Since VHF is line of site, and on the water there is generally nothing that would obscure your signal, like buildings, forests, etc. The height of your antenna won't be as critical as it would be on land, but a quality antenna, and quality coax make a big difference because those aspects make sure that your getting as much output power to the antenna as possible. Higher antenna should get you farther over the horizon.
I like to recommend getting a hf transceiver. You can get amateur "ham" license easy because of no code required. This will give you added peace of mind with beyond line of sight commutation. Something I learned, for every 3db of gain, you double your power out and the same for receiving power.
Thanks for watching and commenting. We have a HF SSB Radio, the Icom IC-M802 on board. We also have 2 satellite communication systems so we are never out of touch. Thanks again, Jim
I always thought.....he who dies with the most antennas wins! You have educated me and the specific antenna (162 MHz) for AIS is something that interests me. I was unaware that antennas could be that specific. Great video! Keep them coming. Definitely enjoy the tech talk.
when were out and about the hardest thing is contacting commercial boats for information and safe passing. seems no one has a vid on how to do this. many times i tried but no response . this video is great and brought me up to date on the equiptment
Jack, Glad you like the video. I have had the same experience trying to contact commercial boats. They are required in US waters to monitor channel 16, unless over 300 feet in length, then they monitor channel 13. I'll talk to some of the commercial fisherman here and find out why it is that they don't tend to answer their radios and report back what I find out. Thanks for watching, Jim
HI, found you chanel last week, catching of on your refit, love your boat beautiful job by both of you. My 2 cents....... You might want to hit the head go to the galley and get a beverage first. ok now we can begin. The narrow band Nature of the boat owners AIS antenna is due to its design and it is referred to Q factor, any antenna can only be it most efficient at its design frequency any departure from that frequency above or below it is a compromise and that's ok a practical solution as mentioned. The Q of an antenna is a measure of the bandwidth of an antenna relative to the center frequency of the bandwidth. If the antenna operates over a band between f1 and f2 with center frequency fc=(f1+f2)/2, then the Q is given by: antenna Q quality factor Antennas with a high Q are narrowband, antennas with a low Q are wideband. The higher the value of Q, the more sensitive the input impedance is to small changes in frequency. I saw a comment here about the length of an antenna of 8 feet in length was possibly a cb antenna, its quite difficult to know what an antennas design frequency is by the length of the the whip antenna or radome or the fiberglass enclosure of the antenna, inside the radome you can have a loading coil or colinear stacked elements to make a very high gain antenna. an example is the rubber ducky antenna on a Hand held radio to the very large antenna installed on this gentleman's boat in the video. both are optimized to transmit on 156.8 Mhz = Channel 16 marine VHF and have drastically different lengths. granted this example a bit of an exaggeration but it holds true. Do i dare say" you cant judge an Antenna by its cover" Someone mentioned that VHF frequencies pass through the ionosphere in to space yes that is true making satellite communications possible, but lower frequencies in the HF or high frequency bands "short wave" or as many boaters like to refer to as SSB single side band radio bounce of the ionosphere and rebound like a ball on a pool table to a distant location and depending on the amount of ionization in the atmosphere which is dictated by the time of day summer or winter and year as well as a 10 year solar cycle will permit you communications out to thousands of miles and NVIS Local beyond line of site ability. its great to get weather in a fjord when local VHF weather broadcast is out of range, its available in two services Commercial marine or Amature Radio, if you haven't guessed by now i am a "HAM" -KE6ENI To the comment about using low power, it is the mantra of the radio man to use the least amount of power to maintain communication, one caveat, if its in low power and you are in a Pan Pan situation and the person who has to issue the radio call is not completely familiar with all the buttons on the radio like the HIGH and LOW power and may be calling on low one watt and nobody hears them clearly as you would wish or worse not at all, sometimes that extra power overcomes weakness in the receiving stations radio system. just a precautionary note you may want to add it to the MAYDAY call sheet you of course have conspicuously placed at the radio operating position "Verify Radio at Hi Power setting" .....Check! If it is a MADAY use the DSC Button. also you may not have time to make a Voice transmission and anyone can be instructed to push and hold the red button for five seconds before stepping up to the life raft. Although i sell marine radio equipment at my place of employment, as a "Ham" a radio hobbyist i would encourage some of you to try to build antennas similar to the AIS antenna shown in this video, i am not talented enough to create the plans to show you myself how to do it, but i am providing a link here from some one who can, hopefully with the unsolicited permission of the chanel owner. Just in case your so inclined you can try building an antenna. boatbeaconapp.com/arundale/aerial.htm Even if you don't own a boat or your on "Shore Leave" you can become a AIS information gatherer with your new antenna connected to a AIS receiver helping those still out on the water. www.marinetraffic.com/en/p/expand-coverage Fair Winds Dave SV. El Faro
Thank you for all the great information. We also have a SSB radio and sat phone for communications. Again, thanks for all the information. I really enjoy learning more about it. Jim
Thanks for making a theoretically boring topic quite interesting. It’s especially helpful that you and Rosie often communicate the logic and reasoning in your decisions, caveats, etc. I look forward to your videos and sharing your sense of wonder. Be well . . .
As a Radio guy for the 15 years you did a good job explaining a topic that isn't easy for most. Have always enjoyed your tech talks. Thanks for sharing.
This is the first video I've watched from your channel. I liked your tech talk and I subscribed. I will be another guy to recommend amateur radio (ham). I'm in Texas and I regularly listen to the marine traffic net on 14.300Mhz and hear sailboats in the south atlantic "checking in" and getting weather updates. I know It doesn't replace VHF marine but it is yet another way to communicate. It's another thing to learn but I know quite a few blue water guys that use ham radio and winlink to send and receive email via HF radio frequencies from anywhere in the world. Also, thanks for reminding people not to use 16 or other "bridge-to-bridge" channels for radio checks. Stay safe and thanks for the video.
