Wednesday, June 22, 2016

MLS Seamanship Series – Marlinespike

Figure Eight Knot
Good knots are easy to tie, are easy to untie, and hold well.  A good knot will not untie itself.  In sailing vernacular, a knot is used to tie a line back upon itself, a bend used to secure two lines together, and a hitch is used to tie a line to a ring, rail or spar.  A knot used to secure a line to an object, such as a ring or eye, is a hitch.  The knots listed below are those most commonly used in boat operations.

Reef Knot
A figure eight knot is an overhand knot with an extra twist.  It will prevent the end of a line from feeding through a block or fairlead when loads are involved.  It is also easier to untie and does not jam as hard as the over hand knot. This knot resembles a figure eight and is also known as a stopper knot.

Becket Bend
Called a square knot by Boy Scouts, the reef knot is one of the most commonly used knots in marlinespike seamanship.  Reef knots are primarily used to join two lines of equal size and similar material.  Reef knots do not effectively hold two lines of different sizes or diameter. Caution should be used if the line is going to be under heavy strain since the reef knot can jam badly and become difficult to untie afterwards.  Reef knots are best used to finish securing laces (canvas cover, awning, sail to a gaff, etc.), temporary whippings, and other small stuff.

The sheet bend also known as becket bend is a bend that joins two lines that are if unequal size and diameter together.  It is the best knot for attaching a line to an eye splice and can be easily taken apart even after being under a load. When tying the sheet bend the running parts should be left long because there is some initial slip in the knot when the knot is first brought under tension.

The sheepshank is a type of knot that is used to shorten a rope or take up slack. This knot is not stable. It can easily just fall apart under too much load or too little load. The knot has several features that allow a rope to be shortened:
  • It provides two loops, one at each end of the knot which can be used to pass another rope through
  • The knot remains somewhat secure under tension; the coarser the rope the more secure it is (see Disadvantages, below)
  • The knot falls apart easily when tension is remove
The bowline is a versatile knot and can be used anytime a temporary eye is needed in the end of a line.  It also works for tying two lines securely together, though there are better knots for this.  An advantage of bowlines is that they do not slip or jam easily.


Saturday, April 30, 2016

MLS Seamanship Series - General Rules of the Road Definitions

International Rules are specific rules for all vessels on the high seas and in connecting waters navigable by seagoing vessels. The Inland Rules apply to all vessels upon the inland waters of the United States and to vessels of the United States on the Canadian waters of the Great Lakes to the extent that there is no conflict with Canadian law. The International Rules were formalized at the convention on the International Regulations for Preventing Collisions at Sea, 1972. These rules are commonly called 72 COLREGS.

Inland Rules vary from International Rules primarily because of the addition of certain extra precautions. In our discussion of basic rules, each rule stated is the same for both international and inland waters unless a distinction was pointed out. When the term power-driven vessel is mentioned, for example, it means in both International and Inland, any vessel propelled by machinery as distinguished from a sailing vessel.

For the purpose of these rules, except where the context otherwise requires, the following definitions apply:

The term Inland waters means the navigable waters of the United States shoreward of the demarcation lines which divide the high seas from harbors, rivers, and other bodies of waters of the United States, and the waters of the Great Lakes of the United States’ side of the international boundary.

Demarcation lines are the lines that designate those waters upon which mariners must comply with the 72 COLREGS and those waters upon which mariners must comply with the Inland Navigation Rules. Nautical charts typically include a demarcation line that shows when the Navigation Rules transition from inland to international, so that boaters can be aware of changing standards of navigation. In general, these demarcation lines follow the coastline and cross-inlets and bays. On the seaward side of the demarcation lines, international rules apply.

With regards to the Rules of the Road the term Underway means that a vessel is not at anchor, made fast to shore, or aground.

The word vessel includes every description of watercraft, including non-displacement craft and seaplanes, used or capable of being used as a means of transportation on water.

The term power-driven vessel means any vessel propelled by machinery.

The term sailing vessel means any vessel under sail provided that propelling machinery, if fitted, is not being used.

The term vessel engaged in fishing means any vessel fishing with nets, lines, trawls, or other fishing apparatus that restrict maneuverability, but does not include a vessel fishing with trolling lines or other fishing apparatus that do not restrict maneuverability.

The word seaplane includes any aircraft designed to maneuver on the water.

Restricted visibility means any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms, or any other similar causes.


Monday, February 22, 2016

MLS Seamanship Series - Understanding Chart Symbols

Many different types of symbols and abbreviations are used on nautical charts.  This system provides mariners with a quick way to determine the physical characteristics of the charted area and information on Aids to Navigation .

These symbols are uniform and standardized, but may vary depending on the scale of the chart or chart series.  These chart symbols and abbreviations are shown in the Pamphlet ‘CHART No. 1’; published jointly by the Defense Mapping Agency Hydrographic Center and the National Ocean Service.

