Parachutes in the sea

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The basic notion is simplicity itself. If you get overtaken by a great storm, you drop a substantial nylon parachute in the water and connect it to the bow of the sailboat with a very long nylon line.

As the strong gale or storm-force wind blows the yacht downwind, the horizontal line tugs at the parachute, which opens and fills with water and becomes an almost stationary point in the sea. When large waves sweep past the boat, the nylon line tightens and stretches, and tends to align the yacht parallel to the long line.

Because nylon line is elastic as well as strong, it's almost as if the boat were attached to a giant rubber band as she rises on crests and dips in troughs. In case a large breaking wave sweeps down on the yacht, the parachute and its tether hold the vessel's bow into the passing wall of water.

The size of the parachute generally runs from 6 to 24 feet in diameter for the 25- to 55-foot monohull yachts that we're discussing in this book. In terms of displacement or all-up cruising weight, the numbers go from 10,000 pounds for a 30-footer to as much as 45,000 pounds for a 55-foot sailing vessel. We know that with all the gear and provisions on board, cruising boats gain 15% to 20% in weight over their designed displacement.

An idealized sketch of a 45-foot sailing yacht hanging on a small parachute. In an offshore Force 9 strong gale that's been blowing steadily for 10 hours, the significant wave height would be about 24 feet, and the crests would be roughly 260feet apart. Ideally the parachute should be on the second crest ahead ofthe boat, which would suggest some 500feet of34-inch-diameter nylon. The parachute experts' figure for the 45-foot vessel would be 450feet ofline or ten times the length of the vessel.

An idealized sketch of a 45-foot sailing yacht hanging on a small parachute. In an offshore Force 9 strong gale that's been blowing steadily for 10 hours, the significant wave height would be about 24 feet, and the crests would be roughly 260feet apart. Ideally the parachute should be on the second crest ahead ofthe boat, which would suggest some 500feet of34-inch-diameter nylon. The parachute experts' figure for the 45-foot vessel would be 450feet ofline or ten times the length of the vessel.

Alby McCracken of Sale, Australia, manufactures the Para-Anchor, and supplies many multihull and monohull yachts as well as large numbers of fishing boats. "The parachute must be of sufficient size so it has more resistance than a sailing yacht," cautions Alby. "If the parachute is too small, the boat may pull the parachute."

It's well known that when you drag an ordinary metal anchor along the bottom, the tip-off that it's not embedded is that a modern monohull sailboat will lie beam-on to the wind as the anchor bumps along the sea floor. And we know that not heading into the wind when lying to a parachute puts the vessel in a bad position because of the danger that a breaking wave could capsize the yacht.

New Zealander Bill Coppins, of W. A. Coppins, also manufactures para-anchors and agrees with Alby: "A para-anchor too small for the boat will tend to let the boat point off and end up beam-on to the wind. In addition we've worked on the shape of our para-anchor to maximize drag. We've found that a good shape in the para-anchor creates more drag, which allows us to cut down on the size a little. This reduces bulk and cost and eases handling and stowage problems. This has cost us a lot of time in trial and error and testing. I've been designing and manufacturing sea anchors for the last 38 years, and this has paid off on the safety side of things."

The people who sell parachutes tell us that during severe storms a parachute sea anchor should be deployed on a line 300 to 600 feet in length. The recommendation is twice the distance between wave crests or ten times the overall length of the boat; say 400 feet for a 40-footer, 500 feet for a 50-footer, etc.

Alby McCracken points out that nylon has a stretch factor of about 30% when wet, which means that a 400-foot rode under load is actually about 520 feet long. Because of the stretchiness, about 25% of the initial loading is captured by the rode itself. When the stretchiness is used up, then the full load is applied. The longer the rode, the less the strain on the boat and the parachute.

"Both rode diameter and length are important to achieve maximum comfort and safety from the Para-Anchor system," says Alby. "Too large a diameter and the stretch of the line is reduced. But a line that has too small a diameter likewise reduces the elasticity, because the rode is stretched to its maximum too much of the time. If the diameter is too small, the risk of a rode line breaking becomes very real."

Supposedly when you utilize a parachute, the boat faces directly into the wind, which exposes the strongest and most streamlined part of the vessel to the storm. You've anchored the boat to the sea, and the waves thunder past harmlessly. Assuming that you have plenty of sea room and that shipping traffic is not a problem, you can retire to the cabin and wait in safety until the storm eases or passes. Then you recover the parachute, pack away the line, and continue on your way.

This is all a grand idea, but it's not quite that simple in practice for four reasons:

1. The boat must head (or almost head) into the oncoming seas.

2. The vessel cannot be steered and needs ample sea room. Once the storm rages and a parachute is deployed, it's impossible to haul it in until the wind drops. If there's shipping traffic or problems with islands, a coastline, a troublesome tidal stream, current, or a lee shore, you need to consider other options.

3. At times the connection between the yacht and the long line coming from the parachute can have a load of thousands of pounds and must be kept free from chafe. This takes forethought and careful preparation because it may not be possible to inspect the bridle or connection on the foredeck during a storm.

