Kahlenberg frequently asked questions
Find put more about sound signals and how they relate to law and best practice
We’ve collected some of the many questions we get asked during the year and placed them here for you. Just clock on the headings to reveal the answers.
Have we answered your question here? If not, please contact us
A whistle is defined by the IMO as “…any sound signalling appliance capable of producing the prescribed blasts and which complies with the specifications in…these Regulations.”
Your boat’s LOA, the sound you want, its compliance, and finally your pocket!
First, take the boat’s Length Overall (see another FAQ below) and refer to the IMO requirements for sound signals to determine which Class your boat is.
Second, choose how many trumpets you would like. One, two, or three – the more, the better the sound. For top end super-yachts, Kahlenberg offer up to eight trumpets.
Third, verify a Certificate of Compliance will accompany the horns when you buy them.
It’s as simple at that.
Certainly not! An approved horn is required on any vessel over 12m, but not at the expense of reliability, functionality or design.
Kahlenberg horns offer a great balance of all of these priorities – and they sound magnificent!
Whether the boat is coded or not, and provided she is 12m (39ft) or more in length, she must be fitted with an IMO approved horn, irrespective of local regulations and charter or commercial codes.
A common question asked by so many boaters. Yes, vessels of 12m (39ft) or more must be fitted with an IMO approved horn.
So many people have different ideas of exactly what this is.
Officially, the length overall (loa) of the vessel is measured from “the foremost part of the stem to the aftermost part of the stern, including any fixed projections extending beyond the stem and stern.”
Our oil tanker has two whistles. One is fitted as a back-up. Are there any regulations for a twin whistle installation?
Yes. If the two whistles are fitted more than 100m apart they must not be able to be sounded simultaneously. If they are fitted within 100m of each other, and if they are designed to be sounded simultaneously, each must differ in frequency by more than 10Hz.
If you boat or vessel is 20m (66ft) or more, an IMO approved bell must be fitted. This applies whether the vessel is for leisure or commercial purposes.
A gong is needed if your vessel is 100m or more in length and is fitted in addition to the whistle and the bell. The gong must make a sound which cannot be misinterpreted as that from the bell.
The manufacturer must be able to provide a Certificate of Conformance from an independent Class Society or Flag State Authority such as ABS or Lloyds. This is an important difference from a manufacturer supplying their own certificate stating the horn complies with the IMO specifications.
Bottom line? Without a Certficate of Compliance, the horn in not approved.
My boat was built to the Recreational Craft Directive and is CE marked. Do I still need an IMO compliant horn?
As bizarre as it might seem the RCD does not cover the horn, and hence there is a chance, quite high in our experience, that your horn is not IMO compliant. For further information see the sound signal policy statement from the RCD department of the EC Commission can be seen and downloaded in our news pages.
Now that’s a good question. Would the authorities take you to task? Probably not. Are there inspectors roaming marinas seeking offenders? Not to our knowledge.
However one major boat builder in the UK now only fits approved horns since they were advised that if a customer of theirs had an accident, the boat builder may well be found to have been complicit if the horns were not IMO approved.
There is also a question about whether your boat’s insurance would be valid in the event of an accident.
When I am in restricted visibility, sounding the horns in the correct manner interrupts my concentration. What can I do?
You can install an inexpensive automatic sound signal controller to make the correct sound signals for you.
No it doesn’t. Neither the manufacturer nor the owner can hide behind the CE mark.
The horns must be approved which means you must have a Certificate of Compliance.
Inland Waterways often have their own byelaws which must be met. These may or may not define whether a horn must be approved. So the answer is for you to check your local bye laws.
However, note that if you move from an inland waterway to the sea, you will need an approved horn since your boat is over 12m.
The horn should be mounted pointing straight ahead – not angled down. It must also be mounted as high as possible so there are no obstructions in front of it.
Note that approved horns are LOUD. So don’t mount them behind a crew member’s head – take care you don’t damage the crew’s hearing!
Have a read of our Safety advice for Kahlenberg horns.
Firstly, Kahlenberg horns are very distinctive in their sound. Secondly, their yacht, motor yacht and super yacht horns look impressive and are the horn of choice of their Captains.
As far as reliability is concerned, Kahlenberg’s documented warranty claim is less than a quarter of one percent.