Buoys are shown with the following symbols:
  • The basic symbol for a buoy is a diamond and small circle.
  • A dot will be shown instead of the circle on older charts.
  • The diamond may be above, below or alongside the circle or dot.
  • The small circle or dot denotes the approximate position of the buoy mooring.
  • The diamond is used to draw attention to the position of the circle or dot and to describe the aid to navigation.
Lighthouses and other fixed lights use a basic symbol that appears as a black dot with a magenta “flare” giving much the appearance of a large exclamation mark (!).  Major lights are named and described; minor lights are described only.

Daybeacons are indicated by small triangles or squares, which may be colored to match the aid.  Daybeacons, also commonly called day marks, are always fixed aids.  That is, they are on a structure secured to the bottom or on the shore.  They are of many different shapes.

Prominent landmarks, such as water towers, smoke stacks, and flagpoles, are pinpointed by a standard symbol of a dot surrounded by a circle.  A notation next to the symbol defines the landmark’s nature.  The omission of the dot indicates the location of the landmark is only an approximation.

Wrecks, Rocks, and Reefs are marked with standardized symbols, for example, a sunken wreck may be shown either by a symbol or by an abbreviation plus a number that gives the wreck’s depth at mean low or lower low water.  A dotted line around any symbol calls special attention to its hazardous nature. 

A system of abbreviations used alone or in combination, describes the Bottom Characteristics allowing selection of the best holding ground when anchoring. Knowledge of bottom quality is very important in determining an anchorage.

Shorthand representations have been developed and standardized for low-lying Structures such as jetties, docks, drawbridges, and waterfront ramps.  Such symbols are drawn to scale and viewed from overhead.

Monday, February 15, 2016

MLS Seamanship Series - Understanding Wind Chill

Just as there are persistent hot places around the world, there are persistent cold places. The cold air alone can be deadly but when the air is moving if feels much colder. 

Wind chill is the perceived decrease in air temperature felt by the body on exposed skin due to the flow of air. The wind chill temperature is based on the rate of heat loss from exposed skin caused by wind and cold and is intended to give you an approximation of how cold the air feels on your body.

As the wind increases, it removes heat from the body, driving down skin temperature and eventually the internal body temperature. If the temperature is 0°F and the wind is blowing at 15 mph, the wind chill temperature is -19°F. At this level, exposed skin can freeze in just a few minutes.

The only effect wind chill has on inanimate objects, such as car radiators and water pipes, is to shorten the amount of time for the object to cool. The inanimate object will not cool below the actual air temperature. For example, if the temperature outside is -5°F and the wind chill temperature is -31°F, then your car’s radiator temperature will be no lower than the air temperature of -5°F.

The Wind Chill Chart

To determine the wind chill temperature:
  1. Find the value closest to your outside air temperature.
  2. Find the value that most closely represents your present wind speed.
  3. Your wind chill temperature is the value where this column and row meet.

Wind Chill and Your Safety

Q:    What is important about the wind chill besides feeling colder than the actual air
A:    The lower the wind chill temperature, the greater you are at risk for developing frost bite and/or
        hypothermia.  Frostbite occurs when your body tissue freezes. The most susceptible parts of the
        body are fingers, toes, ear lobes, and the tip of the nose. Hypothermia occurs when body core
        temperature, normally around 98.6°F falls below 95°F.

Monday, February 8, 2016

MLS Seamanship Series - Entering Port in Bad Weather & Rough Water

While operating your boat there will be times when you will need to enter a port in rough and challenging conditions. Although certain inlets and rivers have extreme conditions much more often than others, learning how rough weather affects the various harbors and entrances throughout your local area is necessary to operate safely. 

Knowing as much information as possible prior to entering a harbor, inlet, or river in rough weather will help guard against potential dangers or impending problems. In these cases local knowledge can make the difference between a safe passage or getting you and your crew in trouble. If you are operating in an area which is new or unfamiliar to you “local knowledge” can also be gained through the use of cruising guides or Coast Pilots found in many ship stores or online. 

Here are a few things you should be aware of before entering any of these areas:
  • Watch where waves break. Know how far out into the channel, whether near jetties or shoals, or directly across the entrance the waves break.
  • Pay close attention to how the entrance affects wave patterns. An entrance that has jetties may push waves back across an entrance where they combine with the original waves.
  • Some entrances have an outer bar that breaks, and then additional breaks farther in. Others are susceptible to a large, heaving motion that creates a heavy surge as it hits rocks or structures.
  • Know where the channel actually is. If shoaling has occurred, room to maneuver may be significantly reduced.
  • Know the actual depths of the water. Account for any difference between actual and charted depth due to water stage, height of tide, recent rainfall, or atmospheric pressure effects.
When entering a harbor, inlet, or river you will need to pay special attention to the direction of the current and seas. The most challenging condition you can encounter is when the current opposes the seas when operating near an entrance. In this case the current will have the effect of shortening the wavelength, and increasing the wave height. This makes waves much more unstable and closer together. 

