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PostPosted: Tue Mar 20, 2012 4:31 am 
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How to mount a radar reflector at the top of the sailrig?
I do not realy rely on radar reflector effects, but before I send the idea to the trash bin, I wonder if there are some experience in the forums about this.

I do not own an AI yet, but I don't think I will transform the original sail mast to stayed. And the optimal place for a radar reflector would be as high as possible.

BR

thomas


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 Post subject: Radar reflector REVIEWS
PostPosted: Tue Mar 20, 2012 8:15 am 
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If you don't know what type of radar reflector to buy...you should read the reviews on them in Sail Mag (US) a couple of years ago. The design and installation height make a big difference on reflection.

Here is a web review of tests done on reflectors in 2007:
http://www.hotribs.com/Library/Radar_Reflectors.pdf


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PostPosted: Wed Mar 21, 2012 3:18 am 
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Thanks for the link, TIDALWAVE! I am reading everthing I find on internet and I don't know what type of radar reflector to buy yet.

TIDALWAVE wrote:
If you don't know what type of radar reflector to buy...you should read the reviews on them in Sail Mag (US) a couple of years ago. The design and installation height make a big difference on reflection.

Here is a web review of tests done on reflectors in 2007:
http://www.hotribs.com/Library/Radar_Reflectors.pdf


Seems to me that radar reflectors are not commonly used by AI owners. I have searched this forum without any useful results. Since the sail mast is unstayed I don't want anything heawy at all in it. And if it should be any function of the radar reflector it must be mounted as high as possible.

I will keep on searching and reading on the internet...

BR
thomas


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PostPosted: Wed Mar 21, 2012 5:03 am 
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I guess someone has to ask... What is driving you to need a radar reflector? I understand what they do, but there are several reasons which might reduce the necessity.
* The need for radar diminishes when away from shipping lanes
* Not all powerboats have radar
* Not all skippers keep a good watch on their radar
* A radar reflector is much more necessary outside daylight hours.

I suppose the fact that nobody seems to have any experience on one is a guide. Maybe you are far better off to just rely on a super strong whistle (like a Fox 40 Sharx high performance whistle) and/or aerosol airhorn to warn off potential threats to being run down

This might be of interest to you http://www.akff.net/forum/viewtopic.php?f=3&t=37108

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PostPosted: Wed Mar 21, 2012 8:11 am 
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tonystott wrote:
I guess someone has to ask... What is driving you to need a radar reflector?
I will be in waters with merhant ships and it is of course necessary that they see me. Therefore I am curious about radar reflectors.
tonystott wrote:
I understand what they do, but there are several reasons which might reduce the necessity.
* The need for radar diminishes when away from shipping lanes
* Not all powerboats have radar
* Not all skippers keep a good watch on their radar
* A radar reflector is much more necessary outside daylight hours.

I suppose the fact that nobody seems to have any experience on one is a guide. Maybe you are far better off to just rely on a super strong whistle (like a Fox 40 Sharx high performance whistle) and/or aerosol airhorn to warn off potential threats to being run down

This might be of interest to you http://www.akff.net/forum/viewtopic.php?f=3&t=37108


Thanks for the link! I think you are right all the way and I can skip this extra cost and buy something useful instead.
Like a PLB with a button I can press when I have been ran over. :D

BR
thomas


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PostPosted: Wed Mar 21, 2012 10:52 am 
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There are 'active' radar transmitters that send a pulse out rather than having a commercial vessel try to bounce a signal off a small reflector that is very close to the water surface. If you are often in an shipping lane which has dense fog...an 'active' radar unit may the way to go...even if it is expensive. You might want to carry a high decibel fog horn. Tho' fog horns are not that effective...the sound can be refracted in weird directions.


