Electronic Navigation – ‘Unfolding’ Electronic Charts

Almost all electronic plotters include the same kind of capabilities for creating and storing waypoints that are found in GPS receivers. They have an important advantage, though, in that you don’t have to enter waypoint positions in terms of their latitude and longitude coordinates; there is a much simpler procedure for creating waypoints graphically, in effect by just pointing at the chart image and telling the plotter where you want to go.

At present, electronic charting is still in the process of rapid development; different manufacturers use different types of cartridges and discs, with different software and different keyboards and control panel layouts. With that said, there are a number of processes that are similar and common to all chart plotters.

Zoom in / zoom out are self-explanatory terms referring to the way in which the scale of the displayed image of the chart can be changed. From the user’s point of view, zooming is usually a very simple process.

Scrolling and panning are ways of moving the screen image to make different areas visible: scrolling generally refers to a north–south movement and panning to an east–west movement. Many programs also include different ‘centering’ options that allow you (for instance) to lock the center of the display to your own position. Other options allow the user to choose whether to view the chart in the conventional ‘north-up’ mode, or to turn it round to ‘course-up’ mode.

Decluttering is only available on vector charts. In effect, each type of information is stored in a different database: contour lines in one; spot soundings in another; major lighthouses in another; buoys in another; and so on. The effect is rather as though a paper chart were built up using many different layers of tracing paper, each of which can be removed or replaced at will. Most software programs add and remove some layers automatically as you zoom in and out, in order to stop the screen becoming cluttered. Many, however, allow you to choose ‘more detail’ or ‘less detail’, or to make your own selection of exactly what kind of information you want to see. It’s important to realize that the accuracy of information depends on the scale of the original chart, not on the zoom level you happen to have chosen, and to be aware that it is possible to inadvertently hide information, which could turn out to be important.

Cold Water Survival – Dressing for Cold Water Survival

Cold is the greatest killer in cold-water latitudes. The Marine Safety Unit defines “cold water” to mean water where the monthly mean low temperature is normally 59ºF or less. According to the Coast Guard, a temperature of 60ºF was selected because, “a person of average body build, in good health, wearing work clothes and a life preserver could be expected to survive about eight hours”. However, regulations are one thing and real life is another. So for the purposes of this writing we will consider cold water to be anything less than 70ºF.

Remember the first rule of cold-water survival is to stay dry. With this said, there are three basic guidelines to follow:

1. Do not get into the water if you can avoid it.
2. If you do go into the water, get out as soon as possible.
3. If you can’t get all the way out, get as much of your body out as you can, especially your critical heat loss areas: head, neck, armpits, sides, and groin.

Shelter is the primary key to cold-water survival.  To be considered sufficient, shelter must offer some sort of thermal protection and flotation.

Clothing

The type of clothing that you wear provides an important component of your “shelter”. The clothing that you wear should be broken down into three layers: Inner, mid, and outer. These three layers work together to trap heat, wick moisture, breath, block wind, and repel water. You will need this layered protection even if you are wearing an immersion suit. Your head is the source of 50-70 percent of your body’s heat loss making it important to remember to wear a watch cap or hat to cover your head.

Flotation

The only cold water survival device that will provide adequate protection for extended time in cold-water is an immersion suite. These anti-exposure suits are ultimately the best wearable cold-water survival devises sold on the market today. However, they do not cover the necessary need for every day flotation protection. Without some form of flotation, even strong swimmers will find it difficult to remain afloat in cold-water.

Personal Flotation Devices

Crewmen must wear some sort of flotation as a routine component of their personal gear, especially in heavy seas, at night, or during dangerous operations. Because there are so many different types and styles available today, it is absurd not to wear something.

Note: It is important to remember that everyone floats differently and just because a PFD works for one person doesn't not mean it will work correctly for you. Ideally, the PFD should float you face up, feet down; your head should be inclined 20 to 30 degrees back from vertical. The water level on your chest should be no higher than the armpits, preferably lower. You should be able to maintain the HELP position with only occasional swimming strokes. Do not allow yourself to be lulled into a false sense of security just because the device is Coast Guard Approved. Unless you have actually put it on and tested it in the water, you will not know if it works properly for you.

So You Want To Be a Captain - Which USCG Captain’s License Can I Qualify For?

Which License should you get? We recommend that you get the best license you qualify for! There are a couple of options depending on your citizenship status and boating experience.

