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By the numbers

Jan 1, 2003

Long before the advent of electronics and high tech wind measuring devices, a qualitative wind estimating method called the Beaufort Scale of Wind Forces was used. It was invented by an early English navigator by the name of Francis Beaufort (1774 to 1857) who wanted to correlate ships' log reports of wind speed with the ensuing action taken by the ships' skippers to set the proper amount of sail on the square riggers. Too little sail and the ship was not combat ready; too much sail and the ship risked having its sticks blown out.

His scale ranged from 1 to 12, with word descriptions of wind and sea and acceptable sail combinations for those conditions. Since square-rigged ships had great commonality in rigging and sail plans, this scheme became rote for sailing masters, and ship performance became "by the numbers."

Can this same idea be applied to recreational sailing today? Possibly, provided that a few warnings are observed:· The skipper must know the Beaufort scale of wind forces.· He/she must know how to handle the vessel.· He/she must have it properly equipped for storm sailing· He/she must know the capabilities of the crew.Relating sailing decisions to Beaufort's numbers

Force 4 means good sailing for all boats, large and small, with normal sail plans.

Most sailboats will reach hull speed with Force 5 winds.

It is time to raise the working jib (or reef a reefable furling jib) and single-reef the mainsail for more comfortable sailing. Overpowering the boat can actually reduce speed and makes the crew unnecessarily uncomfortable.

Racing boats can do their best since waves are still small.

Now is the time for serious powering down. Shortening sail should be done early and progressively ahead of the deteriorating weather. Small craft should double-reef the mainsail to go along with the working jib. Be absolutely certain that your roller-furling jib is tightly furled and wrapped with several turns of the sheets, or else remove it if the seas permit.

This is a good wind to practice the vital heavy-weather tactic of heaving-to, which you should know how to do long in advance of having to do it.

Small craft should head for harbor or heave-to. Offshore voyagers should fully furl the mainsail and replace it with a trysail, or run with no main. Beating to windward becomes difficult for any but the most skilled or persistent, making the options to run or stop the boat viable. A speed-limiting drogue can be deployed, enabling the boat to run comfortably downwind or on a slight broad reach with active steering by helm or self-steering. Traditional tactics of lying a-hull or heaving-to should be considered. Stopping the boat by drag devices, like a sea anchor, is an option should crew fatigue or boat problems make it necessary to stop sailing. Choosing a drag device means you need the necessary gear already on board with the proper means of deploying it.

At this (and higher wind force levels) crewmembers working on deck will appreciate having goggles to keep salt spray out of their eyes.

Small craft advisories are posted at 34 knots and small craft should head for or stay in the harbor.

Offshore sailors should hank on a storm jib or a small staysail if they want to continue sailing, but it may be more appropriate to seriously consider heaving-to, sea room permitting. When heaving-to with storm sails, the addition of a sea anchor on a "Pardey' bridle can materially improve the boat's riding ability. The long-term value of deploying a sea anchor at this time is that it will already be there should the storm get worse and last a long time. Heaving-to is a good tactical maneuver for facing extreme storms and is also good for waiting out a blow before closing on a coastal destination.

The use of boat-stopping drogues as tactical equipment can be considered, assuming the boat has been properly fitted for their use. These drogues essentially bring the boat's forward progress to a halt. The bridled tether keeps the stern in alignment with the breaking waves, negating any need to actively steer it; in fact, the crew retires to the cabin and hangs on. Loads on the tether are extremely high and waves breaking over the transom (pooping) can severely impact the aft cabin structure and fill the cockpit with water.

Dedicated ocean racers will carry-on with reduced sail. Gale warnings are raised at 41 knots. Lying a-hull with bare poles has been a traditional tactic at this and sometimes higher Beaufort numbers, the boat being said to find its own "comfortable position" in the waves and riding them rather than resisting them. Unfortunately, the boat nearly always assumes a broadside attitude to the seas; inviting a knockdown or rollover from a breaking crest with a resulting dismasting. Once dismasted, a boat becomes even more vulnerable to cresting waves because of the reduction of the roll inertia due to the loss of the mast. Lying a-hull is also likely to be very uncomfortable for the crew inside, described by one Fastnet survivor as being "tossed about like a shuttlecock." One rule of thumb says that a boat cannot safely lie a-hull in seas whose height is greater than the boat's beam, which occurs at much smaller Beaufort numbers. When lying a-hull becomes uncomfortable to the cabin-stressed crew due to cresting and breaking waves, it is time to raise the trysail and heave-to.

