I have read the posts in the archives and wanted to get the groups updated point of view. I am thinking of installing the Raymarine RL70CRC Radar / Chartplotter system for my cockpit pedestal. I am debating on installing the pole radar dome vs. the mast dome option. We have a 46' Morgan....would installing the mast option requirer unstepping the mast? How high does the dome need to go?? How is dome interference with tacking? Does anyone have an opinon on this vs the furuno systems. We sail mostly in the chessy but have taken a few trips to RI and the fog has basicly made me nervous enough to start this purchase. Starting my legwork. Thanks Rob
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J
Jack
I have RL70CRC
Rob, We have the Raymarine RL70CRC on our pedestal. The dome is about 1/2 to 2/3 the way up the mast of our Catalina 350. Have never had a problem with it during tacking. I can't address your other questions re. Furuno or unstepping the mast. Good luck! Jack s/v Friendship C350, #80
Rob, We have the Raymarine RL70CRC on our pedestal. The dome is about 1/2 to 2/3 the way up the mast of our Catalina 350. Have never had a problem with it during tacking. I can't address your other questions re. Furuno or unstepping the mast. Good luck! Jack s/v Friendship C350, #80
R
RonD
Rob I have the older Raytheon RL70RC chartplotter on my C320; it uses the C-MAP NT charting modules. It is a B&W chartplotter integrated with my radar & GPS, as well as the other wind, speed, depth instruments and autopilot. All systems were factory installed. The integration of these systems on-board is generally non-trivial. The current NMEA interface bus standards are voluntary and interpreted liberally by manufacturers. Raytheon (now Raymarine) uses their own bus standard as well. In general, it is better to purchase compatible systems from the same manufacturer. Raymarine systems have a good reputation for working well together. I have no experience with the Furuno systems. My preference is mast-mounting. It is generally mounted on the forward side about 1/3 to 1/2 way up. If you have a deck-stepped mast, you'll most likely have to un-step it to install the cabling. From a maximum radar range perspective, there isn't much difference between that type of mast mounting and pole mounting. I have had my jib snag on the radome once or twice. Generally, that occured only while tacking in very light air when my crew's timing on pulling the jib sheets was a tad off. You can install a radome guard fence if that is a problem. Pole mounting unfortunately places the cockpit & crew inside the near-field radiation pattern, and consequently exposed to higher levels of radiation for longer periods of time. Quite frankly, not enough is known or understood about the effects of low-level RF radiation on the human body (current Gov't RADHAZ standards are based on the gross near-term effects -- essentially heating of surface tissue -- rather than deeper, low-level cumulative penetration into the organs). My preference is to have the chartplotter mounted where the helmsman can use it -- on the pedestal. If you have the $$ and want the convenience, you can install a slaved display below at the Nav Station (I do have the Raymarine ST60 Multi-Display unit there to read wind, speed, depth, lat, long, temp, etc. while plotting positions during a passage. Very convenient.) The chart database modules are "extras" and aren't cheap, so look closely into whatever charting technology is used by the chartplotter manufacturers under consideration. The C-MAP NT (and the new NT+) chart database modules used by Raymarine are pretty good in my experience. You can join the C-MAP Club and get annual updates, use their "lease" program for short-term trips outside your module coverage areas, etc. This past Summer we left Plymouth, MA in pea-soup fog (about one boat-length visibility) and stayed in it all the way north until we reached the center of the Boston traffic separation area. It was GPS & radar all the way; that chartplotter was a real help in maintaining position & situation awareness. I still kept my hand-held GPS on & tracking as a backup though ... Good luck --RonD
R
Rob
Ron and ljack! thank you
Excellent feedback! I was looking at buying the package RL70CRC Raynav300 DSM250 w/transducer, 2kw 18"dome maybe add the second rl70 next year. Im a pretty go DIY er but is this something I should hire a tech to calibrate?? thanks Rob
Excellent feedback! I was looking at buying the package RL70CRC Raynav300 DSM250 w/transducer, 2kw 18"dome maybe add the second rl70 next year. Im a pretty go DIY er but is this something I should hire a tech to calibrate?? thanks Rob
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neil brand
Radar mount
The calibration is definetly a job best left to a professional. As to the mounting. We mounted a seperate pole at the stern for the radar. The advantages are that if service is needed, I need only to lower the unit for a technician,and no need to climb the mast. I also use the pole to add a lifting davit for my dinghy.additionally, it makes no sense to me to add weight up the mast. Most sailors make every effort to reduce weight aloft. All, just my opinion
The calibration is definetly a job best left to a professional. As to the mounting. We mounted a seperate pole at the stern for the radar. The advantages are that if service is needed, I need only to lower the unit for a technician,and no need to climb the mast. I also use the pole to add a lifting davit for my dinghy.additionally, it makes no sense to me to add weight up the mast. Most sailors make every effort to reduce weight aloft. All, just my opinion
R
RonD
Additional Notes
