Home made para-anchor/drogue.

[mickshep]

Morning everyone, About a year ago a pal and I were discussing the varied methods of surviving the sort of weather that hopefully we never come accross, one of the subjects that came up was the use of Drogues and Sea Anchors made from ex-military parachutes, more accurately the small extraction chutes which are designed to withstand massive shock loads, with this in mind I have bought a 7' diameter extraction chute which is very light but immensly strong being made up of concentric rings of cloth reinforced with webbing. Having checked the stitching etc the canopy shows no sign of use whatsoever but is missing its control lines. Is there a formula to work out the correct cord length? Once we have the thing sorted we will be testing it by towing behind a large powerfull Mobob and will let everyone know the results. Regards, Mike.

<hr width=100% size=1>My Mum say's I'm not a fat b@st@rd, just heavy boned.

 

[Talbot]

going to be much to small for a mobo to act as a para anchor. and a bit large for a drogue! A lot of people have used ex WD parachutes for this, but the one normally selected is the cargo chute, which obviously is beefed up to cary a lot of weight. I have seen suitable ones paratech version.

as an example of size, a 25-33 ft boat should normally have a 12 ft paratech chute.

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[mickshep]

Sorry, I should have made myself clearer. The chute will be used if it works on a 32' yacht. The mobo idea was as a test, ie what effect on speed through water with/without chute, I read of tests involving a cargo chute but results suggesed it was perhaps too effective and was hard to recover. If it were to prove at all effective then the compactness of it not to mention the price of £10 would make it an atractive alternative, I agree that it would probably be too small as a Sea Anchor but am also interested in its viability as a drogue. I will need to make up new control lines and a swivel arrangement to minimise twisting, hence my need to find out what length the lines should be. Cheers, Mike

<hr width=100% size=1>My Mum say's I'm not a fat b@st@rd, just heavy boned.

 

[Talbot]

The danger of using a chute that is too small is that you will make considerable stern way and this is potentially daangerous to your rudder. I am not sure which lines you are referring too that you wish to know the length . From the paratech site:

"The Sea Anchor relies very heavily on the stretch of the long NYLON rode for yielding to the seas (and not standing up to them). Even in moderate conditions, pay out at least 300' of rode or 10 to 15X the boats overall length in heavy weather situations. "

You should also be aware that they do not recommend 3 strand nylon. There is a danger of this kinking when it has been under very heavy strain . This creates a weak point which may well break the next time. They recommend octoplait and this is also much easier to control.

I would really recommend a thorough study of the paratech site, as there is a lot of good information about the advantages and disadvantages of drogues and sea anchors.



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[seahorse]

There's a report of a Hallberg Rassy 29 using a builders bag to lie to a storm in the Atlantic. I've made one up for my Centaur but havent had the chance to try it.

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[hylas]

Re: Jordan drogue

For my own boat, I have manufactured a Jordan Serie drogue, it seems to be actually the TOP of the art.. Fortunately for me I never have the occasion to try it.. but just in case...

You will find more info on www.acesails.com/drog_02.htm and on Goggle at Jordan drogue

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[duncan]

having just emptied 4 bags that have 'non refundable/reuseable on them I was considering trying one as a drogue when fishing wind against tide - will be interesting to see how it works out!

<hr width=100% size=1>madesco madidum ..../forums/images/icons/smile.gif

 

[seahorse]

Let us know howU get on, recovering etc...

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[Zack_Smith]

If you need to add shroud lines (control lines) to a parachute canopy measure the diameter of the canopy first. You do this by laying the canopy flat on the ground so it forms a large circle. Place a measuring tape on one edge of the canopy and pull it to the opposite side of the canopy. If you're measurement is 8' (2.44 m) for example, then your shroud lines can be 8' (2.44 m) long from the edge of the canopy to the hardware that is used to connect to your anchor rode. Because the surplus chute you have is "very light" I'd add two extra feet to the shrouds to help reduce strain on the canopy. Another point to consider is how many shroud lines must be attached on the canopy. The 9' Offshore anchor that I designed for Fiorentino uses 16 lines. Para-tech's 9' offshore anchor uses 8. Both companies also have different size guidelines you may want to reference.
Their websites are: para-anchor.com & seaanchor.com. Good luck with your test!

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[Harry25]

Home made Drogue

Really old post I know (7 years) but Duncan still posts here, and I wondered how he got on with using a builders bag for a drogue, or has anyone else tried it?

 

[Lady Campanula]

I made up a para-anchor 6 years ago for a cat-trip round Ireland, down to Spain, and back. I picked up a 24' cargo drop-chute for a few pounds and cut off the shroud lines close to the canopy. Then I reinforced the nylon shroud lines still sewn onto the panels' seams, using 2" nylon lifting sling tape ( like seat belt straps ) from edge to edge via the crucial centre hole, with sewn loops at the ends.

I then re-attached the shroud lines' ends to the tape loops.

The rest of the assembly is much as the diagram above, but with ~800' of ex-HMCG 18mm nylon rocket line attached. Instead of chain, I used a heavy lifting swivel to keep the canopy-and-lines immersed. The canopy and shroud lines is kept in a deployment bag, attached to the rode, trip-line and inflatable pickup float.

The whole lot is contained in a plastic open-top crate, with bungy cord holding everything in place. The heavy-duty bridle is boat-specific and separate.

Cost? Less than £50 overall - and a lot of persuasion of the seamstress....