I am about to add radar to my (new) H44 and I need to decide on whether to go for 2KW or 4KW. In either case, it will be Raymarine to maintain compatibility with the rest of the on-board electronics. I was told that the higher power radar is more effective in "punching through" rain. Is this consistent with people's experience? Also the question came up about whether to use a gimballed mount or a fixed mount. Any suggestions on which power level to go for, and whether or not to use a gimballed mount, would be appreciated. Larry Jackel
Radar: 2KW or 4 KW? Gimballed or not?
- Thread starter Larry Jackel
- Start date
- Status
Radar
My 2kw is mounted on the mast and works really good except when you are heeling. If you intend to use it only in fog when you are mortoring, use the mast, but if you are going to go off shore and use it while out to sea I would recommend ar gimbaled mount. Off shore your can barely see even with radar out 6-7 km and then you are looking at sky and to use a mount up on the mast that can see 20+ km out to know where gives you a lot of information you really canot digest. My vote is gimballed and a 2kw
My 2kw is mounted on the mast and works really good except when you are heeling. If you intend to use it only in fog when you are mortoring, use the mast, but if you are going to go off shore and use it while out to sea I would recommend ar gimbaled mount. Off shore your can barely see even with radar out 6-7 km and then you are looking at sky and to use a mount up on the mast that can see 20+ km out to know where gives you a lot of information you really canot digest. My vote is gimballed and a 2kw
4KW
I first installed a 2KW gimbled unit (Furuno) and was never happy. It just would not light up small things nearby. I changed out to a 4KW Raytheon and did away with the gimble mount. I am now very happy. I can see the things that you really need to see in the dark or in fog--small things like small boats and channel markers. As far as the gimbled thing, go ahead and get that if it is important to you, but I strongly recommend the 4KW unit. Remember, it is the things that are close that are the biggest threats and a big threat can be a small thing. The 4KW also will punch through rain much better!
I first installed a 2KW gimbled unit (Furuno) and was never happy. It just would not light up small things nearby. I changed out to a 4KW Raytheon and did away with the gimble mount. I am now very happy. I can see the things that you really need to see in the dark or in fog--small things like small boats and channel markers. As far as the gimbled thing, go ahead and get that if it is important to you, but I strongly recommend the 4KW unit. Remember, it is the things that are close that are the biggest threats and a big threat can be a small thing. The 4KW also will punch through rain much better!
Go 4KW because......
...it is not just the extra power for punching through rain. That is true. But equally important is the larger diameter antenna- 24" vs 18". This allows a higher horizontal resolution of smaller targets. It can make the difference between seeing a harbor cut in the edge of land or just a solid shoreline. The higher power and range I find handy to look for thunderstorms. With the Raytheon 4KW 48 mile range, I can see thunderheads and rain cells up high in the sky. I can watch their direction and speed and it is a comfort to know when they will hit and when they will be leaving. I am not sure if you can do this with the lower power 2KW units. Yes, I have mine gimbaled. I have no idea how it would be on a heel without a gimbal. I believe that most of the times that you really *need* the radar is in low visability and you are probably motoring and on the level. I have mine on a backstay pole and have a range to the water of about 4.5 nm. Realize that objects higher than the water surface will show up at greater distances- like other boats, land, buoys, etc. Rain clouds, being high in the sky, can be seen at great distances if you have enough power. Hope this helps you decide.
...it is not just the extra power for punching through rain. That is true. But equally important is the larger diameter antenna- 24" vs 18". This allows a higher horizontal resolution of smaller targets. It can make the difference between seeing a harbor cut in the edge of land or just a solid shoreline. The higher power and range I find handy to look for thunderstorms. With the Raytheon 4KW 48 mile range, I can see thunderheads and rain cells up high in the sky. I can watch their direction and speed and it is a comfort to know when they will hit and when they will be leaving. I am not sure if you can do this with the lower power 2KW units. Yes, I have mine gimbaled. I have no idea how it would be on a heel without a gimbal. I believe that most of the times that you really *need* the radar is in low visability and you are probably motoring and on the level. I have mine on a backstay pole and have a range to the water of about 4.5 nm. Realize that objects higher than the water surface will show up at greater distances- like other boats, land, buoys, etc. Rain clouds, being high in the sky, can be seen at great distances if you have enough power. Hope this helps you decide.