Concerning the Radome you select: For a sailboat the physical constraints of location dictate a radome type system (versus a linear horizontal array). Raymarine makes two models of radome arrays: an 18inch/2KW and a 24inch/4KW. For a recreational sailboater, getting the lowest receiver noise figure and the narrowest horizontal beamwidth are the driving technical considerations as they enable the ability to spot and discriminate small targets. A higher transmit power can help see small targets at a given range, too. The 18inch model has a 5.2deg horizontal beamwidth; the 24inch has a 3.9deg horizontal BW. Both have the same receiver noise figure. Probably not a lot of difference when you do the triginometry; consider at a range of 1nmi, that beamwidth is a difference of 546ft (18inch) vs 409ft (24inch); not a whole lot of discrimination to be had! Given where we mount the radomes on recreational sailboats, you are not likely to see much out to the maximum theoretical ranges they advertise. At 9 GHz, treat range as you would optical line-of-sight; from your deck you probably can't see further than 3-3.5 nmi; at 20 ft up from your deck, that may extend out to 8 nmi or so. Concerning mast vs pole mounting the physics is that of a weight on a pendulum arm: a turning moment is essentially weight x distance (in foot-pounds). If you have about 16 lb (18inch radome plus hardware) at the end of a 10 ft pole that's about 160 ft-lbs ignoring the weight distribution of the pole. For 1/3 of the way up a 60 ft mast, that is 320 ft-lbs. Compare that to the weight-distance of the mast, rigging, sails, etc. and it is probably quite small. On a boat of your size, I doubt if the mast mount will seriously affect your stability (certainly hasn't affected mine on a smaller (32ft) vessel). Further, the mast tends to be closer to the pitch & yaw rotational centers on the boat, and directly over the roll rotational center. A stern pole mount is often located at a corner rather than at the transom center. That adds something to unbalance the pitch, roll, and yaw equations. Probably not a lot, but something. So, I feel the 18inch radome model makes the best economic sense on a recreational sailboat. The 24inch radome might be practical on larger vessels that go faster, hence need more range to enble anti-collision decision making, providing they can mount them higher to achieve that range. And, as I indicated in my previous post, I prefer the mast mount for safety reasons. --Ron
Concerning the Radome you select: For a sailboat the physical constraints of location dictate a radome type system (versus a linear horizontal array). Raymarine makes two models of radome arrays: an 18inch/2KW and a 24inch/4KW. For a recreational sailboater, getting the lowest receiver noise figure and the narrowest horizontal beamwidth are the driving technical considerations as they enable the ability to spot and discriminate small targets. A higher transmit power can help see small targets at a given range, too. The 18inch model has a 5.2deg horizontal beamwidth; the 24inch has a 3.9deg horizontal BW. Both have the same receiver noise figure. Probably not a lot of difference when you do the triginometry; consider at a range of 1nmi, that beamwidth is a difference of 546ft (18inch) vs 409ft (24inch); not a whole lot of discrimination to be had! Given where we mount the radomes on recreational sailboats, you are not likely to see much out to the maximum theoretical ranges they advertise. At 9 GHz, treat range as you would optical line-of-sight; from your deck you probably can't see further than 3-3.5 nmi; at 20 ft up from your deck, that may extend out to 8 nmi or so. Concerning mast vs pole mounting the physics is that of a weight on a pendulum arm: a turning moment is essentially weight x distance (in foot-pounds). If you have about 16 lb (18inch radome plus hardware) at the end of a 10 ft pole that's about 160 ft-lbs ignoring the weight distribution of the pole. For 1/3 of the way up a 60 ft mast, that is 320 ft-lbs. Compare that to the weight-distance of the mast, rigging, sails, etc. and it is probably quite small. On a boat of your size, I doubt if the mast mount will seriously affect your stability (certainly hasn't affected mine on a smaller (32ft) vessel). Further, the mast tends to be closer to the pitch & yaw rotational centers on the boat, and directly over the roll rotational center. A stern pole mount is often located at a corner rather than at the transom center. That adds something to unbalance the pitch, roll, and yaw equations. Probably not a lot, but something. So, I feel the 18inch radome model makes the best economic sense on a recreational sailboat. The 24inch radome might be practical on larger vessels that go faster, hence need more range to enble anti-collision decision making, providing they can mount them higher to achieve that range. And, as I indicated in my previous post, I prefer the mast mount for safety reasons. --Ron
H
Harry Greenspun
We've got that system
Rob, We've got that system with displays on the pedestal and at the nav station on our Hunter 456. Radome is on the mast and hasn't interfered at all. Since we have an entirely Raymarine system, it's very well integrated. One point (which is a bit irrelevant since you're starting off with one unit) is that in the Raymarine sytem, a few advanced radar functions (like guard zones) can only be done on the display which is attached to the radome. The system has worked great for us. It is very easy to use, pretty intuitive, and has good visibility. Harry Harry Greenspun, MD Bethesda, MD Hunter 456 - "Czech Mate" harry@greenspun.com
Rob, We've got that system with displays on the pedestal and at the nav station on our Hunter 456. Radome is on the mast and hasn't interfered at all. Since we have an entirely Raymarine system, it's very well integrated. One point (which is a bit irrelevant since you're starting off with one unit) is that in the Raymarine sytem, a few advanced radar functions (like guard zones) can only be done on the display which is attached to the radome. The system has worked great for us. It is very easy to use, pretty intuitive, and has good visibility. Harry Harry Greenspun, MD Bethesda, MD Hunter 456 - "Czech Mate" harry@greenspun.com
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