Wednesday, May 31, 2023

Marine VHF radios

 This is the follow on from the PLB and EPIRB post (with or without GPS). A caveat, this information is for Australian waters and local area. It's always best to check with your local authorities first as regulations/channel frequencies differ a bit interstate or overseas (eg USA).

VHF is a good short range radio, more capable than a 27Mhz unit. It has increased range, power and signal clarity. Range depends on the height of the transmitting and receiving antenna's, the higher the better. It ranges from 5 nautical miles to 60 nm. The low ranges are when the antenna is mounted to a small crafts deck and the long ranges are thanks to repeater towers on mountain tops. Medium ranges are when the antenna is located on a ships' masthead or shore bases' tower.

VHF's (or any type of marine radio) must never be operated on dry land. Also false distress messages are absolutely taboo and huge fines apply for this offence.


VHF radio, navigation and safety area on Teria

Chanel 16 is monitored 24/7 by marine authorities ashore and commercial shipping.  In Australia, a licence to operate a VHF radio is required. (Unlicenced boaters can make emergency calls only or  listen in.) There are 3 recreational boat talk channels ch 72, 73 and 77. 

VHF's have two power settings. 1 watt and 25 watts. low 1 watt power is used most of the time. If the first call can't get through, i then use the repeater channel still on low power.  High power is rarely  needed, perhaps only when at maximum range or when in a serious situation.

VHF courses for a Marine radio short range operators VHF certificate of proficiency (SROCP) can usually be done at most volunteer rescue bases or through  navigation training companies.


 

I just completed my SROCP exam with a local navigation training company in Townsville (The Navigation Center) in conjunction with online resources of the AMC (Australian Maritime College) in Tasmania.  All VHF radio exams in Australia are certified through this one authority. 

Most of my study was at home, using the $30 VHF radio book and AMC online non-assessable "self-test" multiple choice questions to see how much you could understand. Then it was back and forth between book, self-test and any online web pages i could find on the subject. This was a good method as there was no time limit or "crash course" forcing you through it. Just study as long as you like until fully prepared for the exam, this suited me better. All up it cost $155.

The course covers all the operating procedures in different priority situations. Distress, Urgency, Safety/weather notices or regular calling and working transmissions. Channels are "protected" or reserved only for certain uses, messages are kept brief and to the point, mostly about trip plan/changes or difficult situations requiring assistance. The aim is to transmit on your designated channels only, short as possible, so marine radio traffic doesn't become congested.

My radio is an old GME GX548 Electrophone.   It has a power selector, squelch knob, on/off volume knob, channel buttons.  "AUS" selection button for Australian channels which MUST be on to get Australian/International channels (the other option is USA channels, which are different). There is also a button to flip between Ch 16 and a channel of your own choosing (usually the local repeater)

Teria's VHF antenna (or "whip") has been re-mounted on the aft rail's top 4 feet above the waterline (so the "whip" tip is 9ft high) to give a mile or two extra range. It was 2 ft lower before. It's a practical spot for a simple trailer sailer, because there's no problem with mast lowering or getting into a garage at home. It can also be easily removed and stowed for the road.

Yachts with fixed masts often mount their VHF whip permanently at the mast head, about 30-50 feet high. Big cargo or cruise ships whips are even higher.

My radio is an old model without DSC (digital select calling), so old-style radio procedures are used. 

DSC equiped radios can quickly transmit emergency information to other DSC VHF radios with the touch of a button. This feature increases chance of rescue significantly if the radio is connected to a GPS, as the coordinates are also transmitted instantly. An example is the Uniden UM455VHF at BCF.  They also have dual or triple watch scanning.

Uniden UM455VHF radio with DSC emergency button

I was looking through my old Qld boating guide 2012 and it listed all the LCS (limited coast stations) , all their watchkeeping channels (27mhz, VHF and HF) and phone numbers. In my more recent edition 2019 only VHF repeater chanels and phone numbers were listed in the table. The info booklets sure are changing with time. 

Each LCS usually only operates Ch 16 watchkeeping during daylight hours and each area can have different hours. After hours full Coast Stations continue the watch (eg Queensland State Governments, MSQ Maritime Services Qld). The LCS are usually volunteer marine rescue, yacht clubs (recreational vessels) and are "limited" in what they can do. The "Coast Stations" are for the Commercial and Government sectors eg. Big ships and their ports. They have advanced radio equipment and technology, including advanced VHF gear. My SROCP course covered a bit of this advanced technology as well.

