Heres a dumb question. I am considering removing my mast mounted radar, going to a backstay self leveling unit. I am tired of the genoa and spinnaker halyards getting fouled in the mast mounted unit as well. What to do with the holes in the mast when I remove the mount? Do I have to do anything special? Should I be concerned with cracks at these holes? Or just fill them with thickened epoxy, sand and touch up? All ideas appreciated. Thanks, RT
Howard Keiper
Moderator
Rob...
Give the move a lot of thought. I'm on the opposite tack so to say, having been very disappointed in the performance of the radar mounted on the backstay.I am seriously considering moving my radome up to at least the 1st spreader. You'd be amazed what an extra 10' or so can do for the display presentation.
howard keiper
berkeley
Give the move a lot of thought. I'm on the opposite tack so to say, having been very disappointed in the performance of the radar mounted on the backstay.I am seriously considering moving my radome up to at least the 1st spreader. You'd be amazed what an extra 10' or so can do for the display presentation.
howard keiper
berkeley
treilley
Sustaining Partner
Doing a lot of racing it was important for me to mount my radar on the backstay. I built my own backstay mount(not self leveling yet) but I am very happy with it's performance. It is about 13 ft. above the cockpit sole. I originally had a Furuno 1621 that died this season so I replaced it with a Garmin GMR18. They both work great from that position. I am sure I am not getting the same amount of range but for near shore cruising, it is enough. If I were to go offshore, I would mount on the mast and get a larger radome. Another benefit of the backstay mounted radome is the mast creates a smaller shadow. Of course, now the shadow is in front of you but I have never had any problems seeing objects directly in front of me even at close range.
Filling with thickened epoxy and sanding/painting is a good way to fill the holes. This is how I did it when I repainted my mast last winter.
Filling with thickened epoxy and sanding/painting is a good way to fill the holes. This is how I did it when I repainted my mast last winter.
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Rob,
There is past discussion in these archives about locating the radar... you might want to do some searches. Try the generic terms like -radar- and then try by brand.
We have the antenna on a stern pole. It works fine for us.
"YMMV"
Loren in PDX
ps: here is one such thread, with a very quick search on -radar mount-
http://www.ericsonyachts.org/infoexchange/showthread.php?t=2024&referrerid=28
There is past discussion in these archives about locating the radar... you might want to do some searches. Try the generic terms like -radar- and then try by brand.
We have the antenna on a stern pole. It works fine for us.
"YMMV"
Loren in PDX
ps: here is one such thread, with a very quick search on -radar mount-
http://www.ericsonyachts.org/infoexchange/showthread.php?t=2024&referrerid=28
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Dave Hussey
Member III
mast holes
As for the holes in the mast...I used JB WELD epoxy, which seems to have held up so far, (only one year though)
Does anyone have knowledge on filling holes (around 1/4 inch size) by welding, or should that be avoided: would it cause heat related problems (annealing of the alloy, or other)...
As for the holes in the mast...I used JB WELD epoxy, which seems to have held up so far, (only one year though)
Does anyone have knowledge on filling holes (around 1/4 inch size) by welding, or should that be avoided: would it cause heat related problems (annealing of the alloy, or other)...
Thanks for the replies! Kinda what I figured on the filling/sanding routine.
Regarding the halyard comment the halyards are all internal. The spinnaker halyards get fouled sometime when prepping or retrieving the A sail-in-a-sock. Just a pain sometimes.
Lastly, I have considered the difference in performance that reducing the height of the radome can make. I have sailed in some heavy fog this summer and was quite surprised when a few small powerboats failed to show up on the radar and popped up right in front of us, say less than 50yards. I cannot say if this was a function of the heeling or the height of the current setup. The current system does work very well on large things like ferry's and big aton's. Consider this regarding the height of the radome. If you look at commercial boats, Sea Tow, and the smaller boats of the USCG there is not a lot of effort to place the radome as high as possible. Certainly not as high as the 1st spreader location. These applications all seem to work fine or they would have the units on towers, would they not? They seem to make do with just putting them on the top of the wheelhouse, etc. I have read all the posts regarding the pro's and con's of different locations and the gimbaled backstay mount seems to be the best idea for my application. Frequently here in RI the wind can blow quite strongly and with thick fog at the same time. I will likely opt for some extra height in the backstay mount to sorta split the difference. Thanks again, RT
Regarding the halyard comment the halyards are all internal. The spinnaker halyards get fouled sometime when prepping or retrieving the A sail-in-a-sock. Just a pain sometimes.
