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Boating Skills and Seamanship
By United States Coast Guard Auxillary
The McGraw-Hill Companies, Inc.Copyright © 2007 United States Coast Guard Auxiliary
All rights reserved.
Which Boat Is for You?
The objectives of this chapter are to describe:
The importance of boating safety.
The U.S. Coast Guard Auxiliary.
Parts of a boat in proper language.
Types of hulls and means of propulsion.
The variety of boats available to match your needs.
How to get information on possible defects in a vessel.
Considerations in a contract to purchase a boat.
The importance of boat insurance.
A BOAT is anything used for transportation on the water. Huck Finn's raft was a boat. A seaplane is a boat when it is on the water. Canoes, kayaks, rowboats, and other small craft are boats. Boats range in size from personal watercraft (PWC) to large ships, and they might have deep or shallow hulls; flat, round, or V-shaped bottom sections; and tall or short cabin sides and superstructures. They can be slender or stout, and they might have one, two, or even three hulls. They vary, too, in the materials from which they're built. As defined by the Federal Boat Safety Act of 1971, all boats are vessels, but a vessel is not a boat (and therefore exempt from certain commercial safety regulations) unless it was manufactured or is engaged primarily for noncommercial use or is engaged in carrying six or fewer passengers for hire.
Boats come in such a large assortment because they serve many purposes. In this lesson you will learn about these purposes and how vessels are designed for them. You will also learn the basics of boat construction, materials, and uses.
Newcomers to any subject usually must learn a new vocabulary. Boating is no exception. The language of mariners has been developing for many centuries. It has the virtues of utility, economy, and an exactitude you need when talking about boats and boating.
As we introduce terms, we will usually define them for you. You can also find some of them in the Glossary at the back of the book. If you do not find a word listed in the Glossary, look for it in the Index. The first time we use a technical term, we will print it in red.
ORIGINS OF BOATERS' LANGUAGE
Boaters have been around a long time, so the vocabulary has come from many places: ancient Greece, the Roman Empire, Scandinavia, England, and elsewhere.
Some nautical terms have found their way into our everyday vocabulary. The term "blue Monday" came to us from England. The British Navy disciplined sailors on Mondays for infractions over the preceding week. The punishment consisted of lashes with a cat-o'-nine tails, or whip. No wonder Monday was blue. When not in use, the cat stayed in a sack. Of course, the cat was "out of the bag" when used.
Other terms came from Norway. Most vessels are steered by rudders. On an ancient sailing boat, the rudder was to the right of center at the rear, or stern, of the vessel. There it was protected from damage when the ship was in port. The tiller, which turned the rudder, was kept under the helmsman's right arm.
In Norway, the rudder was a "stjorn" board or steering board. Stjorn, when pronounced, sounds like "starn." So the right side of a vessel when looking forward became known as the stjorn board or starboard side (Figure 1-1).
When a vessel came into port, it was with its left side next to the wharf. This was the side most visible to the helmsman. It was also the side for the "load board." No wonder the left side of the vessel became known as the larboard side. "Larboard" and "starboard" are more exact terms than "left" and "right" since they do not change if you are facing forward or aft.
Because larboard and starboard sound somewhat alike, they are easily confused. Thus, larboard was changed to port. This was a logical choice, as this was the side of a vessel next to the wharf when the vessel was in port. Larger vessels load through ports, or openings, in their sides.
Remnants of ancient boats made of large, hollowed-out tree trunks or keels still exist. These unstable vessels took on water easily. Although they didn't sink, they were of little value when slightly submerged in rough or icy water.
Planks were added later, and the trunk became but one part of the vessel. The name keel remained, however. The body of the vessel, formed by the keel and the planks together, became known as the hull.
The aft terminus of many boats is a flat, vertical surface extending from one side of the vessel to the other. This part of a boat became known as a transom, from the Latin root "trans," meaning across (Figure 1-3).
The bow is the forwardmost portion of a vessel. This term came from the Norwegian word "bov," meaning shoulder, and pronounced "bow." You can almost see the shoulder of a boat pushing its way through the water.
Types of Boats
Boats come in a wide range of sizes and a great variety of types and models, each optimized to serve a specific need. It would be a wonderful boat that could do all things equally well, but in the real world this is not possible. Boat design and construction involve compromise, and a boat developed for one purpose may serve poorly for another. Likewise, a boat that is safe in one set of conditions may not be safe in conditions for which it is not intended. When you select a boat, be sure it will suit your needs. Also, be certain to operate it in appropriate sea and weather conditions.
