DogCavalry
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- Sep 22, 2019
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This was my very first thread on the forum. I now know the source of the lines I first asked about. They are from the David Taylor Model Basin, hull number 4309, work done in 1955. Unfortunately the test showed a rather poor showing which had an effect on boats in general for the almost 70 years since.
The question I asked originally, which was not answered, I can now answer. If you look at the lines you will see that the chine moves inboard as it goes aft, ultimately increasing the width of the chine flat to almost 45% of the beam. I wondered if this was necessary, or if it would hurt performance.
Since then @baeckmo has kindly posted some of his own work that shows flow lines under one of his own sleds in a typical planing configuration. The flow lines diverge from the centerline of the hull outward at roughly 10°. Visualize the wetted surface of Model #4309, with those flow lines crossing the model sled's keels. They would almost all show a ghastly hockey stick shape. I shudder to think of how that would effect the results. A slight hook in the bottom of a planing hull at speed is bad. What then a hideous knuckle?
The question I asked originally, which was not answered, I can now answer. If you look at the lines you will see that the chine moves inboard as it goes aft, ultimately increasing the width of the chine flat to almost 45% of the beam. I wondered if this was necessary, or if it would hurt performance.
Since then @baeckmo has kindly posted some of his own work that shows flow lines under one of his own sleds in a typical planing configuration. The flow lines diverge from the centerline of the hull outward at roughly 10°. Visualize the wetted surface of Model #4309, with those flow lines crossing the model sled's keels. They would almost all show a ghastly hockey stick shape. I shudder to think of how that would effect the results. A slight hook in the bottom of a planing hull at speed is bad. What then a hideous knuckle?