MacGregorSailors.com

I have a 96 X, and installed a Furuno 16 mile radar, which performed fairly well the last month. I formed two mount locations for it, 1 hung from the lower mast shroud bolt, the other from the old transom mounted support crutch brackets on the starboard transom. Having the unit on the mast is nice except when tacking and having to backwind the furling jib (which I have to do anyway, just farther,) The problem with this location is the signal bloom from the mast, on close ranges, reflections from the mast degrade signal...... (especially on the narrow little fog shrouded channels with heavy currents it seems) and the alternate location in the old (non pedastal match crutch) seems sorely understrength for an 8 ft. pole holding a 1.5 lb bracket and 11 lb radar. thre less signal bloom on the display, but some forward sensitivity is lost from mast blockage.

So, what have all you other techno savy individuals done to improve radar placement on the 26 X, my other ideas are just getting wilder for placement

does anywone make an arch that clears the full bimini enclosure, or perhaps a large u shapped arch over the transom..inline with the back stay??

btw, Never put in a lectrasan treatment toilet system without having a manual backup. Lightning is not the only destroyer of electronics......lol

I have the JRC 1500. I mount mine on the mast @ the baby stay holes using 2 homemade ss pins. (I drilled an extra set of holes in the mast.) At this height, I can install the unit when I need it or leave it below deck if I want it out of the way. Takes only about 1 minute to install and tie off the cable. Even at this level, it still seems to reach the 16 miles and the headsail slides by with little problem. No problems on the screen; even occasionally picks up those floats on lobster/crab traps.


My mount is homemade too. I bent a small square plate of ss into a crescent shape that fitted to the front half of the mast. Then welded an arm to the plate to hold the radome. Drilled the holes in the plate to match the holes in the mast and installed with the pins.

I don't know a lot about radar, but wouldn't "what's safe" be as important as "whats successful"?
I think being in a direct line with a ships radar beam, at short range, can be fatal. So, I would think you would want it to be above anyone going on deck.
I may be wrong on this, and maybe a radar the size used on a Mac isn't unsafe, but I hope someone jumps in here with safety precautions. Thanks

Bill, My experience has been around large military radars for most of my life, but the physics is the same for these small radars. They are pulse radars which means they send out a small burst of energy and spend most of the time listening for the reflected signal to return. A 16 mile radar may have a peak signal of 2 or 3 kilowatts but that is only for a few milliseconds and the listen time is 20 to 50 times the pulse duration thus the root mean square or average output power is very small. It is the average output power that you need to be most concerned with. The beam pattern is fairly narrow in azimuth but spreads out to something like 20 or 30 degrees vertically, thus there is a great deal of beam dispersion as well. The beam rotates at something like 20 RPM therefore the beam pattern does not dwell long on anyone direction. These small radars depend on receiver sensitivity rather than transmitter power to achieve their effectiveness. I suspect the field strength in the main lobe of one of these small radars is not much more that that found at a similiar distance from a VHF antenna transmitting at 25 watts. The hazard should not be totaly ignored but since the field strength is inversly proportional to the square of the distance from the antenna any installation on the mast should be perfectly safe and any installation near the cockpit above head height shoud pose no RF radiation hazard. Hope this helps. John L

Bill at BOATS 4 SAIL wrote:I don't know a lot about radar, but wouldn't "what's safe" be as important as "whats successful"?
I think being in a direct line with a ships radar beam, at short range, can be fatal.

I've had my radar beeeeam mmmouhted just aft of m y pedesstal for fiiiive yeeeeears now with no adverrrrrsse afffects whatso ever!

I jssssut don't see whyyyyy it issss such a bigggg deealll.
Doooo YYoouuu?

You just gotta luv Frank's reply I was thinking of just getting a reflector so that I can be seen by bigger ships like ferries. I'm not really sure that I would need radar itself.

Depends where you sail. I was out at Penobscott Bay this summer. Every day dense fog in the morning and evening. Got caught a couple of times in less than 100 ft visibility. Eventhough I had a radar refector, it still is a scary feeling not to see anything.

We had one occasion that the GPS told us we were in Camden harbor but could not see anything until we almost ran in to anchored boats. Radar would have been great.......

I'm not a radar expert either, but have had a lot of physics classes.
The thing that concerns me about high frequency radar (microwaves) is that the waves are such that they tend to influence organic molecules. That's why they work well in microwave ovens i think. The particle nature of radiation (part of that duality stuff) dictates that the photon energy is E=h V . or solely dependant on the frequency or wave length and not the intensity. If you imagine the DNA lattice as a bunch of marbles held together by rubber bands, and you shake the lattice hard enough, (such as could occur from a weak resonance tuned wave), the marbles break the bands (chemical bonds) and rearrange. (mutation) . If the mutation is self replicating, then you may get cancer from it. You don't have to shake the lattice all day, just long enough to cause the mutation, which when viewed on a molecular time scale, can be a very short time period. But then it is like playing a long shot in roulette. even if all the conditions are right, there is no guarantee the marble will land on a certain number.
I think the danger may not be realized due to lack of direct rapid cause and effect measurablity, and simply some people will get cancer and there will be no direct evidence linking it back to the cause.