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PostPosted: Wed Mar 21, 2012 2:47 pm 
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I don't know about anyone else, but I would be petrified if I was in a shipping channel in a dense fog. I have had fog roll up on me a couple times, and it is almost impossible to navigate, even with my GPS and compass it was really difficult to get back to where I launched from. I was in Sarasota bay which is around 15 to 20 miles long and 3-4 miles wide at some points. I launched from the south end and was at the north end when the fog came in following a sudden downpour (not in forecast). There are no ships in there but lots of powerboats, very few would have radar. To get home I avoided the channels, and hugged the shore all the way back. I have a whistle, an airhorn, and a light that I shine on the sail at night, plus the required white light that I place at the stern. None of these items helped much in the daytime fog, I wonder if a strobe light flashing on the sail might be more effective if it ever happens again. On a TI or AI it would be pretty easy to get a small portable strobe light and attach it to the sail clew when you feel you are in danger. If they make anything like that I have no idea (or if it's legal), those strobe lights seem to be pretty effective on school buses in the fog.


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PostPosted: Thu Mar 22, 2012 5:32 am 
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Thomas, the bottom line is that whether or not you have a radar reflector or any other safety devises, a tiny AI is going to be hard to spot out there in the shipping lanes in open water, and I suspect you are going to have to look after your own safety and not rely on other shipping noticing you or taking avoiding action. I know that masters of vessels are required to maintain a proper watch, but as that story I linked to demonstrated, in practice this might not be enough.

Good luck though, and I hope your ambitious trip is successful

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PostPosted: Thu Mar 22, 2012 11:47 am 
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I agree with tonystott. Having a radar reflector, transmitter, horn, light, strobe, etc. may give you the feeling that you are safer than you really are. In a dense fog, you are like a moth in front of a car in the middle of the night. I would never attempt a sail if there is a chance of obscuring fog. Being in a fog after a storm is similar to betting that you are not going to get hit by lightning. There is not much you can do to protect yourself, except being lucky.


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PostPosted: Fri Mar 23, 2012 2:26 am 
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@TIDALWAVE, fusioneng and tonystott.

Thanks for your concern and your feedback.

About active radar transponders I have found out that there are different kinds with different purposes. So called SART (Search And Rescue Transponders) are meant to activate only when in trouble. Thats not what I wanted. There are also others and yes they are expensive.

And no, having lots of equipment will NOT make me feel safe. There must be someone on the bridge with some attention on intruments if it is going to make a difference.

In Sweden we have many thousands of small islands were it is possible to hide if you want to avoid big ships and even powerboats. But sometimes you need to make a crossing and there is the risk. Dense fog is a b--ch! With a GPS you can hide in waters were not even powerboats can go but if you are suprised with dense fog under a crossing, you are in deep sh-t. Darkness is possible to avoid if you just keep an eye at the clock and there is navigation lights and headlamps to use if you must paddle in the dark. GPS will be some help.

About my trip in mind, it is not even a plan yet. I am free to abandon it at any moment. Even at the stage when I am under way I can abort and turn back. To a certain point. Point of no return. That trip has some longer crossings over open water (longest is 45 miles). I can avoid darkness and I hope I can avoid fog. But there will be comercial vessels and I have to pay attention. The combo of comercial vessels and dense fog is my greatest fear. Weather forecast is essential.

I have, at this moment, decided that following equipment is needed: 2 GPS, compass, VHF, PLB (or something similar that alerts nearby boats/vessels with AIS that I am in trouble) and a horn. I have not yet found a suitable active radar transponder and I think I skip the passive radar reflector.

Of course there are other things to be afraid of, like technical breakdowns, weaknesses of my body and realy bad weather. Combos of these are truly worst case scenarios.

I will use a drysuit and PFD at all open water crossings.


BR
thomas


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PostPosted: Fri Mar 23, 2012 5:31 am 
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Let us know when you get your AI.

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www.scenefromabove.com.au


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PostPosted: Fri Mar 23, 2012 6:44 am 
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tonystott wrote:
Let us know when you get your AI.