The two main captain’s licenses issued by the USCG are the Operator (OUPV/Six-pack) and the 25/50/100 Ton Master. There is no requirement to start with a OUPV/Six-pack – you can go straight to Master license!

The USCG Operator of Uninspected Passenger Vessels (OUPV/Six-Pack Captain’s License) allows the holder to carry up to six paying passengers on uninspected vessels up to 100 gross tons (about 75-90 feet long). These are usually smaller vessels that normally engage in charter fishing, SCUBA diving, or tour cruises. As such, these vessels are limited to six paying passengers plus crew-hence the term “Six-Pack.” The OUPV License is issued in three forms:

1- OUPV Inland License: The OUPV Inland License is restricted to operation shore-ward of the boundary line, excluding the Great Lakes. This license is valid on uninspected vessels up to 100 gross tons.

• This license requires at least 360 days of documented experience in the operation of vessels, with 90 of the 360 days occurring in the last three years. Experience gained prior to 15 years of age may not be counted.
• The OUPV Inland License can be upgraded to an OUPV Near Coastal License once 90 days experience seaward of the boundary line has been achieved.

2- OUPV Great Lakes & Inland: 360 total with at least 90 days service on the Great Lakes.

3- OUPV Near Coastal: This license is valid on vessels up to 100 gross tons and out to 100 nautical miles.

The OUPV Near Coastal License also requires at least 360 days of documented experience in the operation of vessels, 90 of which must be gained seaward of the boundary line. Ninety of the 360 days must be in the last three years. Experience gained prior to the age of 15 will not be counted.

The USCG Master License allows the holder to operate inspected vessels as well as uninspected vessels. Any vessel that is certified (authorized) by the USCG to carry more than 6 paying passengers plus crew must have a Captain who holds a 25/50/100 Ton Master License. Ferryboats, harbor tour boats, and whale watching boats are examples of inspected vessels.

There are 4 different Master Licenses a mariner may qualify for such as the Master Inland or Master Near Coastal. Both the amount of sea service time and the size of the vessels you have been on will influence the license you are eligible for. Master licenses are tonnage rated at 25 GT (gross tons), 50 GT, or 100 GT. The tonnage you are awarded is determined by the size vessels you've gained experience on in the last 3 years – it’s called “recency experience.” You are not required to advance through the different licenses one at a time. If you meet the USCG requirements for the Master 100GT Near Coastal, you’ll get that license as your first license. The 4 types of up to 100GT Master licenses are listed below along with the requirements:

1. Master Inland: 360 days underway experience since age 15; 90 of those 360 days in the last 3 years. Completion of approved Course and Test.
2. Master Inland/OUPV: 360 days underway experience since age 15; 90 of those 360 days in the last 3 years; 90 of those 360 days outside the boundary lines. Completion of the Mariners Learning System™ Coast Guard approved Course.
3. Master Inland/Mate N.C.: 360 days underway experience since age 15; 90 days of those 360 days in the last 3 years; 180 of those 360 days outside the boundary lines. Completion of the Mariners Learning System™ Coast Guard approved Course.
4. Master Near Coastal: 720 days underway experience since age 15; 90 of those 720 days in the last 3 years; 360 of those 720 days outside the boundary lines. Completion of the Mariners Learning System™ Coast Guard approved Course.

Additional Requirements of the Coast Guard Include:

• Application for license.
• TWIC Card.
• Documentation of sea time experience – letters or sea service forms signed by the vessel’s owner or captain or sea service forms signed by you for your own boat(s) or DD2-14 and Transcript of Service for your military sea service (if applicable).
• Proof of vessel ownership – if you are submitting forms for your own boat(s).
• Physical Exam (within 1 year, on USCG Forms). There are certain medical conditions and/or prescription drugs that may disqualify you for a license or require a waiver. Ask for info if applicable.
• Drug Screen (within 6 months, on USCG Forms or proof of random program).
• Proof of U.S. Citizenship for Master/Mate (Birth Certificate or Passport) or Proof of Permanent Residency for Six-Pack/OUPV.
• Complete a First Aid & CPR approved course within the last year.
• 3 Letters of character reference.

The licensing process is relatively straightforward. I personally believe that you would have a hard time finding another opportunity with an equal return. The only regret I have with regards to getting my Captain’s License is that I wish I did it sooner!

Understanding Marine Weather – Global Circulations

Global Circulations explain how air and storm systems travel over the Earth’s surface. The global circulation would be simple if the Earth did not rotate, the rotation was not tilted relative to the sun, and had no water.


