We will be getting a new vhf radio for next year. We now have a handheld, but we need more range than that can give us. My question is two fold. Do they come with an antenna, and can you get mounting brackets for the radios? Our handheld is an ICOM, and we are pleased with it, so we will likely buy the same brand. I guess a have a third question. About how much power does the average radio use. We are trying to figure out the battery situation as well. Thanks in advance Dale
VHF question
- Thread starter dale17781
- Start date
- Status
Icom VHF with CommandMic
I don't think vhf radio comes with antenna. You've order it separately. There's a Squatty model at WM comes with bracket for mast top mount. VHF usually comes with hanging bracket. For panel mount you probably have to order the "L" bracket separaelt (again). If you're mounting the vhf in cabin, I suggest you also order a CommandMic for mounting at the pedestal (cockpit area). Using fix mount vhf at pedestal beats the handheld ones anytime. I recommended this setup to a friend and he love it. I'll be doing same for my boat in coming weeks.
I don't think vhf radio comes with antenna. You've order it separately. There's a Squatty model at WM comes with bracket for mast top mount. VHF usually comes with hanging bracket. For panel mount you probably have to order the "L" bracket separaelt (again). If you're mounting the vhf in cabin, I suggest you also order a CommandMic for mounting at the pedestal (cockpit area). Using fix mount vhf at pedestal beats the handheld ones anytime. I recommended this setup to a friend and he love it. I'll be doing same for my boat in coming weeks.
I don't know of any non-portable
VHF that comes with an antenna. My guess is that you'll have to decide where the antenna is going to be mounted and then buy an appropriate one for that location. Most VHF antenna's mount at the masthead, where they are most efficient. Yet mounting the antenna there is somewhat difficult in that you've either got to go aloft or have the mast down in order to snake the cable inside the mast, then thru the deck, then to the radio itself. Some mount their VHF antenna on the stern or stern pulpit to avoid these tasks. If you choose this location, you'll probably give up a bit of performance as the height of the antenna is a key factor here. And while adding a RAM mic in order to have VHF capability from the cockpit will give you more power than using your current portable VHF, I think you will have the perfect combination without the RAM mic. I could have added a RAM mic on my Icom 402 but chose not to as (1) they are an expensive add-on and (2) I already had a portable VHF like you have. The portable gives you far more flexibility of use than does a RAM mic, but at the cost of reduced performance. I think that's a good tradeoff, at least for me.
VHF that comes with an antenna. My guess is that you'll have to decide where the antenna is going to be mounted and then buy an appropriate one for that location. Most VHF antenna's mount at the masthead, where they are most efficient. Yet mounting the antenna there is somewhat difficult in that you've either got to go aloft or have the mast down in order to snake the cable inside the mast, then thru the deck, then to the radio itself. Some mount their VHF antenna on the stern or stern pulpit to avoid these tasks. If you choose this location, you'll probably give up a bit of performance as the height of the antenna is a key factor here. And while adding a RAM mic in order to have VHF capability from the cockpit will give you more power than using your current portable VHF, I think you will have the perfect combination without the RAM mic. I could have added a RAM mic on my Icom 402 but chose not to as (1) they are an expensive add-on and (2) I already had a portable VHF like you have. The portable gives you far more flexibility of use than does a RAM mic, but at the cost of reduced performance. I think that's a good tradeoff, at least for me.
I don't think a VHF draws much current unless
you are transmitting. Just leaving it on will draw some current but having lengthy conversations will draw much more. I would look into a solar panel for trickle charging your battery while away from the boat. Our boat came with a mast head antenna with a stern rail mounted fiberglass antenna as backup. The first radio check I did with it came from 11 miles away which I thought was pretty good and way better than I would expect from our handheld VHF. If you are going to get a new VHF consider getting one with the new features. We recently installed a Uniden Solara DSC radio ($100-WM) that works well but I still have to finish hooking up the wiring to enable the GPS to deliver our coordinates if we make a distress call. Nice feature. Hope I never need to use it (and that it is properly hooked up when I do).
