Low visibility

[greatpapabear]

Originally Posted by BruceK

A couple of times I`ve been caught off the coast in sea fog which occasionally occurs in warm, not cold conditions, over here. I`d use lights, more in hope than expectation they`d help. When you use fog lights on your car, you aim them low so they shine up under the fog (well that`s what we did in car rally competition).
If using the horn, as I think we should, at what intervals should it be used? Does anyone have an automatic facility for this so you don`t watch a clock or timer?

One prolonged blast (4 seconds) every 2 minutes. If you are stopped and making no way, it's 2 blasts every 2 mnutes with 2 seconds between them.

I used to use a Kahlenberg M485, but have recently upgraded to an M511C. Takes all the stress out of it.

GPB

[greatpapabear]

Originally Posted by Marin

Ron is correct, the horn interval for fog is two minutes. We have a Standard Horizon intercom/ loud hailer that will do all sorts of pre-programmed horn sounds and yelps through the main hailer horn. Now the hailer horn is nowhere near as loud as our big dual-tone air horns, but when we're in fog we turn on the hailer's two minute fog cycle and every time it goes off the person at the helm hits the air horn button.

There are programmable control units that can be wired into a boat's horn circuitry. What we do is the poor man's, or in my case the cheap, lazy man's version.

Hi Marin - Just as long as another boat listening doesn't think there are two boats around....

[markpierce]

Originally Posted by greatpapabear

I used to use a Kahlenberg M485, but have recently upgraded to an M511C. Takes all the stress out of it.

Yes, the M511C helps relieve my stress.

[greatpapabear]

Apologies for the succession of posts....just got up and seen the amount of comments I've missed overnight (I'm UK).

Around the English Channel, there are many times when vis is restricted, mainly by thick radiation fog which can last many hours, and at times, days.

The routine we follow is simple nav lights on, horn auto sounder on, and one of us mans weapons (radar) full time. Max speed 8kts.

We leave the pilot house doors open to listen. We don't go to the front of the boat because our horns are loud and hurt if we are in front to them.

GPB

[greatpapabear]

Originally Posted by markpierce

Yes, the M511C helps relieve my stress.

Do you have Kahlenberg horns? If so, which?

[markpierce]

Originally Posted by greatpapabear

Do you have Kahlenberg horns? If so, which?

D2








Love the horns' sound, especially when it echoes off the hills. No rinky-dinky horn for me.

[markpierce]

Originally Posted by greatpapabear

We leave the pilot house doors open to listen. We don't go to the front of the boat because our horns are loud and hurt if we are in front to them.

Same here. No one forward of the pilothouse when horns sound.

[greatpapabear]

Originally Posted by markpierce

D2.

Love the horns' sound, especially when it echoes off the hills. No rinky-dinky horn for me.

Same here - D2. Simply stunning! Wouldn't be without them.

GPB

[Marin]

Originally Posted by greatpapabear

Hi Marin - Just as long as another boat listening doesn't think there are two boats around....

Being as how anyone inside a running powerboat's not going to hear the horns anyway it's sort of a moot ( or in this case mute) point.

And if by chance someone does hear the horns and thinks it's two boats, well, they'll be twice as vigilant. Which should mean that we only need to be half as vigilant, right?

So less work for us.

[greatpapabear]

Originally Posted by Marin

Being as how anyone inside a running powerboat's not going to hear the horns anyway it's sort of a moot ( or in this case mute) point.

Hi Marin,

If there's a set of Kahlenbergs sounding, you'll hear them! The point being IMO compliant horns are super loud.

The regs call for a minimum of 120dB (for <20m LOA) and 130dB (for 20m to 75m LOA). Kahlenbergs exceed this - you'll hear them!

GPB

[markpierce]

Originally Posted by Marin

Being as how anyone inside a running powerboat's not going to hear the horns anyway it's sort of a moot ( or in this case mute) point.

Yes, perhaps with the pip-squeak horns most pleasure (you would call "toy") boats possess. Still, it helps to keep doors or windows open to hear what's happening outside (part of keeping a good lookout).

[markpierce]

Originally Posted by greatpapabear

If there's a set of Kahlenbergs sounding, you'll hear them! The point being IMO compliant horns are super loud.

The regs call for a minimum of 120dB (for <20m LOA) and 130dB (for 20m to 75m LOA). Kahlenbergs exceed this - you'll hear them!

I concur!

[greatpapabear]

Originally Posted by markpierce

I concur!

