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Steering in Waves

2009 December 1
Simple helming techniques can reduce uncomfortable, and potentially dangerous, pounding

The airtime can be impressive after you've been launched upward from a bunk down as the boat suddenly plunges from beneath you. Then you begin that wait for the inevitable SLAM! back to earth as the hull crashes into the water below. The impact staggers the mast; the hull pounds with a vibrating thud; rigging shakes and the crew's teeth rattle. Any sane person's impulse at this moment is to locate their personal overboard satchel of goodies before the mast is driven through the boat.

Nobody likes this scenario, but we've all endured the consequences of shock loading on hull and rigging, plunging boat speed and a startled crew. A racing helmsman must also endure those derisive groans from the peanut gallery on the rail.

The 2009 Marion-Bermuda race provided crews with ample opportunity to hone their driving skills, particularly those of negotiating big waves without damaging boat and crew. In truth, slamming bows can result from much smaller waves as well, such as those steep little ones that develop in newly freshening winds, or ones arising in shallow waters. There are a couple of tactics to use when negotiating large or steep waves to prevent the boat from slamming this way.

In moderate winds with short, choppy waves, cruisers can simply take some speed off the boat so the bow "steps" over the wave rather than plunging over the crest. Rolling in some jib or reefing the main is often enough to stop the pounding. However, losing too much drive can cause the boat to "wallow" as it assumes a deeper roll motion. Racers, of course, resist giving up boat speed, so they use steering techniques to negotiate the waves. This is also a great option for the cruising sailor in large waves at sea, where slowing up the boat may not prevent the bow from plunging down the backs of big waves.

The trick is to watch the waves as they approach and make your maneuver on those that threaten to induce a slam, particularly the large, steep waves.

For a boat that is close reaching in waves over which the bow plunges and slams, maintain course while driving the boat up the face. As the bow approaches the crest, but before reaching the apex, steer a few degrees to leeward so that the boat descends gently along the wave's backside, rather than at a direct angle. The bow will stay in contact with the water, preventing it from pounding.

As the bow traverses the crest and begins to descend, steering back toward course to sail the wave downward can actually provide a brief speed increase-small-boat racers often benefit from this technique. Simply releasing the wheel for a brief moment will usually bring the boat back on the correct course; the wheel will spin toward windward, taking the boat back on course. However, I always have to guard from a tendency to head too high at this step, which stalls the boat's speed.

The object of the technique, then, is to climb the wave face, steer down the at the crest to avoid slamming, and then come back up to pick up some speed when sailing down the back of the wave (Figure 1). This takes a little practice, but when the technique is mastered the helmsman negotiates troublesome waves smoothly, automatically steering down as the bow approaches the wave crest and sailing the backside smoothly.

In Figure 1, a boat is driven up a wave and bears off near its crest. In this illustration, it then proceeds down the wave back at a safe angle that avoids plunging into the trough and yet avoids a shallow angle that could allow it to trip over the rudder and fall laterally. Racers, in moderate wave conditions, often take advantage of the opportunity to steer a bit steeper angle down in an effort to generate more speed.

This same principle applies to the boat sailed down wind in large waves. The main concern in this situation, however, is in safely negotiating the wave's face rather than pounding the hull. Steering slightly off at the crest and maintaining a safe attitude down the wave is the technique of choice to stay safe. The helmsman must gain a sense for the proper attitude at which to descend the wave. On one hand, he or she must prevent the boat from plunging downward too steeply, which can result in the boat pitchpoling, and on the other hand avoiding a shallow angle at which the boat can broach, toppling over its beam ends and falling laterally down the wave. This also is a matter of experience and feel, and eventually becomes second nature.

In the midst of the Marion-Bermuda race I was awoken below while being propelled across the aft port berth and slammed against the hull. After gaining a sense of position, I grabbed the light that hung from a pendant around my neck and pointed it at the cockpit port, only to see water flooding the cockpit. With my foul weather gear still on from the last watch, I struggled toward the companionway, and climbed the steps sideways to the cockpit. My two mates, Tim and John, were clinging to their tethers as John screamed in terror. Slowly but surely the keel won the balancing act; the mast rose out of the water and soon the boat was upright once again.

We rigged a new boom vang and repaired a torn mainsail, and after a change of underwear we were under way once again. This was the result of traversing the backside of a 30-foot wave at too shallow an angle. The wave pushed the hull over, tripping the boat on its own keel and capsizing her. The trick to avoiding this situation in big waves is to find the right angle at which to descend the wave. I like to maintain the same angle of heel as when ascending the wave face as a key guideline to angle of descent.