you are transmitting. Just leaving it on will draw some current but having lengthy conversations will draw much more. I would look into a solar panel for trickle charging your battery while away from the boat. Our boat came with a mast head antenna with a stern rail mounted fiberglass antenna as backup. The first radio check I did with it came from 11 miles away which I thought was pretty good and way better than I would expect from our handheld VHF. If you are going to get a new VHF consider getting one with the new features. We recently installed a Uniden Solara DSC radio ($100-WM) that works well but I still have to finish hooking up the wiring to enable the GPS to deliver our coordinates if we make a distress call. Nice feature. Hope I never need to use it (and that it is properly hooked up when I do).
no antenna
They don't come with antennas as there are several different styles and it is up to the owner to decide which is best. A high db gain antenna will focus your signal a lot and give you cleaner signal. A lower db gain will give you better overall performance. High db is like using a telescope, lots of magnification but limited viewing angle while low db is like using a fish-eye lens, no magnification but a panoramic view. Since the range of a VHF set is line of sight no mater which antenna you use it is probably best to get a low db antenna. Where you put it has more effect on range than the db gain of the antenna. Up high the line of sight is farther away, 25 miles max if both antennas are up high. 15 miles is a more reasonable distance between boats. You will probably find that your hand held will transmit just as far as the base station unit when talking to other boats. Mounting the antenna up on the mast has the advantage of increased range but the disadvantage of providing a path for lightning to get right into the boat, and are a real pain to install. If the mast comes down the VHF stops working till you rig an emergency antenna. Better to just start with a stern rail mount and be done with it IMHO They draw 1.0 to 1.5 amps while receiving and 5-7 amps while transmitting. Oh yea, going to 25 watts output will not increase your transmit range. It will allow you to blast through others using 1 watt however and transmitting over other folks is illegal.
They don't come with antennas as there are several different styles and it is up to the owner to decide which is best. A high db gain antenna will focus your signal a lot and give you cleaner signal. A lower db gain will give you better overall performance. High db is like using a telescope, lots of magnification but limited viewing angle while low db is like using a fish-eye lens, no magnification but a panoramic view. Since the range of a VHF set is line of sight no mater which antenna you use it is probably best to get a low db antenna. Where you put it has more effect on range than the db gain of the antenna. Up high the line of sight is farther away, 25 miles max if both antennas are up high. 15 miles is a more reasonable distance between boats. You will probably find that your hand held will transmit just as far as the base station unit when talking to other boats. Mounting the antenna up on the mast has the advantage of increased range but the disadvantage of providing a path for lightning to get right into the boat, and are a real pain to install. If the mast comes down the VHF stops working till you rig an emergency antenna. Better to just start with a stern rail mount and be done with it IMHO They draw 1.0 to 1.5 amps while receiving and 5-7 amps while transmitting. Oh yea, going to 25 watts output will not increase your transmit range. It will allow you to blast through others using 1 watt however and transmitting over other folks is illegal.
Lightning
I would not think the extra 2 feet an antenna sticks up above your mast is going to matter to lightning v. I would much rather have the greatly increased range which could make the difference in a call for help, not only from you, but if you are called upon to relay information.
I would not think the extra 2 feet an antenna sticks up above your mast is going to matter to lightning v. I would much rather have the greatly increased range which could make the difference in a call for help, not only from you, but if you are called upon to relay information.
Mast Top Antenna
VHF radios are Line Of Sight devices and putting the antenna up 30 ft or so does greatly increase your range. Here is some of the stuff I found on the web about sailboat antennas. Calculation for Range of an Antenna: Square Root of Height (in feet) above water x 1.42 = Range in miles Remember to perform the calculation for BOTH vessels, and then add the results for the range between two vessels. Sailboat Antennas Shorter antennas are rated at 3dB and transmit energy in a less concentrated and broader pattern. This makes 3dB antennas ideal for sailboats, since the less concentrated signal works better when the boat and antenna are heeled fron vertical. Mounting a 3dB antenna at the top of a sailboat's mast will usually compensate for its nominally shorter range than a higher dB rated unit. A short antenna mounted atop a sailboat's mast can give performance equal to or better than a long antenna on a small boat. Stainless Steel or Fiberglass? The best sort of antenna for masthead mounting is a stainless steel whip model, for lightness and low windage. Fiberglass and polyurethane-coated fiberglass antennas are more attractive for deck and roof mounting and provide the torsional stiffness necessary for longer antennas. VHF antennas should be mounted vertically (i.e., not raked back).
