1. NAVIGATION TRAINING
Section 9
Tides

2. Table of Contents Section 1 Types of Navigation
Section 2 Terrestial Coordinates
Section 3 Charts
Section 4 Compass
Section 5 Nautical Publications
Section 6 Navigational Aids

3. Table of Contents Section 7 Buoyage Section 8 Position Lines and Fixes
Section 9 Tides
Section 10 Currents
Section 11 Weather

4. “Getting Acquainted Lecture”
Section 9: Tides
“Getting Acquainted Lecture”
Instructor Bio:
Commissioned May, 1993; NROTC Unit, IIT
Reported to Hue City (CG-66) homeported in Mayport, FL for a 42 mos tour
24 mos - Engineering Dept (Auxiliaries Officer & Damage Control Assistant)
18 mos - Operations Dept (Air Warfare Officer/BW Flag Liaison Officer)
Command Employment (while aboard Hue City)
1995 Med Deployment 95-2 with USS Theodore Roosevelt
1996 Baltops ‘96 (Scandinavian countries)
1997 Med Deployment 97-2 with USS John F. Kennedy
Midshipmen Cruises (emphasize student contribution to course)
CV (CV 63) - Secrest
Tico’s (LKE, VLG) -Waterston, Pope, Sullivan
Burkes (DDG 61) - Kuckel
OH Perry (FFG 61) - Phillips
LHA/LHD (LSD 44) - Fink, Sutherland
AOE (AOE-8) - Hertel
Review Syllabus:
Course objectives
Course resources (webpage, Textbook, Workbook)
Case studies - provide vivid and intriguing examples of the the fundamental principles taught in this course.

5. Tides Defined
Tides are the vertical rise and fall of the ocean level due to the gravitational and centrifugal forces between the earth and the moon, and to a lesser extent, the sun.

6. Spring Tides
When the tidal effects of the sun and the moon act in concert.

7. Neap Tides
When the tidal effects of the sun and the moon are in opposition to one another.

8. Tidal Reference Planes
Mean high-water springs (MHWS)
average height of all spring tide high-water levels
Mean higher high water (MHHW)
average of the higher of the high-water levels each tidal day, 19-year period
Mean high water (MHW)
average of all high-tide water levels, 19-year period
Mean high-water neaps (MHWN)
average recorded height of all neap tide high-water levels

9. Tidal Reference Planes
Mean low-water neaps (MLWN)
average recorded height of all neap tide high-water levels
Mean low water (MLW)
average of all low-tide water levels, 19-year period
Mean lower low water (MLLW)
average of the lower of the low-water levels each tidal day, 19-year period
Mean low water springs (MLWS)
average of all spring tide low-water levels

10. Tidal Reference Planes
Height marked on chart
Depth marked on chart

11. Tidal Patterns
In general in most of the world, the tides go up and down on a semi diurnal curve

12. Tidal Patterns - Semidiurnal

13. Tidal Patterns - Diurnal

14. Tidal Patterns in the Georgia Strait
With the tidal waters of the Georgia Strait being restricted north and south of Vancouver Island, a stand of higher water occurs between one of the two high waters.
The result is shown:

15. Tidal Patterns as found in Georgia Strait

16. Calculating Rise of Tide
Q. If a low water was at 0600, with a height of 0.2 metres, and the next high water was at 1200 , with a height of 5.6 metres, what would be the approximate rise of tide and therefore approximate height of tide if your vessel was setting out at 0900.

17. Calculating Rise and Height of Tide
A LT High water m
0600 LT Low water m
6.00hrs Range 5.4 m
0900 LT
0600 LT Low water m
3.00 hrs
Approximate rise of tide is (3hrs/6hrs) x 5.4m = 2.7 m
Approximate height of tide above chart datum, if your vessel was setting out at 0900 would be : Ht of LW (0.2m) + rise of tide (2.7m) = 2.9 m.

18. Calculating Rise of Tide
In this case allow only 2.5 metres. Always allow less rise of tide close to low water due to the rate of change of height being least close to time of low water (and high water).

19. IMPORTANT NOTICE
At best, tidal prediction is a chancy business. It relies on field measurements and data collection that can be subject to any of several kinds of errors. Typographical errors, programming errors, and numerous weather and human activity error sources can contribute to a rather large level of predictive uncertainty.