Monday, October 18, 2010

More Thoughts on the Ferry Rescue in Chapter 17

In Chapter 17, there is a short sidebar article by Christopher Cunningham entitled, "Paddling in the Lee." As I promised in my previous blog post, I'd like to take some time to consider this aspect of the story in more depth. Not fully understanding the concept of paddling in the lee contributed to the incident in this chapter as well as several other incidents throughout the book, "Deep Trouble". Paddlers found themselves suddenly facing conditions well beyond their abilities and experience because they made a 'go-no go' decision based on the conditions they observed 'in the lee' of a shoreline. They did not realize that there would be a significant escalation in the severity of the conditions once they left the protection of the wind shadow.

In order to better judge conditions on the water, it is helpful to understand how waves are formed. Waves develop as wind passes over water. The friction of the wind against the water's surface transfers some of the wind energy into the water. The water begins to move and waves start to develop. The waves will continue to grow based on three factors: 1. Wind Speed (how strong the wind is), 2. Wind Duration (how long the wind has been blowing in that direction), and 3. Fetch (the distance which the wind can travel over the water). So a 30-mph wind will create bigger waves than a 10-mph wind. A 30-mph wind that started 3 seconds ago has no time in which to develop large waves, but after 12 hours those waves will be much larger. Finally, a 30-mph wind blowing offshore will have very little in the way of noticeable waves next to the shore, but five miles offshore the waves will be much larger because the wind has had more distance to travel over the water.

When a wind blows over a land form and then out onto the water (an offshore wind), there is an area on the water next to the shore that is somewhat protected from the wind and its effects. This is referred to as the lee. Depending on the height of the land in relation to the water's surface, there can be a significant amount of protected water, or very little. If you are paddling at the base of tall cliffs, this protected area could be quite tranquil even with a gale force wind raging over your head. On the other hand, there will be almost no reduction in wind speed or protection from the wind, if you are paddling next to a flat, sandy island with no trees or vegetation. Someone who is camped on a pocket beach at the base of large cliffs might be tempted to go out paddling based on the calm conditions seen on the water near camp, but as soon as that person leaves the protection of the cliffs, he could immediately find himself in a maelstrom of wind and rough water making it very difficult, if not impossible, to turn around and head back into the protected water at the base of the cliffs.

Add tidal or river currents to this mix and conditions can become even more confused. When wind is blowing in the same direction as a current, the waves will appear to flatten out somewhat. On the other hand, a wind blowing in opposition to a water current will cause the waves to steepen and appear larger. If the waves are large enough, they may even begin to break. For paddlers, breaking waves are generally more dangerous than non-breaking waves because they have the power to knock a kayak over. When paddlers capsize in non-breaking waves, it is usually a case of the paddler losing his/her balance perhaps due to a lack of skill or experience. But in breaking waves, the wave is releasing energy and can very easily knock the kayak itself over unless the paddler takes appropriate preventative measures (aggressively bracing into the wave). Paddlers need to be aware of the possibility of breaking waves developing in shallow water, at the mouths of rivers, and anywhere that tidal currents may be running in opposition to the prevailing wind direction.

Beginning paddlers and people who have limited experience on the ocean are often unfamiliar with these situations and the way that they can cause conditions to change suddenly and rapidly. The paddlers in Chapter 17 (and several other chapters in the book), made their decisions about whether to paddle or stay on shore based on the conditions they saw in front of them, not realizing how the severity of those conditions would change quickly. Once they found themselves in the area of deteriorating conditions, their skills were not adequate to control the kayaks, prevent capsize, or perform the necessary rescues.

This summer, we had a kayaking tragedy on Lake Michigan that involved a little girl who was quickly blown off-shore by strong winds into the rougher water farther out. While it was reported that the water near shore was calm, once this little girl found herself beyond the protection of the land, she was unable to paddle the kayak back toward shore.

Have you taken the time to really understand wave formation and the effect of wind and current on waves? Have you ever found yourself in rapidly deteriorating conditions that were beyond your skill level? As the terms "lee" and "weather" can sometimes be a little confusing depending on the context in which they are being used, I recommend that you read the short article "Lee versus Weather" in the book, "The Complete Sea Kayaker's Handbook" by Shelley Johnson.