Garmin Radar Dome

[b393capt]

New Sailors and Radar

New to sailing and you have a radar ... good for you, just beware the term "radar assisted collisions" happens to newbies and experts alike.Some advise:1. Use the radar under power only, not while sailing, till you know one or the other skill cold. 2. Read "RADAR afloat" by Tim Bartlett. It's a short read, at 95 pages. Gives you enough information to play with your new toy. 3. Don't even think about using it in the fog, until you take a USCG class. The class is too short in my opinion. But if you read the book, and play with your own radar set before the class, the class will make a complete package.

 

[Brian D]

Welcome to the wonderful world of....

Sailing. And with it, a host of many individuals. After a short time, Bob, you will find who you can trust and who is talking out their shorts. For me, I am also still learning, both that is. The sailing and the who to trust factor.Enjoy the boat, enjoy the radar, enjoy the... Hey, get out of my way, damn weekend motorboaters! Oh... yeah... Hehehehe

 

[sailortonyb]

I Cant Believe What I'm Reading

People putting down a major piece of safety equipment? truth be known, most of them probably never sailed out of their bath tub."Radar Assisted Collisions"? Now that beats all. I have no idea wher some of these people read this stuff. "Dont think about using it in the fog unless you take a CG class"? Where do these things come from? Anyone who would suggest that radar is not necessary for a newbe never sailed at night, never got caught in a blinding rain and never got caught in fog.So, how much sailing do you think they have done? maybe back and forth in a small pond where land in never more than 10 feet away.I used to run Crew Boats and Supply Boats in the Gulf of Mexico. The weather didnt matter, we still had to make our runs. We worked 12 hrs on and 12 hours off, thru rain, fog , darkness and every other kind of weather imaginable in oil fields where you could hardly fit between platforms, and the bussiest boat traffic in the country. Some of our runs were 13 to 15 hours away, one way. Up until that point, most of us never used radar in our life. Its not that difficult. Read the instruction manuel that came with it. Use it all the time, no matter how clear the sunny day is. The major problrm with radar is the AUTOMATIC Rain Clutter and Sea Clutter. The word automatic is a joke. You must practice with YOUR radar to the point that you can adjust the rain and sea clutter manually without giving it a thought. That way, if the weather degrades , you dont panic.The other thing to keep in mind is in good weather, dont get too fixated on the radar. Glance at it from time to time. Look at targets and adjust your radar. It changes adjustment with weather cnditions, so everyday it seems different. Someday, hopefully not, you will be forced to steer by radar alone. That is if you decide to become a sailor and traveler.One more thing, try to sail with someone that has radar experience on their boat, you can learn alot. have fun and be safer.Tony B

 

[mortyd]

radar

you can't believe what YOU'RE reading? where the hell is your sense of responsibility, admiral?the guy writes he's EXTREMELY NEW to sailing so you and others jump right in and encourage him to sail in bad weather and at night. what are you people thinking about?how is your vast blue water experience going to help some guy, and the innocents he takes with him, if he probably never heard of 'red right returning' or an accidental jibe when he gets into trouble in the rain night with hysterical scared passengers on board? i am a certified flight instructor and by far the hardest thing flying teachers have to teach students is judgement and responsiblity, and you best believe an airplane commands lots more resepect than a sailboat and a pilot's license takes a lot more to obtain than some old cutter which only requires the money.am i glad there's a conitnent between many of you and me.

 

[Ross]

Bob, all of the debate here is from

people with years of sailing and at sea experience. I recommend that you gain a couple of years of experience when you have blue skies and daylight. Take the courses recommended, Play with the equipment, Learn how to use it in clear weather, then anchor out, in a safe place, away from the shippong channel, and wait for the dark and learn what the radar can do for you while you are safely anchored. It took a long time to train the radar operators in the Air Force that were expected to be able to keep track of several aircraft at one time from a ground station.

