The International Maritime Organization describes survival-craft portable two-way VHF equipment as equipment intended for on-scene communication: between survival craft, between a survival craft and a ship, and between a survival craft and a rescue unit.

It is therefore useful to think of the handheld VHF as one link in the wider Global Maritime Distress and Safety System (GMDSS) , rather than simply as another portable radio.

What Makes a GMDSS Survival-Craft VHF Different?

A radio intended for survival-craft use is designed around an emergency environment. IMO performance standards call for portable equipment that can be used for on-scene communication and operated by personnel in demanding conditions. The standards include requirements relating to portability, operation by personnel wearing gloves, resistance to the marine environment and watertightness.

The exact number and type of portable radios that a vessel is required to carry depends on the vessel, its flag, operating area and the statutory regime applying to it. For that reason, carriage requirements should always be checked against the vessel’s applicable certification and flag-state requirements rather than assumed from a general article.

If you want the wider background to marine VHF installations, see our guide to marine VHF radio systems .

The TR30’s Clever Part: One Radio, Two Very Different Battery Roles

One reason the Jotron Tron TR30 is useful for explaining this subject is that the battery fitted to the radio changes how the unit is intended to be used.

That distinction matters. The emergency battery is not merely a spare rechargeable pack waiting for its turn in the charger.

The TR30 manual identifies the orange emergency pack as a lithium primary battery designed specifically for emergency use. The rechargeable battery, by contrast, is the battery used when the radio is performing normal maritime VHF duties.

What Happens When the Emergency Battery Is Fitted?

In a real emergency, simplicity matters. The operator should not have to work through a complicated menu system while dealing with an abandonment situation.

On the TR30, fitting the dedicated emergency battery changes the radio into its emergency operating configuration. According to the current TR30 documentation, the radio starts with a restricted set of functions and loads emergency-oriented settings.

The Emergency Battery Seal Is There for a Reason

A crew member picking up a GMDSS handheld in an emergency needs confidence that the emergency battery has not already been used or compromised.

On the TR30, the dedicated emergency battery is therefore kept sealed. Manufacturer instructions state that an emergency battery must be replaced if its relevant expiry date has been reached or if the protective seal has been broken.

Battery Shelf Life and Service Life Are Not the Same Thing

Battery dating can sometimes cause confusion because a battery may spend part of its life in manufacture, distribution or stock before it is placed into service.

Jotron’s January 2025 technical bulletin lists the TR30 GMDSS emergency battery with a 30-month shelf-life allowance and a five-year service-life period, giving a stated maximum combined period of 7.5 years under the manufacturer’s system.

That does not mean every battery installed aboard a vessel will have 7.5 years remaining. The date actually marked on the battery is what matters in service.

How Should a GMDSS Handheld VHF Be Tested?

This is where the difference between the batteries becomes particularly important.

The TR30 manufacturer’s maintenance procedure specifically says not to use the GMDSS emergency battery for routine testing. Testing is carried out using the rechargeable battery or the dedicated test battery.

The manufacturer’s routine test procedure includes selecting an appropriate working channel, avoiding Channel 16 for the routine test, verifying transmission to another radio, verifying reception from another radio, and then confirming that the emergency battery remains valid and sealed.

The current TR30 maintenance instructions also call for inspection of the battery connection pins, gasket and locking mechanism, inspection of the housing for defects, and verification that the antenna and jack cover are correctly assembled.

Battery Endurance: What Does the Manufacturer Specify?

Battery endurance is not simply a statement of how many hours a radio can sit switched on. Test conditions and transmit/listen/standby duty cycles matter.

These figures are manufacturer test figures, not a promise that every battery in every condition will deliver exactly the same endurance. Battery age, temperature, condition and actual radio usage all matter.

When Does a Handheld VHF Need Attention?

Many problems are easier to deal with alongside the quay than on the day of a survey or — worse — during an emergency.

A GMDSS handheld should be investigated if the radio is damaged, the antenna or sealing arrangements are compromised, the emergency battery is out of date, the seal has been broken, the rechargeable battery no longer performs correctly, transmit or receive operation is unreliable, or the required parts are no longer available.

If a vessel has already experienced a survey-related radio problem, our radio survey failure case study provides further context on why defects in safety-critical radio equipment should be dealt with promptly.

Choosing a Replacement GMDSS Handheld

The important point is not to choose solely by appearance or by comparing an ordinary handheld VHF specification sheet. If the radio is being used to satisfy a statutory survival-craft requirement, the equipment selected must be appropriate to the vessel’s regulatory requirements.

A Handheld VHF Is Only One Part of the GMDSS Safety Picture

Go back to our opening scene. The crew are now in the survival craft.

The handheld VHF provides voice communication. But other parts of the vessel’s distress and safety equipment perform different jobs.

An EPIRB can transmit the vessel’s distress alert through the satellite-based search-and-rescue system. A Radar SART or AIS-SART can assist rescuers in locating survivors or survival craft during the search phase. The portable VHF then provides the vital human link: people speaking directly to ships and rescue units once communications are established.

If you are unsure how the locating devices differ, see Radar SART vs AIS-SART .

For the wider safety-equipment picture, read Marine Emergency Beacons & Survival Equipment Explained .

The Simple Check That Matters

Most of the time, nothing dramatic is happening around a GMDSS handheld radio. It may be sitting in its charger, secured near its emergency battery, waiting.

That quiet period is exactly when it should be looked after.

Check the radio. Check its housing and antenna. Test the radio using the correct battery. Check the dedicated emergency battery’s seal. Check its marked expiry information. Make sure the equipment is stored where it is meant to be and that the people who may need it understand the difference between the rechargeable battery and the emergency battery.