Lets Lie AHull

When a boat is hove-to under shortened canvas and the wind and seas increase, the balance of the yacht can be upset. The sails may start to shake and the yacht's motion may become nervous and unsteady. Each yacht acts differently depending on:

1. Her hull form.

2. The number of masts.

3. The amount of sail that's up and how the area is adjusted.

4. The windage of the hull, deck structures, exposed dinghies, dodgers, cockpit weather cloths, biminis, furled sails, and so on.

With more wind, the hove-to boat may put half her side deck underwater. She may start to sail faster than you think is safe. Or the yacht may head up and then fall off uncontrollably. Heavy water may begin to thump on board.

Another scheme that can work in Force 7 and 8 and perhaps higher winds, depending on sea conditions, is simply to take down all the sails and let the vessel drift slowly before the storm. This is called lying a-hull. Most boats with their deep under-bodies will lie at right angles to the seas and skid downwind sideways at a slow and steady rate.

This sounds terribly dangerous, but if the wind has been blowing from one direction for a number of hours and there is plenty of water depth, the seas are often remarkably regular, and the boat will ride well with the waves broad on the beam. At first the noise and motion are alarming, but as long as there are no upset or irregular seas, you can get along tolerably well.

In the past, many deepwater small-boat sailors regularly took down all sails in gale or near-gale conditions. The well-known English sailor Humphrey Barton, who made dozens of Atlantic crossings, preferred to remain hove-to under suitable canvas until the wind was strong enough to keep his boat comfortably heeled without any sails up at all.

While sailing from Bermuda to Newport on one trip, the great sailor K. Adlard Coles wrote: "By 2000 . . . [the wind] had attained Force 8 by hand anemometer at deck level, and at least Force 9 on the Beaufort notation which is taken at 33 feet above the surface of the sea. Following my usual practice in gales, all sail was lowered and Cohoe lay a-hull all night under bare pole. On deck it was difficult to distinguish between air and water on account of the spindrift and torrential rain. Next morning, Friday May 26th, we were able to get under way again at 0730, running under storm jib."20

Another captain wrote of his arrival on the Atlantic side of the Panama Canal Zone in strong weather:

"We lay a-hull for a few hours to avoid arriving at Cristobal during the night. I was much impressed by the way . . . [the yacht] behaved; I suppose the seas were running about ten feet high and the wind was Force 7, for we had sailed with a strong trade for three days . . . [The boat,] with her helm lashed down and sailing at about half-a-knot from the pressure of the wind on her masts and rigging, tried to head up into the wind, but then fell away, so that she pursued a slow and wavering course on each side of a line at right angles to the wind. Meanwhile she drifted to leeward at about the same speed, leaving a short slick to windward, caused by the water boiling up under her keel."21

Speaking for myself, in lying a-hull in a ballasted long-keeled monohull with no sail up to steady the boat, one of my yachts rolled terribly. Many sailors, however, report that the force of the wind keeps their boats heeled to leeward with little or no rolling. I suspect that the motion depends on the beam of the boat, its ballast arrangement, the keel depth, the amount of top-hamper, and the strength of the wind.

The yacht's alignment to the wind can be adjusted to some extent with her rudder. You can lash the tiller a little to leeward (or turn the wheel to windward) to keep the head of the yacht from falling off. Depending on the boat's design, she may even respond well enough to her rudder to lie with the wind 45 or 50 degrees off the bow.

As the boat drifts sideways before the wind, the hull leaves an area of settled water to windward. Sailors call this a smooth or slick, and it tends to isolate the boat somewhat

Lympne Airfield

from waves that slide past outside the area of the slick. The trouble with the slick, however, is that the yacht has to be carefully oriented to the wind and seas. If the boat gets turned for any reason or the waves increase in size, the protection of the slick is lost.

