I am currently trying to decide how best to mount my new Raymarine Radar Antennae. My boat is 40 foot. I sail in the busiest shipping lanes in the world, so wish to ensure that when needed, the radar picks up what is out there. I have read all kinds of reports on different kinds of radar mounts, but would like to hear what people who actually sail say about it. I am trying to decide cost/benefit of mast mounted vs radar pole mounted vs gimballed backstay mounted. Anybody have experience they would like to share?
- Status
KISS It
After going through (and beyond) a gimbaled one, I now have my Raymarine Pathfinder mounted on a Raymarine solid mount on the mast and have passed the Gulf Stream off South Florida many times and have seen every target well in advance, even in sloppy seas. Remember, the KISS principle works best on a boat. I assume that you are mounting the display head at the helm? Good!
After going through (and beyond) a gimbaled one, I now have my Raymarine Pathfinder mounted on a Raymarine solid mount on the mast and have passed the Gulf Stream off South Florida many times and have seen every target well in advance, even in sloppy seas. Remember, the KISS principle works best on a boat. I assume that you are mounting the display head at the helm? Good!
I went with a backstay mount
I chose a gimbaled backstay mount for my h40.5 with the display head at my helm. It was the lowest cost mounting option and allows me to remove the radar without yard help if needed. No extra charges by the boatyard for mast storage, more direct and easier routing of the antenna cable to the display. I think the gimbal mount is a real advantage and I would use one no matter where the antenna was mounted. I have a range to the water surface of about 4+ miles. I have found this to be adequate for picking up targets of interest. You really don't need to see a buoy at 6-10 miles away. Larger and higher ships and land are visible at longer distances. I routinely pick up tugs and barges and other large ships at 6+ miles. Mounting up on a mast gives a bit more range, but that range is not really necessary. I use my radar on 1.5 and 3 mile range at most times except in harbors where I use 1/4 mile or less. Rain storms are easily visible on 24 or 48 mile ranges.
I chose a gimbaled backstay mount for my h40.5 with the display head at my helm. It was the lowest cost mounting option and allows me to remove the radar without yard help if needed. No extra charges by the boatyard for mast storage, more direct and easier routing of the antenna cable to the display. I think the gimbal mount is a real advantage and I would use one no matter where the antenna was mounted. I have a range to the water surface of about 4+ miles. I have found this to be adequate for picking up targets of interest. You really don't need to see a buoy at 6-10 miles away. Larger and higher ships and land are visible at longer distances. I routinely pick up tugs and barges and other large ships at 6+ miles. Mounting up on a mast gives a bit more range, but that range is not really necessary. I use my radar on 1.5 and 3 mile range at most times except in harbors where I use 1/4 mile or less. Rain storms are easily visible on 24 or 48 mile ranges.
Attachments
Go gimbaled
We had the same backstay mount as Rich on our O'Day. Our new boat has no backstay so had to rethink the process, but went with a Waltz gimballed mast mount. I don't see a lot of difference in target range (especially since we seldom look beyond 3-6 miles), but would never go to a fixed mount for the simple reason that at some point when healing with a fixed mount your radome is bound to be trying to scan the skies or the underwater action - neither of which will help you in busy shipping lanes. For us, it is well worth the extra money to know that when we need it the radar is "on the level" - the name of the backstay mount I believe! The backstay mount was actually pretty economical as I recall and we did the installation ourselves. The mast mount was more complicated and will cost us extra money when we haul and launch each year, but I still think for us it was the right move. Good luck whatever you decide.
We had the same backstay mount as Rich on our O'Day. Our new boat has no backstay so had to rethink the process, but went with a Waltz gimballed mast mount. I don't see a lot of difference in target range (especially since we seldom look beyond 3-6 miles), but would never go to a fixed mount for the simple reason that at some point when healing with a fixed mount your radome is bound to be trying to scan the skies or the underwater action - neither of which will help you in busy shipping lanes. For us, it is well worth the extra money to know that when we need it the radar is "on the level" - the name of the backstay mount I believe! The backstay mount was actually pretty economical as I recall and we did the installation ourselves. The mast mount was more complicated and will cost us extra money when we haul and launch each year, but I still think for us it was the right move. Good luck whatever you decide.
