Section 3: Error in Position Fixing and Risk Assessment Flashcards
An echo sounder is described by the manufacturer as having an accuracy of 2% of the UKC as one SD. If the echosounder was showing UKC as 15m, within which range in meters would your UKC lie within a 95% probability?
You are on a course of 270°(T), and dead ahead of you, at a distance of 14nm, there is an isolated danger mark. The specifications of your automatic pilot state that the instrument will steer within ±1° of the set course as 1 standard deviation.
If your vessel altered course at this point and steered 265°(T), what would be the approximate likelihood of passing 1nm or more due south of the danger, neglecting wind, current etc.?
You are on a course and dead ahead of you; at a distance of 10nm, there is an oil production platform. The automatic pilot can steer within ±2° of the set course as 1 standard deviation.
If your vessel alters the course 10° to the starboard, what would be the likelihood of keeping the platform about 1nm or less to port when abeam neglecting wind, current etc.?
The differences between the actual tides at a place and the predicted tides are normally distributed with the predicted height as a mean and a standard deviation of 0.5m. You have to cross a bar at this place at HW, predicted as 3.0m. The bar has a charted depth of 13.5m and your draft is 14.0m. Squat on transit is 1.0m.
What is the probability that your vessel will cross with less than 1.5m UKC?
What is the probability that your vessel will touch bottom?
A vessel intends to cross a bar with charted depth 11.0m and predicted HOT 2.0m. The maximum draft of the vessel is 10.0m and the maximum squat expected while crossing the bar is 0.5m. The Standard Deviation is 0.5m.
a. What is the probability that the vessel will cross the bar with more than 2.0m of UKC?
b. What is the probability that the vessel will have less than 1.0m UKC?