 

[abe]

this is a fun thread....happy sailing

nm

 

[sailortonyb]

Mortyd

I'm certainly glad that i never had a hysterical flight instructor like you. Maybe if you had better reading comprehension, you would understand what i wrote. No one here is encouraging a newbe "jump right in and sail in bad weather and at night" You are reading ahead of yourself and jumping to conclusions. These are things that he will do in the future. IF you had any balls at all, you would have left your bathtub at one point in your long sailing history and maybe got CAUGHT in bad weather. However, if you never leave the nest, then you dont have to worry.Your over reaction to things makes me think that you only sail 10 feet from the dock. Boats are safe in harbors, but that is not where they are meant to be. You on the other hand are possibly suggesting that IF he got caught in fog, that he turn OFF his radar?Did I read that correctlt? And you are a Flight instructor?What the hell do you fly? And what does red right returning and accidental jibes have to do with Radar? I fail to see the connection? Have you taken your medication today? I dont know what kind of flight instructor you are, but you certainly are CERTIFIABLE.I'm not impressed with your pilots license, if that is what you are using for your sailing credentials. I still fail to see the connection.As a Crew Boat Captain, i had as many as 70 passengers on board day and night that had to get back and forth safely. I'm very familiar with the water.Oh yes, the responsibility thing, you are responsible for discourageing people to use the latest technology in safety gear. One can sit at the dock and learn to use the radar, the same way one can learn to use a GPS in their living room. And one does not have to be wreckless to sail at night. You on the other hand have to squat to pee. If you would like to keep on with the insults, please be more coherent and show some relevancy.By the way, are you the one that Bob referred to as an ass? And yes, we too are glad that there is at least a half a continent between us.

 

[sailortonyb]

As for Ross...

I can respectfully disagree with Ross.

 

[R Kolb]

This is great stuff

My daughter is taking Abnormal Psychology at college. I am going to send her this thread for her class to study.

 

[mortyd]

radar

you got me, admiral - i really never did get out the bathtub; how on earth did you ever guess? i'd really like to know, when you have the time, how you managed to squeeze so much sailing knowledge, the ability to rate flight instructors from the written word, and perfect grammar into one lifetime.

 

[Honeyman]

One other point...

if radar is installed on a boat, it MUST be ON at all times to comply with Coast Guard regulations.

 

[patrick]

As to regs requiring radar to be turned on

I don't believe it. Can you cite a rule which requires that? Absent a citation, it is not true.

 

[Jerry Clark H356 SV Persistence]

No blind spot behind mast

There is no blind spot behind the mast for a mast mounted radar. Works fine 360 degrees.

 

[Ross]

Sailortonybob, You respectfully

disagree with what part of what I said?Written by sailortonybob"As for Ross... I can respectfully disagree with Ross." I covered quite a bit of territory in my post. Should he NOT gain some blue sky experience before he tries to sail in adverse condition?Should he NOT anchor out and see how the radar works while he is not moving?Did it NOT take a long time to train radar operator for military ait traffic service?Or, Do most of those responding to this thread NOT have many years of sailing experience and sea time?I respectfully await your reply.Ross

 

[sailortonyb]

Ross !!!