Bass boats, for example, help their owners get to good fishing holes quickly (Figure 1-2). They are propelled by one or two high-horsepower outboard motors, and many of them have a small electric motor mounted off the bow to maneuver the boat at slow speeds around fishing holes in a manner that does not spook fish. These boats have sharply pointed bows and minimal V-shaped hulls at the bows. Their design permits them to operate safely at high speeds in sheltered water.
A bass boat can be dangerous, though, when used in a tidal inlet, rough water, or the large swells of an open sea. One feature that makes it dangerous is its low freeboard, which is the vertical distance from the gunwales, or tops of the boat's sides, to the surface of the water. In many boats the freeboard is lowest at the transom, higher amidships, and even higher toward the bow, but a bass boat has low freeboard everywhere so that an angler can play a fish with equal ease anywhere on the boat, moving around as necessary. Bass boat owners place a high emphasis on this "360° fishability."
Another feature that may make some bass boats dangerous in inlets and other rough water is a foredeck that slants downward toward the bow. Such a bow shape can bury or "stuff" itself in a wave, shipping water over the bow and swamping the boat. This is not to say that a bass boat is unsafe, which would not be true. What it does say is, "Operate your boat only under the conditions for which it was designed."
We will explore other boat types later in the chapter. For the moment, let's look at one other type. Suppose you are in a runabout, a small, mostly open boat powered by one or two outboard motors. These are the boats that populate lakes, reservoirs, rivers, and sheltered coastal waters on pleasant summer days, engaged in fishing, waterskiing, or simply day cruising. A runabout is at its best in those conditions, but it is not designed for a strong wind and a choppy sea.
Suppose you get caught in rough conditions and your runabout is dead in the water, or adrift. This means that it is not under power and not moored, anchored, or aground. As with other boats that are higher in the bow than the stern (as most boats are), its bow will be blown away from the wind. This means that the stern, with little freeboard, turns into the waves. Let's further suppose that there is a cutout in the transom where the outboard motor is mounted (see Figure 1-3), and let's assume that there is no self-draining well between the transom and the boat's open cockpit to intercept a boarding wave. It is all too easy for a wave to roll over the transom and swamp the boat. (And by the way, this example is anything but hypothetical; this sort of accident happens frequently, and the victims are usually unaware of the danger until the wave comes aboard.)
Select your boat to suit your needs, and use it only under the conditions for which it was designed. It always pays to check the weather before you go out and while you are on the water. You can get continuous weather information on your VHF-FM radio. (See Chapter 12 for more on predicting the weather.)
Types of Propulsion
Most recreational powerboats less than 25 to 30 feet long have outboard motors (Figures 1-2, 1-4, and 1-5) or stern-drive engines (see Figure 1-6 opposite). Stern drives are also called inboard/outboards, or I/Os. Most boats longer than 35 feet have inboard engines, and those from 30 to 35 feet long might have any of the three.
An outboard motor bolts or clamps to the transom. In the past most outboards were two-cycle (also known as two-stroke) engines, meaning that the crankshaft requires two revolutions to complete a power stroke. Many small engines, such as lawnmower engines, are two-cycle. These engines operate at high revolutions per minute (rpm) and produce a large amount of power per pound of engine weight, but this higher engine stress usually results in a shorter engine life and higher maintenance costs. Also, in part because their lubricating oil mixes with the fuel rather than recirculating through separate passageways, two-cycle outboards are characterized by incomplete combustion and resultant pollution, although these problems have been greatly decreased by electronic fuel injection and ignition technologies.
For all these reasons, four-cycle outboards are increasingly popular. These operate like automobile engines (or like stern-drive and inboard marine engines, for that matter) in that the crankshaft requires four revolutions to complete a power stroke. These engines are heavier and produce less power per pound of engine weight, but they are also more fuel efficient, more reliable, and generally quieter.
A stern-drive engine is mounted inside the hull (like the inboard engine of a bigger boat), but the engine is connected to a drive unit through a system of gears. This drive unit, also called the lower unit or outdrive, protrudes through the boat's transom and functions much like the lower portion of an outboard motor. Outboard and stern-drive boats are steered by turning the lower unit in one direction or the other, thereby directing the stream of water discharged by the propeller (Figure 1-6).
Comparing outboard motors with stern-drive engines, outboards are easier to remove for servicing and easier to replace, take up less space inside the boat, and are lighter than stern drives of the same horsepower. Stern drives, however, are quieter and burn less fuel than two-cycle outboards.
Stern-drive engines have longer service lives than two-cycle outboards, and, like inboard engines, they are quiet, efficient, and out of sight. Yet like outboards, they derive significant speed, steering, and trim advantages over inboard engines from their adjustable, steerable lower units. They are especially popular on fresh water, where the inability to raise the lower unit out of the water when not in use, as you can by tilting an outboard, is of less consequence. In the water, and especially in rough weather, it is easier to work on a stern-drive engine than an outboard, because the stern-drive engine is in the boat and not behind the transom.
