When the foghorns sound in the early morning of a hazy day in Metro Vancouver, the loud drum is usually enough to wake up those dreamers close enough to the shrouded sea.

Historically, the blare of a foghorn in Metro Vancouver has been ill-received by many, leaving some to question why the seemingly old technology is still necessary.

Hi <a href="https://twitter.com/PortVancouver?ref_src=twsrc%5Etfw">@PortVancouver</a> & <a href="https://twitter.com/CityofVancouver?ref_src=twsrc%5Etfw">@CityofVancouver</a> - what's with fog horn or vessel that is sounding over & over for several days? <a href="https://twitter.com/hashtag/Vancouver?src=hash&ref_src=twsrc%5Etfw">#Vancouver</a> <a href="https://twitter.com/hashtag/noise?src=hash&ref_src=twsrc%5Etfw">#noise</a> —@andrea_coutu

But the captains behind the iconic horn want people to know the technology isn't as dated as everybody thinks.

"It's the sound of safety," said Capt. Robin Stewart, executive director of B.C. Coast Pilots. "From the small pleasure yacht to the new container ships and cruise ships ... the process is successful."

Radar reigns supreme?

When visibility is low, by national and international regulation, the use of foghorns is mandatory for large vessels including container ships

"[When the fog rolls in], you don't have many visual references or very few," said Stewart. "You have to worry about all those things you can't see."

The Port of Vancouver is shrouded in fog and mist on the morning of Wednesday, Jan. 3. (Jon Hernandez/CBC)

However, large container ships and freighters making the noise also have sophisticated radar systems to detect any structures and vessels that might be in their way.

"All modern vessels have at least two radars on them, as well as full [automatic identification] systems," he added.

"But you're still always worried about missing something."

'It's not comfortable'

Egge Kloosterboer, manager marine operations for the Vancouver Port Authority, says the biggest concern is the safety of small boats that might not see large ships due to the haze.

"If you have a smaller vessel, they don't have the [sophisticated radar system] or they don't have a pilot," said Kloosterboer. "When the visibility is reduced, you lose your vision — so all you have left is your sound."

The sound of horns could be heard throughout the Burrard Inlet on Wednesday Jan 3. (Jon Hernandez/CBC)

B.C. Boating president Don Prittie knows what it's like to be in the water on a small boat when the haze rolls in.

​"I've been in fog, and it's not comfortable for me," he told CBC News. "If every boat on the water had radar and if every individual operating those boats knew how to use the radar, then the foghorn would not be as important."

"[But] when it comes to a [sail boat] that possibly gets stuck in the fog, which they weren't expecting — you're probably very thankful for somebody making some noise out there."

Like living next to train tracks

Stewart says the long, loud hum is a small price to pay for living in a port city — akin to sidling up next to the train tracks.

"I'm sure it must create some frustration, maybe some sleepless nights for some people on the shore," he said. "But I'd suggest it's a relatively short term requirement."

The fog will inevitably roll out. And when it returns, so too will the horns.

"The fact is, if it will prevent someone from getting hurt — it's worthwhile."