Hydraulics

May 16, 2009

We woke up in Langley and walked into town for a great cup of coffee and free WiFi at the Island Coffee House, an establishment run by high school students. Did some shopping, confirmed that the grocery store continues to stock our de la Estancia organic polenta and then we were back at the boat ready to cast off at 1055. Five hours and 45 minutes later we finished motoring 40 uneventful nautical miles, through the Deception Pass, and arrived to pick up a mooring buoy at Spencer Spit State Park on Lopez Island in the San Juan Island group. The weather has been fair since the start of this trip with a mix of clouds and sun - no rain. So far we haven't had our sails up but we're still trying to speed our departure from the urbanized part of Western Washington and using our motor is the best way to quickly accomplish that objective. The LIBERTE can make about 7 nautical miles per hour running her engine at 2200 revolutions per minute, towing her inflatable dinghy and assuming she has a freshly painted bottom (which she does). To those seven knots we have to add or subtract the effect of the current. In any event, here in the San Juan Islands, we have finally reached an area where the shoreline is mostly forested and not filled with houses so our push can slow down and we won't often again travel so many hours per day.


Deception Pass

Now it's time to give our readers the lay of the land for this voyage, or maybe more accurately, the lay of the sea. Attached to today's entry is a chart showing the Pacific coastline from Washington State to Alaska. This 1000 nautical mile stretch (or about 1200 statute miles) is the fabled Inside Passage. It's most notable features are:

1. The Straight of Juan de Fuca which divides Washington from Vancouver Island in British Columbia

2. The enormous fjord to the south of the Straight called the Puget Sound which extends 125 miles (every distance in this blog will be in nautical miles) from the eastern terminus of the Straight

3. Vancouver Island itself which was obviously ripped from the North American Continent by geologic forces eons ago and which at 270 miles long is one of the biggest islands in the world

4. The Straight of Georgia, a 20 mile wide straight separating the southern half of Vancouver Island from the mainland

5. Queen Charlotte and Johnstone Straights which separate the northern half of Vancouver Island from the mainland

6. Queen Charlotte Sound

7. The Queen Charlotte Islands

8. Southeast Alaska and

9. The 10's of thousands of islands, big and small, that lie sheltered from the brunt of fierce Pacific storms.

The Inside Passage

No finer cruising ground exists anywhere on the planet. There are snow capped mountains on the islands and on the continent, dense virgin stands of conifer forests, the greenest of clear ocean water, myriad channels running between the islands and sea birds, fish and animals everywhere. Once a vessel passes Vancouver on the mainland and Victoria on Vancouver Island most of the Inland Passage is almost entirely devoid of human population with only the odd little settlement clinging to the shore here and there reachable only by boat or sea plane.

Take a look at the next chart and you'll begin to understand how the hydraulics of the flow of sea water governs life in the Northwest. Pacific Ocean water rushes in though the Juan de Fuca Straight when the tide is flooding. The water divides when it crashes into Whidbey Island at the terminus of the Straight. Some turns south and fills the Puget Sound and some turns north and fills the Straight of Georgia. At the same time, the water is flooding around the northern tip of Vancouver Island and filling Queen Charlotte and Johnstone Straights. When the tide is ebbing the direction of flow is reversed. In the Northwest there are two high tides and two low tides every day so the water is constantly reversing its flow. The tidal difference in the Inside Passage is enormous, almost the greatest on earth. The difference in height between the highest tide of the year and the lowest is nearly 17 feet.

Vancouver Island: Strait of Juan de Fuca on the south and Queen Charlotte and Johnstone Straits on the north

Puget Sound, the Straight of Georgia and in fact all the channels, straights and passageways that dot the Inside Passage were carved out by glaciers during the ice ages. These glaciers carved deep valleys between the mountain ranges. When the glaciers melted, the valleys filled with water. The visible tops of the mountains are today the many islands that make up the Inside Passage. The valleys are the channels between islands - hundreds of feet deep. You can imagine how much water has to enter and recede twice a day to change the water depth by 17 feet. All that flowing water creates currents that have the capacity to overwhelm even the stoutest ship and on the LIBERTE we have to be constantly aware of the state of the tide, which direction the current is flowing and at what speed .