This page has been archived on the Web

Information identified as archived is provided for reference, research or recordkeeping purposes. It is not subject to the Government of Canada Web Standards and has not been altered or updated since it was archived. Please contact us to request a format other than those available.

Secrets of the St. Lawrence

The wind in your sails - Fast or slow?

10 nautical miles off Matane

Destination: Grande-Vallée - Wind direction: Southwesterly; wind speed: 15 knots.

- "We're going to head for the shore. If my grandfather is right, the wind will pick up closer in."

When the wind is blowing parallel to the shore, it creates a narrow band in which the wind picks up speed or drops off sharply, depending on whether the shore is on your right or your left with the wind at your back.

Convergence

When the shore is on your right and less than 3 nautical miles off, the convergence effect means that the wind will automatically be 25 % stronger.

The wind will shift slightly to the left because of the friction created by the shore and will join forces with the sea wind.

When traveling with the wind at your back and the shoreline on your right wind speeds at the shoreline will be quicker due to convergence.

Divergence

The effect is the opposite when the shore is on your left.

The airstream that diverges to the left because of friction on the shore will meet and slow down the sea wind.

When traveling with the wind at your back and the shoreline on your left wind speeds at the shoreline will be slower due to divergence.

Intersection

Watch out for drainage winds. Where there is convergence, the wind over the ground will flow down a valley and, when it meets the sea, may give a nasty shock to anyone caught hugging the shore too closely.

The area where a valley reaches the shoreline can create an area of convergence and thus stronger wind speeds.

Page 6

Introduction

1. Fore to aft
2. What Cartier missed out on
3. Conversion
4. The Secrets of the St Lawrence
5. The wind in your sails - Hard a-port!
6. The wind in your sails - Fast or slow?
7. The wind in your sails - The wind's paths
8. The wind in your sails - Against the wall
9. The wind in your sails - Solar energy
10. The wind in your sails - Under the stars
11. The wind and the waves - The windway
12. The wind and the waves - Wave wars
13. The wind and the waves - Graveyards
14. The wind and the waves - Conflicting seas
15. Symbols
16. The St Lawrence, from 1 to... - Legend
17. The St Lawrence, from 1 to... - Calling all sailors
18. The St Lawrence, from 1 to... Hot spots
19. Local listings - Québec - Pointe-des-Monts
20. Local listings - Pointe-des-Monts - Cap Whittle
21. Local listings - Cap Whittle - Blanc-Sablon
22. Local listings - Gaspésie - Baie des Chaleurs
23. Local listings - Îles de la Madeleine
24. Sailors take warning - White-outs
25. Sailors take warning - The sky above us
26. Sailors take warning - Keeping a weather eye
27. Sailors take warning - Fair weather and foul
28. Sailors take warning - The unexpected
29. The four seasons - Wind aplenty
30. The four seasons - Vessel icing
31. The four seasons - Ice cycle
32. Extra - Beaufort
33. Extra - Handy references
34. Extra - Old Salts and Sea-dogs
35. Extra - The crew
36. Extra - A to Z
37. Extra - Stations
38. Extra - Areas
39. Credits

Print Friendly Layout

Date modified:: 2013-07-09