VHF radios are Line Of Sight devices and putting the antenna up 30 ft or so does greatly increase your range. Here is some of the stuff I found on the web about sailboat antennas. Calculation for Range of an Antenna: Square Root of Height (in feet) above water x 1.42 = Range in miles Remember to perform the calculation for BOTH vessels, and then add the results for the range between two vessels. Sailboat Antennas Shorter antennas are rated at 3dB and transmit energy in a less concentrated and broader pattern. This makes 3dB antennas ideal for sailboats, since the less concentrated signal works better when the boat and antenna are heeled fron vertical. Mounting a 3dB antenna at the top of a sailboat's mast will usually compensate for its nominally shorter range than a higher dB rated unit. A short antenna mounted atop a sailboat's mast can give performance equal to or better than a long antenna on a small boat. Stainless Steel or Fiberglass? The best sort of antenna for masthead mounting is a stainless steel whip model, for lightness and low windage. Fiberglass and polyurethane-coated fiberglass antennas are more attractive for deck and roof mounting and provide the torsional stiffness necessary for longer antennas. VHF antennas should be mounted vertically (i.e., not raked back).
Confused
What kind of range can be expected from a stern mounted antenna? I am not sure of the range of my handheld, but it seems unlikely that it would be about the same as a 25 watt unit. Am I missing something here? Also is there a problem with lighting and a mast head antenna? If there is how can this be addressed? Dale
What kind of range can be expected from a stern mounted antenna? I am not sure of the range of my handheld, but it seems unlikely that it would be about the same as a 25 watt unit. Am I missing something here? Also is there a problem with lighting and a mast head antenna? If there is how can this be addressed? Dale
VHF radio is line of sight range. You will get
more range from the masthead than from the rail. I get weather from Sudlersville, Md about fifty miles but they have a tall antenna mast and I have a rail mounted whip. With one watt I can talk to anyone I can see. I haven't tried to call the CG but their station is only about 15 miles. There is a formula for calculating line of sight for various elevations but I don't have it at hand.
more range from the masthead than from the rail. I get weather from Sudlersville, Md about fifty miles but they have a tall antenna mast and I have a rail mounted whip. With one watt I can talk to anyone I can see. I haven't tried to call the CG but their station is only about 15 miles. There is a formula for calculating line of sight for various elevations but I don't have it at hand.
clarification hopefully
Antenna height has more effect on your VHF range than the power. As I said before a VHF signal is Line of Sight and your range is limited by the curvature of the earth more than power. As for the power of the unit VHF works much like FM radio. Meaning that the more powerfull transmisson will block out the weaker one. For normal comunications you should always start at low power setting then step up if they cannot read you. As for lightning the extra 2ft of antenna will not make a significant difference over the mast and if you are worried about equipment damage they sell lightning arrestors for antennas that will prevent your radio from getting fried. Here is a link that may help. Handheld to Fixed Mount Hook-Up While fixed mount radios can transmit with 25 watts of power, most handheld VHF radios have 5 watts or less. This, combined with miniscule antennas, limits their effective range to very short distances. Fine for harbor communications, but not much else. This is particularly worrisome if you’re offshore and your fixed mount radio breaks down or is rendered inoperable by electrical problems. To get around this, you want to be able to hook your handheld radio up to your fixed mount antenna. This will significantly improve its range. Ordinarily you need to purchase a small adapter fitting for connecting the two, it costs less than ten bucks. Check with your radio’s manufacturer or retailer for the correct fitting.
