The Art of Boating & Sailing – How to use a VHF Radio


In the first article of our new “The Art of Boating & Sailing” series, we’ll be presenting some techniques and know-how about marine VHF radios. This is a common question “How do I use a VHF radio?” is brought up frequently in conversations between boaters, at marinas or even in our chandlery. Marintech Marketing carries a wide range of VHF radios, with the most popular brand being ICOMWe often have new boaters approach us about the usage of a VHF radio. It is important to know how to use a VHF, especially during an emergency. Do not purchase a VHF radio just because you are mandated by MPA to have one onboard.

Singapore Spectrum Chart by IMDA


  • Cellular

Everyone has a cell phone these days and it can be convenient to make a phone call with people on land. However, the cell phone is limited by range due to relay towers. Also, Search-And-Rescue (SAR) and the Coast Guard cannot direction find cell phone signals. Hence, it is imperative that a boater has a VHF radio onboard (as mandated by MPA)

  • Very High Frequency (VHF)

For routine communication or emergency calls out at sea, the VHF radio is a popular choice. The VHF signal range is greater than line of sight as they are able to bend slightly over the horizon. For a fixed VHF set with typical 25W transmitting power, the range is about 20NM from boat to boat but are limited by antenna length. The marine VHF bands falls between 156 and 163 MHz. Within this band, there are multiple channels for different type of communications. We will cover these in a section below. 


  • Satellite Communications
    Satellite communications offers a stable way of communications globally. They also support distress calls which have global coverage. However, not only is the satellite equipment expensive to purchase and install, one has to consider the additional charges for the data subscription. 
  • Single Sideband Radio/High Frequency (SSB/HF)
    Beyond the range of VHF radios, the next frequency to use would be the SSB/HF which can transmit up to hundreds of nautical miles. The SSB/HF is also extremely useful because it can receive weather broadcasts and even e-mail services.


VHF Marine Radios can come in either the fixed mounted or portable (or handheld) type. Handheld radios typically have a far lower transmitting power due to limitations of the battery and antenna length. Fixed radios come with a separate antenna that can be mounted high on a ship to provide longer ranges. VHF radios are also usually capped at 1 watt transmit power on certain channels in order to avoid over-powering signals.

MPA mandates that every recreational boat be equipped with a VHF radio. They are not permitted to be used on shore. It is imperative that every boater tune in and monitor channel 16 at all times in order to increase the probability of a distress call being heard. If your boat has both an SSB/HF and VHF radio, it is advisable to always use the VHF radio as SSB/HF frequency can hog a channel over a long distance.

1 WATT (Typical minimum power of handheld VHF Radios)2 NM
5 to 6 WATTS (Typical maximum power of handheld VHF Radios)5 NM
25 WATTS (Typical Fixed VHF Power)Up to 20NMBoat to Boat
Up to 30NMBoat to Shore


Parts of a VHF Radio equipped with GPS
  • Channel

As the name implies, the channel shown on the screen is the current VHF Channel. The average number of channels in the VHF spectrum is usually about 90.

  • Squlech

Suppresses signals below a threshold set by user. It eliminates static (fuzzy) noise. A tip to getting the right amount of Squelch is to reduce it until static can be heard then moved slightly higher to eliminate it.

  • Distress Switch (DSC)

A distress button is hidden under a switch to prevent accidental misuse. This button is found only on radios equipped with Digital Selective Calling (DSC). Press this only during an emergency. It will send a signal on the DSC Channel (70) and provides your identity and location (if equipped with a GPS) to other boaters that have DSC-equipped radios.

  • HI/LO Function Key

This key allows a radio to switch between the low 1 watt transmit power for short range communications and higher power for longer range communications (See table in previous section)

  • WX Function Key

This key allows a user to switch the VHF from the typical communications channel to the NOAA weather channel.

  • DSC Function Key

This key allows a user to call another radio which is equipped with DSC and whose number is also stored within the radio. This is akin to calling someone’s number who is saved on your cell phone. The receiver will have a DSC alert and will automatically switch the channel to the receiver’s.


Example of a Flybridge VHF Radio with Intercom
  • 16/9

Pressing this button immediately sets the current channel to 16 (Calling, Distress & Safety Channel). Pressing it again will set the current channel to 9 (Alternate Calling Channel).

  • Intercom

Some radios allow for VHFs that are connected to each other to “talk” to one another. For example, a VHF on the flybirdge can be used to relay docking orders to the cockpit VHF radio. Intercom communications are not transmitted to VHF Channels.

Example of a Loud Hailer
  • Hailer

A boat can have loud-hailer/speakers on board for communication with nearby boats. Hailer communications are not transmitted to VHF Channels.

  • Scrambling Function

A VHF radio might be equipped with an additional scrambling function to add a layer of security to private conversations.

VHF Channels

VHF Channels and their specific usage varies between countries. Since there are far too many to cover, we will cover the most important Channel 16 and VHF Channels in Singapore.

  • Channel 16

Channel 16 is the international distress frequency. It is also used for safety messages and calling (initiating a call). All boaters should monitor this channel for distress calls and relay them again if no reply is received.

  • VHF Channels in Singapore

An official consolidated list of VHF Channels and their purpose does not exist in Singapore. We sincerely hope Maritime and Port Authority of Singapore will be able to issue a guideline for VHF Channels and usage in the future.

For a unofficial complied list of VHF Channels and their use, you may visit the following website, kudos to Mr Shawn for putting this together!

We hope you have found this article useful. We will cover in-depth topics regarding VHF radios such as VHF Radio Call Procedures and the Phonetic Alphabet in the next article.