Captian Jack's Basic Navigation

by Jack Davis

Overview

Jack I. Davis has written this very easy to understand instructional navigation book. After traveling thousands of miles on the water and teaching hundreds of navigation and boating courses, Captain Jack has put his vast experience into this excellent book. Filled with knowledge, sea stories and humorous anecdotes, this book is not only a learning tool but thoroughly enjoyable to read. He has even thrown in a few boating lessons to help you at sea.

Captain Jack takes the reader through each phase of navigation by first explaining, in detail, the steps needed to complete each phase. This is followed by a list of questions to answer, using your new found knowledge. After you have completed the questions, you can check your answers at the end of each chapter. All the calculations are accomplished with simple, grade school math using an inexpensive calculator and basic plotting tools.

If you believe you do not need these Old Time navigational skills, in this modern age of electronic navigation, Captain Jack makes this suggestion to you. "Tape a mirror below your GPS display. When the electronics fail, you can look in the mirror and see exactly who is lost."

140 Printed Pages. Illustrated.

Product Details

ISBN-13:	9781892216090
Publisher:	NetPV
Publication date:	09/05/2000
Edition description:	SPIRAL
Pages:	132
Product dimensions:	5.50(w) x 8.50(h) x 0.31(d)

First Chapter

Chapter 1
 
DISTANCE SPEED
AND TIME
 
Being a good navigator can't be traced to one single skill. It's a composite of many talents.
Today, with the availability of electronic aids, such as GPS (Global Positioning System), you could cross an ocean without the navigational talents in this book. Provided there is no electronic failure.
 
I see inexperienced people go to sea without the proper abilities. Many make their landfall without major problems but there are some who do have complications. I talked to one of these people and his comment was, When the electronics failed, it was the most frightening experience of my life. I was not only lost, but I didn't even know where I was before I was lost.
Which brings us to:
 
Rule # 1 - Always maintain a D. R.
 
These letters stand for Dead Reckoning. All the time you are under way, keep a record of the course, speed and the elapsed time.
 
I can not overemphasize the importance of keeping a systematic record of your distance, speed and elapsed time, while at sea. For the electronic sailor who does not maintain a DR, I recommended he glue a mirror just below his GPS or Loran. When the electronics fail, he can then look in the mirror and see who is lost.
 
In order to plot your course, time and speed onto your chart, you must learn to calculate distance, speed and time.
Don't worry about the difficult calculations. The most complicated math involved in our navigational procedures is elementary math. As simple as it is, you should use your hand held calculator to further simplify checking the answers.
 
Everyone does a certain amount of these calculations while driving from point A to point B. If these points are 60 miles apart and your car speed is 60 miles per hour, it's going to take an hour to make the trip. You can conclude: You're traveling one mile per minute at 60 miles per hour, in 30 minutes you will be halfway there. Navigation is that simple.
 
In this case you are solving for distance. You know your speed (60 mph) and the elapsed time (30 minutes). The formula to solve this problem is Distance = Speed x Time. We put down 60 mph for speed and .5 for elapsed time (30 minutes is one half of an hour, or .5). Then 60 times .5 equals 30, or 30 miles, the answer to the problem.
 
We may also need to solve for speed. This formula is:
S = D / T (The / symbol represents Divided By). If we have made 30 miles in 30 minutes (.5 hours) we divide 30 by .5 which equals 60 (mph).
 
To solve for time, the formula is T = D / S. If we have traveled 30 miles at a speed of 60 mph, we divide the 30 by 60 which equals .5 (.5 hr = 30 minutes)
These formulae are critical. If you use the wrong formula, as is so easy to do, the answer will definitely be wrong. Instead of trying to remember all these formulas there is a better solution.
 
Please be certain you understand this and do not try to remember the formulas. Always write the formula on the work paper.
 
In the examples given for distance, speed and time, the examples were mph (miles per hour) and the distances were statue miles, used by most landlubbers. The statue mile is 5,280 feet, but the nautical mile is 6,080 feet.
 