4. If the boat slides backward for any reason, the loads on the rudder become significant.

Let's look at #1. A real problem with a parachute sea anchor is whether the yacht will face into the wind and waves or turn sideways to oncoming seas. We saw in the last chapter how the vessel of John Voss (from 1901) and a representative modern monohull sailboat (the Swedish Malo from 2006) have completely different rigs and underbodies.

A modern boat swept by seas coming at the bow tends to pivot on its center of lateral resistance, sometimes known as the center of lateral plane (CLP) or the center of lateral area (CLA). This underwater center tends to be aft of amidships, and the pivoting motion is augmented by the windage of the forward-placed rig and especially the bulk of a roller-furling headsail. A rolled-up headsail with a luff measurement of 45 feet and an average diameter of 5 inches has an area of almost 20 square feet. These two forces impart a turning motion to push the bow sideways to the wind. Remember, the force on a given area increases with the square of the wind velocity as the wind speed picks up.

Experts have shown that the wind force on an anchored boat increases substantially with side-to-side yawing. On an anchor line the forces "can treble or quadruple average rode tension," writes oceanographer Dr. William Van Dorn.32 Presumably the same thing happens with a sea anchor. In addition to this, the water in a breaking wave crest adds to the forces against a boat. These two effects greatly increase the loads on both the boat and every part of the sea anchor gear as the vessel presents more side area to the wind and water.

We know that exposing the side ofthe boat to breaking waves is what we must avoid! Each vessel acts differently, of course, but any forces that fail to keep the bow close to the wind are problems for yachts hanging on parachutes. Nevertheless a stationary parachute of adequate size and a long, stretchy connecting line tend to minimize yawing and keep the bow of a yacht facing the wind much of the time.

To keep the bow of a monohull sailing yacht into the wind, Fiorentino, a Newport Beach, California, company that specializes in selling parachute sea anchors in the United States and elsewhere, reprints an article on its website (as of September 2008) that discusses a sequence of responses called "Trilibrium Factors." The sequence suggests (1) that you reduce sail forward. If the boat persists in lying sideways to the wind, the article's next recommendation (2) is to use the rudder to steer more into the wind. If this is unsuccessful, the next suggested response is (3) shortening the long line between the sailboat and the parachute to reduce any slack in the line to the parachute.

These suggestions do not seem feasible because in the 40-knot winds and higher that we're discussing, the yacht may already be down to bare pole(s). In Force 9 and above, many sailors are extremely reluctant to go to the foredeck to shorten the line to the parachute. In any case, such a step may be impossible because of waves crashing on board, the heavy loads on the line, plus having to deal with chain and perhaps complicated chafing gear.

Additionally, I find it hard to understand the rationale of adjusting the rudder of a yacht hanging on in 40 knots plus. A parachute sea anchor of sufficient size used off the bow almost anchors a boat to the sea.

Under these circumstances the rudder is largely useless. Indeed, one of the basic problems of using a parachute is that a particularly severe wind gust or a giant wave may shove the yacht backward and put severe loads on the rudder. These can be minimized by building stops on the hull to limit the rudder movement and lashing the tiller or wheel mechanism with heavy shock cord. In the next chapter, I tell the account of Prisana II, a 45-foot heavy-displacement ketch, that survived a horrendous storm by using a parachute only to find that her 2-inch-diameter grade 316 stainless steel rudder shaft had twisted 15 degrees.

Australian Alby McCracken, who supplied the parachute and gear for Prisana II, has another view. "It's an impossible task to adjust the rode length in stormy conditions. Who wants to be on the foredeck playing games with the line at 0200 hours with minimal crew as backup in 50 knots? An impossible task."

New Zealander Bill Coppins, who has been making parachute sea anchors for yachts and fishing boats for decades, agrees with Alby. "It's too risky to go up to the bow to shorten the rode to reduce slack. We place weights along the rode from the midpoint of the line toward the yacht. We do this with heat-shrink tubing filled with lead shot. These weights are only to take up the slack when the rode goes limp. They help ease the rode as the tension comes on and reduce the jolt at full tension."

Often a length of chain with or without a weight is added to the nylon to weigh down the system. This means that when the yacht pulls on the line, the boat will have to lift and straighten out the chain before any tension is directed to the nylon and the parachute. Whatever the length of chain, three-quarters or more of the rode should be nylon so there's plenty of stretch in the system. Long lengths of chain may not be as helpful as formerly thought.

"I agree that chain anywhere but at the boat end adds a complication," says Don Whilldin of the Para-Tech Engineering Company of Silt, Colorado. "I'm familiar with the case of a 40-foot boat in Force 9 conditions with 200 feet of rode, 100 feet of chain with a 45-pound anchor at mid-chain, and then 200 feet of rode to the boat. The report: the rode was straight, the chain was straight, and the anchor was thrashing around the chain.