Glad you liked the video. We also have a SSB Radio with a Pactor Modem on board. The Modem is just a back up since we also have satellite communications for email, text, and phone from anywhere in the world that is really easy to use. It's not budget friendly like the SSB, which we keep just as a reserve. Cruisers do not use the SSB in the North Pacific, but we will use it in the fall of 2021 when we head to Mexico. Thanks, Jim
A talk on VHF etiquette would probably be a great idea, especially if the "codes" used when passing or being overtaken are different from The Loop or the Eastern ICW LOL . Frequency tuning is how Morad squeezed that extra db of gain from the antenna, you probably _could_ still get the AIS signals from the new VHF antenna, but at _GREATLY_ reduced range/signal strength. To _REALLY_ maximize your radio you have to consider the cable run between the transceiver and the antenna as well. Ideally it should be a multiple of the wavelength at the _center_ of the frequency band you're using. I'm a former USN electronics tech who loved (still do) to play with the CB radio band.
Realized after we published the video that we should have addressed cabling as well. We will do a Website Blog Post update at some point after some more time playing with range, and when I do we will talk about cabling as well. Thanks, Jim
I am a west coast bc log truck driver and use vhf everyday in canyons and mountains. I am also the owner captain of a motor yacht with vhf and AIS. To extend your range to the max , pick up a antenna match meter. Very cheap and easy to use and it will check your signal easily and be extremely efficient. No need to crawl the super structure to use it. I get approximately 35 to 50 miles with clear conversations on average, while others around me 4 to 8 miles until they dial in the antenna
Thanks, Jim. I'm glad you kept it on the "[...] for Dummies" level. Now, we just need a course on why "My 48-mile radar on the 15-foot ASL arch can't see an aluminum skiff only 20 miles away." 😊😊😊 Be sure to include pictures and only use words of one syllable or less. 🤣🤣 Sometimes I feel giddy at the fact that someone of my intelligence and coordination is still allowed to drive a 50,000-pound missile (OK, at < 9kts, but still, that's a lot of mass).
Agreed. We have a 72 mile radar. The same formula applies to radar. I can pick up something at 72 miles, as long as it's a 2,500 foot tall mountain. But if the target isn't high enough or your end not high enough - it won't work. More power doesn't do anything. I was just reading the Voyager Spacecraft was 13 billion miles from earth and communicating with a 23-watt radio. Thanks, Jim
When I was stationed in Key West Florida I would go out to Smith Shoals to fish and dive in my boat (no radar, just a compass and charts). it was21 miles out there. At 9 miles we would lose line of sight of the 300' smokestack at the power plant. At my duty station we used a variety of radars which could see from 4 ft off the water to around 60,000 ft line of sight but not over the horizon.
Since air and space may be regarded as insulation, then transmission and reception of radio waves can be treated as electromagnetic signals passing through a capacitor. A capacitor is an interesting electronic device that can handle alternating voltages and currents and basically, it is two conducting plates placed at an insulated distance from each other. Antennas come in various forms and they can be omnidirectional and directional in nature, They can be vertical and horizontal and they can be single-pole or an array of poles. Basically, the manner in which they operate is that THE RATE OF CHANGE OF VOLTAGE will be felt at a distance ( Curl H= J+ dE/dt) and this rate of change will be picked up by the receiving antenna and tuned to select one appropriate channel. When one designs and tests an antenna one normally places it isolated at the centre of a free, clear zone, and where no other surrounding metallic object is so close as to interfere with the mathematical and practical ideal design of the unit. This is what the circumstances demand when one claims the Decibels gain of an antenna. The distributed conductors which form the elemental inductances and capacitances of the antenna the unit normally forms its characteristic, tuning and the gain and the impedance concerned. If any other uninvited piece of metal is close to the antenna then this will interfere with the original design of the antenna and the claimed polar and gain will not be as those predicted by the manufacturer. Still, we have to be practical and accept the misgivings of having many antennas placed close together on a ship. Also, every antenna has its image reflected in the ground and the sea and the ground is are normally treated as a perfect reflecting conductor or as a mirror. Mounting vertical and horizontal antenna at various heights at sh8ich high frequencies will affect the interference pattern between the real antenna and its image and hence the polar diagram is changed accordingly. In this case, the resulting polar diagram is not like a ball, but more like an apple with the vertical antenna placed at the centre. Depending on the length of the antenna and the separation of the image antenna the surrounding apple polar diagram can be carried to act as a round flat pizza to achieve a longer range than when the polar diagram is shaped like an apple! One can say that electronic engineers can have interference patterns to shape what looks like an apple into what looks like a Pizza polar diagram................all assuming that the antenna is working alone only with its reflecting image or images or directors for other effects including shaping the apple like a long thin pencil. In phased array antennas we can also rotate the pencil without having the old type of dish rotating antennas as in radars. It would be very interesting to compare the polar diagrams claimed by the antenna manufacturer and the real practical polar diagram obtained after the same antenna is mounted on a metal rack above a trawler which rolls and pitches and changes height with respect to the difference between the image below the sea and the real antenna above the deck. Not an easy situation to deal with but it is certain that one cannot be too optimistic in believing the polar diagrams and the Gains claimed by all antennas.
I think you'll find that you will cover a lot more range than 7miles,i would expect at least forty. If Tropo ducting takes place you'll be covering possibly hundreds of miles especially if sporadic E's takes place or if you use a beam antenna you'll cover a few hundred miles. Other factors which are quite important is the coax feeder from the radio to the antenna if you've not the right grade of coax you'll incur massive losses down the cable such as power from the radio and your db gain.Have a look at Amateur Radio, I think you would really enjoy this as a hobby. If you can find a local club near you go down and visit them for a taste of what its all about,think you'll love it.
Thanks. We expected from talking to the fisherman we might get more range, but I thought it best to stick to the mathematical conservative numbers until we could demonstrate a difference. Since we have heard Juneau NOAA Weather Station which is 126 miles away from Sea Venture. We have our radio license and a SSB radio on board, along with a Pactor Modem. There are no cruising nets in the North Pacific, so we haven't used it up here. When we go to Mexico in the fall of 2021 we will use it more. Thanks, Jim
@@CruisingSeaVenture yes no problem Jim. If you do managed to have a look at Amateur Radio and decide that you want to get licensed, you'll be able to install some nice kit on the boat and talk to people all over the world also being on a boat is the best thing for radio as sea water is a super ground plane for radio propagation. yesterday i spoke to a chap from Schwenksville,PA and the other one the day before was up in Dunlop, Canada from here in the UK so all good fun. anyway I know nothing about boats, looks like you guys are having a lot of fun and your videos are amazing, some stunning places your getting to see. all the best to you and the family Cheers Allan
Important info for people to learn about. But you missed the quality of the connection between the antenna and the receiver, the coaxial cable. Size and quality make a big difference with the longer the distance between the two. And the biggest reason for poor performance, a bad connection. Hope you have a good trip around Punta Gorda headed south, its a beautiful area that few get to enjoy. Noyo
TECH TALK...my favorite!! Jim these tech talks are very very good. I appreciate them a ton. A storm just busted my old antennas and I was just beginning to look into all new stuff so this is right on time. I have a good idea what I am going to get now. It wont be fancy like yours but it will be properly spec'd. Thanks again.