2KW Can see storms
My Raymarine 2KW is mast mounted with no gimbal mount and I can see images about 35 to 50 feet from the boat. I also track storms from about 25 miles out and use the Marpha function to estimate the time to closest approach of the storm. The only limitation of the 2KW is that the resolution of the 4KW is a little more precise. Having said that, I use the radar overlay on the chartplotter to navigate at night all the time on Kentucky lake. I can see buoys, small fishing boats, barges and bridge supports. If I had it to do over, I'd buy the 4KW because the price is not that much more and it is a little more precise. If budget is more important, you will be happy with the 2KW. I see no need for the gimbal mount for either one. I also have a guard installed that helps protect both the jib and the radar unit when tacking. The greatest value of either is to use as an overlay on a chartplotter. Between the two, your positional awareness is much greater than radar or chartplotter alone.
My Raymarine 2KW is mast mounted with no gimbal mount and I can see images about 35 to 50 feet from the boat. I also track storms from about 25 miles out and use the Marpha function to estimate the time to closest approach of the storm. The only limitation of the 2KW is that the resolution of the 4KW is a little more precise. Having said that, I use the radar overlay on the chartplotter to navigate at night all the time on Kentucky lake. I can see buoys, small fishing boats, barges and bridge supports. If I had it to do over, I'd buy the 4KW because the price is not that much more and it is a little more precise. If budget is more important, you will be happy with the 2KW. I see no need for the gimbal mount for either one. I also have a guard installed that helps protect both the jib and the radar unit when tacking. The greatest value of either is to use as an overlay on a chartplotter. Between the two, your positional awareness is much greater than radar or chartplotter alone.
Larry, thanks for asking that question
That's the exact queston that I have been asking for the exaact same boat. My new 44ac, hull #164, is in the yard and awaiting final rigging. I'm looking at a late April launch. From what I have heard about the areas that I will be cruising (Lake Erie and the Great Lakes), the 2kw on the mast is going to be good enough. Based on what others have said though, I may look again at the cost to go to the 4kw. I'm sure that you are experiencing the same thing I am in that it's no longer BOAT ( Break Out Another Thousand), it's more like BOST (Break Out Several Thousand) every time you want to add someting! Happy Sailing Brian Hanna s/v The Journey Continues...
That's the exact queston that I have been asking for the exaact same boat. My new 44ac, hull #164, is in the yard and awaiting final rigging. I'm looking at a late April launch. From what I have heard about the areas that I will be cruising (Lake Erie and the Great Lakes), the 2kw on the mast is going to be good enough. Based on what others have said though, I may look again at the cost to go to the 4kw. I'm sure that you are experiencing the same thing I am in that it's no longer BOAT ( Break Out Another Thousand), it's more like BOST (Break Out Several Thousand) every time you want to add someting! Happy Sailing Brian Hanna s/v The Journey Continues...
4KW
If you are ever going offshore get the 4KW and gimbal mount. You will really appreciate the better resolution of the 4kw model and yes you will heel in waves especially offshore. Now if you are just cruising Lake erie- 2kw on a post should do fine. We used a 4KW unit on a gimbal post during a 1400 mile offshore passage. You can pick up ships at about 10-12 miles and storms much further out which was especially helpful in avoiding some rain squalls. Approaching Norfolk the longer the range the better because those aircraft carriers can really sneak up on you when then doing 35 knots.
If you are ever going offshore get the 4KW and gimbal mount. You will really appreciate the better resolution of the 4kw model and yes you will heel in waves especially offshore. Now if you are just cruising Lake erie- 2kw on a post should do fine. We used a 4KW unit on a gimbal post during a 1400 mile offshore passage. You can pick up ships at about 10-12 miles and storms much further out which was especially helpful in avoiding some rain squalls. Approaching Norfolk the longer the range the better because those aircraft carriers can really sneak up on you when then doing 35 knots.
verticle beam width
The beam width is an identicle 25 degrees vertical on both units. You can see all the clouds you want on a 2kw radome, as long as you know how to tune it for weather. (Same goes for close objects, it's all in the tuning.) I went with a 2kw. I like the smaller size for reduced windage, and I like the lower power consumption. Mine runs at 28 watts (9 standby) as opposed to 34 watts (10 standby) for the 4kw unit. Think about it this way, when you're making an offshore passage, the radar is your biggest power drain. And if you're sailing for multiple days, the energy budget becomes all the more important. I don't think I ever sail with the radar set at greater than the 12-mile range. Ever.