"Recently I talked to a second person who had a similar experience," says Whilldin. "After going over the loads, it's clear that the weight of 100 pounds (in this second case) would have to be significantly more to generate any real force to help the situation. In my judgment, the only practical location for chain is at the boat end to deal with chafe."

Two hundred pounds of 3/8-inch-diameter BBB chain is 122 feet long. It seems a bit much to ask of a person at the bow to deal with difficult-to-handle chain and to make the hookups with the nylon line at each end while the boat is dancing around.

Depending on the strength of the storm, the duration of the wind, and the distance over which the wind blows, the seas tend to grow longer and higher. To keep the parachute far ahead of the yacht on a 10x line means that ideally the captain should anticipate sea conditions hours ahead. Yet he presumably has only one parachute and a given length of long line. Once it's in, that's it, although it might be possible to bend on another length of line.

Setting the parachute by slipping the line into the water without tangles when the boat is rolling heavily is by no means a simple job. To help with these problems, the alert makers of parachute sea anchors have designed special stowage bags that hold both the parachute and the line. These bags or satchels are easy to use from the cockpit area and in most cases go overboard with the long rode. This assumes that the line from the bow has been rigged in advance and led around outside the lifelines (to which it's held with breakaway ties). The bag or bags allow the parachute and line to run out quickly. A useful tip if a deployment bag is not used is to douse the parachute with sea-water to keep it from ballooning out and inflating like an unwanted spinnaker.

All the parachute companies urge their customers to practice setting the parachute and to work out the lines and handling details in light weather, and if possible to deploy the chute in daylight.

As you might imagine, it's hard to recover a parachute after a storm, particularly a large chute. To deal with this, there are various retrieval schemes that incorporate light floating lines and small floats attached to the head of the parachute. Once a retrieval line is secured on board, the main nylon line can be slackened or dropped over the side. This collapses the parachute, which can then be easily recovered.

Yet retrieval lines can cause terrible tangles and snarls, and some captains refuse to use them. Floats and trip lines are notorious for fouling propellers, steering-vane water paddles, rudders, and the sea anchor itself. You can make a strong case for not employing them at all and dealing with the recovery by a capstan or winch at the bow. Or— with the greatest care—using the engine at its slowest speed during daylight hours.

The parachutes themselves are usually made of 4- to 8-ounce nylon with reinforced seams. Various U.S., Australian, and New Zealand companies sell chutes from 3 to 40 feet in diameter, which are used to stabilize boats that range from small outboard-powered inflatables up to commercial fishing and research vessels 150 feet long.

Most of the business of these companies is with fishing boats. Commercial boats put out parachutes on fishing grounds (engines off) or when the crew is resting. Recreational powerboats sometimes employ chutes, and catamarans and trimarans use them to advantage in storms.

For monohull sailing yachts of 25 to 55 feet, the parachutes range in size from 6 to 24 feet in diameter (recommendations vary) and cost from $200 to $2,000 (in 2008) plus shipping. It's worth checking what comes with the parachute because a complete setup requires the main nylon line, a heavy-duty swivel, floats, recovery lines, and launching bags.

Smaller yachts from 25 to 35 feet in length often use inexpensive 9-foot-diameter surplus military parachutes from the U.S. Bureau of Ordnance (BuORD), although these may be no longer available except in consignment shops. These small chutes are constructed of coarse-weave nylon that tends to give a little under load and allows some water to pass through the material. This keeps the whole system a bit springy and flexible.

Reports of torn or pierced panels during storms suggest that adequate performance is quite possible from less than perfect chutes. Indeed, professional delivery skipper Charles Kanter, who was caught out in a 37-foot sloop in a Force 10 storm in the Caribbean, tied a line to the three corners of a genoa, fed it over the side, and lay to it as to a sea anchor. Kanter was amazed to see large waves roll up to the sail in the water and collapse into harmless spray and foam.33

"In the 38 years that we have been making para-anchors we have had only one rip because of storm conditions," says Bill Coppins. "Fortunately, the anchor held. Today, however, we use high-density ripstop nylon, which is four times stronger. We also cut the nylon on the bias, which prevents the para-anchor from ripping the complete length of the panel, because the weft and warp are at 45 degrees."

To stop parachutes from revolving, twisting the line, and possibly collapsing the chute, the panels on one side may need a few lead weights while the opposite side may require a small float or two. Most users fit a heavy swivel between the parachute and the main nylon line. One maker (Don Whilldin's Para-Tech Engineering Co. in the U.S.) says that it constructs its parachute panels so that spinning or rotation is impossible.

Bill Coppins believes that on a well-shaped and well-balanced parachute sea anchor, weights and floats are unnecessary. "Of the thousands of para-anchors from 1.5 to as much as 52 meters in diameter we have made, I have never had a problem with an anchor twisting to the point of fouling. The main difficulty is the deployment and the setting of the anchor, which is where problems can occur. That's because some brands do not have a good deployment system. This is really important, because in a big storm you get only one chance. If the para-anchor fouls in those conditions, you will not be able to recover it."

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