Awesome if it was some help. It took me some time to just understand the concepts behind it all so I could make some type of informed decisions. Thanks, Jim
I so enjoy the time you spend with us and I agree you are a excellent communicator. You also have a great group of subscribers that have already asks the few questions I had but 1. Do you worry about lighting strikes and how have you prepared for one. Thanks again for your time and knowledge. PS Love You getting photo bombed by the playing cat.
Thank you so much! Your comments are very much appreciated. Lightning Strikes could be a serious issue. We know boats can be struck, but it does seem very rare. Our Aluminum Superstructure has it's own grounding plate through the hull, for what's it worth. But if struck by lighting, I suspect we might have lots of electronic equipment issues. Thanks, Jim
Thanks for watching. I was not specifically a trainer or teacher, but I was in a leadership position where I had to chance to communicate and present ideas, strategies, and processes to groups of people over a period of many years. I also taught Karate for many years. I have always enjoyed sharing and engaging with people, especially when the topic is something I enjoy so much. Thanks again, Jim
there are 2 methods for communication that are almost a guarantee of reaching someone. 1) sat phone. this is where service provider coverage area is the limiter, most don't get much further North than Nome, or comparable on the South polar regions. They can be blocked by mountains if it gets between you and where the satellite is. 2) Shortwave radio ( amateur radio is the common name ) You do need a specific license for these radios not covered by the marine radio license. shortwave radio is a line of sight system but it's frequencies have been known to bounce so you can talk with someone halfway around the world on occasion. I would also get a shortwave receiver to listen to. You should be able to find local weather channel on it besides global entertainment ( music / news ) stations.
Hi Jaqui, Thanks for watching. We have a sat phone and SSB radio as well. The VHF is primarily used for talking to other boats in the area where we are and talking to marinas and of course, if needed, the Coast Guard. Thanks again, Jim
@@CruisingSeaVenture Jim, as you mentioned in the video you have been cruising in places where there is no one in range of the VHF, the sat phone you can call the Coast Guard if needed in those circumstances. even SSB might not give a connection for calling for assistance when needed.
Hi Gavin, We did look at this item, I just didn't include it in the video because I thought it was getting too long and boring, but several viewers have ask about it. On Sea Venture, our cable run is 25', which gives us a 1.06 Db loss on the cables. We considered upgrading the cables to LMR-400 cables, but given the short run, it would have only saved about .33 Db, so we didn't make that change. If we had longer runs I think we would have upgraded the cable. We are getting greater range then we expected, which is a good thing. We can now hear multiple weather stations, including Juneau, 126 miles away. Cabling is something we can always revisit and would be easy to change out. Thanks, Jim
There was a "Septic" in Port Vila, and he had a 2 way radio in every corner of every one of the 4 cabins, (of his game-fishing boat), and the locals called him "CIA", - and the bar-owner, where we went for our morning heart-starter was a "White-Russian", so his nickname was KGB, and I was called ASIO... - So what is your nickname in the local bar?
also it depends if you have a full wave or half wave antenna (1/4 wave or 3/4 wave as well).145 mhz is on the 2 metre wave so a half wave would be 1 metre long... also you need a low SWR (standing wave ratio) say below 1:5
I talked as much as 30 miles eith a handheld radio, but of course he is using 1 watt I was using 5 watts, most marine handheld radios only put out 1 watt, working ham radio you are using much higher powered radios. You also have to take into accunt the power output, are you using 1 watt 3 watts or 5 watts or more, with ham radio you can very often higher power with longer range. With every 3 Db of gain you ars effectively doubling your power output, my Comet GP9 has a gain of 11.3 Db, on simplex I can talk well over 60 miles with a power output of around 15 watts on land, on the ocean that would come out to be better than 80 miles line of sight.
VHF tech talk was outstanding! Thank you. And just curious, have you ever had to use your satellite radio in an emergency? Or do you have an iridium phone so your children feel comfortable with mom and day are alone in remote places?
Not yet! We do have an Iridium Phone. We also have a Garmin Inreach Explorer, with unlimited satellite texting, so we text the kids just about every day. They, and you, can always know where Sea Venture is real time with this link as well. Thanks, Jim forecast.predictwind.com/tracking/display/SeaVenture
Jim, Well I can't get everything right the first time. :) In hindsight - I know. With the short run I don't think the db loss is much, but why stop now? I have the LRM400 cable sitting here. At least it's easy to change out and each run is only 25'. If it would only stop raining. Thanks, Jim
Bryan, So I have learned. A couple of viewers sent me links as well. Thanks so much for the feedback. I'll point out what I learned in an upcoming Q&A. Thanks again, Jim
Very interesting and informative topic. I cruised a small boat from Tacoma to Glacier Bay 30 years ago. North of Petersburg I was tied at a float in a bay with a small gillnetter who advised me you can feel pretty alone out here but there is almost always someone who can hear you on the radio.....essential safety gear. It must perform. I am interested in your opinions on good boatyards in the Puget Sound area for major refits? Can we talk via email or you could just respond here?
Thanks for sharing! We had a superstructure and swim step work all done at the Port Townsends Shipwrights Co-Op. Aaron Day, one of the owners, was our go to guy. It's really the only place we have hired someone to work on Sea Venture, and I can recommend them without any reservation. Hope that helps. You can always email me as well at: CruisingSeaVenture@Gmail.com
You are dealing with the marine allotted portion of the VHF band. Amateur radio also on VHF about 144 to 148.000 MH. An 8 ft antenna is CB which is HF. VHF antenna is 2 meters.If you have line of sight VHF range is about 40 miles on 25 watts. You could also use 5/8 of 2 meters or 1/2 of 2meters (1 meter) antenna length. Some antennas are directional known as a beam.
ok I will admit I am a cheap and simple person. I think I would have bought a long aluminum pole and attached the current antenna to it and just made it higher than your outriggers. I guess the dB gain would make a slight difference in overall receiving/transmitting quality and range though. Thanks for the video.