Listen hear (scroll down to find the D2 and listen to the sound track)

Yacht Horns, Yacht Air Horns, Megayacht Air Horns - Kahlenberg Industries, Inc.

GPB

[markpierce]

My observations are that most all pleasure boaters, when sounding their horns (if at all) such as entering/leaving marinas or in limited visibility when a prolonged (4 to 6 second) blast is called for, only sound a short, one-second blast. Maybe many are trying to conserve the compressed air in their hand-held horns, whatever. It's pathetic/wrong. One advantage of automatic horn controls is that the length and interval of the sound conforms to the rules.

[Marin]

Originally Posted by greatpapabear

Hi Marin,

If there's a set of Kahlenbergs sounding, you'll hear them! The point being IMO compliant horns are super loud.



GPB

Our air horns are pretty much the same as the ones you have in terms of volume. But even inside our boat they don't sound all that loud. The horns on the Washington State ferries, which make Kahlenbergs and our horns seem like rabbit farts in comparison, are not discernible inside our boat until the ferry is fairly close. And our boat is not particularly loud inside. I've ridden in boats that are far louder.

Sailboaters tend to hear horns when they're a long ways off, of course. But all the powerboaters I've talked to in person about this, like the folks in our club, all say the same thing-- they don't hear horns until the boat blowing them is very close.

And here's an eye- opener for you. We have an acquaintence who's a Washington State ferry officer. And he told us that on the bridge of the ferries on cold days when everything is closed up, they don't hear horns either, other than their own, unless the other boat is real close.

I'm certainly not advocating not sounding horns in low visibility. In fact we'll probably start turning our nav lights on, too, under these conditions in the daytime even though we know from experience that nobody will see them until they're close enough to see our boat itself (and assuming that we even remember to turn them on) . I think FlyWright made a good point earlier.

But I don't think it's a good idea to drive around in the fog thinking that everyone hears you coming because there's a real good chance some of the other boats driving around in the same fog won't.

We use the intercom/hailer to help us hear the horns on other boats and it helps some but only for boats in front of us. The horns are a great safety aid but in low visibility as far as were concerned it's all about radar and how to use and interpret it properly.

We really enjoy boating in the fog. We both like the challenge. It's like flying on instruments which I really enjoyed until I stopped flying landplanes after moving to Washington.

[greatpapabear]

Up to 20m LOA, IMO compliant horns COLREGS need to be heard at 1/2nm. 20m to 75, it's 1nm. So as has been said, not far at all.

I love how the IMO defines the range,

"The range of audibility ... is for information and is approximately the range at which a whistle may be heard on its forward axis with 90 per cent probability in conditions of still air on board a vessel having average background noise level at the listening posts (taken to be 68 dB in the octave band centred on 250 Hz and 63 dB in the octave band centred on 500 Hz)".

GPB

[greatpapabear]

Originally Posted by Marin

We use the intercom/hailer to help us hear the horns on other boats and it helps some but only for boats in front of us.

Good idea - wish I'd thought of that....

We really enjoy boating in the fog. We both like the challenge. It's like flying on instruments which I really enjoyed until I stopped flying landplanes after moving to Washington.

I agree - just like being on instruments. I think I've said before, that when I flew for British Airways I gained 5,000 hrs on the 707 - fantastic plane.

GPB

[rwidman]

Originally Posted by Marin

......... But even inside our boat they don't sound all that loud. ........

Run the boat from the flybridge. You'll hear your horns and the other boat's horns!

And you'll have much better visibility.

[markpierce]

The Kahlenberg D2 air horn produces 132 decibels versus 130 being 50 feet distant from a military jet taking off from an aircraft carrier using the afterburner. The typical air-raid siren also produces 130 decibels.

I hear the echo from my boat's D2 from hills a quarter mile away (sound traveled 1/2 mile) with the engine running. (I haven't attended loud rock-music concerts, so your results may vary.)

The typical small-boat horn produces at least 120 decibels, comparable to a chainsaw.

Comparative Examples of Noise Levels | Real World Examples and Decibel Levels |Industrial Noise Control
Decibel Chart - Netwell Soundproofing Materials & Acoustic Sound Panels

[Marin]

Originally Posted by rwidman

Run the boat from the flybridge.

Never. Hate the sight picture from up there and we feel totally disconnected from the rest of the boat.

And you'll have much better visibility.

You do realize we're talking about running in dense fog, right?