In a situation such as this, the sun heats the entire surface, but where the sun is more directly overhead, it heats the ground and atmosphere more. The result would be the equator becomes very hot with the hot air rising into the upper atmosphere.

That air would then move toward the poles where it would become very cold and sink, then return to the equator. One large area of high pressure would be at each of the poles with a large belt of low pressure around the equator.

However, since the earth rotates, the axis is tilted, and there is more landmass in the northern hemisphere than in the southern hemisphere, the actual global pattern is much more complicated.

Instead of one large circulation between the poles and the equator, there are three circulations:

1. Hadley cell – Low latitude air movement toward the equator that with heating, rises vertically, with pole ward movement in the upper atmosphere. This forms a convection cell that dominates tropical and sub-tropical climates.
2. Ferrel cell – A mid-latitude mean atmospheric circulation cell for weather named by Ferrel in the 19th century. In this cell, the air flows pole-ward and eastward near the surface and equator-ward and westward at higher levels.
3. Polar cell – Air rises, diverges, and travels toward the poles. Once over the poles, the air sinks, forming the polar highs. At the surface, air diverges outward from the polar highs. Surface winds in the polar cell are easterly (polar easterlies).

Usually, fair and dry/hot weather is associated with high pressure; rainy and stormy weather associated with low pressure. You can see the results of these circulations on a globe. Look at the number of deserts located along the 30°N/S latitude around the world. Now, look at the region between 50°-60° N/S latitude. These areas, especially the west coast of continents, tend to have more precipitation due to more storms moving around the earth at these latitudes.


Between each of these circulation cells are bands of high and low pressure at the surface. The high-pressure band is located about 30° N/S latitude and at each pole. Low-pressure bands are found at the equator and 50°-60° N/S.

Electronic Navigation – Cartography – Raster vs. Vector

Although there are many suppliers of electronic charts, the charts themselves can be divided into two groups: raster and vector. Raster charts can be regarded as electronic photocopies of paper charts, produced by scanning a master copy of a paper chart, in much the same way as a fax machine scans a document that is about to be sent. The chart is broken down into a vast number of tiny dots (pixels), and the position and color of each pixel is recorded. Instead of sending this information down a telephone line, as a fax machine does, the chart scanner stores it on the cartographer’s computer, from where it can be copied onto flash memory cards or CD-ROMS, and supplied to customers.

Raster charts are relatively cheap and simple to make, but each chart uses a lot of memory or disc space. Because they are electronically copied straight from the paper chart, they are familiar in appearance, and contain exactly the same information: nothing is added or taken away. The drawback is that they can only be used effectively at about the same scale as the original chart: if you zoom in, then letters and symbols become huge, but without any extra detail becoming visible; while if you zoom out, names and symbols become illegible.

Vector charts are produced by electronically tracing raster charts. The fundamental difference is that lines are not stored as strings of darkened pixels, but as lines. Vector charts originally became popular for small boat hardware plotters because although they are more expensive to produce, they occupy much less memory. The vector format also allows more flexibility in the way the chart is used: a vector chart can be zoomed in or out much further than a raster chart, but the letters and symbols always stay the same size.

On a raster based chart, a feature such as a buoy is represented by a cluster of colored pixels that make up the shape of a buoy symbol exactly as it appears on the original paper chart. On a vector chart, however, the buoy’s position is linked to a database of information about the buoy. The software can use this database in various ways. Some programs will represent all navigation aids by means of the same diamond-shaped symbol. When you select one (by ‘pointing at it’ with the cursor) the data is revealed in a text panel somewhere on the screen. Other systems use the database information to display a symbol showing the shape and color of the buoy itself.

More sophisticated versions of this are used on some electronic charts to provide graphic representations of the changing height of tide at particular places, to provide additional information such as lists of port facilities, or to superimpose arrows showing the tidal stream on top of the main chart.

Cold Water Survival – Preventing Heat Loss

This writing is in response to Captain Rande and the comment he made in an earlier blog I wrote on Cold Weather Precautions:

“Unfortunately, you forgot to mention the most important thing. Wearing a life jacket. In cold water, you will never die from hypothermia, unless you are wearing a life jacket. You will assuredly drown first.”