The beam width is an identicle 25 degrees vertical on both units. You can see all the clouds you want on a 2kw radome, as long as you know how to tune it for weather. (Same goes for close objects, it's all in the tuning.) I went with a 2kw. I like the smaller size for reduced windage, and I like the lower power consumption. Mine runs at 28 watts (9 standby) as opposed to 34 watts (10 standby) for the 4kw unit. Think about it this way, when you're making an offshore passage, the radar is your biggest power drain. And if you're sailing for multiple days, the energy budget becomes all the more important. I don't think I ever sail with the radar set at greater than the 12-mile range. Ever.
Have I told you guy's my radar story?
No? Just a minute, I'll go get it and be right back.
Here it is: In my opinion,,, I love our R20X by Raytheon (JRC) It is a 24Mi with the enclosed dome. We bought it in '91 and have used it as our primary form of navigation from Brownsville Washington to Trinidad and back. The antenna is mounted on a radar arch on our Hunter 34, Epitome'. Our unit is jumperd on the motherboard so that it displays the 32 mile range ring. It has the same display and power as the 32 mile model but without the open array antenna. Here is how we use the longer range. We set the range at 12 miles, then use the offset feature to our stern as far aft as it will move us. After the unit displays in offset mode we can increase the range to 24mi and low and behold, we can see ahead to 39.999999mi. That forty mile range is great for finding headlands when off shore or looking for the next 'bend in the road'. That range would not be available if we didn't jumper the motherboard to 32mi. The laws of physics apply with radar so there is little that we sailors can do with these things except select one to work with our personal style. Here is some other stuff I've learned. More important than power or range for close in viewing is 'Horizontal Beam Width'. The lower the number, the better the resolution. Our radar has a HBW of 2.2 degrees. That is much less than those lower powered units with smaller radomes. What that does for us is it lets us see the difference between a tug and a tow. Important in Puget Sound. We also find ourselves dodging DUCKs so factor that in too. And we can see the wake of ski boats and airplanes at low altitude. (as long as they aren't stealth). After a lightning strike off the coast of Panama (us too), our unit was in the shop for repairs. I had taken it to the States for repair but had to buy a Sitex with the same size dome but only 2kw of power. The first thing I noticed was that the buoys marking the channel to the Balboa entrance of the Panama Canal melded into one target before running out of buoys! That was scary enough but what really freaked me out was what we saw, or didn't see the next week in the Caribbean. We were sailing off shore past Isla Provedencia with no intention of visiting. It was a clear afternoon. We were looking at it. GPS said we were 17 miles from the near shore. It is 1700 Feet tall. The radar NEVER SAW IT on 24 mile range, or any range. I called the manufacturer when we reached the states and they had NO solution. The tuner was automatic so it's lack of performance could only be attributed to lack of power. We sold it and took a loss. Fortunately Raytheon was able to affect repair at a reasonable cost. A couple of years later, a idiotic navigational error by the skipper, (me) had us forty miles, or more on the wrong side of Grenada from Trinidad. I had used the wrong compass course for over 12 hours. The GPS was down because of a software defect. They were too expensive to carry a backup then. Besides, who needs GPS in the eastern Caribbean, right? Well at that point, all we had was dead reckoning and Radar. Our DR position plot was also based on a guess of 8 1/2 knots speed and a two knot favorable current. I say 'guess' because our knotmeter was down too. We plotted a course for Granada at sunset. (a friend was with me and we were suppose to pick up my wife at the airport the next afternoon) Of course the island was suppose to be now dead to windward (and 'currentward') We powered up! At 0400 local time, the airport of Grenada appeared at 33mi using the offset feature DIRECTLY OFF THE BOW!. The altitude of that airport is only about 20 feet but there it was! Never, have I felt such a sense of relief. You see, I don't study those dead reckoning 'how to' articles. We might have found the island without radar but I wouldn't have wanted to find out. We drove right in to Prickly Bay and met the flight. When my wife stepped out of Customs I acted like I had been hanging out and waiting for a week, HaH! Sure glad I got rid of that Sitex! Some other things to consider, the US Navy's primary means of navigation is radar. Since Pearl Harbor, no active Navy ship, anywhere, by regulation, is allowed to turn OFF its' radar. Also radar is not DR or even GPS. Those methods place your position in a 'cocked hat'. Your observed position on the radar screen is EXACTLY where you are! OK, these are just my personal experiences and opinions. I COULD BE WRONG! Fred Ficarra My web site is down since a big wind storm yesterday. My ISP didn't know about it until I called them moments ago. I'm a hero! P.S. OK, the site's back. The Unix server locked up. That has never happened in the history of computers.
