8 points from the stern

8 points from the stern

Tightly wrapped in storm clothing, the crew huddles under the deckhouse awning in search of shelter from the streams of water falling on the deck. And at this time, in some T-shirts, we fully feel on ourselves "all the delights" of a stormy swimming at full backstage. We were lucky that we didn't have to go against the wind!

True, such luck is often deceiving. After all, the increase in the wind at full backstay can be ignored and noticed only when the wind is driving the yacht in full force. In contrast to the movement in side-hauled, the roll on full courses is insignificant, the wind is almost invisible, and swimming is very exciting. It would be a shame to take the reefs right now ... We can wait a little longer until, finally, the signal comes in - an abrupt change of tack, because the stern is suddenly off course too quickly. The yacht can lie on its side, and the crew, on a heavily heeled and flooded deck, is forced to collect the sail beating in the wind.

Bianca 107

"Take reefs in a timely manner" It is very important for safety on board to observe this rule, especially when sailing when the wind is blowing from the stern. The signs that you should take the reefs are simple: it becomes more difficult to steer, the yacht is difficult to hold and to avoid yawing - in short, steering becomes torture. This is already an extreme situation when you just need to take the first reef on the mainsail. Although it would be better to perform this maneuver immediately after the first gust of wind, when the sea is still moderate.

Apart from the advice to be especially attentive to the increase in wind when driving on the backstay, it is hardly possible to give any other universal recommendations. After all, the degree of reduction of the sail area depends to a large extent on the sailing properties of the yacht and its maneuverability, the ability to control the vessel, the number and experience of the crew and, to a large extent, on the type of yacht.

These are, so to speak, common truths. But:

“If the sea is very rough, then you should set as many sails as the ship can carry; after all, you need to ensure a speed of at least ten knots in order to quickly take the yacht away from the waves that collapse with all their might on the deck and threaten to damage the vessel, designed for sailing in fordewind. "

So it is written in "Handbook of maneuvering at sea"issued in 1830 for fishing sailing ships.

So you need to set sails instead of taking reefs? Awesome advice! However, it makes sense: such ships were built to sail with a tailwind. Their voluminous hulls, round stems, shallow draft with a flat keel and two-masted gaff spars hardly allowed the vessel to climb, under favorable conditions, at 65 degrees at best. At a certain wave height, these ships simply "buried" in the wave, were forced to drift and wait for a more favorable wind.

A great danger to the crew and the yacht arose, of course, with high waves from the stern. If a wave hit the stern, then a huge mass of water could break the hatches (gangway) or carry sailors overboard. In addition, the ship's controllability was lost, it was turned across, as a result of which the side of the yacht took on the subsequent blows of the waves. This counterintuitive advice - to keep as many sails as possible - allowed you to maintain control of the boat when moving on high waves, and significantly weaken the destructive energy of breaking waves.

This recommendation - to set as many sails as possible when moving at full backstay - is confirmed in the notes of the Argentine. Vito Dumas, who for the first time single-handedly circumnavigated the world (1942-1943) in the "roaring forties" latitudes. His yacht, wooden Bermuda ketch Legh II (Colin Archer type), has proven to be an extremely stable vessel and has served as a model for the development of many new yacht models. Dumas set on both masts separated small sails made of especially strong canvas. There weren't even reefs on his grotto. Dumas walked away from the waves or moved along their crests. If it became difficult to control the rudder due to the great pressure, he would remove the mainsail and swim further under the mizzen and foresail. At the same time, the waves entered the stern of the yacht along an oblique line.

"If you move with the speed of waves, then they do not pose a danger", he writes and adds: “In the books of other sailors, I am amazed at the number of accidents they have experienced. They are probably due to the small distances traveled by the vessel per day "

And how do modern yachts behave when a wind of eight (or more) points blows from the stern? Here's what he writes Wilfried Erdmann on her first non-stop solo voyage around the world in 1984 on an aluminum short-keel yacht with a length of 10.60 meters and a displacement of 5.4 tons:

“In the end, I figured out: you should move at the speed at which the least wave drag is created, and set small, separate sails. Thanks to this, the yacht remains manageable. She lifted the stern when the waves rolled in, and the bow never sank too deep into the water. Before entering the "roaring forties" latitudes, I almost completely emptied both the stern and the bow to give these sections of the vessel more buoyancy. Due to its low overall weight, the Kathena Nui picked up speed quickly, which reduced the power of the waves hitting it. "

Erdmann's yacht received the waves entering from the stern obliquely, and the mainsail and the head sail were adjusted to the wind speed so that the yacht was sailing at the speed at which the least wave drag was created, and due to this, it retained optimal performance.