The transom on a boat with an outboard motor usually has a large section cut away (refer back to Figure 1-3). This is done to get the lower unit and propeller deep enough for best performance, but a cutaway transom lowers a boat's freeboard and invites swamping.
To keep boats with transom-mounted outboards from swamping, many have a well forward of the transom into which their motors tilt when raised. The well drains overboard, and its forward wall is made high enough to keep most waves from entering the boat. A well takes up deck space, but the lack of a well can be dangerous when waves approach from astern, as described earlier.
The need for a cutaway transom can be eliminated by attaching an outboard motor to a mount, or bracket, that extends aft of the transom. A bracket-mounted motor is entirely outside the boat, permitting a full transom and unimpeded interior volume. When mounted this way, an outboard will make less noise in the boat, and the full transom will be safer for small children. A bracket-mounted outboard does increase the effective length of the boat slightly, which could be a disadvantage when maneuvering in close quarters (or when renting a marina slip by the foot), and the engine is harder to reach from inside the boat, but these considerations are outweighed by the advantages of such an arrangement (Figure 1-7).
There are three significant disadvantages of a stern drive. The first is the loss of deck space, since the engine is mounted inside the hull near the stern and enclosed under a large hood. Second, the articulated mechanism connecting the engine to the lower unit may be a source of problems. And third, any engine mounted within a boat's hull presents dangers from fire and explosion; these can be controlled with proper ventilation, however, as described in Chapter 2.
Outboard motors and stern-drive engines are rarely found on boats longer than 35 feet, because their smaller props don't develop enough thrust to move heavy boats effectively. That is why big boats usually use inboard engines, which are generally mounted below the deck amidships or slightly aft of amidships. (Stern-drive engines, by contrast, are mounted aft, against the transom, where there is rarely enough belowdeck room to accommodate them. They therefore require a full or partial abovedeck enclosure.) Inboard engines usually drive straight propeller shafts (Figure 1-8). Inboards are simpler in design and generally more reliable than I/Os, but the propeller is fixed below the hull and inaccessible if it becomes fouled.
Outboards and I/Os can be raised to allow easy removal of debris from the propeller or to escape from a shoal, and an outboard or I/O drive on most boats can be adjusted to trim the boat's bow up or down to the optimum running angle.
Personal watercraft (PWC), as well as some other boats, have a jet drive, which is simply an engine-driven pump with an impeller mounted in a tube that jets water out the back end of the tube to serve as a propellant. The advantages of jet drives include fast acceleration, an enhanced ability to operate in shallow water, and enhanced safety for people in the water. The propellers on conventional-drive boats often continue to turn slowly even when their gears are in neutral, and an exposed propeller can cause serious injury. The enclosed impeller of a PWC jet drive does not present the safety hazard to a swimmer that a propeller does (Figure 1-9).
Jet drives are often favored in shallow, rock-strewn waters where propellers are easily damaged. For example, sightseeing boats in the Hell's Canyon area of the Snake River use jet drives. An operator should use caution around rocks even with a jet engine, however. Rocks can puncture a boat's hull.
Although PWCs can operate in shallow, muddy, or sandy water, other jet-propelled boats should not. The difference is in the size of their engines. The engines of runabouts and cruisers equipped with jet drives pump large quantities of water. The mud or sand that is pumped with the water quickly damages parts in their pumps and propelling mechanisms.
In a tunnel drive configuration, the propeller and part of the driveshaft are partially recessed in a trough in the bottom of the boat. The trough, or tunnel, acts as a shroud to protect the propeller and increase its efficiency. It also provides a more favorable thrust angle for the propeller and a better angle of attachment of the driveshaft to the engine. These drives are advantageous in shallow water.
One way to classify boats is by how they ride in the water. Displacement boats move through the water and push it aside or displace it. Planing boats move faster and, after gaining speed, ride more nearly on top of the water.
There is no single, all-purpose, perfect hull design. Each design is a compromise, and you must make a choice based on your boat's projected use.
All boats at rest or moving slowly are displacement boats. Each displaces a volume of water equal in weight to its own weight. If the weight of the boat exceeds the weight of the water displaced, it sinks deeper into the water until the two weights are equal. This is true of a planing hull, a semidisplacement hull, and a displacement hull, but only the latter is designed specifically to achieve greatest efficiency at slow speeds.
Excerpted from Boating Skills and Seamanship. Copyright © 2007 by United States Coast Guard Auxiliary. Excerpted by permission of The McGraw-Hill Companies, Inc..
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