Steve Austin, Senior Policy Lead at the UK Maritime & Coastguard Agency (MCA) explains: "The COLREGs apply to all vessels, there is no differentiation between coded and non-coded vessels. Should the whistles (horns) prove not to conform then they will need to be modified or changed.
"Whistles should conform to the performance in COLREGs, Appendix III and the appropriate parts of IEC 60945 to EN60945 which deal with the marine operating environment."
Compliance with the COLREGs is enshrined in the national laws of nearly every country worldwide.
The insurance company of your vessel is also likely to take the view that IMO compliance is essential to ensure cover.
Read our Marine sound signals - the law as it applies to you leaflet to obtain more facts on this important subject.