Chapter - 13

Boat Handling Under Various Sea Conditions

With the advent of the motor boat as an important acquisition to our national defense, motor boating can no longer be looked upon merely as an exhilarative pastime. Its affiliation with military and naval forces guarding our extensive coast lines has placed motor boating upon a basis where responsibility and serious work go first, with sport and pleasure as a secondary consideration. This being the case, it becomes the duty of owners and operators of motor craft enrolled for defense service to acquire and cultivate not only a thorough understanding of the handling of the boat and engine, but also a knowledge of various wrinkles which in time of actual service may prove of value. The following suggestions apply in particular to a motor unit assigned to scout duty which through unforeseen exigencies may find itself in strange waters and, therefore, will have to rely upon the skill and resourcefulness of its commander to carry out his scout work and at the same time avoid the pitfalls likely to be encountered in navigating unknown sections of the coast.

Indications Of Shallow Water

Upon approaching a shoal spot in the water, the attention of an observer will be attracted either by a rise in the height of the waves, with a tendency to curve over and break, or by their taking on a troubled, agitated appearance, in marked contrast to the waves in deeper water. The extent of the irregular water will, in most cases, clearly define the limits of the shoal, and, when traversing shoal places, the deepest water will always be found where the waves are of normal size and most regular appearance. They will be clearly distinguished from either the lifting kind, which are inclined to topple and break, or the smaller jumbled type. At times, the water over the shoal will be smooth and the water in the channels ruffled; this is particularly likely to be the case when the shoal bordering the channel has a growth of weeds reaching nearly to the surface.

If in strange waters and a line of ripples stretches across the course, the ripples should be approached with caution. The line may be caused by the changing of the tide, or it may be a reef or bar fairly close below the surface. These small ripples are often seen along the edge of shoals when the surrounding water is smooth, particularly when the outside water is deep; they are caused by the flow of the tide being shunted off by the shoal. During a strong breeze, when traversing a shoal having from 3 to 20 feet depth of water over it, the deeper parts may invariably be distinguished by watching for the heavier, more regular waves, while the shallow spots of the shoal are indicated by choppy, breaking waves.

Crossing A Bar

Necessity may at times compel the passage of a boat through a reef or a bar, over which a strong sea is running. In such cases it is well to run slowly along the reef at a moderate distance and search carefully for regular waves. If there is an opening, or channel, through, it will show water distinctly different from that over the rest. In such deep places, the water will remain without breaking until the sea has attained such violence that even the deep places have practically become shoals. The passage through comparatively unknown reefs and bars when heavy weather prevails should not be attempted except by the most experienced men. The sea may look smooth and regular at some distance off the bar, but on approaching, the conditions may be such as to require an intuitive skill at the helm to get the boat safely through.

Wave Motion

To run smoothly, a wave requires a depth of water as great as is the distance from its own trough to trough. If that distance is 15 feet, the wave requires 15 feet of water to roll in or it will begin to rise in height and form a crest, this being the result of the friction of the wave motion on the bottom. It is the wave motion that travels, not the water, as can be readily seen by dropping a colored liquid of any kind into the sea—the color will remain stationary, or nearly so, while the motion of the wave will continue to advance.

When running along a beach at night, the beach being free from rocks, the line of safety can be felt by the lifting of the boat; if too close in, a sharp lift will be felt when a sea passes under—the motion being distinctly different from that felt when the boat was in deep water—and is a sure indication that the boat is within the line where the wave begins to top the breaker. In a heavy onshore wind, the best traveling will be found a mile or more offshore. The reason is that heavy seas on striking a beach or a reef give a strong recoil that causes a series of opposing waves which, meeting those coming in, produce rough, irregular water.

Occasionally there will be seen a solitary lift or leap of the water where there are no other evidences of disturbances; this is generally caused by a small mound or boulder arising at that spot from the bottom.

Tide Rips

Tiderips are the result of strong currents. With no visible signs of disturbance and the sea smooth all about them waves of this character will rear and tumble. They are clearly distinct from anything about them, and do not take one unawares. Almost invariably they have white foaming crests and roar in an unmistakable manner. Even in a white-cap breeze, they are clearly whiter than anything about them, and are so definitely marked that one can sail down their edges and admire the wildness of the scene. The wave motion in them is short and steep. When wind increases their turbulence, none but the staunchest of boats and best of helmsmen should attempt to enter the turmoil. When compelled to encounter them in bad weather the boat should be kept to the edges where the water is always deep. If in the rip and it is running strong (which is generally the case during four hours out of the six), the boat should be kept head-to; she will lift and pound badly, and perhaps get strained, but that is better than the risk of rolling over. At the slack of the tide the rips do not exist.

Head Sea

During a hard blow, the sea will be found to present waves that are regular in general, but interspersed with seas that are too sharp for comfort for a boat of light construction. If going to windward, many of these seas will compel one to head into them; then will come a lift and, if the boat has not a sharp V-section forward, a smashing fall down the back of the wave. These falls pound the bottom of a boat so severely that it is not good practice to permit many of them. They are avoided by turning the boat a trifle off the wave, though if the swell is steep enough to throw the boat there is no help but to take it head on. Should swinging her off, to give more bearing surface, take the boat too much off the course, the remedy is to take the seas on one bow for a stated time and then on the other for the same interval, the result being an equalization of the course.

