2012-03-22 / Outdoors

Bow waves and bottlenoses

As we sailed southwest on Charlotte Harbor the southeasterly breeze was giving us a fun ride. A port tack, beam reach at eight knots kicks up a good bow wave, as well as a stern wave.

Monohull sailboats have a theoretical hull speed that is reached when the width of the waves produced by the sailboat are the approximate waterline length of the sailboat. Operating in a moving fluid mass introduces many other factors: the shape of the hull, the speed of the wind and the direction of sail.

In the early days of yacht racing, some boats were designed with a long overhang at the bow and at the stern, giving them a short waterline length and thus an advantage over sailboats of the same size with a longer waterline. It was discovered that as the wind heeled the boat, leaning it over, and the boat moved through the water, the boat would depress into the water, causing the waterline to increase and thus giving more speed. The hull speed for any given displacement hull is half of 1.34 times the length of the waterline. At all angles of heel, this formula would work great. However, designers found the way around this by redesigning the hull shape to increase the waterline length as the boat heels. In light winds, more sail can be carried aloft producing more speed.

One wave was at our bow while there was a dip at our beam and the stern wave rose next to our starboard quarter. As the boat heels over and settles into its groove, I like to sit against the lifelines or stern rail and steer, especially on the low side (lee side), just inches from the rushing water.

I was startled when I heard what sounded like a sneeze in the stern wave. A dolphin had surfaced and exhaled through its blowhole, alerting me to its presence.

These playful creatures are found around the world. Most common in Charlotte Harbor is the bottlenose dolphin, which averages 8 feet in length and weighs around 500 pounds. Dolphins can live to more than 40 years, feeding on fish, squid, crustaceans and other marine life. They are very intelligent and very playful. This makes them a favorite for wildlife watchers. A fun pastime of the bottlenose dolphin is to ride the waves the same as surfers do. These aquatic creatures are more adept at sensing the pressure inside a wave and this is a distinct advantage when surfing. A surfer rides a wave’s surface while a dolphin rides inside it.

On any displacement hull vessel, the bow wave is the most prevalent, created when standing water is pushed aside by the boat’s movement. This is also the place where playful dolphins can most often be seen.

On our sailboat, and many others, the next big wave is the stern quarter wave. This particular dolphin seemed to prefer this type of wave, probably because there was another creature to interact with, and that was me. I spend more than 250 days a year on the water and every day I love it more. You may think it gets boring at times, but it never does. I live the outdoors. I love the outdoors and all it brings and shows us.

Enjoy the outdoors while you can. Any outdoor activity involving nature is refreshing and enlightening.

Fair winds calm seas. ¦

— Capt. Dennis Kirk owns the Nav- A- Gator, a riverfront restaurant in Lake Suzy, just off Kings Highway. He has been traveling the Peace River since 1979. For more information, call 627- 3474.

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