Friday, February 6, 2009

Beaufort Sea State Scale

February 5, 2009, Thursday.

Down to "The Shores" for a quick paddle on my morning break. Wanted to get in before the storm hit this weekend. From the Lifeguard Tower to the Boat launch there was virtually no surf. What surf there was had a height of about 6 to 8 inches. However, I could see that the surf north was big. Upwards of six feet at Scripp’s Pier.

But the wind was blowing and there was quite a bit of wind chop. Back in my Coast Guard days I was able to gauge the Sea State visually, using the Beaufort Scale. By observing the characteristics of the wind generated waves you can estimate the sea state and wind speed. Today the wind was generating some good-sized chop with the occasional white cap. Trying to recall what sea state this was I guessed it was about a 2 or 3. But I could not remember the wind speed that is associated with this part of the scale. Probably around 5 to 8 knots.

So when I got back home I searched for a website that showed the Beaufort Wind Force and Sea State Scale. (See link to this under Dive Links) I found one and determined the Sea State. It was about 3. The description of that level on the Scale is 7 to 10 knots with a wave height of 2 feet (.6 meters) described as a Gentle Breeze, and the appearance of the Sea is as follows; "Large wavelets. Crests begin to break. Foam of glassy appearance Perhaps scattered white horses."

This Sea State of 3 is exciting to be in. Going with the wind it pushes you right along at a nice clip (The winds are going between 7 to 10 knots, or about 8 to 12 mph.) And on the return this wind is not too much to paddle against. But you must definitely pay attention to your aspect to the waves. Coming directly at your Bow or Stern is fine and even or even from you quarter is okay. But at this Sea State a wave on your Beam could tip you. And if you were to find yourself in a Sea State of 4 or greater it would most likely tip you if it caught your kayak on the beam. And fighting the wind would be very exhausting. Being out in a Sea State of 4 for a short while would not be too bad. But any extended period in a kayak out in this weather could lead to trouble. A Sea State of 5 is now up to 19 to 24 mph and six-foot waves. It would be very difficult to paddle against winds and seas of this force. Beaufort Scale 6 is a Small Craft Advisory.

Sunday, February 1, 2009

The Art and Science of the Graceful Exit

Thursday, January 29, 2009

Long mid-morning break today so I went out to La Jolla Shores for a paddle. Launched and went directly out to the Far Kelp Bed to watch for whales. I did not see any after searching the horizon for whale sign for about half an hour. Turned back to The Shores.

When I got to the surf zone I decided that I would practice my entries and exits. Surf was about two to three feet in front of the Lifeguard Tower, just at the south end of the surf zone. Down at the boat launch they were just small ankle-slappers.

The ultimate goal is to look good while exiting the surf. If you tip over all the time you are not going to instill confidence in your kayak and dive buddies. Also, tipping could result in the loss of gear. So the graceful exit is what you should aim for. Of course, realistically, as long as you get in without injury to yourself or an innocent bystander it was an acceptable exit. (Any landing that you walk away from is a good landing.)

There are of course, different degrees of gracefulness. The ultimate is coming in perpendicular to the wave and the beach and washing up onto the shoreline, stepping out of the kayak, and pulling it out without getting wet above the waist.

The next desirable degree of gracefulness would be coming nearly all the way in, controlling the kayak sufficiently so that the breaking wave stays on your stern quarter. Then you scrape sand or jump off the kayak in time to save you from a spill.

The least graceful exit (without actually getting dumped) is the frantic paddling, shifting of the lateral center of gravity, and the bail and grab. I will briefly discuss some of the techniques for achieving these different degrees of the "Graceful Exit".

The Mechanics of the Surf Exit; When coming back to shore in your kayak there are a number of forces acting on the kayak. First, is the weight distribution of you and your equipment on the center of gravity. When encumbered with dive gear the center of gravity is shifted back and down. This is the most stable of configurations. And you are least likely to get tipped. Without dive gear the center of gravity is forward of the aft end of the kayak and higher above the water line. Thus making the kayak less stable.

As you and the kayak enter the surf zone the breaking waves will push on the rear of the kayak. The front end sticking many feet out in front of you will be traveling at a slightly slower speed then your rear end. This will cause the kayak to turn and become parallel with the wave. This is to be avoided, as it will lead to the ungraceful effect of being tipped over in the surf. This is especially embarrassing if done in front of other kayakers, Lifeguards, or cute girls in bikinis. (Ladies, this is to be avoided unless your goal is to instill in the male of the species the Knight-in-Shinning Armor Syndrome.)

There are many possible solutions to the problem of turning abeam to the wave. Thinking about how a kayak maneuvers on the surface supplies you with several strategies for overcoming this dilemma. When paddling there are two basic ways of turning. One is to paddle on just one side of the kayak. Paddling on the starboard (right) side will turn you to port, and vice versa. Or, if you have forward momentum, putting the paddle into the water on one side (say port) will turn you to port. Just how effective these strategies are will depend on the size and strength of the surf. If it is too big you are going to get dumped. You may resort to the "Bail and Grab" strategy.

Timing is everything. It is very important to watch the surf. Waves come in sets. There will be larger and smaller sets. Generally, you will be able to see about how many waves are in a set. By looking out to Sea you will be able to observe if the set coming at you is large or small. This is not foolproof and rogue waves do appear unexpectedly. Try to choose the smaller sets for exiting. This requires a little foresight. For, by the time you paddle into the breaking surf, that small set may have passed you by and a large set is coming up on your stern. At this point you need to decide whether to abort re-entry or continue.

Having chosen your time start paddling with all the speed you can muster. The waves are going faster than your kayak and there is not much that can be done about it but compensate for it. The "Rudder Approach" was the first strategy I tried. As I entered the surf I continued paddling as fast as possible. Once the kayak starts to turn I then placed my paddle into the water on the side away from the wave. This should turn the kayak’s nose back towards the beach. This works as long as the wave is not too fast, big or powerful. This is one of the more graceful appearing exits, as it looks effortless.

This next strategy is the "Paddle Approach". As you begin to turn into the wave begin paddling powerfully on the side towards the wave. Theoretically, this will point the nose back to the beach. Again, this will depend on the speed and power of the wave. This is the second most desirable strategy. It does not look and is not as effortless as the previous approach.

The last and least elegant strategy is the "Frantic Counterbalance" approach. I discovered this one quite by accident and it was done, at first, completely intuitively. As I was doing one or both of the previous approaches I felt my kayak reaching the tipping point. Neither of the strategies was working sufficiently to keep me from tipping. Instinctively one or both of my legs went out over the side of the kayak towards the offending wave. This seemed to counterbalance the wave pushing on that side of the kayak. Though this does nothing as far as maneuvering the kayak back perpendicular to the wave it does act by shifting your weight out over the side of the kayak. This is the least graceful of the exit strategies and is the last step before the using the "Bail and Grab" approach.

This last strategy should be avoided if at all possible. If you use it too often you might even gain the attention of Lifeguards who may, rightfully so, view you as a hazard to yourself and other beach-goers. If you need to use this strategy there are two procedures you can use. You can either "Bail and Grab" towards the wave. The downside to this is not grabbing in time and having you kayak plow into shore without you. This can endanger others on the beach as your kayak comes rushing in. Or, you can "Bail and Grab" on the side away from the wave. This can offer more control, but if the wave is very large or powerful you may be run over by your own kayak. Very embarrassing.

Now back to the beach for more practice.