Jordan Series Drogue in Dyneema

[Fi2010]

Gusset thimbles are strong. Just takes a good rigger to splice the rode. Something I'm sure you already know.

For our drag device manufacturing we use solid thimbles without the hollow tubes. Similar concept to the gusset thimbles. Numerous drag device units using our custom hardware have been used by many Naval and Coast Guard ships. Happy to report results have been really good.

[Fi2010]

Originally Posted by StoneCrab

Morgan's Cloud has several articles on this topic. Where possible, John interviews sailors who have used their JSD's. These reports support the use of gusseted thimbles. The loads are tremendous and even the shackles can become deformed.

https://www.morganscloud.com/2013/06...launch-system/ This link goes to one of the chapters in the Attainable Adventure Cruising book on drogues.

Is there a reason why John never interviews sailors who've successfully used competing para-anchors or speed-limiting drogues?

And yes, if you have shock loading you can definitely deform equipment. Especially stainless steel, since it's a softer metal than galvanized.

[StoneCrab]

Originally Posted by Fi2010

Is there a reason why John never interviews sailors who've successfully used competing para-anchors or speed-limiting drogues?

And yes, if you have shock loading you can definitely deform equipment. Especially stainless steel, since it's a softer metal than galvanized.

I wouldn't say that he never interviews them. I don't have time to look right now, but I believe he did get testimony regarding the other options like the para-anchors. I'm not a shill for Morgan's Cloud, but I do think he has some good information on his site.

In my brain fog, I seem to recall bridling the para-anchors for a proper drift angle was a subject of discussion and requiring frequent adjustment. Bow-on created a lot of whipping back and forth, so you needed a quartering drift.

I always considered the JSD to be a speed limiting drogue. From what I understand (and I am trying to understand) it doesn't stop you, just slows you down to about 2 knots and keeps you from surfing down the face of the waves. A feature in its favor is that its long length and small cones give you built in redundancy from cone failure and stays in contact with the water.

Did you do a bunch of testing in the 90's and write a book? Drag Device Database? If that was you, I have the book. I did a lot of experimenting back then. It is still a topic of great interest for me. Thankfully and maybe a bit disappointingly, I've never been in a situation where I had to do a real field deployment under life threatening conditions.

[fxykty]

With our UHMWPE bridle lines we plan on using a soft shackle to attach each bridle eye to a u-bolt on each respective chainplate - avoiding as much as possible any hard components. The only hard piece we’ve got is a galvanised open thimble at the end of the tail, to which the chain end-weight is attached with a galvanised shackle. We’ve covered the eyes and soft shackles with dyneema chafe covers and expect minimal movement of the shackle on the u-bolt. That’s another benefit of using soft connections - unlimited articulation, hence less movement.

We’ve got a short offshore passage planned for the Christmas break and plan to finally test our JSD. Including the chain weight it’s 145m long, so in our area you have to go quite a ways out from the coast to see enough depth to deploy without dragging on the bottom. We’ll try to take some decent video of deployment, laying to (hopefully not in real storm conditions!) and retrieval.

Plan for retrieval is to release the bridles from their respective chainplates and retrieve over a bow roller while motoring slowly forward. We prefer that method as that will also be a good attitude to raise the mainsail once we’re done, and avoids having to have a retrieval line in the water along with the bridles and dragging the drogue up to the boat.

[StoneCrab]

Originally Posted by fxykty

With our UHMWPE bridle lines we plan on using a soft shackle to attach each bridle eye to a u-bolt on each respective chainplate - avoiding as much as possible any hard components. The only hard piece we’ve got is a galvanised open thimble at the end of the tail, to which the chain end-weight is attached with a galvanised shackle.

It would be great to see some pictures of your setup, attach-points and photos of your deployment and retrieval. Most pictures of JSD's are just taken with the JSD on a dock...lots of cones. It would be good to see the details and how it deploys.

[BigBeakie]

Fxykty;

So you shackle the bridle eye to the U bolt? Aren't you concerned about the tight bend radius of the HMWPE around the shackle pin? As I understand it, that area of a tight bend ( ie a bend radius less than 3 to 5 times the line diameter) can be a failure point in high loads. Or am I mis-remembering something from Brian Toss or Starzinger?

[Dockhead]

Originally Posted by BigBeakie

For all our structural components that have expected high loads, we built carbon chainplates, attachment points etc.

We sought the advice of those knowledgeable in the dark arts of composite engineering as applied to performance multihull boat building.

For our two JSD attachment points we used high quality 450 gsm unidirectional carbon stitched and we use Scott Bader laminating Vinylester resin with high mechanical properties in a wet layup technique, taking care to roll out excess resin or to vacuum bag when possible. Surface finishing layers are 200 gsm double bias glass. The carbon is multi layer and the straps are splayed out in a uniform fashion for load path spreading, and are tied to any other structural component if possible.

