A skipper must be prepared to manage the boat in all sea conditions — head seas, beam seas, and following seas. Each has its own characteristics and dangers. Each requires different operational maneuvers and techniques.
Today we will look at Head Seas
When you're taking the waves on your bow, you're running into a head sea. This usually poses little danger to the average powerboat. However, open-bow boats (referred to by lake-patrol rangers as "water scoops") are at greater risk than closed-bow boats. Most small, open-bow or low-freeboard boats should not be operated in heavy weather on large bodies of water at all. Larger vessels have a bow designed to meet waves. With an experienced skipper, they can safely handle moderate to severe conditions so long as the boat is trimmed (leveled) properly and operated at an appropriate speed. When trimming the boat, pay attention to the center of gravity, at the bow, the stern, the trim, and list. Here's how:
Trim the boat so it's flat:
A bow trimmed too low will cause the boat to plow through the water and plunge into and under oncoming waves, giving everyone a wet ride while taking on dangerous amounts of water. A bow trimmed too high may provide a drier ride, but the boat will pound and be very uncomfortable. The stern, already a vulnerable area, will be even lower in the water than normal. Engine trim should be adjusted so the props don't cavitate as the boat pitches, rolls, or makes sharp maneuvers through breaking waves. Generally, this means the outboard or outdrives should be in the full down position. Prevent list: Canting from side to side, or listing, reduces stability and is very dangerous. Vessels equipped with adjustable trim tabs or planes and engine trim provide the operator with options for improving the boat's ride and performance in heavy seas. As a general rule, trim tabs should be set so the vessel rides as level as possible.
Lower center of gravity:
Passengers and heavy objects should be moved to the center of the vessel to lower the center of gravity and increase stability. Gas cans, ice chests, and heavy gear need to be secured to prevent loose items from tumbling about and causing injury. In heavy weather, there's enough to worry about without dodging flying gas cans. Even a well-trimmed boat can get into trouble if it isn't operated at a proper speed for the conditions. Almost everyone tries to go too fast. Pounding is hard on the vessel and crew and should be avoided. One boat I saw that had been operated on a choppy day for only a few hours by an inexperienced Park Service employee looked as if it had been in combat. Pounding through waves had stripped screws and loosened the cabin bulkhead; the dash was held in place only by the instrument wiring. Heavy-weather boating is displacement boating. Don't even think about getting up on plane. Never go fast enough to fly through the wave crests or cause the props to clear the water. Too much speed can result in the bow plunging under waves as the vessel pitches over the crest into a trough. I've seen good, seaworthy boats flooded or sunk because the operator didn't slow down and let the bow rise with each wave. The bigger the chop, the slower the speed. Operating in head seas requires constant tending of the helm and throttle to allow the boat to ride up and down with each wave. Slow down and angle into and through each crest, then resume course and speed up. If your prop comes out of the water as you pitch over a crest, throttle back to avoid racing the engine. In choppy seas over four feet, you will just barely make headway when meeting the seas on your bow.
One of my worst experiences with a head sea occurred one winter day when I was dispatched to rescue a sinking vessel in the main body of the lake. I headed out of a protected cove into the largest combers I'd ever seen (a comber is a large wave that has reached its peak and broken into foam). As each successive wave struck, it buried the forward half of the boat in swirling, foaming water. In those conditions, I could not continue meeting the waves head on. Instead, I began tacking into the seas, zigzagging to take the waves on the bow quarters. Taking the waves at an angle converts some of the severe pitching motion to rolling motion, giving a more comfortable ride at a slightly faster speed. To tack in a head sea, select a course that meets the seas at an angle of about 45 degrees. After traveling in one direction for a while, change direction 90 degrees to take the seas at roughly 45 degrees from the other side. How long you stay on one course before changing direction to the other angle is a judgment call. Because turning in high seas presents some risk and requires an alert, skillful operator, travel as far as you can in one direction before changing course.
The Art Of "Heave To"
There can come a point when the seas grow so large that it's no longer safe to try to make headway. When this happens, you can "heave to." Head into the waves, reduce speed while maintaining steerage-way, and hold your position. Heaving to under power allows you to wait for the storm to pass while taking the seas from a relatively safe direction. This survival technique will reduce pitching and reduce or eliminate rolling, the motion that frequently causes seasickness. As one wit put it, "Heave to or your crew will heave, too!"