However, not only the type of yacht plays a role in choosing the right maneuver, but also the type and shape of the waves, their steepness, as well as whether the waves travel evenly or crash chaotically. Here is an example: in the Atlantic Ocean, about a week before the discovery of the coast of Barbados, the north-east trade wind of 68 points was constantly blowing with strong squalls at night.

I was sailing on a fast, short-keel yacht of 10.70 meters, with a sharp bow and a relatively wide stern (Bianca 107). Probably due to the old, oncoming swell, extremely steep waves arose. Having doubled the mainsail and leaving a small stormy foresail, we sometimes glided into the troughs of the waves at a speed of more than 12 knots, and the yacht was often brought to the wind. In the end, at some point, the yacht was jerked so sharply to the side that we lost the rudder of our autopilot, and after an unexpected sharp change of tack, the mainsail broke at the level of the sails. Since the yacht was constantly trying to get out of control, the need to stay at the helm all the time became a real challenge, and we had to change each other every two hours. We could have avoided this stress if we had removed the mainsail - but we did take part in the regatta (ARC) and had every chance of winning first place in our group.

The constant and uncontrollable urge of the yacht to lead to the wind can be explained simply: traveling waves captured the bulk stern, lifted it and dragged it with high speed into the wave cavity. At the same time, the sharp nose plunged deeply into the water. There was a difference in speed or torque between the stern and bow, as if the stern was trying to overtake the bow of the yacht. The yacht was turned to the side and thrown sideways into broching.

This behavior is also enhanced by the circular (orbital) movement of water particles inside the wave: in the crest of the wave, they move forward with the stern of the vessel, and water particles in the trough of the wave rush in the opposite direction, which enhances broaching. With the mainsail lowered, we would not go so fast, but due to the location of the forehead pressure point far ahead, for sure, the yacht would not be thrown to the sides. Or it would be possible to go on a course as close as possible to a full backstay. The course would have been more stable, but we would have had to change tack more often in such difficult conditions.

sailing on the Gulf Stream, I had a similar situation. Since the current is constantly changing its direction, and its speed reaches 34 knots, sailors are wary of entering this region due to its chaotic, steep waves. It was here that a storm caught me when I was sailing on a short-keel vessel almost 8 meters long (type Freedom 25) with a cat-type spar, i.e. with a mast without stays located far ahead of the vessel. In just half an hour, the wind force exceeded 8 points, and the erratic waves became dangerously steep.

At first, I walked under a threefold reduced mainsail, and the yacht often began to planing (when the speed of the vessel exceeds double the speed at which the least wave drag is created, the planing state sets in). But as the wind continued to pick up, the yacht became uncontrollable - even after I removed the mainsail and sailed without sails in an oblique line relative to the waves. The yacht was jerked several times so that the subsequent waves hit her right in the bow - although the stern did not experience strong water impacts.

Cause: a wide-profile kevlar / carbon mast created a strong enough thrust in winds (according to my estimates) of about 10 on the Beaufort scale and acted like a storm sail. Without this mast and, if necessary, to receive waves at the bow of the yacht, it would probably not have been possible without capsizing the vessel. If I had a regular spar and a stormy foresail, I think that I would not have been able to safely survive a similar situation at sea on such a relatively small, albeit extremely floating, yacht. In general, during this voyage in the Atlantic, I had to deal with gusts of force 8 Beaufort (measured on deck) from the stern many times. True, sailing under a threefold reduced mainsail, even with an automatic vane control device, was not difficult, since the waves were less steep than in the Gulf Stream.

I had to face a similar situation during the trip between the Azores and England, but this time I was sailing in a wooden boat with a sharp bow and narrow stern (old model of the Colin Archer type). Like a bolt from the blue, a wind of more than nine Beaufort points suddenly hit with powerful squalls, we barely had time to remove the sails. Huge waves rose incredibly quickly. We gave up the idea of putting the storm foresail on the jib, because the yacht was steering and sailing without sails at an average of six knots. Waves rolling obliquely from the stern rushed under the stern without any harm, no spray even got to our deck. After about six hours, the seas began to subside. The wind weakened to five points, we put the jib and confidently went on the course, although the waves were still high enough.

