Thread: Horn fetish?
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Old 02-11-2011, 01:32 PM   #47
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
RE: Horn fetish?

Quote:
nomadwilly wrote:
Don't you guys feel a bit guilty making your little boat sound like a monster ship? Great at the yacht club but in open water and limited visibility it would seem a joke would be out of place at best. I think the sound of one's horn should match the size of the boat. Well ..sorta.
Boat/ship length determines frequencies and volumes.* What I don't want is a rinky-dink horn.* If not heard, one is just playing boats.*


*The 1972 Intemational Regulations for Preventing Collisions at Sea ('72 COLREGS), ANNEX III, entered into force by the International Maritime Organization (IMO), specifies the technical requirements for sound signal appliances on marine vessels. Frequency range and minimum decibel level output is specified for each class of ship. The class is determined by the vessel's length. Sound pressure level intensity at a distance of one meter from the horn is stipulated, which determines the theoretical range of the horn, although the actual range will, under many conditions, be much greater than this. This information is displayed in the following table:

<table border="1" cellpadding="0" cellspacing="0" style="width:400px;"><tbody><tr bgcolor="#2266a7"><td align="center" valign="middle"><b class="white">Whistle Class[/b]
</td><td align="center" valign="middle"><b class="white">Length of Vessel in Meters[/b]
</td><td align="center" valign="middle"><b class="white">Limits of Fundamental Frequency[/b]
</td><td align="center" valign="middle"><b class="white">Minimum Sound Pressure Level Measured in 1/3 Octave Band at 1 Meter[/b]
</td><td align="center" valign="middle"><b 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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