Why is it that so many boaters don't know what the inland waterways sound signals are? If you don't, here they are. We suggest you keep a copy of these notes near your helm, especially on tidal waters used by commercial craft.

Before we start, let's lay a few ground rules:

• when facing the front of your boat, Port is on your left, Starboard is on your right. The Bows are at the front; the Stern is at the back.
• A short blast lasts for a second; A long blast for 4 seconds; the interval between two consecutive blasts is about one second

The following signals are sent to a boat coming towards you:

One short blast

I am altering course to starboard (to the right)

Two short blasts

I am altering course to port (to the left)

Three short blasts

My engines are going astern (note that the vessel may still be moving forwards)

Four short blasts followed by one short blast

I am turning around to starboard

Four short blasts followed by two short blasts

I am turning around to port

Five short blasts

I am unable to understand your intentions or a collision is imminent

One long blast

A warning where the view is restricted

One long blast followed by two short blasts

Keep clear of me. I am manoeuvring with difficulty

If you wish to overtake a boat ahead of you (going in the same direction as you are), to get his attention, sound:

Two long blasts followed by one short blast

I intend to overtake you on your starboard side

Two long blasts followed by two short blasts

I Intend to overtake you on your port side

Don't forget the other boater may not know what sound signals mean!

The above details are for guidance only. If you are sailing on new waters, you should always check that the above signals apply. NABO will not be held responsible for any action boaters may take as a result of reading these notes.

These sound signals will generally be understood on most inland waterways in the UK, although the turning signals are specific to the River Thames (see River Thames Byelaws). The International Regulations for Preventing Collisions at Sea (COLREG) are also generally applied on river navigations in the UK but not on Inland Waterways in mainland Europe where the CEVNI regulations apply and differ in some major respects from the above information.