ASA 106 Special Piloting Techniques Flashcards
Circle of position
every object on the line is equidistant from an object
COP
Circle of Position
Double the relative bow bearings (say 30 and 60 degrees)
At exactly double, forms an isosceles triangle, so the distance run between the bearings is the distance off
When taking the first bearing of a running fix it is important to immediately
… start a stop watch or note the distance log
When taking a running fix, it is important not to change the boat’s
course
When taking a running fix, the first bearing will ideally be between ___ and ___ degrees
30 and 45
Instead of doubling the angle with a bow relative reading, half the angle when taking a
stern reading for distance off. The distance run between bearings is the distance off when object was abeam.
Range of visibility is equal to (equation)
1.144 x sq. root height in feet = X nautical miles
Bobbing the horizon can give distance off by adding together two ranges of ______. Describe method
visibility – the objects and the eye. Sit or stand, lower and raise head by about 1 foot. If blinks, then boat on that COP.
To convert nautical miles into statute miles, multiply by
1.15 (6076/5280)
To convert statute miles into nautical miles, _____ by 1.15
divide
Three important uses for COPs
- Plot an estimated position
- Combine with an bearing LOP and you have a fix
- Keep you a safe distance from shore
Using a COP, the EP is where it passes closest to the…
DR position for that time
Using a COP, the EP is where it passes closest to the…
DR position for that time
How get distance off using sound?
Sound travels at 5 seconds per nautical mile. Watch for loud event, count, calculate.
Eye blink method for distance off
Hold out a pen, close one eye, align pen with object, switch eyes, estimate on-land distance of how far the pen moved, multiply by 10
Counting trees
3 miles off can see the water meeting the shore; 2 miles off can count windows on a house; 1 mile off can make out individual trees
Hand width calculation of distance off (method)
Need two objects of known distance apart (from chart) Hold hand/palm a distance infront of eyes to just cover both objects. Formula Distance Off = (distance face to hand (inches)x(ground distance (miles) / width of hand
Two marks to put on chart with danger bearings
NLT NMT
Bear in mind that danger bearings are bearings ___ ____ ____, not about a ___ ___ _____.
to an object, course to steer
When there is current or strong winds, it is improper to tell the steerer to steer directly to a _____ _____, since could be moving sideways into danger while steerer doing _____ _____.
single object; nothing wrong
You can also draw a ____ ____ all the way around a danger point
Danger Circle
What is The Rule of 60 to avoid a hazard?
Calculating a course alteration when a hazard is a known distance ahead. Formula = 60 * desired distance off object / distance hazard ahead
Ideally the most difficult part of a passage should be done a what point of sail? Why?
A reach. More speed and maneuverability, less going on when beating.
One safe way of plotting routes is to deliberately sail toward…
lighted objects
One safe way of plotting courses is to plan a series of ____ legs of pre-computed time duration. Set ___ at set intervals.
short; watch/timer
Keep well clear of a _____ shore
lee
If at night (or even during day) and confused about location with potential dangers nearby, ____-___ and figure it out.
heave-to