"I think you're talking about a separated wake, which is what occurs behind a bluff body as it moves through a fluid," says Nick Newman, a professor of hydrodynamics at the Massachusetts Institute ofTechnology and a keen small-boat sailor. "Picture the wake behind your hand as you move it palm-first through the water. It includes a lot of vorticity. If it is organized into large alternating vortices on each side, it is known as a Karman vortex street, but my perception of a yacht lying a-hull is that it will leave to windward a somewhat random and disorganized wake with a lot of small-scale vorticity. You can probably picture what this would be like in smooth water, but in waves it is more difficult to see.

"I can't give you a simple explanation of why the interaction between the waves and vorticity is beneficial," says Professor Newman. "However I suppose one could say that the relatively random motions of the wake destroy some of the more organized structure of the wave, especially near a steep crest that is already somewhat unstable and close to breaking."22

Professor Newman feels that the word "slick" should be used differently—to denote pouring oil on water. Doing this creates a thin layer of a different kind of fluid right on the surface. This type of interaction with a wave is completely different from the separated wake mentioned above.

It's well understood that the tactic of lying a-hull works best when the wind is steady and the seas are regular. If you're 5 miles off a weather shore, for example, and the wind is whistling from the land, the seas will have had no time to build up to dangerous sizes.

Long-time sailor and scientist Dr. John Letcher recently suggested to me that in heaving-to or lying a-hull, sailors should consider the difference between the port and starboard tacks. As a storm progresses, the wind generally changes direction slightly (usually veering—i.e., shifting clockwise—in the Northern Hemisphere) while the seas continue to roll in from the old direction. Unless the drift of the yacht is straight downwind, one tack or the other will send the slick off in the direction the waves are coming from and give the boat a better ride.

"When either lying a-hull or heaving-to," writes Dr. Letcher, "one tack will put the waves more on the bow while the other tack will put them more on your quarter." The latter is a lot more comfortable in terms of motion and wetness.

Remember that our little game in a strong wind is to play for time and a change in the weather. With luck, after 4 or 5 hours of lying a-hull, the storm may decrease or move off.

The danger in lying a-hull with the seas broad on the beam is considerable, and you need to make this move with caution and a constant eye on the sea conditions. If the swells begin to get confused, the wind shifts, or the storm increases, the seas may get out of phase with one another and become upset and irregular. Then it's possible that a whopper may break near or on top of your vessel and overwhelm her with tons of water. An argument can also be made for seas that get in phase with one another and augment already existing seas. Whatever the cause, we must avoid big seas that thunder on board and strike the side of the vessel.

"Every cubic meter of seawater contains slightly more than one ton of mass," writes Captain William Kielhorn in SAIL magazine. "A breaking sea wave may easily contain 500 tons or more, curling and racing downslope at speeds up to 20 or 30 knots."23

Even a small breaking wave is extremely dangerous. Think of a waterfall suddenly landing on top of the vessel and shoving her bodily to leeward. The impact is the same as being dropped on concrete. Damage almost always occurs on the leeward side of the boat and can mean a stove-in coachroof, collapsed portlights, or heavy damage to the hull. The force of the water can easily carry away pulpits, sails tied to lifelines, dinghies, deck gear, and even the rig itself.

If you're lying broad-on to the seas, and the waves increase in size and the white water around you begins to look and sound nasty, you must promptly stop lying a-hull. If you have the length of the boat parallel to the waves, you present the entire side of the hull to the storm. A much more sensible defensive posture is to run off downwind or take other steps that we will consider later in the book.

If the seas increase in the middle of the night, you must bestir yourself and take immediate action. You must not hope that things will get better or decide to wait until daylight. You need to act at once.

Think of the yacht as a 40-foot log in the ocean. If the log is parallel to the waves and they become dangerous, the log will be rolled over and over. In a large breaking wave, the log may be dropped from the top of a crest all the way to the bottom, perhaps 35 feet. But if the log is kept at right angles to the wave crests by various means, the log has a chance of making it through the storm without being rolled or flipped.

