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USING A PARACHUTE ANCHOR Peter Clutterbuck (MOCRA Safety Officer)

Parachute anchors have been used by yachtsmen in the Pacific for decades, with demonstrated results, but are almost unheard of in the Atlantic. Over here in Europe, people have read a little about them, but still think of them in the same category as drogues or sea anchors.

I started long distance ocean racing in the Pacific in the 1980s, so have been familiar with their use and success. I have never heard of a boat being capsized or lost when properly tethered to a parachute anchor of the correct size. They work even better on multihulls than monohulls, due to the wide beam allowing a good bridle angle.

conventional anchor
A conventional sea anchor of some 3-6 ft diameter does nothing more than slow the rate of drift, and has questionable use. If set off the bows, it has too much sternway to hold the bows to the wind, and a frequent complaint is that the bows fall off in the troughs of the waves when the boat and sea anchor are moving towards each other in the wave cycle, and there is often a lower wind strength reducing the pull on the warp.

The result is that the boat is at the mercy of the next breaker, which it will often take nearly beam on. I have used sea anchors in this mode, and read numerous reports, dating from the 19th century, which confirm this. Off the stern, it is more likely to hold the stern into the waves, but reduces the ability for the boat to accelerate down a steep face, and can therefore worsen the impact of breakers.

parachute anchor
The answer is to have two distinct devices: a parachute anchor for use in extreme conditions off the bows, and a drogue for use in heavy (but not extreme) conditions, off the stern. The drogue should allow a boat speed of about 10 knots, and there are several designs which increase drag as boatspeed goes up, therefore allowing a steady speed as crests and troughs go through. A Para-anchor will stop the boat dead (less than 1/4 knot in a gale), and should never be set off the stern.

The para-anchor must be large: ours if 18 ft diameter for the 43 ft Spirit of England. For a multihull, its diameter should be around half the beam, or a third of the LOA. You need a bridle, warp, chain and tripline and you should rig it up before leaving harbour to get familiar with the set-up. When you need it, it will be a real emergency, maybe at night, and your crew will be tired, sick and probably scared: no time for trying to read instructions.

In moderate conditions it can be run without the accessories off the bow on the anchor warp, but it works best with the add-ons, most of which can be used for other purposes - i.e. fenders, spinnaker gear etc. It will allow a multihull to survive a hurricane, it allows you to do serious repairs in heavy weather, it prevents you going the wrong way, and it gives you room off a lee shore.

Notes on Para-anchor set-up

bridle
Ensure this is set up before leaving the dock - you can use the spinnaker guy lines provided that the blocks on the bows (not snatch blocks) are strong enough, and the guys long enough. You should have at least 1.5 boatlengths, so you may need to tie extra sheets on. Lead back to winches and adjust to point the bows into the waves, which may not be in line with the wind. Ease out a few inches every few hours to alter the chafe points.

warp
We use 200 ft of 20mm braided nylon anchor warp, anchor chain in the middle and 400 ft of 16mm para-anchor warp. Smaller boats can use smaller sizes. The length is governed by the maximum likely sea size, and should be two wavelengths to avoid snatching or going slack. In non-extreme conditions, shorter warp (200 ft), and no chain will suffice.

swivel
Stainless steel is preferred - the weight also helps deploy the chute from its bag when you throw it in (it is best not to get the chute out of its bag on deck as it can blow around).

buoyancy float

Prevents the para-anchor diving too deep - ideally set to keep the chute just below the surface. A large fender on 20 ft of line will do.

retrieve line

We use a 130 ft buoyant partial trip line - water-ski rope is good. A full trip line to the boat is likely to tangle badly. You can do without any trip line, but will probably have to wait for quiet conditions to be able to haul the chute aboard (by one of its lines). A fascinating aspect of a partial trip line is that you can see that it concertinas like a snake to about half its length on the face of each wave, clearly demonstrating wave mechanics: in other words, if you have a short warp and the boat is in the trough, and the para-anchor on the crest of the same wave, the warp will go slack. Conversely, when the boat is on the crest, and the para-anchor in the trough, there will be a violent snatch. A long warp will keep its tension evenly, especially if the para-anchor and boat are on different waves.

retrieve float
Allows you to catch the line with a boathook. A small fender is ideal.