Lastly, I have considered the difference in performance that reducing the height of the radome can make. I have sailed in some heavy fog this summer and was quite surprised when a few small powerboats failed to show up on the radar and popped up right in front of us, say less than 50yards. I cannot say if this was a function of the heeling or the height of the current setup. The current system does work very well on large things like ferry's and big aton's. Consider this regarding the height of the radome. If you look at commercial boats, Sea Tow, and the smaller boats of the USCG there is not a lot of effort to place the radome as high as possible. Certainly not as high as the 1st spreader location. These applications all seem to work fine or they would have the units on towers, would they not? They seem to make do with just putting them on the top of the wheelhouse, etc. I have read all the posts regarding the pro's and con's of different locations and the gimbaled backstay mount seems to be the best idea for my application. Frequently here in RI the wind can blow quite strongly and with thick fog at the same time. I will likely opt for some extra height in the backstay mount to sorta split the difference. Thanks again, RT
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Radar performance
Hey Rob,
We have our RL9 radome on a stern pole that puts it about 10 ft. above the water. We are considering going higher with a new pole, or going to the mast mount when we get around to new standing rigging and mast wiring. We have an insulated backstay that we will preserve for marine SSB/ham radio, so we will not choose that otherwise attractive mount location. We like the leveling backstay mount, except for that.
On the 6 mile range setting, we are getting around 1/2 to 1 mile first hit range on small boats (less for those fiberglass skiffs), larger yachts get us up to 1.5 miles to figure out what to do. A large tug gave us around 2 miles. A Washington State ferry boat, which is about two stories tall, gives us 2+ miles. Height above water of the target is also important. Fast moving craft give us the most heartburn, because they move alot between sweeps. We consider this detection performance the minimum acceptable for our foggy wandering - an opinion we settled on after our trip this year when we had an exciting 4-1/2 hours crossing the Strait of Juan de Fuca. Keep in mind that we are not experts, this was our third experience in actual fog, with a couple other tests in good weather for practice. No way we would have done this without equal confidence in our chartplotter, because we have shipping lanes and sometimes narrow passes to deal with also.
There was no wind when we got this performance, so we think we got a good baseline on our radar with a level deck. I should go measure the height of the radome above the water. All else being equal, higher radome mounting should always be better if you can achieve it.
Now, there are other things that affect radar performance, including whether the operator is good at adjusting the various settings or is using Auto modes. We experienced heavy drizzle and some light rain, which also reduces detection range. One piece of advice I picked up in a magazine somewhere is regarding power output of the transmitter. Obviously, more is better for detection. Higher power should increase detection performance until you reach the horizon, anyway. Our RL9 provides 2KW peak output and we were in Auto Gain and I think it was at about 3/4 output. In retrospect I could have gone to higher Gain manually, but I am not sure how the auto functions interact to give the least cluttered display. Who knows what we were actually putting out as this is a 10+ year old unit and all electronics degrade with age.
It's going to be interesting to choose a new electronic navigation suite in a couple years.
Hey Rob,
We have our RL9 radome on a stern pole that puts it about 10 ft. above the water. We are considering going higher with a new pole, or going to the mast mount when we get around to new standing rigging and mast wiring. We have an insulated backstay that we will preserve for marine SSB/ham radio, so we will not choose that otherwise attractive mount location. We like the leveling backstay mount, except for that.
On the 6 mile range setting, we are getting around 1/2 to 1 mile first hit range on small boats (less for those fiberglass skiffs), larger yachts get us up to 1.5 miles to figure out what to do. A large tug gave us around 2 miles. A Washington State ferry boat, which is about two stories tall, gives us 2+ miles. Height above water of the target is also important. Fast moving craft give us the most heartburn, because they move alot between sweeps. We consider this detection performance the minimum acceptable for our foggy wandering - an opinion we settled on after our trip this year when we had an exciting 4-1/2 hours crossing the Strait of Juan de Fuca. Keep in mind that we are not experts, this was our third experience in actual fog, with a couple other tests in good weather for practice. No way we would have done this without equal confidence in our chartplotter, because we have shipping lanes and sometimes narrow passes to deal with also.
