Stretchy Drogue line or not?

[GMac]

I've been mulling over a thought by a mate who is getting a Jordon Series Drouge. He wants to use a Spectra mainline rather than the usual nylon. I can't see any reason why not but are struggle to see a good reason why so I'm putting it to the board.

The main pros and cons I can think of, add away the things I've forgotten.

Nylon Pros - stretch, cost
Spectra Pros - strength, space (smaller line)

Nylon Cons - chafe
Spectra Cons - cost, possible no stretch.

So 2 options - a larger stretchier nylon line or a smaller no stretch line. But do a JSD really need stretch.

Anyone see any other up or downsides to using a spectra line or what am I missing?

[GordMay]

Ace Sailmakers, endorsed by Don Jordan, as well as SailRite supply the Jordan Series Drogue with tapered nylon double braid line.
Goto: Jordan Series Drogue - Monohull Prcing

“... In all of the many drogue deployments there has been only one report of a failure due to chafe. I believe that this lack of chafe is due, at least in part, to the relatively low loads and the absence of yaw when the drogue is deployed in a moderate storm. The only time that high loads might be experienced is in the event of a dangerous breaking wave strike...”

Jordan Series Drogue:
http://www.jordanseriesdrogue.com/pd...riesDrogue.pdf

Designers notes ~ by Donald J. Jordan
If you have purchased a pack of cones

[GordMay]

From Donald Jordan:
Jordan Series Drogue - About the Builder, Dave Pelissier of ACE Sailmakers

"... Ace Sails refers all technical questions to me and I answer emails every week or so from skippers all over the world ..."

Don Jordan can be contacted at:
Donald J. Jordan, Consulting Engineer
113 Evergreen Lane, Glastonbury, Connecticut
Phone: 1-860-633-1702
E-mail: donaldjordan@worldnet.att.net

Dave Pelissier, of ACE Sailmakers, can be contacted at:
ACE Sailmakers
3-D Colton Rd, East Lyme, CT 06333
Phone: 1-860-739-5999
Fax: 1-860-739-5999
Email: AceSailMakers@yahoo.com

[imagine2frolic]

I would think some stretch would ease any load. Couldn't you always go bigger on line for more strength?

[Hud3]

Skip Allan had a drogue out on a hi-tech line before he abandoned his yacht, Wildflower, in the eastern Pacific. From his account...

"On Sunday, 8/31, the wind was 30-35 with a confused wave train from the NW, N, and NE. At 0915 I winched in the drogue to change from a hi-tech spinny sheet to stretchy nylon anchor line. Unfortunately, I found the drogue had split, and was no longer effective."

It's certainly possible that repeated jerking from the non-stretching line caused the drogue to split. Stretchy is better for the gear, I would think.

[GordMay]

Received the following reply to my query from Don Jordan:
Hi Gord,
Stretch is no problem. Spectra if (sic: "is") Ok
Don

[Talbot]

the characteristics of the Jordan series drogue mean that snatch is not such a problem as for a single large drogue. However, when it comes to that very large breaking wave, I would prefer the stretch characteristics of the nylon to allow the boat to ease through the breaking wave rather than the more rapid deceleration characteristis from the spectre.

Another feature to remember is that the drogue itself helps to create a lee, and I would expect tha the larger diameter nylon would also play a part in this.

My choice would definitely be the nylon. As far as I know, this is either braid on braid or 3 strand. I asked sometime ago about the use of octoplait, as I prefer the characteristics of this sort of rope for these heavyweight tasks. Unfortunately nobody has done any trials with it, and there is a concern that the very factors that make octoplait such a good rope, i.e. the loose lay,, might allow the droguelets to pull out.

[jzk]

Go stretch! Why pay for something that might make things worse? Certainly there is no advantage to using low stretch line on a drogue.

[GordMay]

Originally Posted by Talbot

... My choice would definitely be the nylon. As far as I know, this is either braid on braid or 3 strand ...

The use of 3-strand rope for tether or towline is discouraged.

Three-Strand nylon will try to unlay and torque (spin) under load, leading to hockles and/or stress points that can fail. It may even deform under extreme dynamic loading as the force tries to travel the full length of the rode at the same time that the coil is trying to unlay (untwist). The solution would be to opt for a neutral (no-torque) nylon braid instead.

[Paul L]

Originally Posted by jzk

Go stretch! Why pay for something that might make things worse? Certainly there is no advantage to using low stretch line on a drogue.

The advantage is that you can use a much smaller line. For a larger boat that requires significant strength in the line, being able to down size the 300 or 400 feet of line to something more manageable in size might be worth it. Note, I said might.

Paul L

[Hiracer]

Originally Posted by jzk

Certainly there is no advantage to using low stretch line on a drogue.

There is an advantage: The low stretch line may well take up less storage, and in a small boat that has a lot to recommend it.

I'm in the middle of making a series drogue and I have already purchased the nylon braid. I'm wishing I had gone with a small diameter line and, in fact, may still do so.

The stretch factor is not important in a series drogue because the whole purpose of the design is to avoid shock loads.

My concern about the newer lines is whether they last as long stored in the boat. I once spent quite a bit of effort to find out how long nylon line can be stored without use before it should be replaced, and got much less than clear answers from the manufacturors. I have not undertaken that research with respect to the newer lines, so that is still an unknown factor to me.

[Hud3]

Gord makes an excellent point about three-strand nylon. Braid holds up better to chafe, too.

[Talbot]

Originally Posted by GordMay

The use of 3-strand rope for tether or towline is discouraged.
Three-Strand nylon will try to unlay and torque (spin) under load, leading to hockles and/or stress points that can fail.

Hence my preference for octoplait - a rope that doesnt suffer from this problem, is easy to handle, and very easy to stow.

[GMac]

I'm thinking Nylon but the smaller size of the Spectra does seem appealing, which I gather is the reason he's looking at it.

We've done quite a few lines for them and all except 2 were nylon double braid. 2 were Nylon Octiplait. As far as I know the Octpalit was thought OK by the owners. No way would I go 3 strand due pretty much to what Gord had above. Nylon will firm up a bit once in use.

Having never used one myself I was wondering just how much jerking they actually get. I'm thinking that as they are supposed to be deeper in the water than a parachute for example, they would be subject to a more stable sort of a load. If so then the stretch factor might not need to be as big.

Longevity? Assuming both were looked after and kept dry in a darker spot, I'd say nylon would have to be the best. But Spectra does last and will do quite well as long as the cover is left on it. Looked after I would expect many years of life from both quite easily.

[GordMay]

Drogue Design Load
The design load for each drogue configuration is adjusted for the displacement of the yacht. The design load is the ultimate, once in a lifetime, peak transient load that would be imposed on the drogue in a “worst case” breaking wave strike.
The working load during a severe storm is about 10 % of this value.

MONOHULLS
Displacement ~ Design Load
10,000 # ~ 8,000 #
15,000 # ~10,000 #
20,000 # ~ 13,000 #
25,000 # ~ 16,000 #
etc

MULTIHULLS
Displacement ~ Design Load
6,000 # ~ 10,000 #
12,000 # ~ 12,000 #
18,000 # ~ 14,000 #