No? Just a minute, I'll go get it and be right back.
Here it is: In my opinion,,, I love our R20X by Raytheon (JRC) It is a 24Mi with the enclosed dome. We bought it in '91 and have used it as our primary form of navigation from Brownsville Washington to Trinidad and back. The antenna is mounted on a radar arch on our Hunter 34, Epitome'. Our unit is jumperd on the motherboard so that it displays the 32 mile range ring. It has the same display and power as the 32 mile model but without the open array antenna. Here is how we use the longer range. We set the range at 12 miles, then use the offset feature to our stern as far aft as it will move us. After the unit displays in offset mode we can increase the range to 24mi and low and behold, we can see ahead to 39.999999mi. That forty mile range is great for finding headlands when off shore or looking for the next 'bend in the road'. That range would not be available if we didn't jumper the motherboard to 32mi. The laws of physics apply with radar so there is little that we sailors can do with these things except select one to work with our personal style. Here is some other stuff I've learned. More important than power or range for close in viewing is 'Horizontal Beam Width'. The lower the number, the better the resolution. Our radar has a HBW of 2.2 degrees. That is much less than those lower powered units with smaller radomes. What that does for us is it lets us see the difference between a tug and a tow. Important in Puget Sound. We also find ourselves dodging DUCKs so factor that in too. And we can see the wake of ski boats and airplanes at low altitude. (as long as they aren't stealth). After a lightning strike off the coast of Panama (us too), our unit was in the shop for repairs. I had taken it to the States for repair but had to buy a Sitex with the same size dome but only 2kw of power. The first thing I noticed was that the buoys marking the channel to the Balboa entrance of the Panama Canal melded into one target before running out of buoys! That was scary enough but what really freaked me out was what we saw, or didn't see the next week in the Caribbean. We were sailing off shore past Isla Provedencia with no intention of visiting. It was a clear afternoon. We were looking at it. GPS said we were 17 miles from the near shore. It is 1700 Feet tall. The radar NEVER SAW IT on 24 mile range, or any range. I called the manufacturer when we reached the states and they had NO solution. The tuner was automatic so it's lack of performance could only be attributed to lack of power. We sold it and took a loss. Fortunately Raytheon was able to affect repair at a reasonable cost. A couple of years later, a idiotic navigational error by the skipper, (me) had us forty miles, or more on the wrong side of Grenada from Trinidad. I had used the wrong compass course for over 12 hours. The GPS was down because of a software defect. They were too expensive to carry a backup then. Besides, who needs GPS in the eastern Caribbean, right? Well at that point, all we had was dead reckoning and Radar. Our DR position plot was also based on a guess of 8 1/2 knots speed and a two knot favorable current. I say 'guess' because our knotmeter was down too. We plotted a course for Granada at sunset. (a friend was with me and we were suppose to pick up my wife at the airport the next afternoon) Of course the island was suppose to be now dead to windward (and 'currentward') We powered up! At 0400 local time, the airport of Grenada appeared at 33mi using the offset feature DIRECTLY OFF THE BOW!. The altitude of that airport is only about 20 feet but there it was! Never, have I felt such a sense of relief. You see, I don't study those dead reckoning 'how to' articles. We might have found the island without radar but I wouldn't have wanted to find out. We drove right in to Prickly Bay and met the flight. When my wife stepped out of Customs I acted like I had been hanging out and waiting for a week, HaH! Sure glad I got rid of that Sitex! Some other things to consider, the US Navy's primary means of navigation is radar. Since Pearl Harbor, no active Navy ship, anywhere, by regulation, is allowed to turn OFF its' radar. Also radar is not DR or even GPS. Those methods place your position in a 'cocked hat'. Your observed position on the radar screen is EXACTLY where you are! OK, these are just my personal experiences and opinions. I COULD BE WRONG! Fred Ficarra My web site is down since a big wind storm yesterday. My ISP didn't know about it until I called them moments ago. I'm a hero! P.S. OK, the site's back. The Unix server locked up. That has never happened in the history of computers.2 KW
