019
Posts: 262
Re: Stealth mode - New Generation Ropes

The general rule is “the throat of a splice when it is loaded should be 30 degrees or less”. For safety margin, particularly with high modulus fibers, some people half this to 15 degrees.

In the drogue bridle application, assuming the bridle legs can slide on the rode loop, this angle will be determined by the length of the bridle arms and the width of the transom (the three sides of the triangle).

For a transom which is 10ft wide, you need 19.3 ft bridle lengths to create a 30 degree angle and 38.3 ft bridle lengths to create a 15 degree angle.

That would seem to be the simplest way to keep the throat angle issue under control. However, there are other solutions. You could design it so the brindle arms cannot slide apart on the loop – for example instead of two separate bridle arms you could just have one continuous one with only one cow (or prussic) hitch to the rode loop. There are also hardware solutions – a delta plate with thimbles would be the standard commercial solution – but that would add weight and ‘hard bits’ to what is a nice light and soft textile solution.

Using a textile loop at the join solves the throat angle issue, but adds a 'hoop loading' discussion, which is perhaps a topic for another day.
Breaking Waves is offline   Reply With Quote
Old 25-04-2019, 04:37   #116
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 24,535
Re: Stealth mode - New Generation Ropes

Quote:
Originally Posted by Breaking Waves View Post
The general rule is “the throat of a splice when it is loaded should be 30 degrees or less”. For safety margin, particularly with high modulus fibers, some people half this to 15 degrees.

In the drogue bridle application, assuming the bridle legs can slide on the rode loop, this angle will be determined by the length of the bridle arms and the width of the transom (the three sides of the triangle).

For a transom which is 10ft wide, you need 19.3 ft bridle lengths to create a 30 degree angle and 38.3 ft bridle lengths to create a 15 degree angle.

That would seem to be the simplest way to keep the throat angle issue under control. However, there are other solutions. You could design it so the brindle arms cannot slide apart on the loop – for example instead of two separate bridle arms you could just have one continuous one with only one cow (or prussic) hitch to the rode loop. There are also hardware solutions – a delta plate with thimbles would be the standard commercial solution – but that would add weight and ‘hard bits’ to what is a nice light and soft textile solution.

Using a textile loop at the join solves the throat angle issue, but adds a 'hoop loading' discussion, which is perhaps a topic for another day.

This is really useful.



The Jordan design calls for bridle legs 2.5x the distance between the attachment points, which gives a throat angle of 23 degrees.



I guess that is probably reasonably ok with a long bury splice, isn't it?


But a simple solution to this would be to simple create the splices in all three parts, so that they are looped together. Then there will be purely straight pull on every eye and zero throat angle, no? The eyes of the two bridle legs can't slide apart, if they are looped through each other.



The only thing I can't quite visualize here is the half-turn of twisting which you would get -- would that be harmful? I wouldn't think so, but I can't quite visualize it.
__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Old 25-04-2019, 05:29   #117
Registered User

Join Date: Apr 2019
Posts: 262
Re: Stealth mode - New Generation Ropes

On SWL's loop idea of a loop - thinking about it, I would just make it super super strong and then you can forget the hoop loading engineering. Easiest way would be use large diameter line, to make really big loop (which you would need to do anyway to get the proper bury), then fold it back on itself so you have three loops (not more because if more the legs will not self-equalize in length) That would then never ever be the weakest link. You could then either cow hitch to this loop (would minimize chafe), or spice loops into it (slightly stronger excluding chafe))

DH, there would be many different ways to join the three pieces together so you don't have any throat issue. You could for instance, really easily just lash the two cow hitches together so they can't slide apart on the loop. or as I suggested above, just use one continuous bridle line. Or as you suggest interlock the loops. I do not know what is the preferred solution. The engineering analysis is doable but a bit more complex than normal because of all the pieces and load directions. I will have to ask around - I am sure it is an already solved problem, just not very commonly used.

On bridle length - personally (my opinion), not for strength issues but for cone placement in the water, is that more like 50-60' long bridle arms is preferable. But thats based just from observation of JSD in action, not any particular analysis or engineering.
Breaking Waves is offline   Reply With Quote
Old 25-04-2019, 06:45   #118
Registered User

Join Date: Jan 2014
Location: Sydney, NSW
Boat: FreeFlow 50 cat
Posts: 1,054
Re: Stealth mode - New Generation Ropes

Quote:
Originally Posted by Dockhead View Post
I've had ropes slip off thimbles, and it's not pretty. So maybe there is something in it after all -- chafe-protected soft eyes on a heavy stainless ring.


