icom-m304 Vhf distance capabilities

[CruiserV8100]

Replacing my VHF for the 3rd time in 10yrs. Usually use GME GX600, my first one lasted 7yrs and the second 2yrs with the main unit speaker failing and these where kept out of the boat when not in use. No way am I going to get shafted on a 3rd one. Been looking at Icom brand with several reviews coming in with 2 thumbs up. If anyone is using the icom ic-m304 VHF, how far out to sea is this unit good for. Most my trips range from 40kms to 100kms out wide. There are a few more models with this brand, anyone with info would be a big help as will be purchasing one this wknd.

Cheers

Cruiser..

[Rip it up]

Are you getting a new aerial as well?

The radio broadcast capability relies heavily on the aerial quality.

I've recently installed the lowrance link - 5 radio. Along with a 6ft GME aerial mounted on the gunnel height.

I can comfortably reach the repeater at GLADSTONE from Douglas shoals. 100km approx.

For what it's worth the VMR team at Gladstone just built a new building and installed icom radios.


Damo's dodgy boat building repair centre.

[scottar]

All marine VHF's apart from handhelds and the odd cheap model that has spawned from the Navico stable have the same power output. As such they all have the same potential distance capabilities. The things that will make the most difference are your antenna system and it's height (VHF is termed a line of sight type signal), the frequency used and whether or not it has a repeater and in the odd case atmospherics. Typical maximum range of any VHF using a simplex frequency (direct boat to boat) is generally taken to be about 20Nm with trailer boats. If you have a mast on a yacht/ship or are communicating with a land station with it's antenna on a tower or hill it will be further depending on the height of the mast/tower/hill. On a duplex channel where a repeater is involved the range is once again dependant on the height of the repeater.

As an example, doing radio checks from Manly boat harbour in Brisbane, it would be fairly normal to be able to contact VMR Bribie Island on a simplex channel with a mast mount antenna on a Yacht. Doing the same from a power boat generally results in very poor signal or no contact.

[CruiserV8100]

Ill be getting all new gear, everything old is going in the bin. I currently have a 1.8m GME aerial and dead GME GX600. Aerial upgrade will be slightly taller this time around.

[CruiserV8100]

There are a few models in the Icom VHF range 304 to the 422. I can get a 304 for $279 or the 422 for $449. For overall safety what would be the recommended in this range of VHF for offshore. I don't mind the GME Aerials as its the only thing that seemed to have lasted. My last GME aerial hooked up to GX600 got signal from masthead isalnd off Gladstone.

[Rip it up]

The next question that has to be asked for safety is do you hold a marine radio license?

To connect the full DSC capability of the radio you will need a MMSI number to program it in.

Gladstone VMR run the course regularly and is not overly dear. Give you awesome information about radio systems and how it all works.

DSC Is the next big feature that links all of your electronics together to give you a different option rather than relying on an epirb for location. An exact GPS position can be sent back to Canberra via he DSC button.


Damo's dodgy boat building repair shop.

[CruiserV8100]

Ive done all the skippers responsibilities in licencing. Best thing everyone should do.

[ozynorts]

All marine VHF's apart from handhelds and the odd cheap model that has spawned from the Navico stable have the same power output. As such they all have the same potential distance capabilities. The things that will make the most difference are your antenna system and it's height (VHF is termed a line of sight type signal), the frequency used and whether or not it has a repeater and in the odd case atmospherics. Typical maximum range of any VHF using a simplex frequency (direct boat to boat) is generally taken to be about 20Nm with trailer boats. If you have a mast on a yacht/ship or are communicating with a land station with it's antenna on a tower or hill it will be further depending on the height of the mast/tower/hill. On a duplex channel where a repeater is involved the range is once again dependant on the height of the repeater.

As an example, doing radio checks from Manly boat harbour in Brisbane, it would be fairly normal to be able to contact VMR Bribie Island on a simplex channel with a mast mount antenna on a Yacht. Doing the same from a power boat generally results in very poor signal or no contact.

Ill be getting all new gear, everything old is going in the bin. I currently have a 1.8m GME aerial and dead GME GX600. Aerial upgrade will be slightly taller this time around.

Hey Scottar, I read somewhere that getting a taller antenna can be fools gold as the actual working component of the antenna isn't the full height. Are you able to shed any light on this at all?
What antenna would you recommend for a rec fisherman?

[scottar]

Yes it can be depending on the construction of the antenna. Your VHF antenna (the bit that actually does the radiating) is only about a metre tall. Most reputable manufacturers will run the cable up the blank and put the actual antenna in the top section - thus providing an advantage of height. I have over the years seen the odd example where this wasn't the case and the antenna was in the bottom of a long blank. As for brands - I've been out of the game a few years now and construction techniques and manufacturers places of origin and thus quality can change so hard to make a recommendation. The GME stuff was ok. I used to recommend ZCG Scalar or the high performance Glomex if people wanted something a bit better build quality but no guarantee that that is still the case.

[Dan5]

FWIW and i'm by no means an expert or even very knowlegable on VHF I was running a Garmin VHF100 with a Pacific antenna out of a 5mtr center console mounted on the gunnel and was able to get around 15nm regularly........Matt (Bluefin59) i'm sure was the on that put me on to the Pacific brand.

The Pacific was a better performer than the GME that I did have without a doubt.......Maybe after reading Scotts post it was because Pacific has the actual antenna mounted high in the whip.

Dan

Just looked up the Pacific website and it looks like it was the P6105....I think.

[ozynorts]

When looking at antenna specifications what is the over riding thing that decides an antenna's potential broadcast power. Is it the Db level or something else?

[scottar]

The actual broadcast power is set by the radio and is restricted by law. There may be some variation in the quality of the receivers in the various sets but there won't be much in it. The variation in antennas is in the height and gain. The gain of an antenna is a reflection of it's radiation pattern. A higher gain antenna has a "compressed" radiation pattern that has a greater horizontal range than a lower one and thus will communicate over more distance. In a perfect world we would be trying to get the highest gain possible.

There is however a catch - boats pitch and roll. If the gain of an antenna is too high and thus the radiation pattern very compressed, when the boat rolls away form the receiving station, the signal gets shot off into space going straight over the top of the receivers antenna. There is also the publics liking of the "go fast" antenna angle that will cause the same issue when the boat is directly facing the receiving station. We have found about a 6dB gain to be about as high as is practical for small boats.

[thylacene]

Another consideration with longer antenna is where you intend to mount it, I originally fitted 2.1M whips, and mounted them on top of the hardtop, found that after a couple of months one had destroyed the mount and the other had come apart at the base (GME stuff) replaced them with 1.5M South Pacific whips and bases and my 27Meg whip has just come "unglued" after 700 hours of use. We enjoy around 25NM range, acknowledging that the base is 2.2M above water level.