Hi Larry, Congratulations on the New Boat! I went with the Ray Marine KW mast mount. Less weight aloft and reduced windage. We've had one full season with it and it worked great. No problems with picking out traffic or precip. She worked very well. Good luck with the Boat. Bob Martin
Hi Larry, Congratulations on the New Boat! I went with the Ray Marine KW mast mount. Less weight aloft and reduced windage. We've had one full season with it and it worked great. No problems with picking out traffic or precip. She worked very well. Good luck with the Boat. Bob Martin
Forget the gimbal mount and pole
A gimbal mount like a pole is just one more thing to fail. If you are heeled 20 degrees, your radar use will be already limited by the following: 1. reduced antenna height and therefore the range (do the math ie trigonometry) 2. waves or swells constantly changing your vessels (and therefore the radar antenna) altitude and the target altitude too. 3. seasickness of the crew looking at the radar screen. 4. the fact that you should be reefing the main instead of screwing around looking at the radar and filling up a puke bag. Add to that the fact that the only effect of heeling is a slight reduction of the radar sensitivity due to vertical beam width. Put the savings into a unit with a bigger antenna. A good antenna (bigger is probably better) is more important than the power of the transmitter. Put the scanner high on the mast and away from sails and lines. You will still see close in targets and may actually see them at a closer range - though the ranges will be skewed a little - sorry there is that is trig issue again. The antenna will be safer up there and so will you compared to putting it on a flimsy pole. If you have to use a pole, use a good one and mount it well so it doesn't hit you so hard when it comes down with a big wave. You can also get a CARD radar detector and put that antenna at the top of the mast to see and warn you of other large boat radars nearby. I would not count on using your radar for seeing much past 10 -12 miles. My experience is that radar signals are line of sight and the earth is curved. I still have a hard time with Freds story about seeing something at 33 miles as he describes. No offense Fred it just does not fit my experience and I would not advise someone asking for advice like this to expect that to work on a routine basis. Fred, I have the same radar as you and have not done the modification you describe. Do you have a url for that? I guess that means that since you can slew the received range, the PRF doesn't increase with reduced range. Do you know?
A gimbal mount like a pole is just one more thing to fail. If you are heeled 20 degrees, your radar use will be already limited by the following: 1. reduced antenna height and therefore the range (do the math ie trigonometry) 2. waves or swells constantly changing your vessels (and therefore the radar antenna) altitude and the target altitude too. 3. seasickness of the crew looking at the radar screen. 4. the fact that you should be reefing the main instead of screwing around looking at the radar and filling up a puke bag. Add to that the fact that the only effect of heeling is a slight reduction of the radar sensitivity due to vertical beam width. Put the savings into a unit with a bigger antenna. A good antenna (bigger is probably better) is more important than the power of the transmitter. Put the scanner high on the mast and away from sails and lines. You will still see close in targets and may actually see them at a closer range - though the ranges will be skewed a little - sorry there is that is trig issue again. The antenna will be safer up there and so will you compared to putting it on a flimsy pole. If you have to use a pole, use a good one and mount it well so it doesn't hit you so hard when it comes down with a big wave. You can also get a CARD radar detector and put that antenna at the top of the mast to see and warn you of other large boat radars nearby. I would not count on using your radar for seeing much past 10 -12 miles. My experience is that radar signals are line of sight and the earth is curved. I still have a hard time with Freds story about seeing something at 33 miles as he describes. No offense Fred it just does not fit my experience and I would not advise someone asking for advice like this to expect that to work on a routine basis. Fred, I have the same radar as you and have not done the modification you describe. Do you have a url for that? I guess that means that since you can slew the received range, the PRF doesn't increase with reduced range. Do you know?