Cell phone safety probably falls in this category as well. I'm not sure if the frequency of cell phones is in the same ballpark or not. But I know radar will cook meat nicely. In the early days of navy radar, some sailor in the north atlantic stood in front of the radar dish to stay warm. It basically cooked his insides and he died of massive hemorraging that evening.

I'm sure the newer small boat radars are safer (pulsed and weaker) output than this old case, but still, how long would you like to stand in front of an operating microwave oven with the door open? No amount of exposure is totally safe in my opinion, including what hits you from the boat that is going by you with his set operating. The odds may be very low of mutation, and may take years of exposure to provide significant risk, but I think there is some chance.

Just my opinion. If I was installing radar on my boat, I would put it up pretty high to try and minimize exposure. But then, the weight you are putting up there will hurt sailing performance.

I too have concerns with the safety factor of radar. I felt mounting it 6 feet above the "upper" deck should avoid exposing anyone in the cockpit, yet keep the few extra lbs. low enough not to affect sailing "performance". Since I'm cheap and these things are only good for so many hours, I only use it when I really need it and then switch it off.

Radar was one of the first expensive mods I made and have not regretted it. It has led me around thunderstorms, shown me rusted ball bouys, and allowed me to anchor in unlit crowded harbors at night. It replaces the lost depth preception (white lights @ night). Since I sail more offshore (+/- 100 mi.) and sometimes at night, I would hate to give it up. Combined with the GPS, sounder, and compass, it's like flying IFR, only sailing. And with the zone alarm, it will let you know if anyone comes near your boat--great if a boat with a dragging anchor decides to attack yours.

Reflectors will help you to be seen, but radar will give you sight.

I fly with a moderately powerful radar (APG-65) between my legs that has significantly more power than a marine radar. (I am done having children ). I am behind the transmitter so that does reduce the radiation I receive quite a bit. I have been on ships where if you tried to video tape the tape would record static every time the ships radars swept your direction. I don't think a 16nm marine radar will have enough power to do damage to an adult. I think continuous exposure in the main beam (not the sidelobes) may not be too good at very close ranges.

I have my JRC 1000 16nm radar mounted on the starboard transom area high. It is above my height (6'1") in the cockpit. I am in the main beam when I go forward on top of the cabin. The PEAK power output of my radar is 1.5kw and the beamwidth is 7 deg horizontal by 30 deg vertical. The further from center the less the power.

Having said that I looked around for info on Marine Radar safety. I found this informative Australian ad :

Marine Radars Mounted on Small Craft


Introduction
Many small marine vessels such as pleasure craft, police launches or fishing boats are equipped with a navigational radar of modest power (up to 10 kW). Given the small size of these vessels, the radar antenna is sometimes mounted in close proximity to areas accessible to persons either on the boat itself or on nearby structures (e.g. a jetty). It is possible, although not probable, that these persons may be exposed to levels of microwave radiation above the recommended limits.


What is a Radar?
A radar emits short pulses of microwave radiation, which, like light, is reflected by obstacles. The radar detects the reflected pulses and, from the time delay between the emission of the pulse and the arrival of its reflection, calculates the distance of the obstacle. This process is repeated in every direction as the antenna scans the horizon. The resulting information is displayed on a fluorescent screen as a 360o pictorial representation of the area surrounding the craft.




Are Microwaves Hazardous?
They can be if the intensity is sufficiently high. Microwaves are absorbed by living tissue and their energy is converted to heat that may easily damage some organs, particularly the eyes, which may develop cataracts. It has also been shown that long-term exposure to low levels of microwave radiation can induce a variety of physiological effects in small laboratory animals. The importance of these effects and their relevance to the case of human exposure are not yet fully understood. Microwaves may also interfere with cardiac pacemakers.

The maximum safe levels of exposure to microwaves are specified by the ARPANSA Radiation Protection Standard - "Maximum exposure levels to radiofrequency fields - 3kHz to 300GHz" Persons on or about the craft, other than personnel specifically involved in the installation or maintenance of the radar should not be exposed to average levels higher than 10 W/m2 or to peak levels exceeding 10,000 W/m2.




