VHF to Air Horn

Jokani

Jokani

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My Icom IC-505 has outputs to a hailer/foghorn

HAILER/FOGHORN (–) LEAD (Black)
Connects to a hailer speaker (25 W nominal at 13.8 V/4 Ω).
HAILER/FOGHORN (+) LEAD (Blue)
Connects to a hailer speaker (25 W nominal at 13.8 V/4 Ω).

I have no use for a hailer, but a foghorn would be handy.

Would connecting an air horn work?

150db Single Trumpet Air Horn Kit w DC 12V Compressor

http://www.ebay.co.uk/itm/150db-Tru...ir-Horn-Kit-w-DC-12V-Compressor-/301323300788
 
Talulah said:
I would like to know the answer as well. A hailer is just not loud enough.
Would an air horn work?
Click to expand...

An air horn would work as a foghorn, but the VHF won't drive it.

Those cables are for connecting a speaker. An air horn is not a speaker, it is a pump and possibly a solenoid.

Pete
 
GaryCottam said:
My Icom IC-505 has outputs to a hailer/foghorn

HAILER/FOGHORN (–) LEAD (Black)
Connects to a hailer speaker (25 W nominal at 13.8 V/4 Ω).
HAILER/FOGHORN (+) LEAD (Blue)
Connects to a hailer speaker (25 W nominal at 13.8 V/4 Ω).

I have no use for a hailer, but a foghorn would be handy.

Would connecting an air horn work?

150db Single Trumpet Air Horn Kit w DC 12V Compressor

http://www.ebay.co.uk/itm/150db-Tru...ir-Horn-Kit-w-DC-12V-Compressor-/301323300788
Click to expand...

Talulah said:
I would like to know the answer as well. A hailer is just not loud enough.
Would an air horn work?
Click to expand...

It might be possible to make the hailer output close a relay, although some additional electronics may be necessary to match the hailer output to the relay coil ,that will in turn power the air horn ... They draw quite a few amps,

I take it the attraction is that the system within the Icom will sound the appropriate signal automatically at the appropriate time intervals. I'd be surprised if there is not a "little box of tricks" that will do that independently.
 
VicS said:
I take it the attraction is that the system within the Icom will sound the appropriate signal automatically at the appropriate time intervals. I'd be surprised if there is not a "little box of tricks" that will do that independently.
Click to expand...

I did consider making exactly that, but where I am now it rarely gets foggy. Perhaps "Angus" can oblige.
 
I take it the attraction is that the system within the Icom will sound the appropriate signal automatically at the appropriate time intervals.
Click to expand...

Yes, that was exactly the idea, press a button on the ICOM and it will blast away as appropriate, leaving me to concentrate on other things.

I'd be surprised if there is not a "little box of tricks" that will do that independently.
Click to expand...

If anyone knows of such a device please post.
 
I have a Standard Horizon 2200 which does the same trick. No air horns but signals through a 40 watt speaker mounted on the mizzen mast. Very loud and automated.

The VHF incorporates an intercom which works well when I have crew on deck.

GL
 
Fit a full wave rectifier to the output of the foghorn speaker to turn the AC to DC. Then measure the DC voltage output when you operate the foghorn and select a small relay that would operate at that voltage. then connect the N/O contacts of this relay across the button you use to operate the air horn.
 
VicS said:
Googgle finds several . "Fogmate" probably the simplest.
Click to expand...

I looked at that one a couple of years ago. It should do the job, but I don't really like it. Its core design idea is to be fitted between the existing horn button and the horn, typically on a small motorboat, without having to add any additional switches. So you control it by a series of coded button presses on the horn, and flicking the nav lights on and off. Which is a pretty terrible user interface compared to a simple labelled switch.

The later versions do have additional inputs for a dedicated switch or two, but the instructions still describe it sitting in parallel with the horn button. I would want a single rotary switch between OFF - POWER - SAIL - STOPPED, and it's not clear whether the Fogmate can be wired for this.

It also appears that if you hit the horn button five times (ie, give the "WTF are you doing?" signal) then it will go into "Distress" mode and start signalling SOS continually! If you'd fitted the thing a few years ago and didn't use it much, this would be quite a surprise, and you'd have to figure out why the horn kept sounding (stuck switch?) and then remember how to turn the damn thing off (nav light switch, I think, not obvious), and this is all happening in the middle of a close-quarters manoeuvring snafu because that's why you sounded five blasts in the first place! This seems to be a particularly misguided feature.

I have fog signals on my VHF (which, because it's a speaker rather than a horn, has the additional benefit of anchor signals) but if I did want something like the Fogmate I'd seriously consider building it using a Picaxe to generate the tones, a cheapo amplifier board from eBay, and a water-resistant hailer speaker. Or even better if someone else did that and we could just buy it :)

Pete
 
I have a Standard Horizon VHF with the various fog signals. I simply have a horn speaker mounted on a ply bracket which is shaped to fit around the mast and retained by bungey straps. I fit it only when required and it sits about 3 feet off the deck.
Fairly loud but only audible I would imagine by other small craft, probably not by power boats moving at speed - which I hope they would not be doing ! Forget big ships ever hearing you, no matter what you have. I have used the VHF horn option several times, once for over eight hours. It has the advantage of being fully automatic and the options of bells, at anchor etc choices. Unlike aerosol horns etc it will go on for ever and if single/short handed requires no human input. The listen back facility is handy but would question it's usefullness. The one big plus point is that legally you have been "sounding" should the worse happen and there is an insurance claim. It would be interesting to carry out a practical test and see just how far, on average, it can be heard.
Good luck.
 
GaryCottam said:
I would prefer to use the VHF and a speaker, but had concerns over a speaker being loud enough?
Click to expand...

I wonder about that too, with my Standard Horizon hailer horn. It doesn't sound all that loud from the cockpit, but of course it's a directional horn and it's pointing forwards. (All-round would be better, but none of the makers seem to have thought of that.)

I should really turn it on and then walk away from the boat along the pontoon, but I don't want to disturb people in the marina :)

I would hope that it can be heard from other yachts and small craft. Probably not motorboats travelling at speed, but you'd hope they wouldn't in fog. Anything larger than that I'd expect to see on AIS and radar and avoid by my own actions.

Pete
 
Hi Gary,
That sounds a "sound" idea (!) Sorry.
As an aside to my previous post: on the occasion I used the VHF fog horn for eight hours I was in company with another yacht. We were both under power, heading for same destination and both using chart plotters. We both started out in fairly clear conditions and fog came and went the whole trip. We never had visual of each other, even when the fog lifted a bit, so probably a fair distance apart. Interestingly later that night, in the pub, he remarked the only scary part of the trip was that a ship seemed to be following us the whole time. So perhaps it was working better than I thought. I had not mentioned my new electronic marvel !
 
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