Beamwidth rules
The beamwidth specs for your antenna should determine whether you need to gimble or not. Most radar antenna units used on boats are physically small (size & weight) and therefor have fairly broad beamwidth characteristics (in both azimuth and elevation relative to the sea level). The azimuth beamwidth will limit the resolution of individual targets at any distance; the elevation beamwidth sends signal into the water & sky, but that works for you when heeled over. They are also limited in transmit power & receiver sensitivity, more or less matched to the antenna limitations, which equates to relatively short range usage (more on that below). That said, unless you regularly sail while heeled over 15 degrees, it won't matter a whole lot if the antenna is gimbaled or not. Logically then, I would be more concerned about location and physical mounting & cabling needs. Here the much vaunted KISS principle applies (right on, Bob!). My first criteria would be to keep the radar transmitted signal as far from people as possible. The effects of electromagnetic radiation on biological systems is not an exact science. The existing government standards deal with gross tissue heating effects (the levels associated with microwave oven usage, for instance). Very little is known about the long-term affects of this radiation at significantly lower power density levels (e.g., some scientists are getting nerveous about cell phone usage now, and there has been a vocal concerned group about high voltage powerline radiation). Since these antenna have very broad beamwidths (in both azimuth and elevation) placing them anywhere people are congregating is bound to expose them to some low-level radiation. The second criteria would be to gain some height (not a lot) and an unobstructed forward view (generally you are more concerned about what is ahead rather than what is behind). Radar signals are basically line-of-sight limited so earth curvature is a limiting factor in range. Once you get high enough to be clear of on-board obstructions and to reduce radiated field strength to same levels (say over 12 feet) you don't gain much in terms of range by going higher (use radar antenna height in the same navigation tables for determining maximum distance to see a light at 3 foot height over the water -- probably not much more than 15 nmi, if that much). For that reason, you rarely see radar antennas mounted more than 1/3 of the way up a mast. The more weight (Mass) mounted higher on the mast (Distance) creates a bigger turning moment (Mass x Distance) that affects stability. The mast can typically support the weight at that limited height without any problem. You do need to watch the jib during tacking, however. I found that mine has caught on the antenna once or twice while tacking in light air. I'm personally not in favor of sticking the antenna on a stern mounted pole or backstay. Stern poles add more holes, hardware & stresses in your hull. To do a backstay mount, I'd consider the extra mass x distance loading factors on the wire backstay and maybe relace it with something heavier (consult a competent rigger or marine architect). Good luck --Ron
The beamwidth specs for your antenna should determine whether you need to gimble or not. Most radar antenna units used on boats are physically small (size & weight) and therefor have fairly broad beamwidth characteristics (in both azimuth and elevation relative to the sea level). The azimuth beamwidth will limit the resolution of individual targets at any distance; the elevation beamwidth sends signal into the water & sky, but that works for you when heeled over. They are also limited in transmit power & receiver sensitivity, more or less matched to the antenna limitations, which equates to relatively short range usage (more on that below). That said, unless you regularly sail while heeled over 15 degrees, it won't matter a whole lot if the antenna is gimbaled or not. Logically then, I would be more concerned about location and physical mounting & cabling needs. Here the much vaunted KISS principle applies (right on, Bob!). My first criteria would be to keep the radar transmitted signal as far from people as possible. The effects of electromagnetic radiation on biological systems is not an exact science. The existing government standards deal with gross tissue heating effects (the levels associated with microwave oven usage, for instance). Very little is known about the long-term affects of this radiation at significantly lower power density levels (e.g., some scientists are getting nerveous about cell phone usage now, and there has been a vocal concerned group about high voltage powerline radiation). Since these antenna have very broad beamwidths (in both azimuth and elevation) placing them anywhere people are congregating is bound to expose them to some low-level radiation. The second criteria would be to gain some height (not a lot) and an unobstructed forward view (generally you are more concerned about what is ahead rather than what is behind). Radar signals are basically line-of-sight limited so earth curvature is a limiting factor in range. Once you get high enough to be clear of on-board obstructions and to reduce radiated field strength to same levels (say over 12 feet) you don't gain much in terms of range by going higher (use radar antenna height in the same navigation tables for determining maximum distance to see a light at 3 foot height over the water -- probably not much more than 15 nmi, if that much). For that reason, you rarely see radar antennas mounted more than 1/3 of the way up a mast. The more weight (Mass) mounted higher on the mast (Distance) creates a bigger turning moment (Mass x Distance) that affects stability. The mast can typically support the weight at that limited height without any problem. You do need to watch the jib during tacking, however. I found that mine has caught on the antenna once or twice while tacking in light air. I'm personally not in favor of sticking the antenna on a stern mounted pole or backstay. Stern poles add more holes, hardware & stresses in your hull. To do a backstay mount, I'd consider the extra mass x distance loading factors on the wire backstay and maybe relace it with something heavier (consult a competent rigger or marine architect). Good luck --Ron
- Status