I agree with you in principal on just about everything except, unless I'm reading this wrong, I dont feel that someone needs sailing experience in order to use radar. Radar usage for the average sailor is not that hard to understand or use. There are a few basic things to keep in mind. One is, as i mentioned earlier, learning to tune it manually because the AUTOMATIC rain and sea clutter are not that good, even on the $10,000 units we use offshore. And the other really important item is we are brainwashed by old war movies as to what a radar screen should look like. The TV version leads one to believe that you have a nice clean screen with a sharp blip. In reality, you should have a slightly speckled screen, and this is mentioned in every owners manuel that i personally have seen. Cant swear about the stuff i havent seen.Lastly, I was Radar Certified when i last renewed my 100 ton Masters License. The 2 days of training didnt really cover anything that was not in owners instruction manuels. Radar definately takes practice.I fully agree with your statement "Learn how to use it in clear weather, then anchor out, in a safe place, away from the shippong channel, and wait for the dark and learn what the radar can do for you while you are safely anchored."Essentially , the only thing that i disagree with you is on the impression I get that you feel that someone needs lots of sailing experience prior to learning to use Radar, and i feel that they dont.When i first learned to sail, i was out on my 25 McGregor on a nice morning. All of a sudden, a dense fog bank (not forecast) came rolling in. I knew i was near a ship channel( thats just the way it is in Gulfport. A major ship channel is right next to the entrance to the small craft harbor). I had a very sinking feeling. No LORAN, No Radar, and no visability.It was very unexpected, very scarey and very disorienting (even though i had a compass) for a few minutes. Then it cleared up as fast as it came in.Im not advocating going out in bad weather, but it happens when not forecast. So why not be prepared with radar? This is not intended to be a personal attack, just a disagreement in ideas. Unfortunately everyone does not always agree all the time. Ther is a way however, to RESPECTFULLY disagree without making it personal. In the case with Mortyd, when he stated "where the hell is your sense of responsibility, admiral?", he then made it personal. Respectfully Tony B

 

[sailortonyb]

Radar on all the time?

I dont keep up with all of the laws, COLREGS and rules of the road, but, i dont ever remember seeing where if radar is installed on a boat, it MUST be ON at all times to comply with Coast Guard regulations. If someone has the time and ambition, maybe they can look it up. It should appear in the COLREGS which are on the USCG site on the web. The only thing that came close to that that i know of is.... on commercial boats ( not sure if there is a minimum size), the CG regs for inspection require that if a piece of equipment is on a vessel, it must be in working condition EVEN THOUGH it may not be a required piece of equipment. For Example, a vessel comes in for CG inspection and has 3 VHF radios on board and only 2 are required by law. One of the radios dont work. It will fail inspection. All one has to do is throw away the non working radio, in front of the Inspection officer, and the vessel will pass inspection. Basically, if its on board, it must be in working condition. I dont know if this applies to private pleasure craft.Tony B

 

[Brian D]

Did anyone really answer his question?

About the mast size and will it support the weight of the dome?

 

[Ross]

Tony B, My thoughts were

That whether he has the radar set or not he must learn to sail in good weather and not be distracted by the radar and learning to use it. I am quite sure that if there is enough crew someone keeps a radar watch while someone else has the helm. I have a friend that crews on work boats in the winter time up here and sometimes they must steer by radar. He likes to say that GPS tells you where you were a few seconds before but doesn't tell you what is out front.

 

[Clyde]

The weight's no problem!