Things like AIS (Automatic Identification Systems) transponders (both VHF or satellite connected) which send the position coordinates of a vessel out regularly, so that other AIS equiped ships can see each other plus vessel data on screens. AIS-B is available for yachts or motor-cruisers, it's the simpler cheaper version. (AIS-A is for big ships, expensive and has many more programable functions)


Floating Handheld VHF radios.

A good size in small craft, they can be carried on your person or stowed in or near the cockpit. Could be good if you have to abandon ship or if its overturned/sunk etc. 

A few cons are lower battery time, low transmitting power, lowest range, need to keep recharging if out for a few days and as for any VHF radio,  SROCP operator's licence is still required.

The Pro's. Cheap, small, lightweight, versatile, floats and mobile. It can be charged up by a car or boat's 12 volt system while on the move.



Uniden MHS050 VHF handheld




Uniden MHS155UV handheld VHF and UHF radio.

This VHF and UHF handheld is for the Amphibious crowd. VHF at sea or switch to UHF mode when ashore ( freshwater lakes/ rivers,  beaches, roads and highways). It also floats well. 



Electrical system

Preseason maintenance/upgrade on the 12volt electrical system was needed.

The switch panelwas homemade by a previous owner but lacked access behind it to actually work on it (no idea how he did it..)  However i like the general electrical box setup enough to just slightly modify it. 

After removing the louvred door, used a handsaw to cut the switches and  fuses free. 

3 gang homemade switch panel (Left to Right:  cabin, compass and nav lights)


Able to work on it at long last! 

Once accessible i wired the compass red night light to the vacant center switch and fuse. Red (small wire) connectors used, and a low amp glass fuse. 

Rehung the louvred door by moving the lower hinge up 5cm, so the 3 switch panel is clear and can be removed. 

Did look at proper 4 and 6 gange glass fuse/switch panels ($20-$35) and modern  4-6 gang breaker panels ($45-$60) they'd be an ideal situation, but would have to rebuild the entire front of the electrical box with new plywood to house them etc. Still use the "if it ain't broke don't change it" principle.

Battery isolation switch

This was vast overkill at 300A continuous draw but its nice and very solid. Siliconed a 12mm plywood back board to the bulkhead to attach it inside the electrical box, (and also relocated the solar panels charging regulator)


Narva Battery isolation main switch (and solar regulator)

Main switch wiring

The isolator switch is a "single battery" type with simple wiring.  Connected it to the brass bus bar with heavy wire and yellow connectors (large). It's very convenient and when "off" prevents any inadvertent battery draw down when away from boat, which should help extend battery lifespan. It cost $35 at Bunnings warehouse (they have a neat well priced 12V spare parts section) 

The battery charging cables are not affected as they are seperate circuits. So the house battery can still recharge when the battery isolator is "off". 

There are 3 ways to recharge the 102AH deep cycle battery. 1)  Smart charger  - 240v mains in regulated DC out (on a 24 hr timer at house, off for sleeping and sunny hours.)   2) onboard 37w Solar panel via regulator 3) 6hp outboard DC charger. The 3 cables simply run from each power source to positive and negative battery terminals.

Devices recharging station. 

Cleaned this up by simply using a double adapter 12v cig lighter plug with 2 USB charging ports, plugged into the old 12V cig lighter fitting.


Powertech 12v charging adaptor and LED lamp on recharge

In the picture is an Ironhorse rechargeable 200 /100 lumen LED lamp ($21 at Bunnings).  It's handy to light up the forepeak, quarter berths or cockpit areas. Get extra light where needed and backup if wired 12v fails. Very compact and stows easily. It also forestalls having to wire in extra cabin lights (eg forepeak could do with one). (The yellow 6v 3w LED hand torch was also at Bunnings for $10, it's far  brighter than my 1980's incandescent globe one which finally corroded inside and died) 

Here's some details of the cig lighter 12v DC charging adapter. It has 3amp (fast) and 2.4a (medium) USB A outlets, one 2.4amp USB C outlet, a digital voltmeter,  an on/off switch for each blue led lit cig socket and a 10Amp modern fuse underneath it. The output voltage from the usb's is stepped down to low levels for modern devices (eg 5v) It cost $36 at Jaycar electronics.

Powertech charging adapter specifications


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