There was no wind when we got this performance, so we think we got a good baseline on our radar with a level deck. I should go measure the height of the radome above the water. All else being equal, higher radome mounting should always be better if you can achieve it.
Now, there are other things that affect radar performance, including whether the operator is good at adjusting the various settings or is using Auto modes. We experienced heavy drizzle and some light rain, which also reduces detection range. One piece of advice I picked up in a magazine somewhere is regarding power output of the transmitter. Obviously, more is better for detection. Higher power should increase detection performance until you reach the horizon, anyway. Our RL9 provides 2KW peak output and we were in Auto Gain and I think it was at about 3/4 output. In retrospect I could have gone to higher Gain manually, but I am not sure how the auto functions interact to give the least cluttered display. Who knows what we were actually putting out as this is a 10+ year old unit and all electronics degrade with age.
It's going to be interesting to choose a new electronic navigation suite in a couple years.
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Howard Keiper
Moderator
What's considered 'good' radar performance is strictly a matter of opinion. If 1.5 to 2 miles is adequate for some---so be it...perhaps it might be better to not rest comfortably thinking that because one has has radar one can relax under that condition.
Radar is most effective when it (the radome) has a broad, relatively unobstructed sweep of the horizon...how near or far that horizon actually is is a function of the radome's and the target's height above the water. My own antenna is backstay mounted and, at rest, is about 12 feet above the water. When heeled that drops to about 8-10 feet...gimbled or not, one does not get even reasonable performance at that height. But as I said earlier, performance is relative. If I can't get at least 12 miles, preferably 24 or more out of my radar, I might as well not have it.
Gain, in radar parlance, has nothing to do with output power...it has everything to do with targer acquisition and other things related to that on the receive side...not the transmit side.
howard keipe
Sea Quest
Berkeley
Radar is most effective when it (the radome) has a broad, relatively unobstructed sweep of the horizon...how near or far that horizon actually is is a function of the radome's and the target's height above the water. My own antenna is backstay mounted and, at rest, is about 12 feet above the water. When heeled that drops to about 8-10 feet...gimbled or not, one does not get even reasonable performance at that height. But as I said earlier, performance is relative. If I can't get at least 12 miles, preferably 24 or more out of my radar, I might as well not have it.
Gain, in radar parlance, has nothing to do with output power...it has everything to do with targer acquisition and other things related to that on the receive side...not the transmit side.
howard keipe
Sea Quest
Berkeley
Howard,
Thanks for the correction about radar gain - I did not know that the radar gain was changing receiver characteristics, rather than transmitter power.
I am not sure what point of the rest of your post was supposed to get across, but I did some more thinking about what I learned during that often nerve-racking crossing. It was not all that much fun. In fact, we decided not to take a chance on a repeat at the end of our trip. It's always nice to make it intact, but we did not want to go back out and potentially make the same mistakes.
Anyway, today I searched the Internet for 'distance to horizon' and according to horizon distance calculators, for a height above the surface of 10 feet (horizon = 3.7 nm) to detect something at 12 miles, the target would have to have a reflecting surface about 52 feet above the water (horizon = 8.4 nm). I calculate my max. visual detection distance of a 20 foot tall ferry is 3.7 nm + 5.2 nm = 8.9 nm. So, detecting that ferry at only 2.5 miles is pretty anemic performance. Some of the other factors at play are probably due to my radar's limitations, its installation, and the obstructions in front of it.
Best regards,
Thanks for the correction about radar gain - I did not know that the radar gain was changing receiver characteristics, rather than transmitter power.
I am not sure what point of the rest of your post was supposed to get across, but I did some more thinking about what I learned during that often nerve-racking crossing. It was not all that much fun. In fact, we decided not to take a chance on a repeat at the end of our trip. It's always nice to make it intact, but we did not want to go back out and potentially make the same mistakes.
Anyway, today I searched the Internet for 'distance to horizon' and according to horizon distance calculators, for a height above the surface of 10 feet (horizon = 3.7 nm) to detect something at 12 miles, the target would have to have a reflecting surface about 52 feet above the water (horizon = 8.4 nm). I calculate my max. visual detection distance of a 20 foot tall ferry is 3.7 nm + 5.2 nm = 8.9 nm. So, detecting that ferry at only 2.5 miles is pretty anemic performance. Some of the other factors at play are probably due to my radar's limitations, its installation, and the obstructions in front of it.
Best regards,
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