I'll say it again. You must avoid lying a-hull in big seas that have begun to break. When conditions allow you to lie a-hull, it's still unnerving to be in your bunk listening to the seas hissing past hour after hour and wondering whether the weather is getting better or worse. Again and again the seas slide up and then race away with great bubbling sounds. You doze off. When you awaken and look out, you realize the rolling is less and the storm is moving off. The clouds are clearing. There's sunshine here and there! The storm is over. It's time to put up some sails and start moving again.

But if the storm intensifies and you hear a crash in the distance as a big wave topples into a mass of white foam, it's time to bestir yourself. The roar of a breaking wave is a signal to change your tactics before solid water lands on board and begins to push the boat against the solid water to leeward. These signals have been documented many times in all oceans. And probably even more by vessels that haven't come back.

To take one example, consider the voyage of the Contest 31 sloop Banjo en route from Bermuda to Greenport, New York, in July 1975. This trim fiberglass sloop with three aboard left St. George's with an excellent weather forecast and made good time toward the northwest for three days. Then on Saturday, July 28, at 35° north, crewman Alfred Boylen heard on the radio that a tropical disturbance named Blanche was headed northeast from Bermuda. Boylen hoped they were far enough to the west to miss the storm.

Unfortunately by 1600 on July 28, Blanche struck poor Banjo, and according to Boylen, "We were in it with the wind increasing to hurricane force." The crew went through the usual sail drill. First one reef in the mainsail and a change from the #1 jib to the smaller #2. Soon the three men took off the main entirely and changed to the storm jib. Finally the crew handed all the sails and lay a-hull.

If we assume that a 60-knot wind was blowing across a 100-mile sweep of ocean, the significant wave height would have been about 35 feet. The distance between crests would have been roughly 390 feet, and one of these big waves would have rolled past Banjo every 81/2 seconds at a speed of perhaps 26 knots (see the tables in Chapter 2). The average wave height would have been 22 feet; 10% of the waves might have measured 44 feet. Since Banjo was lying a-hull and parallel to the waves, her sideways speed would have been very low.

"By 1800 the seas had built to 50 feet or more with many big surfs," said Boylen. At 1845, he noted, "There was plenty of motion but it was not too uncomfortable."

Less than 2 hours later, a calamity took place. "About 2000 we felt a big lift, an almost weightless drop, and a sudden stop with a crash that reverberated as though we were inside a kettledrum," said Boylen. "A second later another shudder ran through the ship along with a slashing roar as the crest of the wave from which we had dropped fell on top of us while we lay in the trough. We estimated that we had dropped 50 feet on our side from a crest into a trough."

My interpretation of this mishap is as follows: The yacht was picked up and fell off the top of wave A, which continued to surge ahead at 26 knots and was gone. The boat then plunged into the trough between waves A and B. "A second later" (8.5 seconds?), crest B fell on Banjo. Or could these enormous waves have been out of sync and closer together?

Recall that earlier we calculated the time and distance between the crests passing Banjo at roughly 8.5 seconds and 390 feet respectively, so in 2 seconds, crest A would have moved 92 feet beyond the yacht. In 4 seconds it would have moved 184 feet. Then "a second later" (46 feet), a waterfall from wave B fell on Banjo. This plus the first drop caused fatal damage.

The truth is that we don't have enough facts to know what really happened. Boylen said "a second later." Was that literally 1 second, or was it 8 seconds? We're told that "we felt a big lift, an almost weightless drop, and a sudden stop." Certainly there must have been time intervals between those events. But how long were they?

The men in Banjo were being speeded up, slowed down, and rotated all the time and probably had no idea of the vessel's orientation at any given moment or which waves were doing what.

