What range should I expect from my VHF?

[markpierce]

The USCG must have multiple repeaters in the Bay Area, because I receive their messages to boaters in trouble but rarely from the troubled boaters. Meanwhile, my antennae is over 30 feet above waterline.

[44'cruisingcat]

Repeater syations work through the duplex channels on your radio.

When you're on a duplex channel you can tell if you're accessing the repeater by pressing the transmit button for a moment. If you hear a momentary hiss when you release the tx button, that's the repeater.

[hellosailor]

"I think but am not sure that AM skips far better than FM though"
AM or FM doesn't matter. But the AM broadcast bands are very different frequencies from the FM marine (or broadcast) bands, and how well a signal skips depends on all sorts of atmospheric conditions which in turn bounce different frequencies differently.

[Wotname]

Originally Posted by a64pilot

Skip can play tricks and have you both transmitting and receiving over stupid long distances, however of course that is an anomaly and you can’t count on it.
It seems skip rolls much better at night, and even moreso when there is fog, or it seems that way anyhow

I think but am not sure that AM skips far better than FM though

Originally Posted by hellosailor

"I think but am not sure that AM skips far better than FM though"
AM or FM doesn't matter. But the AM broadcast bands are very different frequencies from the FM marine (or broadcast) bands, and how well a signal skips depends on all sorts of atmospheric conditions which in turn bounce different frequencies differently.

When A64 posted above, I sort of assumed he was comparing apples with apples i.e. AM and FM in the same frequency band like the VHF airband/marine VHF band. In this instance, AM will degrade faster than FM when being ducted though the troposphere due to the ambient noise in the duct affecting the AM signal to greater degree than the FM signal.

However Hellosailor makes a good point if one uses the term AM to refer to the AM broadcast band (540 KHz to 1600 KHz) and comparing it to FM marine VHF.

AM broadcast is regularly skipped by Ionosphere effects in the same way as HF is skipped and can be depended on to a certain degree e.g. range will often increase from dusk to dawn. Tropospheric ducting of VHF is fluky thing and can never be depended on.

[Jim Cate]

Tropospheric ducting of VHF is fluky thing and can never be depended on.

Certainly true! And it can be very interesting... like hearing the Tin Can Bay VMR loud and clear when we were in Noumea (some 800+ nm) and seeing multiple ship AIS signals from West Australia when in Tasmania (around 1500 nm). But only rarely, while HF skip is reasonably reliable, especially when at the sweet spot of the sun spot cycle.

Jim

[conachair]

Originally Posted by Jim Cate

Certainly true! And it can be very interesting... like hearing the Tin Can Bay VMR loud and clear when we were in Noumea (some 800+ nm) and seeing multiple ship AIS signals from West Australia when in Tasmania (around 1500 nm). But only rarely, while HF skip is reasonably reliable, especially when at the sweet spot of the sun spot cycle.

Jim

Marinetraffic can be handy to see if VHF tropospheric effects are happening - find a local receiving station & look at the data >
This a little while ago

[ka4wja]

hd002e,
1) Well, Wotname gave you a succinct answer regarding your line-of-sight...give or take a mile, your radio line-of-sight would be about 9 miles....and another vessel with the same height antenna, would also be the same....so your line-of-sight between your two antennas would be about 18 to 19 miles...

Originally Posted by hd002e

I have a 25W radio that has the whip antenna atop a 40ft mast. I had some issues with the connector when I first installed but recently pulled someone up to fix it. I am comparing it to my 5W handheld when making a test call and don’t know what to expect with the 25W radio. Is there a guideline or practical numbers I can follow to figure out if my radio is working fine?

2) But, this is not the typical range of marine VHF-FM radios....this is the minimum range....
Typical range with 25-watt marine radios is usually 25% to 35% farther than their radio line-of-sight...

That would mean that your expected range to another similar boat (similar antenna height) is about 25miles....again, this is +/- a mile or so....and, of course this can be effected by your angle of heel, etc...

Ranges in excess of this are "possible" but these would be when atmospheric conditions allow...
This is all explained in detail, using mostly layperson terms, in this thread here:

http://www.cruisersforum.com/forums/...ge-149499.html



3) Assuming you're in New Haven, have you listened to NOAA Weather Radio and tried SeaTow Automated Radio Check??

NATIONAL WEATHER SERVICE MARINE PRODUCTS VIA NOAA WEATHER RADIO

NOAA Weather Radio - Map State Selection

a) You should hear your at least 2 local NOAA VHF Weather Radio broadcasts....hopefully three??
WXJ42 in Meridian on Wx Ch. 2 (162.400mhz)
WXM80 in Riverhead, NY on Wx Ch. 3 (162.475mhz)

KHB47 in New London on Wx Ch 1 (162.55mhz) or
KWO35 in NYC on Wx Ch. 1 (162.55mhz)
Depending on your exact location, you hear NYC on Wx Ch. 1, instead on New London...(or you may end up hearing them interfere with each other)

You may also hear WWH33 from Litchfield/Cornwall, on Wx Ch. 6 (162.500mhz)...

In your locale, if you're hearing more than these above, you're receiving these signals because of some radio propagation enhancement (tropo enhancement, not ducting...please read the above referenced page for details)...


b) As for SeaTow Automated Radio Checks...

https://www.seatow.com/tools-and-edu...ed-radio-check

Your Local SeaTow Automated Radio Check station is in Goodsell Point Marina, just east of Branford....on VHF Ch. 27...

You transmit and say "This is sailing vessel Xxxx Yyyy, callsign Wxx 1234, testing on channel two seven"....and then SeaTow's automated system responds and you hear your own transmission sent back to you, so you can hear what you sound like!!

{you should also try ch. 24 for central CT / near Old Saybrook...as well as ch, 24 for the Captain's Cove Marina location, just west of Bridgeport...and also try ch. 28 for SeaTow radio check across the sound in Southold, NY...}



I do hope this helps...

Fair winds..

John