Stephen, That certainly would have been an option. The 10db gain antenna has worked really well. Commercial fisherman up here told us we would in fact be able to communicate up to 60 miles with the 10db antenna. While it shoots off into space once it's over the horizon, apparently it's focused enough that if someone else also has a 10db antenna and there's is doing the same thing, the two signals can meet somewhere in the middle. I probably didn't explain that very well, but it's working. Also, one of the challenges in SE Alaska is that the Coast Guard operates out of Juneau with 37 repeater stations - of which 1/3 do not work. Apparently they contracted with a private company to maintain them and that hasn't worked out so well. As a result, there are areas where you can not communicate with the CG in Alaska. When you are in range of the CG you do hear their regular broadcast letting you know that there are areas they can not hear you, so if you hear a mayday to please relay it to the CG and assume they do not hear it. They also on the regular broadcast recommend all vessels have a sat phone on board and in a mayday situation to call them on the phone if you can not reach them on the radio. We use to go for long periods while cruising and not hear these announcements. Since upgrading the antenna we now have heard them 100% of the time, which is a little reassuring. Thanks for watching, Jim
100 watt linear amplifier would give you 6 GB more gain I believe in an emergency. Mirage amp might be a good choice for emergencies. I don't believe it would be legal for day-to-day use, but in life-threatening emergency you make the choice. The linear amp also has a preamp which will amplify and increase receive signals.
In theory they can. We have tried to minimize it by keeping similar type antennas at different heights, and many of them are not in use at the same time, except for GPS’s, and interference is not an issue for them. So far, we have not noticed a problem. Thanks for watching. Jim
First I would like to know why you keep converting from feet to meters to miles? Is this just to make it seem more difficult? It should be simple geometry. By the way, are you using statute or nautical miles?
Hi Frank. You can add the two together. Due to the vertical height of the signal two boats signals will meet at the horizon for both. Shakespare's website has a really good illustration of this at: shakespeare-ce.com/marine/antenna-selector/ Thanks for watching, Jim
Hi Greg, We carry bear spray and an airhorn. In our almost 30 years of cruising in bear country we have encountered many bears but never had a bad experience or needed to use the bear spray. Thanks for watching. Jim
Darryl - great point - I should have said something along with the radio check on Channel 16 note, but then it would be easy to make an entire video on talking on the VHF radio. One thing that we really enjoy about remote cruising is how quiet the radio is. We can always tell when we are getting close to a populated area with lots of boat traffic - the radio just keeps talking. I don't think we have heard another boat on the radio since September, and up here in Alaska (compared) to Puget Sound in Washington, the Coast Guard rarely talks on the radio - and does not do the "Notice to Mariner" stuff that I have heard. Thanks for watching, Jim
I think that in your example of the antenna signal reaching 6.99 miles that means that a station at 8 miles may not hear you as your signal is only good to 6.99 (assuming no weather impact).
That would be assuming their antenna is almost on the ground and they only have 1 mile of receiving distance. Otherwise you have to do the math for both the receiving antenna and sending antenna and add the two together. Thanks, Jim
So you are saying that if a specific antenna can transmit 6 miles, the receiving antenna does not need to be within that 6 mile range? If the receiving antenna also has a range of 6 miles, it will reach out and pull in the radio waves from up to 6 miles away even though the transmitted radio signal cannot reach the physical location of the receiving antenna? Big fan of your channel - thanks for bringing everybody along!
Exactly - you can add the transmit distance of the two antenna's together. Shakespeare has a really good illustration on their website: Here is a link: shakespeare-ce.com/marine/antenna-selector/ Thanks for watching, Jim
It's very possible, once it's available for boats. We use the VHF to talk to other boats around us and marinas if we are out of cell range. Otherwise, for email, text, and phone conversations, we use our satellite for communications. For long range cruising nets we use our SSB radio as well. Thanks, Jim
I always like your tech talks they are well considered and delivered at a good pace. You do however have difficult curbing your enthusiasm for tech and gadgets.😉. Which leads me to a tool recommendation for zip ties - czcams.com/video/nXiqDy9guZU/video.html - worth it if you have lots to do.👍 Thanks for sharing.😀🛥
Since VHF is line of site, and on the water there is generally nothing that would obscure your signal, like buildings, forests, etc. The height of your antenna won't be as critical as it would be on land, but a quality antenna, and quality coax make a big difference because those aspects make sure that your getting as much output power to the antenna as possible. Higher antenna should get you farther over the horizon.
I like to recommend getting a hf transceiver. You can get amateur "ham" license easy because of no code required. This will give you added peace of mind with beyond line of sight commutation.
Something I learned, for every 3db of gain, you double your power out and the same for receiving power.
Thanks for watching and commenting. We have a HF SSB Radio, the Icom IC-M802 on board. We also have 2 satellite communication systems so we are never out of touch. Thanks again, Jim
Jim A logical and beneficial follow up would be the use of aSWR meter on the boat......a invaluable tool for every boat! Bob
I always thought.....he who dies with the most antennas wins! You have educated me and the specific antenna (162 MHz) for AIS is something that interests me. I was unaware that antennas could be that specific. Great video! Keep them coming. Definitely enjoy the tech talk.
Hey, if it helped at all - great. Morad can make an antenna tuned to any specific frequency. Thanks, Jim
when were out and about the hardest thing is contacting commercial boats for information and safe passing. seems no one has a vid on how to do this. many times i tried but no response . this video is great and brought me up to date on the equiptment
Jack, Glad you like the video. I have had the same experience trying to contact commercial boats. They are required in US waters to monitor channel 16, unless over 300 feet in length, then they monitor channel 13. I'll talk to some of the commercial fisherman here and find out why it is that they don't tend to answer their radios and report back what I find out. Thanks for watching, Jim
@@CruisingSeaVenture If theey are ion a good place the y do not like sharing it,
Great video, I have to admit I was more interested in your kids in the BG a couple times, but hey, I'm a cat lover.