Or what did you think about my idea of simply splicing all the loops together?
I have seen thimble edge chafe on rope with regular open thimbles, but what about these Hampidjan closed & welded gussett ones. I can't see how Acera would chafe if using these.

Wire Thimble Stainless Steel With Gusset

Does anyone have any experience using these & any feedback on chafe or lack of?

The connection of the JSD bridle arms to the JSD leader line loop has been bothering me re chafe & the cow hitch. During a multi day storm, somehow it just seems reassuring to have beefy thimbles like these rubbing on beefy Crosby 209A shackles all moused up.
BigBeakie is offline   Reply With Quote
Old 25-04-2019, 07:24   #119
Marine Service Provider

Join Date: Apr 2010
Location: Newport Beach, California
Boat: Beneteau Oceanis 35
Posts: 127
Re: Stealth mode - New Generation Ropes

Quote:
Originally Posted by Dockhead View Post

How about just going back to the classical configuration used with old fashioned cordage, and use a shackle?


Put thimbles in all 3 eyes.


Maybe that's best of all.


Now here's something else to think about -- do we need a swivel on these drogues? I have heard someone (third hand) tell about his drogue spinning and twisting up. It would not be hard to introduce a big anchor swivel into the system at this point.

Correct. Using two rodes with thimbles connected to the JSD or speed-limiting drogue rode via shackle works best. We realize the JSD suppliers haven't recommended this setup.

To address the Seaworthy Lass concern. We've never seen serious chafe with the three thimble bridle setup. Cheap thimbles can part and create chafe, but we use an exclusive thimble design that doesn't part. If the thimbles have a big enough lip the rode is not likely to slip off the thimble. If this is a concern then go up one size with the thimble. The thimble nearly covers the entire rode. You can then wrap safety tape over the rode and thimble. No chafe to worry about since the rode is completely protected.

We feel the published information suggesting longer bridles will likely lead to shock loading and bridle twisting. Fiorentino recommends the use of shorter bridles to reduce this issue. It contradicts what's suggested by the entire industry, but it does perform better regardless of angle of pull. Only something to consider.

Swivels tend to lock up under load. During slack cycles they can partly spin. Randolph Reeves drogue bridle started to partially twist when the seas began to calm after the storm. Zack Smith recommended Reeves shorten the bridle.

Matt Rutherford has had some success using an anchor swivel at the bridle end.
Fi2010 is offline   Reply With Quote
Old 25-04-2019, 07:36   #120
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 24,535
Re: Stealth mode - New Generation Ropes

Quote:
Originally Posted by Fi2010 View Post
. . . We feel the published information suggesting longer bridles will likely lead to shock loading and bridle twisting. Fiorentino recommends the use of shorter bridles to reduce this issue. It contradicts what's suggested by the entire industry, but it does perform better regardless of angle of pull. Only something to consider.. .

There have been a couple of comments in this thread suggesting varying the length of the bridles.



This sounds dangerous to me. The geometry of the bridle determines the yaw angle at which the drogue will start to correct the yaw. I think the bridle length is critical, and shortening or lengthening it compared to the design will change how the drogue works. I carefully and strictly followed Jordan's design, myself.


If someone wants to try longer or shorter bridles, I think a lot of testing would need to be done to verify what effect it has on performance. I'll stick to the design, myself.
__________________

__________________
"Parce que je suis heureux en mer, et peut-être pour sauver mon ame. . . "
Dockhead is online now   Reply With Quote
Reply

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
Red Mode / Night Mode on iPad DaveWaltersAus Navigation 35 25-07-2017 17:12
Icom M-802 "Open Mode" (Open/Ham/Dial vs. Standard "marine mode") ka4wja Marine Electronics 0 03-11-2014 06:25
Switching from Liveaboard Mode to Sailing Mode Justin R. Liveaboard's Forum 8 07-02-2012 17:31
Stealth Lobster Boats sailorboy1 Off Topic Forum 10 26-08-2011 09:11
Stealth Sailing anotherT34C General Sailing Forum 36 17-11-2009 05:07



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 09:33.


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.