Term
|
Definition
| high intensity and visibility (lighthouses); indicate key Nav points |
|
|
Term
| What are the two types of Major Lights and their definitions? |
|
Definition
§ Primary: strong lights of long range; mark landfall or coastal passage
§ Secondary: established at harbors or other locations; lesser range |
|
|
Term
|
Definition
| serve as navigational aids within harbors, along channels and rivers, and to mark isolated dangers |
|
|
Term
| What are the four possible Light colors? |
|
Definition
| white, red, yellow, green |
|
|
Term
| Define the phase of a light |
|
Definition
o light sequence or pattern of light shown within one complete cycle of the light |
|
|
Term
| What are all the possible phase characteristics for a light? |
|
Definition
§ fixed-f
§ occulting-Oc
§ isophase-Iso
§ flashing-Fl
§ quick flashing-Q
§ alternating-Al.RW |
|
|
Term
| Define the period of a light |
|
Definition
| length of time required for light to progress through one complete cycle |
|
|
Term
| Draw the periods for all the possible phase characteristics |
|
Definition
|
|
Term
|
Definition
o warn navigator of hazards to navigation when approaching from dangerous sectors |
|
|
Term
| What are the two types of publications on lights and what is there jurisdiction? |
|
Definition
§ List of Lights - American
§ Light List - International |
|
|
Term
What are the characteristics of this light:
Oak Island Light FL (4) W 10s 169 ft 24 NM |
|
Definition
· Flashing (Fl), 4 flashes; White (W); 10 secs; 169 ft; Nominal Range = 24 |
|
|
Term
| What determines if a light is visible? |
|
Definition
§ Power/shape of the light
§ Height of the light and of the observer
Visibility conditions |
|
|
Term
| Define Computed visibilty |
|
Definition
| maximum distance which light can be seen in meteorological visibility conditions in the immediate vicinity |
|
|
Term
|
Definition
| max distance a light may be seen in clear weather (IDEAL) |
|
|
Term
|
Definition
o max distance a light may be seen under existing weather (ACTUAL) conditions |
|
|
Term
| How do you calculate Geographic Range? |
|
Definition
§ GR = Observer’s Eye + Height of Light
Find height in feet first then use chart to find there associated visibility distances, then add them together |
|
|
Term
| How do you calculate Luminous Range? |
|
Definition
§ 1. Estimate visibility & mark on diagram
§ 2. Mark Nominal Range of light
§ 3. Determine Luminous range |
|
|
Term
| How do you determine computed visibility? |
|
Definition
§ If GR < LR CV = GR
§ If GR > LR CV = LR
§ LESS OF the two (LR or GR) |
|
|
Term
| What are Electronic charts? |
|
Definition
· Navigational chart computer-usable format, used in combination with electronic devices |
|
|
Term
| What are the two ways to create an Electronic Chart and define them |
|
Definition
o Raster – picture of paper chart; created by scanning a paper chart
§ set of colored pixels representing chart information as a picture
Vector – produced by NGA for DoD; layers of different lines, points and areas to create a bigger image |
|
|
Term
| What are the advantages and disadvantages of a Raster Chart? |
|
Definition
§ Advantages
· Cheap and easy to produce
· Runs easily on PC
· World-wide availability
§ Disadvantages
· Zooming in degrades quality
· High scan resolution is required for detailed chart
· Cannot make chart corrections; cannot be updated or changed
Requires electricity |
|
|
Term
| What are the advantages/disadvantages of a vector chart? |
|
Definition
§ Advantages
· Extremely accurate and easy to update (chart corrections)
· Self-controlled
· Zooming in reveals details
§ Disadvantages
· System can fail; need more powerful hardware
Requires more data; expensive |
|
|
Term
| What are the three types of Electronic charts? |
|
Definition
RNC (Raster Nautical Chart) – scanned image. Cheap and easy to produce
ENC (Electronic Nautical Chart) – vector chart; complies with IHO
Accurate with many features, but expensive with limited coverage
o DNC (Digital Nautical Chart) – vector chart; conforms to IHO
§ High accuracy, multiple layers
§ MAIN CHARTS USED BY USN
§ Advantages: easy information display; improved safety
|
|
|
Term
| How many DNC regions are there? |
|
Definition
|
|
Term
|
Definition
· Electronic Charting Display Information System that complies with IMO (International Maritime Organization) to assist mariners |
|
|
Term
| What are the advantages/disadvantages of ECDIS? |
|
Definition
o Advantages
§ Automated plotting
§ Easy data and information display/manipulation
§ Reduced manning and improved safety
o Risks
§ Over-reliance on information provided
§ Poor sensor performances
§ Chart errors, omissions or outdated work |
|
|
Term
|
Definition
o ECDIS-N –Navy’s version of ECDIS; allows for communication between systems
§ Display radar, visual and celestial navigation fix information |
|
|
Term
|
Definition
· electronic charting system; performs many of the same functions of ECDIS, but does not meet international (IMO/IHO) requirements
o only used for situational awareness |
|
|