Antenna height has more effect on your VHF range than the power. As I said before a VHF signal is Line of Sight and your range is limited by the curvature of the earth more than power. As for the power of the unit VHF works much like FM radio. Meaning that the more powerfull transmisson will block out the weaker one. For normal comunications you should always start at low power setting then step up if they cannot read you. As for lightning the extra 2ft of antenna will not make a significant difference over the mast and if you are worried about equipment damage they sell lightning arrestors for antennas that will prevent your radio from getting fried. Here is a link that may help. Handheld to Fixed Mount Hook-Up While fixed mount radios can transmit with 25 watts of power, most handheld VHF radios have 5 watts or less. This, combined with miniscule antennas, limits their effective range to very short distances. Fine for harbor communications, but not much else. This is particularly worrisome if you’re offshore and your fixed mount radio breaks down or is rendered inoperable by electrical problems. To get around this, you want to be able to hook your handheld radio up to your fixed mount antenna. This will significantly improve its range. Ordinarily you need to purchase a small adapter fitting for connecting the two, it costs less than ten bucks. Check with your radio’s manufacturer or retailer for the correct fitting.
Lightning arrestors
is a contradiction in terms. When you run a conductor (VHF antenna feed) from the top of the mast to your nav station you are inviting trouble. 50 bazillion volts will only slow down at a lightning arrester it will not stop it. It will try and send the lightning down a different path by making the VHF antenna lead a more resistive path but there are NO guarantees with lightning. If you have an anchor/steaming/spreader/VHF antenna/wind instruments.....anything electrical up the mast then you really should consider some active way of dealing with lightning. Techniques vary and all have there followers. Use a stern rail mount high gain antenna vs a low gain mast mounted one. The folks you need to talk to on VHF are always within line of sight. If you need help it will be someone close not somebody 50 miles away. Even if the USCG sends a 50 MPH boat for you it will take an hour. That is why VHF is a ship to ship short range communications means. If you want to talk farther you will have to use your cell or SSB/ham. Sea area B is defined as water less than 25 miles out and within the range of a VHF ground station. Beyond that (area C) is SSB territory or VHF ship to ship. Technically the USCG monitors areas A and B and does not have the means to even receive your signal beyond 25 nm from shore on VHF. Line of sight is just that what you can see. If there is a mountain or even a low hill between your antenna and the other antenna you don't get a connection.
is a contradiction in terms. When you run a conductor (VHF antenna feed) from the top of the mast to your nav station you are inviting trouble. 50 bazillion volts will only slow down at a lightning arrester it will not stop it. It will try and send the lightning down a different path by making the VHF antenna lead a more resistive path but there are NO guarantees with lightning. If you have an anchor/steaming/spreader/VHF antenna/wind instruments.....anything electrical up the mast then you really should consider some active way of dealing with lightning. Techniques vary and all have there followers. Use a stern rail mount high gain antenna vs a low gain mast mounted one. The folks you need to talk to on VHF are always within line of sight. If you need help it will be someone close not somebody 50 miles away. Even if the USCG sends a 50 MPH boat for you it will take an hour. That is why VHF is a ship to ship short range communications means. If you want to talk farther you will have to use your cell or SSB/ham. Sea area B is defined as water less than 25 miles out and within the range of a VHF ground station. Beyond that (area C) is SSB territory or VHF ship to ship. Technically the USCG monitors areas A and B and does not have the means to even receive your signal beyond 25 nm from shore on VHF. Line of sight is just that what you can see. If there is a mountain or even a low hill between your antenna and the other antenna you don't get a connection.
Line of sight is a simplification
VHF radio signals follow the curvature of the earth to a certain extent. So the range can be more than just line of sight. A low gain antenna on the top of your mast will work a lot better than a high gain antenna on the rail. A high gain antenna is more affected by the heel angle of the boat. If you can run coax to the top of your mast easily, that is the best place for your antenna.
VHF radio signals follow the curvature of the earth to a certain extent. So the range can be more than just line of sight. A low gain antenna on the top of your mast will work a lot better than a high gain antenna on the rail. A high gain antenna is more affected by the heel angle of the boat. If you can run coax to the top of your mast easily, that is the best place for your antenna.