HI, found you chanel last week, catching of on your refit, love your boat beautiful job by both of you.
My 2 cents....... You might want to hit the head go to the galley and get a beverage first. ok now we can begin.
The narrow band Nature of the boat owners AIS antenna is due to its design and it is referred to Q factor, any antenna can only be it most efficient at its design frequency any departure from that frequency above or below it is a compromise and that's ok a practical solution as mentioned.
The Q of an antenna is a measure of the bandwidth of an antenna relative to the center frequency of the bandwidth. If the antenna operates over a band between f1 and f2 with center frequency fc=(f1+f2)/2, then the Q is given by:
antenna Q quality factor
Antennas with a high Q are narrowband, antennas with a low Q are wideband. The higher the value of Q, the more sensitive the input impedance is to small changes in frequency.
I saw a comment here about the length of an antenna of 8 feet in length was possibly a cb antenna, its quite difficult to know what an antennas design frequency is by the length of the the whip antenna or radome or the fiberglass enclosure of the antenna, inside the radome you can have a loading coil or colinear stacked elements to make a very high gain antenna. an example is the rubber ducky antenna on a Hand held radio to the very large antenna installed on this gentleman's boat in the video. both are optimized to transmit on 156.8 Mhz = Channel 16 marine VHF and have drastically different lengths. granted this example a bit of an exaggeration but it holds true. Do i dare say" you cant judge an Antenna by its cover"
Someone mentioned that VHF frequencies pass through the ionosphere in to space yes that is true making satellite communications possible,
but lower frequencies in the HF or high frequency bands "short wave" or as many boaters like to refer to as SSB single side band radio bounce of the ionosphere and rebound like a ball on a pool table to a distant location and depending on the amount of ionization in the atmosphere which is dictated by the time of day summer or winter and year as well as a 10 year solar cycle will permit you communications out to thousands of miles and NVIS Local beyond line of site ability. its great to get weather in a fjord when local VHF weather broadcast is out of range, its available in two services Commercial marine or Amature Radio, if you haven't guessed by now i am a "HAM" -KE6ENI
To the comment about using low power, it is the mantra of the radio man to use the least amount of power to maintain communication, one caveat, if its in low power and you are in a Pan Pan situation and the person who has to issue the radio
call is not completely familiar with all the buttons on the radio like the HIGH and LOW power and may be calling on low one watt and nobody hears them clearly as you would wish or worse not at all,
sometimes that extra power overcomes weakness in the receiving stations radio system. just a precautionary note you may want to add it to the MAYDAY call sheet you of course have conspicuously placed at the radio operating position "Verify Radio at Hi Power setting" .....Check!
If it is a MADAY use the DSC Button. also you may not have time to make a Voice transmission and anyone can be instructed to push and hold the red button for five seconds before stepping up to the life raft.
Although i sell marine radio equipment at my place of employment, as a "Ham" a radio hobbyist i would encourage some of you to try to build antennas similar to the AIS antenna shown in this video, i am not talented enough to create the plans to show you myself how to do it, but i am providing a link here from some one who can, hopefully with the unsolicited permission of the chanel owner. Just in case your so inclined you can try building an antenna.
boatbeaconapp.com/arundale/aerial.htm
Even if you don't own a boat or your on "Shore Leave" you can become a AIS information gatherer with your new antenna connected to a AIS receiver helping those still out on the water.
www.marinetraffic.com/en/p/expand-coverage
Fair Winds
Dave
SV. El Faro
Thank you for all the great information. We also have a SSB radio and sat phone for communications. Again, thanks for all the information. I really enjoy learning more about it. Jim
Thanks for making a theoretically boring topic quite interesting. It’s especially helpful that you and Rosie often communicate the logic and reasoning in your decisions, caveats, etc. I look forward to your videos and sharing your sense of wonder. Be well . . .
Glad you enjoyed it! Thanks, Jim
As a Radio guy for the 15 years you did a good job explaining a topic that isn't easy for most. Have always enjoyed your tech talks. Thanks for sharing.
Any more complicated and I would have been lost. Thanks, Jim
This is the first video I've watched from your channel. I liked your tech talk and I subscribed. I will be another guy to recommend amateur radio (ham). I'm in Texas and I regularly listen to the marine traffic net on 14.300Mhz and hear sailboats in the south atlantic "checking in" and getting weather updates. I know It doesn't replace VHF marine but it is yet another way to communicate. It's another thing to learn but I know quite a few blue water guys that use ham radio and winlink to send and receive email via HF radio frequencies from anywhere in the world. Also, thanks for reminding people not to use 16 or other "bridge-to-bridge" channels for radio checks. Stay safe and thanks for the video.
Glad you liked the video. We also have a SSB Radio with a Pactor Modem on board. The Modem is just a back up since we also have satellite communications for email, text, and phone from anywhere in the world that is really easy to use. It's not budget friendly like the SSB, which we keep just as a reserve. Cruisers do not use the SSB in the North Pacific, but we will use it in the fall of 2021 when we head to Mexico. Thanks, Jim
Thanks for the video. I would definitely love to learn more about radio communication while on board.
A talk on VHF etiquette would probably be a great idea, especially if the "codes" used when passing or being overtaken are different from The Loop or the Eastern ICW LOL
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Frequency tuning is how Morad squeezed that extra db of gain from the antenna, you probably _could_ still get the AIS signals from the new VHF antenna, but at _GREATLY_ reduced range/signal strength. To _REALLY_ maximize your radio you have to consider the cable run between the transceiver and the antenna as well. Ideally it should be a multiple of the wavelength at the _center_ of the frequency band you're using. I'm a former USN electronics tech who loved (still do) to play with the CB radio band.
Realized after we published the video that we should have addressed cabling as well. We will do a Website Blog Post update at some point after some more time playing with range, and when I do we will talk about cabling as well. Thanks, Jim
I am a west coast bc log truck driver and use vhf everyday in canyons and mountains. I am also the owner captain of a motor yacht with vhf and AIS. To extend your range to the max , pick up a antenna match meter. Very cheap and easy to use and it will check your signal easily and be extremely efficient. No need to crawl the super structure to use it. I get approximately 35 to 50 miles with clear conversations on average, while others around me 4 to 8 miles until they dial in the antenna
Thanks for sharing! Will do. Jim
Thanks, Jim. I'm glad you kept it on the "[...] for Dummies" level. Now, we just need a course on why "My 48-mile radar on the 15-foot ASL arch can't see an aluminum skiff only 20 miles away." 😊😊😊 Be sure to include pictures and only use words of one syllable or less. 🤣🤣 Sometimes I feel giddy at the fact that someone of my intelligence and coordination is still allowed to drive a 50,000-pound missile (OK, at < 9kts, but still, that's a lot of mass).