Following Sea

In running with a following sea the helmsman meets his hardest task. When a sea passes under the boat, lifting the bow, the next wave comes under the stern and begins to lift, and when the stern has been raised to a greater height than the bow, the latter starts to root—which means that the boat is "down by the head," and does not respond to the rudder. This is the anxious moment for the helmsman, as he waits for the feeling coming with a submerged rudder that indicates the direction in which the bow is going to turn. So long as the rudder is out of water it should be kept steady by the wheel, and the instant the feeling comes that it is submerged the helm should be turned, gently at first, then with all the strength necessary to counteract the sheer; then the wheel should be allowed to turn back freely as the boat balances on the forward drive on the face of the wave.

During the maneuvering the bow of the boat may root until two or three feet of it is buried in the sea ahead. It will not do to let this take place, for, as explained previously, the water is not moving, and the boat is plowing into it, and while doing so the stern may be lifted so high that she is deprived of her bearing, and will either dive or roll over. This is what occurs with boats trying to enter a surf or, when the weather is heavy from the seawards, to gain access to a harbor having a bar before the entrance. The remedy is the same in either case, and is the one commonly employed by life savers in making a landing; that is to tow a drag or sea anchor. If without one, any bulky article attached to a stout line may be dropped over the stern and towed. The resistance offered will help materially in checking the tendency to root.

With some boats and in some seas it will be found that the bow is rooting and the stern being boarded by the following waves. This is a bad case. All the movable weight (passengers, for instance) must then be placed amidships to lighten the ends and the bow swung a very little from a fore-and-aft bearing on the seas. If the boat is of the open-cockpit type, canvas should be fastened over the after end of the cockpit. This is a case in which oil might help some: the boat is run slowly and the oil put out from any part of the boat that will cause the slick to be spread by the time it reaches the stern. The burying of the bow and stern of a boat with fine sharp ends is of little consequence, as the lack of bearing surface in such a boat makes this a condition to be expected, but the sea has not hold enough on either end to do harm, and the end will rise as quickly as the wave passes by.

Beam Sea

In a beam sea, conditions are such as to require the utmost attention on the part of the helmsman. The boat is traveling in the trough and if an oncoming sea is a bad one, one must decide instantly whether to run or head into it. The present position of the boat generally governs the maneuver. If the boat has just recovered from a lurch and the bow is too far to windward to give her time to run off, she must of necessity be thrown head in. If she is too far off the wind to give her time to be swung up she must be sent to leeward. Most of the time the shape of the seas is such that the boat can be held to the course; this gives the helmsman the choice of the maneuver.

Lee Shore

When running along a lee shore for any considerable distance the scend of the sea will steadily set the boat toward the beach. There is seldom a sea so heavy that there are no smooth, well-rounded waves mingled with the rough ones, and in every smooth the boat should be sent on the course as far as she will go. Turn her to windward in the rough seas, and in some of the smooth ones if necessary, but in no case let her fall to leeward.

During a blow a boat should pass to the lee side of islands and shoals where it is possible to do so; no shoal is so deep that it has no influence in smoothing the sea. A shoal near the surface will stop the waves altogether and leave only the wind for the boat to contend with.

Fog

It caught in a fog without a compass or with the compass out of order, the best way in which to prevent a boat from losing her direction is to take guidance from the run of the waves. Thus, if the waves were coming toward the starboard bow when the fog set in, they should be kept coming from the same quarter.

By trailing a line over the stern one may keep running straight ahead, and not in a circle as is often done. The longer the line the better, as with one of good length, any swerving from a straight course will show at once. Verification of the steering in a fog or rain may be gained by watching the slant of rain drops or drizzle.

Reflections Of Rock And Sand

A majority of the rocks and shoals within range of the cruising motor boat are usually unmarked by buoys of any kind, but most of such obstructions betray their presence by reflecting their colors to the surface of the waters immediately surrounding them. The shade, or density, of the color will vary with the different phases of the day, from clear distinctiveness to an indefinable something, yet to the practised eye the hues may be distinguished and used with advantage. It well repays the operator of a motor boat to cultivate the faculty of observing the different shades of the water, as it gives a confidence in running that adds to the comfort and interest, and in combination with a judicious use of the lead line, enables him to pick his way with a degree of certainty into harbors and inlets that are new to him. This applies more particularly to fairly clear waters and not such as are found in or close to the harbors of large cities. A mud bottom is not as good as a sand or rock bottom, but even over mud there will be different shades of color in the shallows and the channels.

When running in open waters, a faint line may appear at some distance ahead and commence to loom. On a near approach the entrance to a small harbor or inlet may be looked for, though the coast at first appears to be one unbroken line. As the boat draws nearer dark spots of brown may be seen at some places, while at others grayish or white shadows prevail; the former indicate deep and the latter shallow water. When approaching to four or five hundred feet, close observation will possibly show water of a decided greenish tint and water having a certain placid or slick whitish appearance. The latter color should be avoided and the deeper green followed, and then with a good lookout in the bow it will be perfectly safe to proceed slowly into the place as far as it is desired. The higher up the lookout is placed, the better he will see the bottom and select the route to be taken.

The entrance to an all-sand harbor over a bar may be made by observing the difference in color when arriving at the 18-foot depth, for the break is clearly visible. When passing into the 12-foot depth, it will be well to slow down to half speed. Here the darker green veins of water should be chosen.

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