Here is an account of its use in adverse conditions after Spirit of England was dismasted in 1995 in the Atlantic:

We knew the mast was suspect, but were racing, and keen to hold our lead. We put in a second reef and changed to the staysail as the wind rose through the night. There was a deafening crash. John yelled "The mast has gone". I switched on our powerful aft deck floodlight. The mast and sails were laid over the side. The mast was broken just outside the starboard hull, the top 40 feet pointing straight down. The seas were now beam on and rising. Visibility closed in. It was now raining hard. The seas were rising more. This was not forecast. The barometer was falling. We started cutting loose what we could with bolt cutters, and an emergency sawknife. There were over 60 points of attachment between mast and boat.

Most of the running rigging was slashed with the sawknife and the smaller wires with the boltcutters. At dawn, we continued methodically detaching lines and salvaging what we could. We had a lot of difficulty releasing the forestay which was under the load of a half ton of mast pulling it down, as well as the drag of the sails acting like a sea anchor on the beam. John got the rotating mast base off, and the boom gooseneck. We cut the mainsail off with the saw knife and threw it over the side.

John cut through the genoa sheets and the remaining lines, then chopped the diamonds with the boltcutters and I scrambled clear as the whole lot sank fast into 16000 feet of water. Spirit started rolling and crashing from hull to hull in the big beam seas, the outer hulls slamming badly. The immense strength of the carbon beams kept the boat together. We urgently needed rest so we could clean up the rest of the wreckage, and get a jury rig up. It was now time to get the Para-anchor deployed.
First we set a partial 130 foot buoyant trip line with a small retrieve fender on the end, and a larger fender on the other to buoy up the parachute and pull its ripcord. We streamed it from a bridle and swivel off the bows on 200 feet of 20 mm braided nylon. It was all fed out in careful sequence to weather, and under the starboard hull. I attached the bridle lines, which were the spinnaker sheets, to the two lines from the bows already reeved for this purpose. It would not have been possible to reeve these offshore on the bouncing bows of the outer hulls. When the system went taught, the weight of the swivel pulled the Para-anchor out of its bag, and it opened up to its full 18 foot diameter, and pulled the bows head to wind, with about a quarter of a knot sternway.

The banging and crashing stopped, and the boat became safe as she rose to the big breakers and was pulled through steadily by the tension on the warp, which never went slack, and maintained a constant bow-on load.

We lay to this for the best part of three days as the wind blew from the NNE at Force 6, with the seas at 15 feet. It was too rough to raise a jury rig.

When the weather subsided, we decided to pull in the para-anchor, and run off under bare hulls to build a jury rig. Getting the para-anchor in was a problem, as the wind was still Force 6, and the waves some 12 feet, preventing us going onto the outrigger bows to release the bridle. John winched in one half of the bridle, allowing me to grab the other slack half with a long boathook off the bows, and clip it through a bow snatch block. Then John winched it in until I could reach the trip line, whereupon I tripped it and we sailed off under bare poles without poles, or "bare hulls".

If we had not had the para-anchor, the boat could have been badly damaged under the onslaught of seas taken on the beam over three days of heavy North Atlantic conditions. I am happy to say that our new carbon mast has been trouble-free in five years of offshore racing, having sailed through more Atlantic gales, and we have not had occasion to use the parachute anchor since. However, it is very reassuring having it on board should an emergency arise.

Heavy weather sailing
March 2009

"I have been capsized, foundered, run-down and placed in more survival conditions than I can remember"

Read more...

A Voyaging Canoe for Tikopia
March 2009
A project to build a sailing double canoe for Tikopia.


Tikopia is a tiny remote Polynesian island in the Western Pacific, which has maintained self-sufficiency for 3000 years.
Read more...

Using a Parachute Anchor
March 2009

Peter Clutterbuck, MOCRA Safety Officer, examines the benefits of carrying one on board, and compares with the conventional anchor.
Read more...

Budget charters in Thailand
March 2009

We sailed "Veni Vidi Vici", one of Siam Sailing's Tiki 30's for two weeks in January

Read on...


 
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