Icom handheld
is also what i have. I've attached a link to a previous thread on this with the recommended handheld to masthead antenna connector.
is also what i have. I've attached a link to a previous thread on this with the recommended handheld to masthead antenna connector.
Do we have some numbers??
I'm hearing lots of "better" "farther" "much farther" etc. If we just look at the "our boat" side of the transmission and use Jeuni's formula I get A 10' off the water rail mount will transmit 4.5 miles A 65' off the water mast mount will transmit 11.4 miles The other side could be anything including the above if talking to another boat. For a USCG station 250' is not unreasonable or 22.4 miles. Imagine you are in trouble and you reach the USCG land station and two boats. One boat is a sail boat and the other is a power. Imagine they are all at the max range for the VHF installed. If I have a rail mount then: the USCG is 4.5 + 22.4 = 26.9 miles away and at 30 MPH + 10 min alert time they are 64 minutes away The sailboat is 4.5 + 11.4 = 15.9 miles away and at 5 knots something just over 3 hours away The powerboat is 4.5 + 4.5 = 9 miles away and at 15 MPH is 36 minutes away. If I have a mast mount then USCG 11.4 + 22.4 = 33.8 miles and 78 minutes away Sail 11.4 + 11.4 = 22.8 miles and 4 and a half hours away power 11.4 + 4.5 = 15.9 miles and one hour away Clearly the speed of the boat responding is an important factor not the range the VHF will transmit. While greater range is a cool thing and might get you help sometime in the future if you can last over an hour you probably did not need to call the USCG in the first place. It will be the nearby boat that will be able to provide EMERGENCY assistance. A question to the group. Assuming I'm just talking on the radio and not calling for help what is the farthest you have talked to someone and it not be a radio check? I typically talk to folks that are 3-4 miles away and approaching the raft up or race starting line. If they are 22 miles away I really can't imagine why I'd be talking to them as they are hours away
I'm hearing lots of "better" "farther" "much farther" etc. If we just look at the "our boat" side of the transmission and use Jeuni's formula I get A 10' off the water rail mount will transmit 4.5 miles A 65' off the water mast mount will transmit 11.4 miles The other side could be anything including the above if talking to another boat. For a USCG station 250' is not unreasonable or 22.4 miles. Imagine you are in trouble and you reach the USCG land station and two boats. One boat is a sail boat and the other is a power. Imagine they are all at the max range for the VHF installed. If I have a rail mount then: the USCG is 4.5 + 22.4 = 26.9 miles away and at 30 MPH + 10 min alert time they are 64 minutes away The sailboat is 4.5 + 11.4 = 15.9 miles away and at 5 knots something just over 3 hours away The powerboat is 4.5 + 4.5 = 9 miles away and at 15 MPH is 36 minutes away. If I have a mast mount then USCG 11.4 + 22.4 = 33.8 miles and 78 minutes away Sail 11.4 + 11.4 = 22.8 miles and 4 and a half hours away power 11.4 + 4.5 = 15.9 miles and one hour away Clearly the speed of the boat responding is an important factor not the range the VHF will transmit. While greater range is a cool thing and might get you help sometime in the future if you can last over an hour you probably did not need to call the USCG in the first place. It will be the nearby boat that will be able to provide EMERGENCY assistance. A question to the group. Assuming I'm just talking on the radio and not calling for help what is the farthest you have talked to someone and it not be a radio check? I typically talk to folks that are 3-4 miles away and approaching the raft up or race starting line. If they are 22 miles away I really can't imagine why I'd be talking to them as they are hours away
Transmission Distances
A couple of hundred miles out in the Gulf on the way back from Tarpon Springs we talked to SeaTow out of Tampa. The top of our anntenna was about 40' I am not sure how high SeaTow was but they said their s was on the top of a condo. When offshore here it is not unusual to talk with Coast GUard Sector Mobile probably 60 or 70 miles away. BTW the formula I was taught for the curvature of the earth is the square root times 1.2, not much differnt for the distance we are talking about here. Put the antenna at the top of the mast if possible it will get broke sooner or later if put on the rail. Lines other boats the dock somthing will take it out.