Get the cold facts here:

Although that blog was about how to prevent hypothermia and the proper treatment of a hypothermic victim, Captain Rande raises a valid point, one that we will now explore.  Few will disagree that the first rule of survival when operating in a cold-water environment is to stay dry. Water robs body heat up to 25 times faster in water than air of the same temperature. So when we speak of heat loss, there is no circumstance or condition in which you are better off in cold water than in air, even if you are exposed to wind and sea spray. If you fall overboard into cold water, your body’s natural cold shock response will be for you to loose control of your breathing as you gasp for air and begin to thrash about in an effort to stay afloat.

An important key to cold water survival is very much dependent on your ability to resist this natural reaction. Admittedly, remaining calm under these circumstances may be impossible. However, if you are aware of your body’s natural response to cold-water immersion you can learn to control your breathing and minimize your state of alarm. If you do panic, struggle, or begin to swim, the flushing action of cold water against your body’s critical heat-loss areas will speed the loss of muscle control, ultimately leaving you incapacitated. In the event that there are two or more people in the water, huddle together. There will be less heat loss and you will be easier to find. If you are by yourself assume the Heat Escape Lessening Posture, or HELP position. This posture can increase the chances of survival by reducing the amount of body surface area that is directly exposed to cold water. In this position, the chest and knees are in contact with each other rather than being in contact with cold water. If you are not wearing a life jacket, this is a difficult position to maintain. There is one rule that guarantees your chances of surviving a man overboard accident – don’t be the person in the water! However, if you do fall overboard your chances of survival will primarily depend on two factors:

1. If and how fast your crewmates can turn the boat around and recover you.
2. Whether or not you are wearing a flotation device when the accident occurs.

If the sun, moon, and stars are in alignment and you’re about to be recovered, do not swim towards the boat. In cold water you will not be able to swim far enough to make a difference in how fast they recover you and the resulting heat loss could be disabling. Without wearing some type of flotation device in cold water, your ability to tread water or swim will most likely be measured in minutes. If you are hurt or unconscious and unable to help yourself, your survival time will be greatly reduced. Unfortunately, most people rarely wear Personal Flotation Devises or PFD’s – The only way to be sure you’ll have the proper flotation and insulation is if you wear it all the time.

In a few weeks we'll discuss Cold Water Survival further, looking at how to best dress for cold water. 

Safe Boat Operations – Waves and Surf

The ability to recognize wave patterns and characteristics is essential to safe operation in surf and heavy weather.  A person operating in these conditions must be able to determine the timing of lulls and series, and estimate wave heights accurately. There are several forces which create waves at sea; the most significant of which is wind.

The factors that determine the characteristics of wind waves are:

• Wind speed
• Wind duration
• Fetch (the distance over open water which the wind has blown)

As the wind begins to blow, it creates seas, which are typically steep, choppy, and have little pattern. As the wind continues, the seas begin to become more defined.  In heavy weather, observing and measuring waves is important.  If the boat operator can get a general sense of the waves in which they are operating, it will allow the crew to operate accordingly. Heavy weather waves and seas are generated by weather systems, either local or distant.  There are many factors that determine what conditions will be generated by a weather system or series of weather systems.

Factors that will affect wave height include:

• State of the tide:  Ebb currents often cause wave speed to decrease and wave height to increase.  Conversely, flood currents often cause waves to gain speed and loose height.
• Rainfall:  Heavy rainfall can reduce the size of waves, but large runoffs from rivers may stop the flood current or drastically change the conditions at inlets or bars.
• The width of the body of water:  The greater distance the body of water is allows for larger waves to be generated.
• Depth of water:  Deeper water allows for larger swells to be generated.  As these swells approach shallow water on the coast, they will loose speed and gain height.
• Air temperature:  Cold air is denser, causing greater impact on the water and building larger swells than warm air.

After waves are generated far out at sea, they move outward, away from their wind source, in ever-increasing curves, and become what are called swells.  The farther the swell moves from its source, the more uniform its characteristics become, as it travels in a series of waves, relatively equidistant, and moving at a more or less constant speed.  Because of this, swells generated from storms far out at sea can be distinguished by their smoothness and uniformity from those that are coarser (peaked and irregular) which have recently originated nearby.  The usual period of these swells is from 6 to 10 seconds.

Interference between different swell systems, which are travelling in nearly the same direction, causes groups of waves to travel outward in patches.  As these groups of several waves (normally 7 to 12) progress outward, those waves in the forefront disappear and new waves, of the same characteristics, appear at the rear of the patch.  This process continues until the waves dissipate their energy at sea, or transfer it to the shore as surf.