Patrick, what's PRF? I don't have my book here.
And the modification is alluded to in my manual. The jumpers on the motherboard are pictured. My first motherboard used standard computer jumpers to get the 32 mile display. After the lightening strike, the replacement board had soldered wire jumpers. Took almost 3 minutes to make the change. (The close-in range is still 1/8 mile) And the jumpers are clearly labeled on the MB.
And the modification is alluded to in my manual. The jumpers on the motherboard are pictured. My first motherboard used standard computer jumpers to get the 32 mile display. After the lightening strike, the replacement board had soldered wire jumpers. Took almost 3 minutes to make the change. (The close-in range is still 1/8 mile) And the jumpers are clearly labeled on the MB.
Fred, PRF stands for
pulse repetition frequency also called rep rate. It is the frequency of the pulsing of the transmitted radar signal. Do not confuse this frequency with the frequency of the radar itself. The range of the radar is necessarily limited by this rep rate frequency. The larger it is, the less the range. If you are to see a reflection at a longer distance, it takes the signal a longer time to travel that distance. It is significant because if you double the range, you will reduce the transmitted pulses and therefore the (theoretical) sensitivity by half. I believe that most small boat radars change the rep rate when you change the range. Therefore, shorter ranges have more pulses to detect and that results in greater sensitivity at lower distances. I do not know if that is the way the R20 is built or not. You might be able to tell if you watch the current used by the radar. If it increases when you change to lower ranges, that would indicate that it does. If you can slew the received range as you describe, your sensitivity may be reduced as a result. It would require a reduced rep rate to do that. Have you noticed any difference in sensitivity before and after the jumper change? BTW, which board are you referring to - the one in the control unit or the one in the scanner? As to your Grenada experience, I am not arguing with you. I just do not have any such experience and do not want someone new to using a radar to expect this to work for them.
pulse repetition frequency also called rep rate. It is the frequency of the pulsing of the transmitted radar signal. Do not confuse this frequency with the frequency of the radar itself. The range of the radar is necessarily limited by this rep rate frequency. The larger it is, the less the range. If you are to see a reflection at a longer distance, it takes the signal a longer time to travel that distance. It is significant because if you double the range, you will reduce the transmitted pulses and therefore the (theoretical) sensitivity by half. I believe that most small boat radars change the rep rate when you change the range. Therefore, shorter ranges have more pulses to detect and that results in greater sensitivity at lower distances. I do not know if that is the way the R20 is built or not. You might be able to tell if you watch the current used by the radar. If it increases when you change to lower ranges, that would indicate that it does. If you can slew the received range as you describe, your sensitivity may be reduced as a result. It would require a reduced rep rate to do that. Have you noticed any difference in sensitivity before and after the jumper change? BTW, which board are you referring to - the one in the control unit or the one in the scanner? As to your Grenada experience, I am not arguing with you. I just do not have any such experience and do not want someone new to using a radar to expect this to work for them.
Patrick,
The MB is in the control head. You are obviously technically trained with these machines. I would never attempt to modify my system. The jumper trick was pointed out to me by a Raytheon technician who came to the boat when I was newly installing it. Nothing is being changed except the 'turning on' of the 32 mile range ring. Raytheon has since discontinued that service and in fact, most all service. And I have not noticed any power variation. I didn't know to look but I will now. Thanks. And I've never turned the unit on without the jumper being set for 32 miles.
The MB is in the control head. You are obviously technically trained with these machines. I would never attempt to modify my system. The jumper trick was pointed out to me by a Raytheon technician who came to the boat when I was newly installing it. Nothing is being changed except the 'turning on' of the 32 mile range ring. Raytheon has since discontinued that service and in fact, most all service. And I have not noticed any power variation. I didn't know to look but I will now. Thanks. And I've never turned the unit on without the jumper being set for 32 miles.
- Status