Everything shown from here on will be nautical miles (nm) and knots (kn). Note, I did not say knots per hour, which is incorrect.
 
A knot is the speed of 1 nautical mile per hour. Derived from the Common Log where the number of knots (about 25 feet apart) which ran out in a quarter minute gave a direct reading of the ship's speed. Thus, if the log was streamed and six knots ran out before the quarter-minute glass ran out, the ship's speed was six knots. To say 6 knots per hour is, strictly speaking, incorrect.
 
I use the abbreviation hr for hours and min for minutes. Remember: when you multiply or divide hours and minutes, you must convert your minutes to fractions of an hour. For instance: 2 hr 15 min must be converted to 2.25 hr (divide your minutes by 60). 15/60 minutes equals .25 hr.
When you have found an answer that is hours and fractions of hours, you must convert it back: 2.25 hr must be converted to 2 hr 15 min (You multiply the fraction by 60). .25 X 60 equals 15 min.
 
If I am using a hand held calculator, I carry all the decimal places hat the gadget will allow me to carry: 2 hr 22 min (22/60 equals .36666666).
 
If I must use long division or multiplication (with paper and pencil), I round off to .367. The difference will be acceptable.
 
It is important to work all of the following problems, even if you think you know how to do them. You may be surprised. The answers are at the end of this chapter.
 

DISTANCE	SPEED	TIME
1. ____________?	7 kn	3 hr
2. ____________?	5.5 kn	4 hr
3. ____________?	13.5 kn	3.5 hr
4. ____________?	17 kn	hr 10 min
5. ____________?	24 kn	3 hr 10 min
6. ____________?	2.7 kn	8 hr
7. ____________?	42.4 kn	16 min
8. ____________?	23 kn	46 min
9. 43 nm	6.2 kn	__________?
10. 32 nm	8.5 kn	__________?
11. 35 nm	12.3 kn	__________?
12. 17 nm	28 kn	__________?
13. 15 nm	3.5 kn	__________?
14. 17.8 nm	29 kn	__________?
15. 6.6 nm	19.3 kn	__________?
16. 8.1 nm	16.9 kn	__________?
17. 22 nm	_________?	29 min
18. 23.8 nm	_________?	0.6 hr
19. 12.3 nm	_________?	19 min
20. 34 nm	_________?	88 min
21. 24.1 nm	_________?	77 min
22. 16.5 nm	_________?	0.48 hr
23. 18.9 nm	_________?	0.77 hr
24. 17.1 nm	_________?	1.5 hr

In school, the stated problem was one of my least favorite problems. Life, as it turns out, is a stated problem. Certainly, navigation on a small boat is a stated problem. Don't be intimidated. Try to look at each problem as if it is a real life situation and you are the navigator in charge.
 
25. The distance between two buoys is 14 nm. The vessel's speed is 11 kn. The running time between the two buoys is ______________?
 
26. Your boat's speed is 12 kn. The speed of the current is 3 kn. What is the speed of your boat over the bottom while going upstream against the current __________?
 
27. Your boat's speed is 12 kn. The current's drift is 2 kn. (The speed of a current is called drift). What is the speed of your boat over the bottom as it travels downstream with the current ___________?
 
28. If you have a 2 kn current and can make 13 kn with a 6 nm run in each direction, how long would it take for a round trip _____________?
 
Be certain to work this problem as two separate legs then add the results together. The answer will surprise most folks.
 
29. Point "B" is 59 nm from point "A" on a course of 345 degrees true. The current sets 165 degrees true at a drift of 1.7 kn. If your vessel's speed is 12.6 kn, how long will it take you to reach point "B" from point "A"____________?
 
You already know drift is the speed of the current. Now, here is a new term: Set. Set is the direction the current is going.
 