Agreed. We have a 72 mile radar. The same formula applies to radar. I can pick up something at 72 miles, as long as it's a 2,500 foot tall mountain. But if the target isn't high enough or your end not high enough - it won't work. More power doesn't do anything. I was just reading the Voyager Spacecraft was 13 billion miles from earth and communicating with a 23-watt radio. Thanks, Jim
When I was stationed in Key West Florida I would go out to Smith Shoals to fish and dive in my boat (no radar, just a compass and charts). it was21 miles out there. At 9 miles we would lose line of sight of the 300' smokestack at the power plant. At my duty station we used a variety of radars which could see from 4 ft off the water to around 60,000 ft line of sight but not over the horizon.
Since air and space may be regarded as insulation, then transmission and reception of radio waves can be treated as electromagnetic signals passing through a capacitor. A capacitor is an interesting electronic device that can handle alternating voltages and currents and basically, it is two conducting plates placed at an insulated distance from each other. Antennas come in various forms and they can be omnidirectional and directional in nature, They can be vertical and horizontal and they can be single-pole or an array of poles. Basically, the manner in which they operate is that THE RATE OF CHANGE OF VOLTAGE will be felt at a distance ( Curl H= J+ dE/dt) and this rate of change will be picked up by the receiving antenna and tuned to select one appropriate channel. When one designs and tests an antenna one normally places it isolated at the centre of a free, clear zone, and where no other surrounding metallic object is so close as to interfere with the mathematical and practical ideal design of the unit. This is what the circumstances demand when one claims the Decibels gain of an antenna. The distributed conductors which form the elemental inductances and capacitances of the antenna
the unit normally forms its characteristic, tuning and the gain and the impedance concerned.
If any other uninvited piece of metal is close to the antenna then this will interfere with the original design of the antenna and the claimed polar and gain will not be as those predicted by the manufacturer. Still, we have to be practical and accept the misgivings of having many antennas placed close together on a ship.
Also, every antenna has its image reflected in the ground and the sea and the ground is are normally treated as a perfect reflecting conductor or as a mirror. Mounting vertical and horizontal antenna at various heights at sh8ich high frequencies will affect the interference pattern between the real antenna and its image and hence the polar diagram is changed accordingly. In this case, the resulting polar diagram is not like a ball, but more like an apple with the vertical antenna placed at the centre. Depending on the length of the antenna and the separation of the image antenna the surrounding apple polar diagram can be carried to act as a round flat pizza to achieve a longer range than when the polar diagram is shaped like an apple! One can say that electronic engineers can have interference patterns to shape what looks like an apple into what looks like a Pizza polar diagram................all assuming that the antenna is working alone only with its reflecting image or images or directors for other effects including shaping the apple like a long thin pencil. In phased array antennas we can also rotate the pencil without having the old type of dish rotating antennas as in radars.
It would be very interesting to compare the polar diagrams claimed by the antenna manufacturer and the real practical polar diagram obtained after the same antenna is mounted on a metal rack above a trawler which rolls and pitches and changes height with respect to the difference between the image below the sea and the real antenna above the deck. Not an easy situation to deal with but it is certain that one cannot be too optimistic in believing the polar diagrams and the Gains claimed by all antennas.
I love your honesty, about the size! A real man always admits when he’s silly 😜
I think you'll find that you will cover a lot more range than 7miles,i would expect at least forty. If Tropo ducting takes place you'll be covering possibly hundreds of miles especially if sporadic E's takes place or if you use a beam antenna you'll cover a few hundred miles. Other factors which are quite important is the coax feeder from the radio to the antenna if you've not the right grade of coax you'll incur massive losses down the cable such as power from the radio and your db gain.Have a look at Amateur Radio, I think you would really enjoy this as a hobby. If you can find a local club near you go down and visit
them for a taste of what its all about,think you'll love it.
Thanks. We expected from talking to the fisherman we might get more range, but I thought it best to stick to the mathematical conservative numbers until we could demonstrate a difference. Since we have heard Juneau NOAA Weather Station which is 126 miles away from Sea Venture.
We have our radio license and a SSB radio on board, along with a Pactor Modem. There are no cruising nets in the North Pacific, so we haven't used it up here. When we go to Mexico in the fall of 2021 we will use it more.
Thanks, Jim
@@CruisingSeaVenture yes no problem Jim. If you do managed to have a look at Amateur Radio and decide that you want to get licensed, you'll be able to install some nice kit on the boat and talk to people all over the world also being on a boat is the best thing for radio as sea water is a super ground plane for radio propagation. yesterday i spoke to a chap from Schwenksville,PA and the other one the day before was up in Dunlop, Canada from here in the UK so all good fun. anyway I know nothing about boats, looks like you guys are having a lot of fun and your videos are amazing, some stunning places your getting to see. all the best to you and the family
Cheers
Allan
Important info for people to learn about. But you missed the quality of the connection between the antenna and the receiver, the coaxial cable. Size and quality make a big difference with the longer the distance between the two. And the biggest reason for poor performance, a bad connection. Hope you have a good trip around Punta Gorda headed south, its a beautiful area that few get to enjoy. Noyo
TECH TALK...my favorite!! Jim these tech talks are very very good. I appreciate them a ton. A storm just busted my old antennas and I was just beginning to look into all new stuff so this is right on time. I have a good idea what I am going to get now. It wont be fancy like yours but it will be properly spec'd. Thanks again.
Awesome if it was some help. It took me some time to just understand the concepts behind it all so I could make some type of informed decisions. Thanks, Jim
Very interesting & educational video. Jim, the best one you did so far. Thank you for sharing your experiences with us. Stay warm & safe.
Thanks, will do! Jim
I so enjoy the time you spend with us and I agree you are a excellent communicator. You also have a great group of subscribers that have already asks the few questions I had but 1. Do you worry about lighting strikes and how have you prepared for one. Thanks again for your time and knowledge. PS Love You getting photo bombed by the playing cat.
