marine radio question

[donaldm]

I need to buy a marine radio which will be used on the pacific southern coast, within 40 miles of coast line. Question is any opionion which I should buy, a hand held or a built in type. Im told the built in need an antana but has more range but im also told that comuncations to emergency coast guard has a limit of 1 watt so a large antana is of no value in that condition. The sole pupuse is for emergency if needed and I think a cell phone will work?? within the 30-40 mile coast for general useage. any recommendations

 

[Ned L]

Re: marine radio question

I would not ever plan on a cell phone working 30-40 miles offshore . Unless things have changed, a handheld VHF is limited to 5 watts, and a 'built in' is limited to 25 watts. A hand held will get you a couple - 5 miles, while a 'built in' will get you a good bit farther. Yes a 'built in' needs an external antenna (which is a BIG advange). VHF is a line-of-sight communication, so the higher the antenna, the farther it will 'reach' around the curvature of the earth. A descent VHF radio with a good high antenna should be capable of 25 - 30 miles on a good day. (Not like the old 'AM' ship to shore days when you could have a 100+ watts and reach a hundred miles or more. That all went away back about 1973.)

 

[Gary H NC]

Re: marine radio question

The hand helds have very little range....
You need a better quality mounted radio and the 8 ft antenna..

I have this setup and it seems to do a good job for a lower cost fixed mount,
http://www.iboats.com/Cobra_MR_F55_...9764663--**********.672349183--view_id.373640

http://www.iboats.com/Shakespeare_5...9764663--**********.672349183--view_id.119236

 

[hubbard53]

Re: marine radio question

VHF is LOS (line of sight) and at that frequency (150 - 160mhz) there is little dissapation of signal- and theoretically, 30-40 miles off shore, there is nothing significant to break LOS between you and shore so you should be fine with a handheld.

Same concept applies to the Space Station which is about 210 nautical miles from the surface of the earth. Ham radio operators can communicate with the ISS with 5 watts and in the same frequency range as marine VHF.

 

[INJUN]

Re: marine radio question

I have both.
I use the handheld when I want to stay tuned while I leave the boat to get something on shore.
Also, to add to the above, the higher you can mount the 'built-in' antenna, the more range you'll get.

 

[jhebert]

Re: marine radio question

...[I'm] also told that [communications] to emergency [Coast Guard] has a limit of 1 watt ...

That is nonsense. Try to recall who told you that and never take any advice from him again about the VHF Marine Band radio service.

 

[Splat]

Re: marine radio question

30-40 miles on 5watts(ERP)...... Maybe, on a good day with good atmosphere under ideal conditions, assuming you could get the antenna vertical, and up high enough, yea it's possible. But I wouldn't bet my life on it. Especially with a cheap hand held that may have a frequency deviation of +/-5k. Your chances aren't that great.

For that far out, you need to invest in a good Fixed mount radio, as well as a GOOD QUALITY antenna. Don't skimp on the antenna. Expect to pay over a $100 for a descent antenna. The antenna is prolly more important than than radio in terms of you get what you pay for, with regards to performance.

I wouldn't rely on your phone that far out, plus I can guarantee your phone won't work if it get s wet. Granted a fixed mount won't work if it sinks with the boat so the ideal setup would be one of each, but atleast with a fixed mount, you can call for help with your current position before you go in the water, with the newer DSC models it's only a matter of pushing a button and the radio will TX distress until it can no longer.

Bill

 

[Boatist]

Re: marine radio question

I lot of bad information here. First a fix mount radio has 25 watt out and a switch for 1 watt. Calling the Coast Guard on channel 16 for a MayDay or any required comm should be done on 25 watts. In a harbor calling the harbor Mastor or the fuel dock or bait station would be done on 1 watt.

VHF range is line of site. With a 8 foot antenna mount 3 foot above the water then you have about 11 feet off the water. You range would be 4.7 miles plus the range of the other station. So Boat to boat to another boat set up like your would be about 9.4 miles. A hand held would be about 3 miles plus the range of the other station.

Calling the Coast Guard you will find they usually have high mounted antenna. Like up here in the San Francisco area the antenna are about 3000 feet high. 3000 feet high would have a range of 77 miles. So if you called them with your boat your range would be about 4.7 miles plus their 77 miles or 81.7 miles.

The formula for finding range is
The Square root of Antenna height in feet times 1.42 equals range in miles.
So 11 foot high antenna the square root is 3.32 times 1.42 equals 4.7 miles plus the range of the other station.

Also with a 8 foot good antenna with 6 db gain your ERP (Effective Radiated Power) would be 100 watts with the fixed mount radio. The extra power does not increase the range of the radio but it will help you get thru.
Example in the San Francisco area the antenna is about 3000 feet high plus they have at least 6 different antenna to recieve inland and offshore to the North and South. On a nice summer day out of San Francisco there may to 2000 boats in range of their antennas. So say your sinking and you try to call the Coast Guard on your 5 watt handheld radio with a - 3DB loss rubber duck antenna. So Your ERP power is about 2.5 watts. You may be only 40 miles out and in range of the Coast Guard Antenna but there are 5 other boats calling their buddies to see how the fishing is. Their all more than 8 miles from you so you can not here them but they are in range of the Coast Guard antenna. There all useing 25 watts so who do you think the Coast Guard Hears. Trust me when I tell you your chances of being heard are much better with 25 watts an a good antenna like a shakespears 5225-XT 6DB Gain and 100 watts ERP.

The reason everyone is required to monitor channel 16 may also save you. As all boats are required to monitor channel 16 when the radio is on and they are not talking on another channel. So when you Put out your Mayday call chances are the Coast Guard and or Several other boats will hear your call.
All boats hearing the call are required to write down the information. If coast Guard does not here you they may try to relay your information or come to your aid.

Also Cell phones towers are designed to have a limited range so are not very high. The reason for this is because there only so many channel and phone numbers on each tower. If they were higher they would recieve a lot more call at the same time and always be busy. That is why each cell recieves only a small area then your move to the next cell. The down side to this is their is not much coverage offshore more than a few miles.

 

[Splat]

Re: marine radio question

Boatist is correct. He gave a way more technically involved answer than I felt like typinh, but his information I'd correct.

Get a good radio, and an even better antenna and get it up high, and as close to verticle as you can.

Bill