Offshore voyagers are able to continue under sail with bare poles by running before the wind (scudding) with the seas on the quarter. If the gale appears to be long-lived and the steering crew is small, consider deploying a speed-limiting drogue during running to ease the rudder loads. If the boat has good directional stability, it may steer itself in moderate seas; if not, let a good self-steering windvane handle the steering. Not all autopilots are capable of long-term steering under these sea conditions.

A short-handed voyager could also deploy a sea anchor over the bow (if that was not done in a heaving-to maneuver) and stop the boat to provide rest for the crew until the gale blows through. This action should be a positive consideration if the weather prognosis calls for increasing or longer-duration winds. Delaying the deployment of the sea anchor and letting the wind and seas build even more may make it impossible to work on the foredeck when needed. The comfort of riding to a sea anchor will be appreciated.

Storm warnings are raised at 48 knots of wind. This was the critical weather situation that faced the boats in the 1979 Fastnet Race in the British Isles. In some places it rose to Force 11. Of the 303 boats that started, only 85 finished. Some 24 boats were abandoned (19 of these were later recovered) and 15 crew were lost in the abandonment. If any single message came through from this disaster, it was that you should not abandon your boat until it is actually sinking.

Up to 1979, little development had been done on drag devices to aid in storm survival, and it was probably this tragic event that spurred the industry to develop them. The only way the Fastnet boats had to survive was to employ traditional survival tactics, including heaving-to, lying a-hull, running off under bare poles, and streaming warps. It is to the credit of the 85 finishers that they were able to continue racing through the maelstrom. In the absence of drag devices, the consensus was that active rather than passive tactics were the best, and those who were able to maintain some speed and directional control fared better.

For racing crews such tactics are all possible, but for the shorthanded voyaging boat, not all are viable. This is probably the highest Beaufort number at which heaving-to is practical, except that if the boat were hove-to with a sea anchor on a Pardey bridle, the bridle could be slipped and the boat allowed to ride to the sea anchor.

Running free with bare poles is something only for the racing crew with skilled helmsmen. Both pitch-poling and broaching are threats. Traditional survival means in the Fastnet storm included towing warps of varying descriptions. Today's state-of-the-art speed limiting drogues, however, will perform better.

Hurricane warnings are issued at 64 knots of wind. Most mariners are familiar with rotating storms known as hurricanes or typhoons. They generate in many parts of the world's tropics and usually within fairly repeatable time periods during the year. Voyage planning should make it a point to avoid areas of intense tropical cyclones during their normal seasons. Lesser known is the weather feature called a bomb, which is a rapidly forming low pressure area with high winds. The Fastnet storm of 1979 was one of these and the Queen's Birthday Storm of 1994 in the South Pacific was another. Both formed suddenly and with great intensity, taking a severe toll on the boats in just a couple of days. The Queen's Birthday Storm caught a voyaging fleet of 60 sailboats making a passage from New Zealand to Tonga. The wind speed in this bomb was clocked as high as 100 knots with 50-foot waves, and Force 12 was recorded by all boats in the core of the storm. The Queen's Birthday Storm would have been more disastrous than the three crew lost and four boats sunk had it not been for the lessons that were learned in the 1979 Fastnet event. Many of the boats carried state-of-the-art drag devices developed in response to Fastnet, and some used makeshift devices knowing full well the value of the drag principle in fostering safety in storms.In extreme storms, the parachute sea anchor stands out as the best possible safety device for the offshore sailor. When the winds exceed Force 11 and the seas grow to phenomenal height, there is little the crew can do to actively control the destiny of the boat. A sturdy state-of-the-art parachute sea anchor, deployed over the bow with critical chafe-resisting gear, can keep the bow of the boat, its strongest part, headed into the sea without the crew's attention. Bow-on to vicious seas, the chances of being rolled over by large waves are minimized, and crew comfort is as good as can be expected.


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