Thank you so much! Your comments are very much appreciated. Lightning Strikes could be a serious issue. We know boats can be struck, but it does seem very rare. Our Aluminum Superstructure has it's own grounding plate through the hull, for what's it worth. But if struck by lighting, I suspect we might have lots of electronic equipment issues. Thanks, Jim
Awesome video thank you for sharing I look forward to more videos on proper radio etiquette
Jim, I wish you were one of my teachers. I would have done so much better at school!!
Thank you. Glad you are enjoying the videos. Jim
A very relevant subject delivered for the average person.Once again well done.
BrianDorling
MV Sealeaf
Thanks, Jim
Great video. I learned a lot. I enjoy learning about the technical aspect of everything on the boat. Thank you
Glad it was helpful! Thanks, Jim
Thumbs up before this video even started.
Good information.
Thanks. Jim
Very interesting Jim , great upgrades...thanks for sharing...
Glad you enjoyed it. Thanks, Jim
Great information and great video. Have fun and stay safe. God Bless.
Thanks, Jim
Great info, presented well organized. Did you used to be a trainer/teacher ?
Thanks for watching. I was not specifically a trainer or teacher, but I was in a leadership position where I had to chance to communicate and present ideas, strategies, and processes to groups of people over a period of many years. I also taught Karate for many years. I have always enjoyed sharing and engaging with people, especially when the topic is something I enjoy so much. Thanks again, Jim
there are 2 methods for communication that are almost a guarantee of reaching someone. 1) sat phone. this is where service provider coverage area is the limiter, most don't get much further North than Nome, or comparable on the South polar regions. They can be blocked by mountains if it gets between you and where the satellite is. 2) Shortwave radio ( amateur radio is the common name ) You do need a specific license for these radios not covered by the marine radio license. shortwave radio is a line of sight system but it's frequencies have been known to bounce so you can talk with someone halfway around the world on occasion.
I would also get a shortwave receiver to listen to. You should be able to find local weather channel on it besides global entertainment ( music / news ) stations.
Hi Jaqui, Thanks for watching. We have a sat phone and SSB radio as well. The VHF is primarily used for talking to other boats in the area where we are and talking to marinas and of course, if needed, the Coast Guard. Thanks again, Jim
@@CruisingSeaVenture Jim, as you mentioned in the video you have been cruising in places where there is no one in range of the VHF, the sat phone you can call the Coast Guard if needed in those circumstances. even SSB might not give a connection for calling for assistance when needed.
Very informative - Thank you
Just to throw another spanner in the works have you tought of co-axial cable losses? Google co-axial cable losses chart.
Hi Gavin, We did look at this item, I just didn't include it in the video because I thought it was getting too long and boring, but several viewers have ask about it. On Sea Venture, our cable run is 25', which gives us a 1.06 Db loss on the cables. We considered upgrading the cables to LMR-400 cables, but given the short run, it would have only saved about .33 Db, so we didn't make that change. If we had longer runs I think we would have upgraded the cable. We are getting greater range then we expected, which is a good thing. We can now hear multiple weather stations, including Juneau, 126 miles away. Cabling is something we can always revisit and would be easy to change out. Thanks, Jim
Great sharing!
Thank you! Cheers! Jim
There was a "Septic" in Port Vila, and he had a 2 way radio in every corner of every one of the 4 cabins, (of his game-fishing boat), and the locals called him "CIA", - and the bar-owner, where we went for our morning heart-starter was a "White-Russian", so his nickname was KGB, and I was called ASIO... - So what is your nickname in the local bar?
also it depends if you have a full wave or half wave antenna (1/4 wave or 3/4 wave as well).145 mhz is on the 2 metre wave so a half wave would be 1 metre long... also you need a low SWR (standing wave ratio) say below 1:5
The coast guard also uses Morad VHF antennas
Awesome! Thanks, Jim
I talked as much as 30 miles eith a handheld radio, but of course he is using 1 watt I was using 5 watts, most marine handheld radios only put out 1 watt, working ham radio you are using much higher powered radios. You also have to take into accunt the power output, are you using 1 watt 3 watts or 5 watts or more, with ham radio you can very often higher power with longer range. With every 3 Db of gain you ars effectively doubling your power output, my Comet GP9 has a gain of 11.3 Db, on simplex I can talk well over 60 miles with a power output of around 15 watts on land, on the ocean that would come out to be better than 80 miles line of sight.
VHF tech talk was outstanding! Thank you. And just curious, have you ever had to use your satellite radio in an emergency? Or do you have an iridium phone so your children feel comfortable with mom and day are alone in remote places?
Not yet! We do have an Iridium Phone. We also have a Garmin Inreach Explorer, with unlimited satellite texting, so we text the kids just about every day. They, and you, can always know where Sea Venture is real time with this link as well. Thanks, Jim
forecast.predictwind.com/tracking/display/SeaVenture
@@CruisingSeaVenture I have your location link bookmarked so I always know where you are. “Think the Michael Jackson song, Somebody’s Watching Me”.
Very interesting, thanks.
He didn't take into account the loss and the RG58 coaxial cable from the radio to the antenna and also you could use better cable and get less loss.
Jim, Well I can't get everything right the first time. :) In hindsight - I know. With the short run I don't think the db loss is much, but why stop now? I have the LRM400 cable sitting here. At least it's easy to change out and each run is only 25'. If it would only stop raining. Thanks, Jim
Kitty video bomb at 7:20 😺
Great info...thanks for your work.
Glad it was helpful! Jim
Just once in real need will pay many times for this upgrade...
They actually make a tool to tighten and cut the wire tie!
Bryan, So I have learned. A couple of viewers sent me links as well. Thanks so much for the feedback. I'll point out what I learned in an upcoming Q&A. Thanks again, Jim
Very interesting and informative topic. I cruised a small boat from Tacoma to Glacier Bay 30 years ago. North of Petersburg I was tied at a float in a bay with a small gillnetter who advised me you can feel pretty alone out here but there is almost always someone who can hear you on the radio.....essential safety gear. It must perform. I am interested in your opinions on good boatyards in the Puget Sound area for major refits? Can we talk via email or you could just respond here?