While heading into the oncoming seas, you will find that the current is coming from behind your vessel thus pushing your boat into the seas at a relatively higher speed. You can reduce this effect (which will also give more time to react between waves) by slowing your vessel, although the current is coming from behind you will still need to keep enough headway to ensure effective steering.

When transiting an entrance, you will find that maneuvering room is often very limited. The only safe water may be found in the area that you just left. Be ready to back down and avoid the breaking crest of a wave. This situation can become critical in following seas with a head current. The waves will overtake your vessel at a higher rate and will break more often. The current will reduce your boat’s speed over the ground (SOG) which will expose your vessel to more waves. In this condition it is important to remain calm and not panic.

Remember that with all following seas, you need to stay on the back of the wave ahead. As these waves become unstable they tend to break more quickly, use extra caution to ensure that you do not go over the crest of the wave ahead. Concentrate both on the crest in front of you and the waves behind. You must keep a hand on the throttle and adjust your power continuously.

Monday, February 1, 2016

MLS Seamanship Series - Selecting an Anchorage

There are many reasons to anchor perhaps the most important being for safety.

Nautical publications often have useful information on the locations of suitable anchorages.

Local knowledge is valuable but you should always refer to your charts when considering your anchoring options.

There are several characteristics to look for when seeking a safe anchorage they include: 

Good Bottom Structure - Try to pick bottom structure that best suits your anchor gear. Clay or mud bottoms are often the best choice. Avoid rocky areas that will hang up your anchor. You can confirm the type of bottom by using the appropriate chart of the area. 

Shelter from Weather - Pick an area that is sheltered from the wind and strong currents. If possible you should select an anchorage that is protected from the wind on all sides, regardless of wind shifts. Another good option would be a cove offering protection from at least the existing wind condition. 

Ample Water Depth - Choose a location that provides adequate water depths through all stages of the tide. An area that is too deep will allow the anchor to drag and an area too shallow poses the risk of going aground. It important to also be aware of any strong or reversing currents that may occur during high or low tide. 

Nearby Navigational Hazards - Avoid anchoring near known navigational hazards. If an anchor drags, your vessel will be that much closer to danger. 

Location to Adjacent Vessels - If possible, try to anchor away from other vessels. This will reduce potential incidents arising from an anchor dragging or accessing the anchorage. 

Proximity to Other Traffic - Anchor outside and away from traffic lanes and vessel movement areas. The risk of collision will greatly be reduced. 

Available Navigational Aids - Choose an anchorage that has several navigational aids available to it. These could be prominent landmarks, lighted navigation buoys or lights. These aids can be used to ensure that your anchor is holding properly. 

Room to Swing - Pick an anchoring site that allows sufficient room for your boat to swing on its rode. Many boaters calculate a drag circle based on the length of their vessel and rode deployed. Using this information, a position fix can be taken periodically or an alarm set on electronic navigation equipment to warn of a dragging anchor.

Having selected a suitable spot, you should run in slowly, always approach the anchorage by heading into the wind or current whichever is stronger, preferably  on some range ashore selected from marks identified on the chart, or GPS data to aid in locating the chosen spot. Use of two ranges will give the most precise positioning. Later, these aids will be helpful in determining whether the anchor is holding or dragging.

Monday, January 25, 2016

MLS Seamanship Series - How Your Body Gains and Loses Heat

Your body operates at its prime within a very narrow temperature range of only two or three degrees. It has only three ways to gain heat but five different ways to lose it.

High Heat Loss Areas

Your body has five major heat loss areas:
  1. Head
  2. Neck
  3. Armpits
  4. Sides of chest
  5. Groin
Although your hands and feet may be the first to feel cold, they are not major heat loss sources.

Heat Gain - Your body gains heat three ways:
  1. External Sources: The sun, fires, and other heat sources warm your body.
  2. Digestion: Heat is produced as your body digest food.
  3. Muscular activity: As you move, your body produces heat, but activity in cold water may cause you to loose more heat than you gain because cold water is constantly flowing past your body's high heat loss areas.
 Heat Loss - Your body can lose heat five different ways:
  1. Radiation: Radiation occurs when heat is emitted from your body. Clothing is the obvious answer to preventing heat loss through radiation.
  2. Respiration: You lose heat by exhaling air that your body has warmed. Some of this heat loss can be prevented by covering your mouth with a loose knit scarf, hat, or other fabric.
  3. Evaporation: When your sweat evaporates, your body looses heat and moisture into the air. This explains why wet clothes make you cooler, which can be a good thing in a hot climate but deadly in a cool one.
  4. Conduction: Being in direct contact with cold surfaces - either solids or liquids - takes your heat away. Insulating yourself from these cold surfaces will stop or greatly slow conductive heat loss.
  5. Convection: Why does it feel cooler on wind days? Convection! This happens when your body's heat is taken away by moving air or water.
The combination of conduction and convection is the reason your body looses heat 25 times faster in water than in air of the same temperature.

Not being able to control your body's heat loss can lead to hypothermia, the lowering of your body's core temperature, which is one of the leading killers outdoors.