It looks like you got either the GMR-20 or GMR-40, since you said that your radar dome was 28". Garmin has replace the 20 and 40 with the new GMR-21 and GMR-41 which have the industry standard size radar dome of 24". The stern radar tower is designed for the weight of the radar. If you still feel the need for extra support, Edson sells extra support struts and rail support brackets you can get to beef up the stern radar tower.The GMR series of radar has a minimum range of 20 meters, or about 66 feet. You can not detect anything closer than the minimum range. All radars have a minimum range; the average minimum range is about 65-75 feet for radars used for recreational vessels.The radar transmits microwaves which are "Line-of-Sight" radio waves. The standard vertical beam is 25 degrees. Which means that the microwave beam is being transmitted 12.5 degrees above and below the level of the radar antenna. The beam is projected like a triangular beam; the height of the radar antenna determines the blind spots below the radar beam. You can use trigonometry to calculate the blind spots of the radar based on the radar antenna height. When using the radar mounted on a stern radar tower, the 12.5 degree microwave beam below the radar antenna might be low enough to zap someone standing on the bow; never turn it on if someone is outside the cockpit. The rule of thumb for the maximum range for the radar is the square root of the height of the radar above the water times 1.23, which is much less than 24 or 48 nautical miles.Having radar on board a vessel puts an added responsible for the captain. Like most regulations and rules, people read the regulations and rules differently. Some people has interpreted COLREGS RULE 7 as requiring a ship's radar must be in operation anytime the vessel is underway, no matter what the weather condition is. The US Coast Guard's response to radar on recreational vessels is really vague. They say it isn't mandated, but if a recreational vessel with radar were to collide with another vessel without radar, more blame for the collision could be place on recreational vessel with radar."Radar is not required on vessels under 1600 GT (Title 33 CFR part 164.35), however, Rule 7 states that proper use shall be made of radar equipment if fitted and operational. In other words, whoever has one must use it. The Navigation Rules are not meant to discourage the use of any device, rather they expect prudent mariners to avail themselves of all available means appropriate...as to make full appraisal of the situation (Rule 5), e.g. the use of radar. At issue is whether the use of radar is appropriate in the prevailing circumstances and that is a determination made by the Master; and, ultimately decided by a trier of fact. Should you be in a collision how would a judge/jury rule on your contention that the use of radar was impracticable (due to electrical drain, crew shortages, etc.)? Also, if a collision does occur, then there was obviously a risk of collision beforehand. Could the determination of that risk have been made sooner with the use of radar? It is difficult to answer such questions because the circumstances of each case are different. More importantly, remember that Rule 7 specifies that assumptions shall not be made on the basis of scanty information, especially scanty radar information."The biggest push for having a radar on while underway has been the US Coast Guard Auxiliary.http://www.auxguidanceskills.info/press/radar.htmlFair Winds,Clyde

 

[patrick]

Clyde's sort of right

Clyde said "The beam is projected like a triangular beam; the height of the radar antenna determines the blind spots below the radar beam." I agree to an extent. The 25 degree figure is measured at the half power points of the radiation pattern. There is radiation far beyond those measurements but it is reduced below half of the transmitted power at its maximum. Thus you will get transmitted signals almost vertically both up and down. They will just be weaker as you move from the focus. It is not unlike a flashlight beam shining through a vertical slit. There will be a focused area and an unfocused area. There will be illumination in almost 180 degrees vertically and the width will be determined by the size and distance of the slit from the source.Thus if you put the antenna on a metal base bigger than the dome, there will be very little signal down through it. If the mount is of a normal dimension, you will still have a good signal very close in to the boat no matter how high you mount the scanner. In fact if you mount it 20 meters high, you will be able to see your deck or parts of it. It will be distorted by the effective distance versus angular attenuation combined with the surrounding reflections at a similar distance. The image displayed does not completely compensate for the vertical target angle. Thus if you pass under a bridge which is more than the 20 meter minimum range above the antenna, that will overwhelm the display and you will not see the other boat which is at the same distance and angle. That is why you need to practice when you can actually see what is there before you really depend on it.If you are in waves of 10 feet, your pole mounted radar is going to be looking at the nearest wave a significant portion of the time. The effective height is reduced by half and thus your effective maximum range. Your chances of seeing more than a minimal distance become a very rapidly decreasing statistic. Considering that the target and your antenna have to be line of sight, the probability of that happening and you seeing it diminish rather quickly. Worst case, both of you must(each) be at the peak of a wave at the same time that the antenna passes the targets direction. The antenna turns at say 30 times per minute so that is 2 seconds per revolution. Lets say the wave period is 20 seconds. That means that you will be at the wave peak maybe for a complete revolution of 2 seconds. That is ten percent of the time. The target is in the same situation so the chance becomes ten percent of ten percent or effectively one percent of probability. Add to that the motion of the boat, the sail area to the wind changing to maximum, the fact that you may be steering at the time you do get a return and you can figure the chances you will see a target. Besides that, I find that looking at anything closely in even moderate waves makes me quite sick.I like a mast mount for mostly these reasons.If you are hit from behind or the side by a breaking wave, it may take your pole with it no matter how well attached it is to the deck. This is not much of a problem if the antenna is mast mounted.I share the concern about exposure to microwave radiation but if you are more than twenty feet away, you should be ok. Another reason for a mast mount.