We also use a Raymarine hailer via the VHF. I guess mine must also be circa 40dB. I can 't tell whether that is "enough". DeciBells being a logarithmic scale, 120dB is many times louder so it can 't harm. But I question whether even that will be heard on the bridge of a freighter above the engines as it hammers down on you at 12 knots.

I think AIS is the best restricted viz tool these days. I assume you broadcast AIS as well as receive? If not, that 's where I 'd spend my dollars.

Finally, some kind of protection against stray halyards is sensible. Mine is mast mounted just below the radar dome and it really shouldn 't possible for a halyard to get there - but it did, half way between Galapagos and Marquesas. The hailer dangling and swinging around on the power wires is not a good idea - we had to send someone up the mast twice to get it secure - inevitably at night - it took about three hours. Deepest joy!

Thank you, Simon, for the warm welcome.

Yesterday, a 40W-capacity hailer was brought on board and experimentally hooked to the 30W hailer output on the VHF radio, which has horn and automated-timing horn functionality.

The hailer 's "horn" output was then compared from a distance of about 70 feet to the output of two different compressed air can horns, and it 's aural impact was estimated to be either in the same range as the cans, or, perhaps, slightly lower.

Therefore, the quest is on to find a suitable horn.

Surprising advice received from a sailor: install it on the mast pointing downwards, for effectiveness from all directions, and not just the direction of travel of the boat. Also, for longevity of the device.

Odette,
Welcome to the Forum. We use the hailer facility on our vhf which seems to work well via a mast mounted speaker. Not sure how many db 's it is but it blasts the appropriate signal automatically so it is very user friendly.
Simon

Hello, new associate member here. We recently arrived in Fort Lauderdale after an 8-month cruise to Nova Scotia and back, none of it on the Intracoastal as our masts are a bit too tall.

In Maine and New Brunswick we used hand-held compressed air horns with a certain frequency because of fog, and did not like:
[ol]
[li]Low volume for marine application[/li]
[li]Debilitatingly high noise at only arm 's length[/li]
[li]The cans run out at the most inconvenient times[/li]
[/ol]
And so we are quoting installation of a 123 db electric horn, twin trumpets, to be installed on our mizzen mast, probably just above the dome of the radar antenna. Now, we can 't seem to find a supplier for a protecting ring in metal to go horizontally around the 18-inch horns, to prevent getting snagged by the mizzen ballooner or mast halyard.

Any comments on the whole (harebrained?) idea, on the protecting ring, on pressurised air (131 db) vs. electric (123 db) horns, and on mizzen vs. main mast is most welcome.

Cheers,