Portable generator or not?

[Dockhead]

Originally Posted by cal40john

. . . I was running my Webasto heater one evening. The exhaust was pointing away from the other boat that must have been at least 150 feet away. The guy on the other boat was fake whispering in a loud voice about jerks running their generator. So any convivial conversation we were having on our boat would have been heard by him, but a mechanical noise that must have been much quieter is what he was complaining about.

In 15 years with this boat, I've never once had a complaint about my low speed sound encapsulated diesel generator.

HOWEVER, my Eberspacher hydronic heating is a different matter. People hate it and I have had various complaints over the years, from people even very far away.

I do my best to avoid bothering people, and one thing I do sometimes if people are nearby is that I shut down the Eberspacher and fire up the generator instead, and use electric heat. Far less efficient, but what is it worth to not be a jerk?

Fortunately where I cruise there is rarely even one other boat in any given anchorage.

[SailingHarmonie]

Originally Posted by GordMay

The further away you are from the sound source, the lower the perceived sound intensity [sound pressure level, or SPL].
The rate of attenuation is approximately 6 dB, as the distance doubles.
A gain of 6 dB is actually a fourfold increase in SPL.
Each time you reduce the distance to the source, by a factor of 2, the SPL increases by a factor of 4 [Inverse Square Law]

Remember: 40 dB is 100 times louder than 20 dB. Similarly, 80 dB is 100 times louder than 60 dB. This is because the decibel scale is logarithmic, and an increase of 10 dB corresponds to ten times more power..

This is true ONLY if the sound is spreading out in a spherical space. But over calm water especially at night this is NOT true. The sound reflects off the water, and then it also refracts downward as the air temperature changes with height. This is why sound carries SOOOO much further over water at night as opposed to during the day. it is not spreading in a sphere, but rather in something closer to a simple torus away from the source.

That's why your neighbors obnoxious generator can be heard so far away on a very calm night, even though they swear it is no louder than any other night.

[BlueH2Obound]

We are a power boat, and once had a sailboat come into a large anchorage, with us as the ONLY boat there, and anchor right on top of us.
He then proceeded to get into his dinghy, row over to us and inform us that if we intended to run a generator, we would have to move farther away, or leave the anchorage . . . .

[Dockhead]

Originally Posted by BlueH2Obound

We are a power boat, and once had a sailboat come into a large anchorage, with us as the ONLY boat there, and anchor right on top of us.
He then proceeded to get into his dinghy, row over to us and inform us that if we intended to run a generator, we would have to move farther away, or leave the anchorage . . . .

Wow! You would think that there would be better social skills and sense of ethics in such a close-knit society as the cruising community.


Just out of curiosity, what was your answer?

[GordMay]

Originally Posted by Dockhead

The inverse square law, sure. But that law applies in free space, not in proximity to a water surface which reflects sound. That's why sound carries so far across water. The sound pressure still diminishes with distance from the source, but at a much lower rate...

Indeed. The sound intensity [in decibels], from a point source [which spreads its influence equally, in all directions, without a limit to its range], will obey the inverse square law, if there are no reflections or reverberation.

The flat surface of a body of water offers few obstacles to sound — there aren’t any trees or rocks or buildings in the way. That probably helps a bit, but it turns out it’s not the real reason. If it was, you’d experience the same effect if you were standing in a meadow or a field. The real reason has to do with the way air temperature affects travelling sound waves.

The sounds that we hear, are actually pressure waves, travelling through the air. The speed of sound depends on the temperature of the substance it’s travelling through. In air at 20°C, sound travels at 343m/s, but that changes by about 3m/s for every degree centigrade; in 10°C air, sound travels at only 337m/s.

When you make noise, sound waves travel away from you, in every direction, making an expanding sphere.

Since the air just above an open body of water, is cooler than the air slightly higher up, the speed of sound is slightly lower, above the water’s surface. The temperature gradient, above the water, translates into a gradient in how fast sound travels; sound waves further from the water will be faster, than those below them.
The difference in speed causes the expanding sphere of sound to change shape, flattening into a wall, or even refracting the sound downwards.
That’s why sound travels further over [calm] water: less is lost up into the air, meaning more of it ends up in your ears, or your neighbours’.
As Dockhead noted [#75], sound waves also may reflect from calm water's surface, bouncing up to the ear.
Additionally, if you are sitting quietly in a still boat on calm water, there may be little [or no] ambient noise, to interfere with sound waves, coming to you from a distance. So distant sounds may seem to be more clear, which may be confused with loudness.

[Pizzazz]

We should also not forget that we are of different ages here and my hearing has significantly deteriorated recently, so some of us are just not as sensitive anymore. Not to mention the eyesight.

[sailorboy1]

Originally Posted by BlueH2Obound

We are a power boat, and once had a sailboat come into a large anchorage, with us as the ONLY boat there, and anchor right on top of us.
He then proceeded to get into his dinghy, row over to us and inform us that if we intended to run a generator, we would have to move farther away, or leave the anchorage . . . .

I hope you jumped into action and started up the generation even if you didn't need to.

[Bowdrie]

Originally Posted by Pizzazz

We should also not forget that we are of different ages here and my hearing has significantly deteriorated recently, so some of us are just not as sensitive anymore.

Should we reply to you with capital letters so you can us hear better?

Sorry, couldn't resist.

[sailingharry]

Originally Posted by Dockhead

HOWEVER, my Eberspacher hydronic heating is a different matter. People hate it and I have had various complaints over the years, from people even very far away.

Fortunately where I cruise there is rarely even one other boat in any given anchorage.

Oh, wow, yes. We have an off-brand hydronic diesel heater, and we truly love it. But, I've been hundreds of yards from it (walking the dog), and amazed at how loud it is. Even in anchorages with no other boats, I worry about houses! The good news is that if I'm running it, there likely aren't people out "enjoying a pleasant evening." But without at doubt, I am aware of how loud it is and try and limit how much I run it. I don't have your alternative, as I have neither generator nor electric heat.


The good news, like you, is I try and be where there are neither boats nor houses.

[RaymondR]

The root of the problem is "optimism".

It's an overcast day and you sit there all day optimistic that you're getting enough solar on your panels to see you through the night and at sundown when you switch on the TV and solenoid gas valve discover there's not enough amps and have to start the genset.

If you'd been pesemistic you'd have started the genset in the morning, bulk charged the batteries for a while and hoped that the solar might top them up.

[BlueH2Obound]

Originally Posted by BlueH2Obound
We are a power boat, and once had a sailboat come into a large anchorage, with us as the ONLY boat there, and anchor right on top of us.
He then proceeded to get into his dinghy, row over to us and inform us that if we intended to run a generator, we would have to move farther away, or leave the anchorage . . . .

Originally Posted by Dockhead

Wow! You would think that there would be better social skills and sense of ethics in such a close-knit society as the cruising community.

Just out of curiosity, what was your answer?

Originally Posted by sailorboy1

I hope you jumped into action and started up the generation even if you didn't need to.

What I WANTED to do was to tell him I only ran my generator to mask the sound of those slapping halyards! Or to immediately start the generator as sailorboy1 suggested.
Or to wait until late at night, swim over to his boat and quietly toss a few rigging pins and/or cotter pins onto his deck . . .

What I actually did was to politely suggest that if we had to use our generator, and the "noise" of the water cooled, noise shielded generator bothered him, he was free to move to somewhere else in the anchorage that was probably adequate for 40 - 50 boats rather than remaining where he was, less than 75' from our boat . My wife has explained to me that sometimes I need to try and be nicer . . . . I'm trying, really I am! . . . . but sometimes it's really, REALLY difficult!