105.7 Fog Navigation

Question 1

Single most important tool in fog navigation is your

Answer 1

DR plot, as its processes do not change when fog sets in

Question 2

Second most important tool in fog navigation is the

Answer 2

depth sounder

Question 3

Depth meter is also know as a

Answer 3

fathometer

Question 4

Six things a fathometer can do in heavy fog
1 with DR plot
2 re: depth
2 re: bottom
1 re: getting a fix

Answer 4

1. Verify DR position
2. Run along a depth contour
3. Find a charted object on a depth contour
4. Position by bottom features
5. Avoiding the depths of underwater objects
6. Establishing a fix by a line of soundings by plotting on a separate piece of paper and finding its fix

Question 5

A fathometer can get a “fix” by a series of soundings by ……….. but cannot be done when the bottom is …..

Answer 5

… recording the series distances on a separate piece of paper and then finding its fit on the chart

flat or unchanging by much

Question 6

“Visual” bearings in fog can be done using a handheld compass and…

Answer 6

…. facing the sound you hear directly

Question 7

In heavy fog and hearing a charted fog signal around you, what three elements can be used to determine position

Answer 7

1. DR position
2. Magnetic bearing of sound
3. Fathometer

Question 8

Two or more charted fog signals around you…

Answer 8

… can create a fix by intersecting their magnetic LOPs. Verify with DR position and fathometer

Question 9

In preparation for one-day facing fog navigation, in clear weather one should practice…

Answer 9

… identifying the mag direction of charted sound (buoy bell) for hearing bearings, or sighted bearings using a handheld.

Question 10

When taking a sound bearing to a charted fog signal, the boat should be kept…

Answer 10

… on a steady course.

Question 11

In heavy fog and under power, it is wise to intermittently…

Answer 11

turn off the engine and listen. Every five to fifteen minutes

Question 12

In heavy fog a crew member should be stationed ahead of the mast (careful of the jib) to…

Answer 12

… listen for sounds away from the noise of the engine or cockpit

Question 13

In heavy fog, skipper should dial up ____ _____ for themselves and the crew

Answer 13

safety processes

Question 14

In heavy fog, the sounds of shipping vessels could indicate a nearby…

Answer 14

shipping channel. Take a bearing compare to chart

Question 15

In fog, the sounds of airplanes could indicate…

Answer 15

…. a flight path. Check chart for airports.

Question 16

In fog, the sounds of a ferry could indicate…

Answer 16

…. a nearby ferry route. Take bearing and check the charts

Question 17

Particularly important, so that other boats can “see” you, to raise a ….

Answer 17

… radar detector, if not already flying

Question 18

In fog, the sound that has terrified sailors throughout the ages is the sound of

Answer 18

… breakers dead ahead.

Question 19

In fog navigation, keeping the sound of breakers along the side of the boat is dangerous since….

Answer 19

… skipper will not be able to detect a slow rising in the noise over time.

Question 20

The sound of breakers can be used to navigate along a coast line by…

Answer 20

… zigzaging into and away from the sound of the breakers (much like zig zagging along a depth contour

Question 21

As with a depth contour zig zag, skipper must be sure to avoid ___________ when zig zagging on breakers

Answer 21

…. underwater dangers

Question 22

In fog, certain non-buoy sightings through the fog can help. These include (three):

Answer 22

1. Shipping or ferryboats
2. Color of fog (green or lighted means land)
3. Marine life (birds fly outbound in morning, to land in evening)

Question 23

In fog, changes in wind and water patterns…

Answer 23

… can indicate nearby land (choppy swells from land pushing back on water; interrupted wind flows)

Question 24

What is the difference between a masthead light and a masthead running light?

Answer 24

A masthead light is white and turned on on a sailboat when at anchor. A masthead running light is tricolor and used when sailing.

Question 25

How is taking a sound bearing on another vessel similar to taking a sight bearing?

Answer 25

If it remains in a fixed position off of boat (say 60% off the bow) then collision is possible

Question 26

If on a potential collision course with a shipping vessel, turn to the other boat’s

Answer 26

stern. Sail behind it (though careful as there may be another vessel behind it following same track)

Question 27

A large ship’s fog signal can be heard up to ____ miles away, but as it gets closer…

Answer 27

… the direction of the sound can become less clear. Lesson: Begin recording bearings early.

Question 28

A strong current is defined as anything over ___ knot

Answer 28

one

Question 29

When we plot our DR position which has been corrected for current and/or leeway, it is called an…

Answer 29

….estimated position

Question 30

Procedure to take current/leeway into effect on DR plotting….

and remember to use….

Answer 30

1. Plot normal DR line from departure to destination
2. Plot a Situation 1 triangle to get heading to sail and TRUE boat speed
3. Use TRUE boat speed to plot likely EPs along the route

Question 31

In estimating ETAs at points along the plotted DR it is important to use _____ boat speed, which take into consideration both ____ and ____

Answer 31

TRUE; current and leeway

Question 32

In fog, a “safety valve” heading toward a coast should be adjusted to be even further…

Answer 32

… upwind

Question 33

If fog sets in, ok to change intended DR plot to be less long legged to

Answer 33

shorter legs from buoy to buoy

Question 34

When in complete doubt as to position, it is an acceptable navigation decision to…

Answer 34

…anchor and wait it out.

Question 35

The correct signal for a boat anchored in fog is

Answer 35

dot dash dot in one minute intervals

Question 36

What is the first thing to do when fog is threatening or when night is about to fall?

Answer 36

Take a DR position

Question 37

As a safety valve, a general rule is to steer the boat __-_____ or __-_____ of the destination

Answer 37

upwind or upcurrent

Question 38

When possible, you should pass rocks, reefs or dangers on their….

Answer 38

downwind or down-current sides (i.e., so the boat would be pushed away from them)

Question 39

When in fog during the daytime, skipper should turn on…

Answer 39

… running lights

Question 40

If under power in fog, stop and listen at

Answer 40

five to 20 minute intervals (shorter if in more congested areas)

Question 41

When approaching a harbor with limited visibility, have the ______ ready so it can be immediately _____ to avoid being pushed _____ ______.

Answer 41

anchor; dropped; further aground.

Question 42

Insurance records show that the three most common reasons for groundings are:

Answer 42

1. Failure to keep track of soundings
2. Failure to keep a DR plot
3. Failure to follow buoys correctly.

Question 43

Best to right on lon / lat minutes to the….

Answer 43

hundreths place so XX.XX’

Question 44

I don’t agree with the printed answer to question Ch 7, 4A of 140 on page F-4.

Answer 44

Believe the correct answer is 148 degrees.

Question 45

For the test, when answering regarding soundsing, don’t interpolate.

Answer 45

Write nearest sounding, if shallower water exists, write “nearby X ft”, or after sounding indicate “range X to Y”

Question 46

ALWAYS in working through problems, be very careful when combining Relative Bearings

Answer 46

with Magnetic Bearings.

Question 47

When asked to go to the “center” of a harbor, if no buoy then a point equidistant from nearest points of land.

Answer 47

True

Question 48

Do the indicated miles of a lighthouse matter more or less than the indicate height of the light?

Answer 48

Matter less, as the height off the ground determines distance seen. An airplane might see the light from the designated mileage. For boat, must combine the visual distances of height of eye with height of light (assuming just coming into view on the horizon.) Square root of height x 1.15