30. Your course from "B" to "A" is north on a leg of 10 nm. Your boat's speed is 10 kn. The current's set is 180 degrees with a drift of 4 kn. What is your speed over the bottom ____________?
 
31. Your vessel is making way through the water at a speed of 13 kn. Your vessel traveled 30 nm in 4 hr 23 min. What current are you experiencing ___________?
 
 
DISTANCE SPEED TIME
ANSWERS
 
1. 7 kn x 3 hr = 21 nm
 
2. 5.5 kn x 4 hr = 22 nm
 
3. 13.5 kn x 3.5 hr = 47.25 nm
 
4. 17 kn x 3.1666666 = 53.8333 nm
 
5. 24 kn x 3.16666 hr = 75.9 nm
 
6. 2.7 kn x .8 hr = 2.16 nm
 
7. 42.4 kn x .266666 hr = 11.30666 nm
 
8. 23 kn x .7666666 = 17.6333 nm
 
9. 43 nm / 6.2 kn = 6.9354838 hr or 6:56 hr & min
 
10. 32 nm / 8.5 kn = 3.7647058 hr or 3:46 hr & min
 
11. 35 nm / 12.3 kn = 2.8455284 hr or 2:51 hr & min
 
12. 17 nm / 28 kn = .6071428 hr or 0:36 min
13. 15 nm / 3.5 kn = 4.2857142 hr or 4:17 hr & min
 
14. 17.8 nm / 29 kn = .613793 hr or 0:37 min
 
15. 6.6 nm / 19.3 kn = .341968 hr or 0:21 min
 
16. 8.1 nm / 16.9 kn = .4792899 hr or 0:29 min
 
17. 22 nm / .483333 hr = 45.517 kn
 
18. 23.8 nm / .6 hr = 39.666 kn
 
19. 12.3 nm / .316666 hr = 38.842 kn
 
20. 34 nm / 1.4666666 hr = 23.1818 kn
 
21. 24.1 nm / 1.2833 hr = 18.779 kn
 
22. 16.5 nm / 0.48 hr = 34.375 kn
 
23. 18.9 / .77 hr = 24.545 kn
 
24. 17.1 nm / 1.5 hr = 11.4 kn
 
25. 14 nm / 11 kn = 1:16 hr & min
 
26. 12 kn - 3 kn = 9 kn
 
27. 12 kn + 2 kn = 14 kn
 
28. Work as two legs:
1st leg 6 nm - (13 - 2) = .54545
2nd leg 6 nm - (13 + 2) = .40000
.94545 hr
 
The temptation in this problem is to reason that the current coming and going balances out. Therefore, you could simply use 13 kn = 0:55384 min which will not provide the correct answer.
 
29. Then:
59 nm / 10.9 kn = 5.41284 hr
Then:
.41284 X 60 = :247706 min = 5 hr 25 min
 
30. The course - North (360 degrees)
The current sets South (180 degrees)
Speed 6 kn
 
31. 30 nm - 4.383333 hr = 6.844111 kn (Speed made good) Then:
Boat speed 13 kn
less 6.8441111 (speed made good)
drift 6.155889 (speed of current)

Table of Contents

Preface to the First Edition
Introduction
Chapter 1	Distance, Speed and Time Answers - Distance, Speed and Time
Chapter 2	Learn to Sail
Chapter 3	Compass Compass Answers
Chapter 4	Read To Be A Better Sailor
Chapter 5	Distance of the Horizon Distance of the Horizon Answers
Chapter 6	Heavy Weather Sailing
Chapter 7	Bow & Beam Bearings Bow & Beam Bearings Answers
Chapter 8	Learn to Maneuver Your Boat
Chapter 9	Chart Reading
Chapter 10	Plotting Plotting Answers
Chapter 11	Follow Your Navigational Plan
Chapter 12	Fear, Remembrance and Reality
Sailing Terms Spoken Every Day
Suppliers and Manufacturers
Glossary
Other Books
About The Author