"Unfortunately," says sailing authority Ed Boden, who reviewed this incident, "both the estimation of distances and the exact description of events during a critical moment in a storm are highly suspect. Certainly at that moment no one was looking out of the main hatch with a stopwatch and a video camera."*

Poor Banjo was severely damaged. Her rudder was jammed, and water came in from a 6-foot-long fore-and-aft split in her fiberglass hull next to the rudder skeg, the vertical appendage to which the front of the rudder was attached. In spite of three pumps, the crew couldn't keep up with the inflow of water. The men set off an emergency position-indicating radio beacon (EPIRB), which brought a U.S. Coast Guard plane that dropped a powerful gasoline-driven pump. By 1000 on July 29, the pumps were dealing with the water, the storm had moved away, and the weather had turned fair.

Unfortunately the split in the hull was worsening. It was impossible to steer Banjo, and she was still 300 miles from the nearest port. The Coast Guard asked a big ship to stand by, and 16 hours after the mishap, the three men abandoned the yacht.24

In a long postmortem discussion, the owner of Banjo believed that the Dutch yacht was well constructed, but he faulted the builder on the way the hull and rudder skeg were laid up separately and then glassed together with a secondary bond. When Banjo fell off the breaking wave, the skeg apparently took a massive blow. Additionally, the skeg may have acted as a lever where it was attached to the hull.

It is the contention of this book that the forces involved between breaking waves and yachts are far greater than owners of small vessels realize. My feeling is that no vessel—large or small—can be expected to survive 50-foot drops and avalanches of water without significant damage, even if the hull is built of welded steel. In my judgment, the crew should have run Banjo off before the storm or taken more aggressive action. To deal with breaking waves we need to refine our storm management techniques. If Banjo had been lying bow- or stern-to the wave that smashed the yacht, she might well have survived without damage.

It was just 50 years ago that Miles and Beryl Smeeton sailed from Coronel, Chile, in their 46-foot ketch Tzu Hang, which they had laboriously rebuilt after a terrible smash before a huge wave in the Southern Ocean. The Smeetons were keen to make it around Cape Horn on their second attempt, but at 48° 30' south, about 300 miles west of Golfo de Peñas, the barometer dropped to 950 millibars and a fierce Force

*This incident has an uncanny resemblance to the foundering of the 55-foot Winston Churchill in the 1998 Sydney—Hobart race. Another source is a 2-minute video, given to me by Don Jordan, in which a Coast Guard helicopter from Miami is over a large yacht that is sideways to a breaking wave and gets smashed. Both incidents reinforce the wisdom of not riding parallel to breaking waves.

10 storm from the northwest began to rage. Following advice given to them by the Chileans in Coronel before they left, Miles handed all sail and lay a-hull. Initially it was satisfactory, but as the seas built up and the two sailors heard the monsters roaring past, their situation grew more dicey.

At 1600 on December 26, a breaking wave roared down on the white-hulled ketch lying with her side exposed to the storm. Like Banjo in the preceding account,

1. Caught by. . .
2. A breaking wave . . .
Mandibulectomy Cat
4. Upright again, with wreckage to windward.

the collapsing wave capsized the yacht and caused great damage; the smash broke each mast into three pieces.

The Smeetons managed to set up a small jury rig, and with a fair wind from the south sailed north for 1,200 miles to Valparaiso. Later Miles made these four drawings, which have a nice feel of realism about them since he was on board. Never again did he lie a-hull when there was a danger of breaking waves about.

Sailingboat Storm Drawing
How To Have A Perfect Boating Experience

How To Have A Perfect Boating Experience

Lets start by identifying what exactly certain boats are. Sometimes the terminology can get lost on beginners, so well look at some of the most common boats and what theyre called. These boats are exactly what the name implies. They are meant to be used for fishing. Most fishing boats are powered by outboard motors, and many also have a trolling motor mounted on the bow. Bass boats can be made of aluminium or fibreglass.

Get My Free Ebook


Responses

  • bonifacio trentini
    What type of sailboat lies ahull best?
    3 years ago

Post a comment