Contrary to rolling

Moving to the backstay with a deflected mainsail, one may encounter the phenomenon of "side rolling", which many yachtsmen fear: the vessel begins to sway more and more and is driven to the wind. If you try to counteract this by operating a yacht, you can even amplify this tendency so that the boom will sink into the water, which could cost you the boom swivel or even the mast itself.

The reason for these uncontrolled oscillatory movements is the so-called Aerodynamic feedback system: Air vortices are generated on the luffs of the sail, increasing the air flow on the leeward side of the sail. "This results in a lateral force that causes a slight oscillatory motion," explains Wolfgang Puechl, yachtsman and professor at the University of Vienna, in his recently published book "Physics of yachting" (published by Wiley-VCH). Thus, strong rolling can occur during sailing even in the absence of rough seas. However, waves cause side rolling more quickly and can greatly intensify it. To counteract this buildup of oscillation, the yacht should be drastically upwind and then set as close as possible to full backstay. Heavy rolling can also be caused by transverse waves, so that even the kick of the boom will sink into the water while heeling. This danger arises especially when reducing the sail by taking reefs, because the distance from the knock to the water decreases. For this reason, you need to be prepared to block the boom guy. Or, to be completely sure, the boom is pulled up the right way, although you have to put up with increased lateral rolling.

The same is done with the safety line, which should prevent a sharp turn of the boom during an unexpected change of tack. If the yacht has a tendency to heel, it is best to let go of the line and bring the boat into the wind. This measure is necessary, first of all, at night, when it is difficult to notice the increase in waves in time. If the wind continues to grow stronger, then it would be good advice to immediately completely remove the mainsail and go further only under the genoa, reduced in accordance with the situation.

And in conclusion, some more recommendations regarding the cut and method of making sails. They must be reliable if you have to deal with winds of eight or more points. To, as advises Wilfried Erdmann, the yacht remained fully maneuverable at the speed at which the least wave drag was created, and could actively take on the full power of dangerous waves.

Boaters planning long voyages that are different in duration from their usual vacation sailing should consider three rows of reefs on the mainsail. In this case, the third reef is set so that the reduced sail in a wind of about nine Beaufort is still on the mast. The sailmaker will reinforce this area of the sail to maximize the distribution of the forces acting on the sail. At the same time, there is no need to use heavy material, since modern types of canvas are quite durable. The correct size of the reinforcing elements on the eyelets, lath pockets and afterliks is also of great importance. However, the mainsail, reduced by three times due to the reefs, will not be able to replace the trisel, which will be needed when the wind strength is ten or more points.

The same is done with the head sail, which today almost always works with a single twist. Of course modern sails are extremely durable. If you have precise control of the boat and do not allow for broaching, in which the sail can hit, then the almost completely retracted sail and mechanical parts will withstand the load, provided the mechanism is strong and the sail is properly reinforced. And all the same: if you are caught in a storm from the stern and the sail is reduced to a minimum size, the sailcloth and mechanics are subjected to extreme stress.

Therefore, sailors sailing long distances equip their yacht with two twists: the front one for the large genoa, the rear one for a small, highly sloped sail made of a special heavy material. In strong winds, the genoa is removed, but the foresail remains.

Output: what action to take in a strong stern wind depends on the yacht and the steepness and height of the waves. Therefore, it is impossible to define any rigid rules of conduct during a storm, as the above examples confirm.

Despite this, some recommendations can be made:

• Waves must always come in obliquely from the stern. The steeper they are, the more the yacht needs to be driven into the wind in order to reduce the braking backflow in the bow of the vessel, resulting from the orbital movement of water particles.

• If the pressure on the rudder increases, you should immediately take the reefs on the mainsail. If the wind is constantly getting stronger, it will be better and safer to completely remove the mainsail and move on only under the head sail (storm foresail). The front wind pressure point stabilizes course and reduces roll.

• All measures should be taken in a timely manner!

• On modern yachts, with their long sails directed towards the stern, it is not possible to deflect the mainsail sufficiently to control the yacht reliably and prevent unexpected tack changes when the wind blows from the stern. Therefore, in the presence of high waves at sea, you should not go to fordewind.

• The steeper the waves and the more they knock the yacht off course, the more the boat should be brought into the wind. Then the yacht moves better on the water, it obeys the rudder better, and steering the yacht requires less effort.

Text and photos: Michael Bohmann

20.01.2013