The core of the structure is stainless thick walled tube, sized to take the appropriate sized rigging screw clevis pin. In the case of the JSD pin we used 19mm. We'll use 3/4" Crosby G209 shackles to take the 14mm Acera bridle eyes that have spliced in Hampidjan stainless gusseted thimbles designed for HMWPE rope. ( see Wire Thimble Stainless Steel With Gusset )

We went this way due to a healthy respect for chafe and the loads expected, instead of soft splices everywhere.

Sounds really good. Photos?

[Dockhead]

Originally Posted by fxykty

. . . Plan for retrieval is to release the bridles from their respective chainplates and retrieve over a bow roller while motoring slowly forward. We prefer that method as that will also be a good attitude to raise the mainsail once we’re done, and avoids having to have a retrieval line in the water along with the bridles and dragging the drogue up to the boat.

You're not concerned about running over the drogue and getting it into the prop?


I like the bow roller, though. In fact, this may be a good reason (besides stern anchoring) to have an anchor roller on the transom.

[Dockhead]

Originally Posted by BigBeakie

Fxykty;

So you shackle the bridle eye to the U bolt? Aren't you concerned about the tight bend radius of the HMWPE around the shackle pin? As I understand it, that area of a tight bend ( ie a bend radius less than 3 to 5 times the line diameter) can be a failure point in high loads. Or am I mis-remembering something from Brian Toss or Starzinger?

Tight bends reduce the strength of all cordage. But 1:1 is considered OK for a Dyneema loop -- practically full strength since each leg carries half the load.

[fxykty]

Originally Posted by BigBeakie

Fxykty;

So you shackle the bridle eye to the U bolt? Aren't you concerned about the tight bend radius of the HMWPE around the shackle pin? As I understand it, that area of a tight bend ( ie a bend radius less than 3 to 5 times the line diameter) can be a failure point in high loads. Or am I mis-remembering something from Brian Toss or Starzinger?

Shackling with a soft shackle that’s stronger than the bridle line itself. The bridle eye is around the two strands of the soft shackle, so almost 2:1. Bend of the soft shackle on the 14mm tube of the u-bolt and the 14mm of the bridle eye (12mm plus a cover) is more than 1:1 in both cases. 1:1 is sufficient.

The 3-5 times you’re remembering is for the length to width proportion of the eye to prevent an overly large throat angle. That’s relevant when splicing an eye around a thimble or LFR.

[fxykty]

Originally Posted by Dockhead

You're not concerned about running over the drogue and getting it into the prop?


I like the bow roller, though. In fact, this may be a good reason (besides stern anchoring) to have an anchor roller on the transom.

We will spin the boat without using engines. Then we will motor forward at the same rate that we retrieve the drogue. Should be OK. Testing will verify. Or not, and we’ll come up with another plan.

We do have 16m and about 3m laterally between our bow roller and the props, so that should provide some time if we over run the drogue while retrieving it.

[BigBeakie]

Ok, thanks for that! [emoji106]

[BigBeakie]

Originally Posted by Dockhead

Sounds really good. Photos?

Hope this comes through, I've not had good luck posting photos in the past...



The carbon straps extend from the top hull side beside the steps, through the hull and run back along the interior surface (about a meter) where they fan out while overlapping to spread the shear force to the hull area.

It is all done in one go with slow hardener so the chainplate and hull fill cures as a unit for maximum strength. Then it's glassed over and faired to become part of the hull.

There are now 2 vertical cuts in the chainplate (thru the glass/carbon/stainless tube) to take the tangs of the
10mm thick stainless rigging screw we had fabricated.

[At Peace]

Recovery of the JSD is the most demanding part of using one. I look at it as a positive! This means I have survived the storm and I want it back on board for the next time I in conditions where I need it. 1) Pull some in, 2)take a break, repeat until you have it all on deck, what's your hurry? You just survived what was probably a fierce storm.
Some good reading from Ocean Brake: https://www.oceanbrake.com/launch-and-recovery

[BigBeakie]

Originally Posted by At Peace

Recovery of the JSD is the most demanding part of using one. I look at it as a positive! This means I have survived the storm and I want it back on board for the next time I in conditions where I need it. 1) Pull some in, 2)take a break, repeat until you have it all on deck, what's your hurry? You just survived what was probably a fierce storm.
Some good reading from Ocean Brake: https://www.oceanbrake.com/launch-and-recovery

Yes, that's the hard part, but there is good info on that and other aspects of JSD deployment and recovery over at Morganscloud.com

Other than the pulling it in over the transom, some have suggested leading the rode to the bow and pulling it in with the capstan if the anchoring arrangement allows that, but that would assume spinning the bow into the waves of the left over sea state.

That's certainly something I'd want to try first in manageable conditions, and practice to avoid fouling the prop or rudder. But it would be alot easier.

By the way, I just came across the beefy Dewalt right angle drill (Flexvolt Stud & Joist drill) that can take 12 Amp/Hr rechargeable Lithium batteries. Finally a battery system that can do high load jobs for a decent period Perfect for winding a JSD back in, or in the sheet winches for trimming or hoisting crew up the mast.