A couple of hundred miles out in the Gulf on the way back from Tarpon Springs we talked to SeaTow out of Tampa. The top of our anntenna was about 40' I am not sure how high SeaTow was but they said their s was on the top of a condo. When offshore here it is not unusual to talk with Coast GUard Sector Mobile probably 60 or 70 miles away. BTW the formula I was taught for the curvature of the earth is the square root times 1.2, not much differnt for the distance we are talking about here. Put the antenna at the top of the mast if possible it will get broke sooner or later if put on the rail. Lines other boats the dock somthing will take it out.
Long range with ducting
I have talked to another boat across Lake Ontario (40 miles from Rochester to Canada). We both have mast mounted antennas and 25 watt radios. The extended range often seen on the VHF band is due to Tropospheric ducting. It can't really be predicted with any accuracy. It is caused by weather, especially temperature inversions. It is an interesting phenomena that leaves most people scratching their heads saying "how did our signals travel so far". Think of it as a bending of radio waves around the curvature of the earth, not a bounce like you get with high frequency (HF) radios. You can get quite a bit more information by Googling "vhf ducting".
I have talked to another boat across Lake Ontario (40 miles from Rochester to Canada). We both have mast mounted antennas and 25 watt radios. The extended range often seen on the VHF band is due to Tropospheric ducting. It can't really be predicted with any accuracy. It is caused by weather, especially temperature inversions. It is an interesting phenomena that leaves most people scratching their heads saying "how did our signals travel so far". Think of it as a bending of radio waves around the curvature of the earth, not a bounce like you get with high frequency (HF) radios. You can get quite a bit more information by Googling "vhf ducting".
Longer antenna
Another quick question. Would it help the range of a handheld unit if you were to install a longer antenna on the handheld radio itself? The antenna on mine is only 6" long. I realize that the hight of the antenna is very important, but could the longer antenna on the radio help solve the range issue to some extent? As I am sure by now, you can tell that I am not a radio wizz. Thanks for being understanding with what I am sure are very elementary questions Dale
Another quick question. Would it help the range of a handheld unit if you were to install a longer antenna on the handheld radio itself? The antenna on mine is only 6" long. I realize that the hight of the antenna is very important, but could the longer antenna on the radio help solve the range issue to some extent? As I am sure by now, you can tell that I am not a radio wizz. Thanks for being understanding with what I am sure are very elementary questions Dale
Radio wave signal strength is measured
micro watts per square meter and your antenna is tuned to match its length to the frequency that you are using. So the simple answer is yes, but not much. If you needed to get all the signal posible than you could use a nice directional Yagi multi element array such as they use for tracking wildlife fitted with radio tracking collars.
micro watts per square meter and your antenna is tuned to match its length to the frequency that you are using. So the simple answer is yes, but not much. If you needed to get all the signal posible than you could use a nice directional Yagi multi element array such as they use for tracking wildlife fitted with radio tracking collars.
1.22 x sq. root height
The distance to the visible horizon can be calculated (visible dip): D = 0.97 x root Hf -or- D = 1.76 x root Hm Where: D = Distance in Nautical Miles root Hf = Square root of Height of eye in Feet root Hm = Square root of Height of Eye in meters. Because a radio signal is slightly refracted, the Radio horizon (range - or radio dip) is calculated: D = 1.22 x root Hf -or- D = 2.21 x root m More: ... cruisersforum.com/forums/f13/vhf-radio-range-376.html http://www.cruisersforum.com/forums/f13/vhf-radio-range-376.html
The distance to the visible horizon can be calculated (visible dip): D = 0.97 x root Hf -or- D = 1.76 x root Hm Where: D = Distance in Nautical Miles root Hf = Square root of Height of eye in Feet root Hm = Square root of Height of Eye in meters. Because a radio signal is slightly refracted, the Radio horizon (range - or radio dip) is calculated: D = 1.22 x root Hf -or- D = 2.21 x root m More: ... cruisersforum.com/forums/f13/vhf-radio-range-376.html http://www.cruisersforum.com/forums/f13/vhf-radio-range-376.html
- Status