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Old 09-05-2011, 10:38 PM   #1
markpierce
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City: Vallejo CA
Vessel Name: Carquinez Coot
Vessel Model: penultimate Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 12,559
When to start blowing your fog horn

When should one start blowing one's fog horn?* In my mind, it should be when the level of visibility is less than the range of one's fog horn.* So, big ships should start blowing when visibility drops to two miles, and the smallest vessels at one-half mile.* Leastwise, this is "according to Mark."* What do you all say?

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<table style="width:400px;" border="1" cellspacing="0" cellpadding="0"><tbody><tr bgcolor="#2266a7"><td align="center" valign="middle"><strong class="white">Whistle Class[/b]</td><td align="center" valign="middle"><strong class="white">Length of Vessel in Meters[/b]</td><td align="center" valign="middle"><strong class="white">Limits of Fundamental Frequency[/b]</td><td align="center" valign="middle"><strong class="white">Minimum Sound Pressure Level Measured in 1/3 Octave Band at 1 Meter[/b]</td><td align="center" valign="middle"><strong class="white">Audibility Range in Nautical Miles[/b]</td></tr><tr><td align="center">I</td><td align="center">> 200</td><td align="center">70-200 Hz</td><td align="center">143 dB</td><td align="center">2</td></tr><tr><td align="center">II</td><td align="center">75 -200</td><td align="center">130-350 Hz</td><td align="center">138 dB</td><td align="center">1.5</td></tr><tr><td align="center">III</td><td align="center">20 - 75</td><td align="center">250-700 Hz</td><td align="center">130 dB</td><td align="center">1</td></tr><tr><td align="center">IV</td><td align="center">< 20</td><td align="center">250-700 Hz</td><td align="center">120 dB</td><td align="center">0.5</td></tr></tbody></table>
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