Thanks for sharing! We had a superstructure and swim step work all done at the Port Townsends Shipwrights Co-Op. Aaron Day, one of the owners, was our go to guy. It's really the only place we have hired someone to work on Sea Venture, and I can recommend them without any reservation. Hope that helps. You can always email me as well at: CruisingSeaVenture@Gmail.com
You are dealing with the marine allotted portion of the VHF band. Amateur radio also on VHF about 144 to 148.000 MH. An 8 ft antenna is CB which is HF. VHF antenna is 2 meters.If you have line of sight VHF range is about 40 miles on 25 watts. You could also use 5/8 of 2 meters or 1/2 of 2meters (1 meter) antenna length. Some antennas are directional known as a beam.
ok I will admit I am a cheap and simple person. I think I would have bought a long aluminum pole and attached the current antenna to it and just made it higher than your outriggers. I guess the dB gain would make a slight difference in overall receiving/transmitting quality and range though. Thanks for the video.
Stephen, That certainly would have been an option. The 10db gain antenna has worked really well. Commercial fisherman up here told us we would in fact be able to communicate up to 60 miles with the 10db antenna. While it shoots off into space once it's over the horizon, apparently it's focused enough that if someone else also has a 10db antenna and there's is doing the same thing, the two signals can meet somewhere in the middle. I probably didn't explain that very well, but it's working. Also, one of the challenges in SE Alaska is that the Coast Guard operates out of Juneau with 37 repeater stations - of which 1/3 do not work. Apparently they contracted with a private company to maintain them and that hasn't worked out so well. As a result, there are areas where you can not communicate with the CG in Alaska. When you are in range of the CG you do hear their regular broadcast letting you know that there are areas they can not hear you, so if you hear a mayday to please relay it to the CG and assume they do not hear it. They also on the regular broadcast recommend all vessels have a sat phone on board and in a mayday situation to call them on the phone if you can not reach them on the radio. We use to go for long periods while cruising and not hear these announcements. Since upgrading the antenna we now have heard them 100% of the time, which is a little reassuring. Thanks for watching, Jim
@@CruisingSeaVenture Thanks for the explanation about the better range with the 10dB Antenna.
100 watt linear amplifier would give you 6 GB more gain I believe in an emergency. Mirage amp might be a good choice for emergencies. I don't believe it would be legal for day-to-day use, but in life-threatening emergency you make the choice. The linear amp also has a preamp which will amplify and increase receive signals.
Thanks for sharing! Jim
So now you have many antennas. Do you have the equipment to check them from time to time? Like everything else antennas require maintenance!
Lekker man lekker
Line of Sight = √ (2*height1) + √ (2*height2) in Miles (boat to boat)
With all those antennas mounted near each other, do they interfere with each other?
In theory they can. We have tried to minimize it by keeping similar type antennas at different heights, and many of them are not in use at the same time, except for GPS’s, and interference is not an issue for them. So far, we have not noticed a problem. Thanks for watching. Jim
First I would like to know why you keep converting from feet to meters to miles? Is this just to make it seem more difficult? It should be simple geometry. By the way, are you using statute or nautical miles?
not sure you can add the two station effective range.
Hi Frank. You can add the two together. Due to the vertical height of the signal two boats signals will meet at the horizon for both. Shakespare's website has a really good illustration of this at: shakespeare-ce.com/marine/antenna-selector/ Thanks for watching, Jim
When you explore estuaries full of salmon what defense for bears do you carry ?
Hi Greg, We carry bear spray and an airhorn. In our almost 30 years of cruising in bear country we have encountered many bears but never had a bad experience or needed to use the bear spray. Thanks for watching. Jim
If you are communicating with a vessel 1/4 or 1/2 mile away toggle down to low power.
Darryl - great point - I should have said something along with the radio check on Channel 16 note, but then it would be easy to make an entire video on talking on the VHF radio. One thing that we really enjoy about remote cruising is how quiet the radio is. We can always tell when we are getting close to a populated area with lots of boat traffic - the radio just keeps talking. I don't think we have heard another boat on the radio since September, and up here in Alaska (compared) to Puget Sound in Washington, the Coast Guard rarely talks on the radio - and does not do the "Notice to Mariner" stuff that I have heard. Thanks for watching, Jim
Coast Guard antennas are avg, 500 feet,,they will hear you 200 miles away
Do you have HF?
Yes, we have a Single Side Band Radio - The Icom IC-M802. Thanks for watching, Jim
I think that in your example of the antenna signal reaching 6.99 miles that means that a station at 8 miles may not hear you as your signal is only good to 6.99 (assuming no weather impact).
That would be assuming their antenna is almost on the ground and they only have 1 mile of receiving distance. Otherwise you have to do the math for both the receiving antenna and sending antenna and add the two together. Thanks, Jim
So you are saying that if a specific antenna can transmit 6 miles, the receiving antenna does not need to be within that 6 mile range? If the receiving antenna also has a range of 6 miles, it will reach out and pull in the radio waves from up to 6 miles away even though the transmitted radio signal cannot reach the physical location of the receiving antenna?
Big fan of your channel - thanks for bringing everybody along!
Exactly - you can add the transmit distance of the two antenna's together. Shakespeare has a really good illustration on their website: Here is a link: shakespeare-ce.com/marine/antenna-selector/ Thanks for watching, Jim
Star link will obsolete radios
It's very possible, once it's available for boats. We use the VHF to talk to other boats around us and marinas if we are out of cell range. Otherwise, for email, text, and phone conversations, we use our satellite for communications. For long range cruising nets we use our SSB radio as well. Thanks, Jim
think vhf straight line and will just go over horizon into space..
I always like your tech talks they are well considered and delivered at a good pace. You do however have difficult curbing your enthusiasm for tech and gadgets.😉. Which leads me to a tool recommendation for zip ties - czcams.com/video/nXiqDy9guZU/video.html - worth it if you have lots to do.👍
Thanks for sharing.😀🛥
Norman, Thanks. Another viewer also directed me to a similar tool. Gota have one of those now. :) Jim
@@CruisingSeaVenture 😂👍
When is America going to join the rest of the world and go to the metric system?
I don’t know exactly what you mean. I am sitting here with a 1.75 ltr bottle of refreshments and a 9mm pistol. In America. Clarification needed.