I have had to go back to my 5th grade grammar to answer your post. "Silence is the absence of sound. It's an absolute adjective, so people don't usually say something is very silent or silenter (not a word) unless they're playing with words. If something makes no noise at all, it's silent. Quiet means something is not very loud." As point, the human hearing will vary by the human who is hearing the noise but this is the decibel scale for the noise we hear from a well-designed electric motor:
Noise source:
Passenger car at 65 mph at 25 ft (77 dB);
freeway at 50 ft from pavement edge 10 a.m. (76 dB).
Living room music (76 dB);
radio or TV-audio, vacuum cleaner (70 dB).
70 - Arbitrary base of comparison. Upper 70s are annoyingly loud to some people
Conversation in restaurant, office, background music, Air conditioning unit at 100 feet.
60 - Half as loud as 70 dB. Fairly quiet.
Mike Electric Yachts of Southern California
---In electricboats@yahoogroups.com, <moriartybob@...> wrote :
One surprise though is that the motor is not "whisper quiet".
Today I took some measurements with an iPhone app, Decibel 10th.
Tied to the dock, with the motor spinning at 1800 RPM (setting 3 on my 0 to 5 throttle) I observed the following:
85 dB @ one foot from the motor.
81 dB @ two feet from the motor with companionway steps in place
At the helm:
69 dB with companionway board removed
65 dB with companionway board in place
60 dB with motor off (ambient noise)
Can anyone share comparable measurements?
Thanks in advance.
--Bob M
Posted by: mike@electricyachtssocal.com
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