What are the Radiation Levels Associated with these Radars?
Obviously they vary according to the particular make and model. However, calculations based on information supplied by the manufacturers and measurements carried out by this and other laboratories(1) indicate that at 1 metre from, and at the same height as the antenna, peak levels of approximately 0.5 W/cm2 may be encountered. The average intensity may be between 0.5 and 0.8 mW/cm2, when the antenna is stationary. The average intensity drops to safe levels (i.e. below 0.2 mW/cm2) at a distance of several metres from the antenna. At points above or below the horizontal plane containing the antenna, the radiation level is lower than that measured at a corresponding point on that plane. However, it must be noted that the radar has a rather large vertical beamwidth, i.e. microwave radiation is beamed also above and below the horizontal plane. This allows the radar to track obstacles on the water surface even during strong rolling movement of the vessel. At 1.5 metres from the antenna and 50 cm below the antenna level, the average intensity can still be in excess of the 0.2 mW/cm1 limit.

During normal operation the average exposure is reduced, because the radar antenna rotates and a person is exposed only when the beam sweeps past.* For example, a person standing one metre away from a 1.2 m (4') rotating antenna is exposed to less than 20% of the average radiation level in the beam.




Safe Practice
Exposures to microwave radiation above the recommended limits are most likely in the immediate vicinity of the antenna when it is stationary. When the antenna is rotating, as required for normal operation of the radar, average exposure is below the recommended limits, even at points as close as one metre.

Some radars are designed to prevent microwave emission unless the antenna is rotating. Other models, however, lack this safety feature. In these cases some care is required on the part of the operator to prevent unnecessary exposure of personnel. Operating procedures should be adopted which ensure that no microwave radiation is emitted except when the antenna is rotating.

A rule of good practice which applies to all small marine radars is that equipment should be turned off when not required, particularly in areas of high population density (e.g. at dockside).




References
1. D W Peak, D L Conover, W A Herman, R E Shuping - "Measurement of power density from marine radar." US Dept of Health, Education and Welfare publication (FDA) 76-8004, 1975.


* The average exposure is reduced by a factor equal to the ratio between the beam width at the exposure distance, and the scan circumference at that distance (at short distances the beam width is equal to the antenna size).

I also found this on the SAAB site for small radars:

Most international standards state that a power density of up to 1 mW/cm2 is considered safe for continuous exposure.

As a comparison it might be interesting to know that in sunshine you are exposed to a power density of 100-150 mW/cm2.

Having said all that I think the amount of time we, as recreational marine radar users, spend around the transmitter should be fine within reason. (Not standing right in front of the transmitter inside a few feet for a long time). I think you would have to spend a lot of time in front of the radar at close range to see long term effects.

My concern is my 14 month old child. I feel comfortable keeping her in the cabin or below the transmitter during operation. I also will not use the Radar (Stby or Off) unless I need it when she is on board as I think a developing child is at more risk from the potential damage. It may be nothing, but I don't want to take the chance with her. I have only used my Radar once anyway to make sure it works (installed by PO)- I am too busy with other things - usually single handing boat while wife takes care of kids. I get enough fun with Radars at work anyway.

Jeff S

Since I will be spending most of the summer in the NW, how much need is there for a Rader? I found the JRC 1500 for $750 on the web. It seems the fog clears about noon. A lot of money for little use.

BK, Many of the the beautiful places in the Northwest experience considerable offshore weather conditions resulting in the formation of a fog every morning.(And no useable wind.... yuk) especially the west side of Vancouver Island in August, Olympia and Shelton forever, and Straights of Juan de fu@. v(Or the funnel as it is sometimes called). Admittedly this is generally fog with calm seas, (the fog and rough seas being limited in most cases to the non summer months. But that is when the reliable winds are also.

Since i use my mac to actually travel distances, there is not a month of the year that doesnt seem to justify using radar at some point in a 300 mile trip. Secondly, It gives you a few more hours of travel time per day in the shoulder seasons such as now. It is dark a little after 7:00 and I can keep going to my planned destination, cruising safely to my anchorage.

Maybe I am chicken, But the ability to see better in fog and night, seems to be worth it.

And as far as the JRC......

Close inspection of both side by side, and or operating(without a West marine clerk standing over your shoulder, telling you to put that screwdriver and pliers away) is difficult.

But what sold me, was how much better the Furuno operated in the rain and rough seas,for about the same cost. (required asking around and riding with those that had either on a nasty day, its amazing how many boats with radar rarely go out) The processing of the return signal is critical for target definition, and I think Furuno (even tho the electronics may have been made or designed by the same outfit) handles clutter, rain, and rough seas a little better. And the display seems a tad more adjustable. I believe the Furono is also a little higher output power.

For either of them tho, it will take a while to get really quick with the menus, Since I never take the manual on deck (Its a guy thing).

The argument I hear for radar from other sailors is....It takes us longer to get anywhere, and the weather is going to change, so be ready.

Staying out is much more comfortably in the mac, than in my good weather power boat. And waiting till noon, takes half of my cruising away, (admittedly the noisy and stinky half, putt, putt putt.....lol)

Good luck in your choice. Fair winds to ya!