Errata for
Navigation Workbook 18465 Tr, 4th printing

8, 86.

Problem 4-12 Question:

Following US Shore Route of problem 2-30 in reverse to the west (WP4 to WP1), select appropriate points (A, B, C) along each leg that would mark the approximate halfway point of the leg and identify a magnetic bearing at those points that would mark that location. Point A is between WP 4 and WP3, B is between WP3 and WP2, and C is between WP2 and WP1. Choose a landmark that is near the beam at each location. Give the name of the mark, the bearing to it, and briefly outline your reasoning for choosing it over others that might be possible. You can use the Coast Pilot to help with descriptions of places you do not know from direct experience. You might also find it interesting to follow this route in Google Earth looking at the terrain. Also note, this exercise is tied to an earlier one so we kept the same waypoint numbers, but it is generally valuable to have your numbers increase along a route.

Problem 4-12 Answer:

(A) WP4 to WP3 offers several options affirming your half-way point. Just past halfway on this leg, the tank on Protection Island aligns with the AERO light on Diamond Pt, bear- ing 165M. Either of these alone would be useful landmarks A natural range, bearing 147M, runs between the tip of Violet and Beckett Points. New Dungeness Light is astern, bearing 254M. You’re in 13 fathoms of water just north of the Dallas Bank, which is detailed in the Coast Pilot.

(B ) The halfway mark from WP3-WP2 is 7.6 miles along that leg. Not so much onshore to rely on. Slightly ahead of abeam is an unnamed point that aligns with Lost Mt. Green Pt. will be slightly behind, bearing 163M. The Coast Pilot lacks details for this section. The west stacks in Port Angeles will bear 204M at the halfway point, Ediz Hook Light bears 214 M— albeit these are behind you. Ahead, you might look for the house, bearing 117 M Remember you can check your depth here as well. You’re at 30 fathoms.

(C) At 5.1 miles, (halfway between WP2 and WP1 the tower at Angeles Pt. bears 104 M, the tower west of Observatory Pt. bears 278 M. The mouth of Colville Creek is about 2 miles off, and slightly abaft the starboard beam, but it might be too low to be seen. Consider using a charted peak ashore, such as the one described as Round top on first low ridge, at elevation 2140. Here, clouds or rain might obscure the noted peak. The point we wish to make here is to use ALL available means to locate yourself. See that the easternmost point in Freshwater Bay aligns with the Round top peak. On clear days, this could be a useful natural range to let you know you are almost halfway to your next waypoint, then you could take bearings to the towers above to verify.

94. Answer 8-21. Current is 3.1 not 3.9 kts.

Errata for
Navigation Workbook 18465 Tr
, 3rd printing

8, 86. Problem 4.7 See tables below.
14. In problem 6-17, change "...assume there is in addition a strong northerly wind..." to "...assume there is in addition a fresh wind from 040T..." Thanks to reader Michael Donatz for pointing out the need for this correction.
82. 2-16. (B) Sand, Shells, and Pebbles. (C) Mud.
88. 5-15 (C) answer refers to "use trig or..." this should be "plot the vectors or..." We do not use trig at all in this course.

Answer to 3-13 is: Geo range = sqrt(49) + sqrt(118) = 7 + 10.9 = 17.9 or maybe more accurately in good conditions x 1.17 = 20.9.
In clear weather we compare this geo range to the nominal range of 15 nmi, to conclude that the visible range is dominated by the nominal range. In visibility of 5.5 nmi, the nominal range of 15 is reduced to the luminous range of 10 nmi, which is then the visible range we expect.

89. Hs used in the equation is the sextant height or sextant angle measured directly from the sextant. This abbreviation is not used in the text, so we need this clarification. The distance off D = 1 nmi x (target height H in feet / 100) / Hs (in degrees). Or in words, D = H/Hs, where H is the target height expressed in hundreds of feet and Hs is the angular height in degrees.

Solution of 8-5. This should reference the official height of tide table. It should also reference the technique outlined in the text in Figure 8-11. Here is the start of that method.

97, 98.

 Any rule reference to 35d should be 35e, and any reference to Rule 35f should be 35g. The answers themselves are OK. (Apparently somethings got renumbered over the long liftetime of our quizzes.)

4.7 Tables

Errata to 2nd Printing