Ooh! :oops: :oops: Thanks for the reminder! :oops: :oops:

You are right, I don't have an AI yet...
Maybe I should start with that annoying issue? :lol:

BR
thomas


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PostPosted: Sat Apr 28, 2012 4:09 pm 
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Everyone wants to know why and provide "expert" advise.
I bungee one down when far out. Damn thing saved my life. A China cargo ship FINALLY saw me and pulled me up of VHF.
Look for one in the 20-30' sailboat range or make one from a pie pan

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PostPosted: Sun Apr 29, 2012 10:14 am 
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tonystott wrote:
I guess someone has to ask... What is driving you to need a radar reflector? I understand what they do, but there are several reasons which might reduce the necessity.
* The need for radar diminishes when away from shipping lanes
* Not all powerboats have radar
* Not all skippers keep a good watch on their radar
* A radar reflector is much more necessary outside daylight hours.

I suppose the fact that nobody seems to have any experience on one is a guide. Maybe you are far better off to just rely on a super strong whistle (like a Fox 40 Sharx high performance whistle) and/or aerosol airhorn to warn off potential threats to being run down

This might be of interest to you http://www.akff.net/forum/viewtopic.php?f=3&t=37108


I might get vilified for saying this, but the kayakers in that post caused the accident. No question in my mind. An apt comparison would be jaywalking on a deserted country road, seeing an oncoming semi-truck, and waiting for it to pass while still on the road; and don't forget, you're lying on your belly the whole time.
Sure, the truck shouldn't hit you, but who would be shocked if it did?

That boat is traveling at 20 knots or about 2025 feet per minute. How far can you paddle in one minute? 400 feet? Maybe 600 feet if your life depended on it?

In any sort of seaway, a boat can veer 15 degrees off course when being hand steered - 30 degrees or more on autopilot and this can last ten to thirty seconds for the correction to occur and the larger the correction, the larger the delay. This means the boat might travel a 1000 feet off course!

Reaction time: it takes a powerboat a minimum of five boat lengths to stop and a considerable amount of time before the boat turns after turning the wheel. A 115 foot (38m) boat weighs around 60-100 TONS, that much mass has a LOT of inertia. Even if the captain sees you, he needs at least three boat lengths to avoid you.

Next, let's discuss visibility. The most visible portion of a kayaker is only six inches off the water and your body is barely three feet. If there are waves, then you will only be visible about 30% of the time! The guy in the boat is scanning a 1000 feet or more ahead of the boat and he is largely looking for something ahead of him, he isn't looking to the sides for something that might hit him! When seated in the pilot seat of most boats, the captain can't see the water near the boat (depending on the boat, he might have a circle 100-200 feet in diameter that is difficult or impossible to see).

Finally, watch keeping: driving a boat is boring. Imagine driving your car at 22 mph, how long can you stay attentive? Now drive 22 mph on a featureless salt plain, with nothing to hit for miles in every direction, and your destination is six hours away. Your attention will wander. To the captain's credit, he was keeping watch. I would have been reading a book. I scan the horizon, check the radar, check the gauges, read a page or two and repeat. I have around 20000 nautical miles of small boat experience and I have never hit anything using this method. It works. Perhaps I've been lucky, but perhaps not.

This kayaker was hit because they were MUCH too close to a fast moving boat and did not take any/enough evasive maneuvers. In a busy channel they would likely have been seen because boats are expected in the channel. In open water, what happened is exactly what would be expected by reasonable operators because boaters do not expect kayakers far out in open water.

To be safe, a kayaker shouldn't be within a circle 5 times the length of the boat. This depends on the speed of the boat and sea conditions, faster boats and worsening conditions increase the size of the circle. We are the lowest of the low on the food chain of boaters, we have very little ability to avoid collision, and so we have to do the utmost to keep ourselves safe. There are extensive rules about what to do to avoid collision, but the first one is that they are to be avoided at all costs. If you are aware of a potential collision, YOU need to do your UTMOST to avoid it even if it violates the rules of the waterway.

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PostPosted: Sun Apr 29, 2012 10:31 am 
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The English Channel is the most heavily trafficked waterway in the world. There are maritime laws controlling shipping lanes, keeping radar watches, etc.
Yet two large ships collided because one was on auto-pilot with the radar collision alarm shut off and the bridge crew were too involved in bridge procedures than to watch where they were going.
I have only crossed one fairly-narrow heavily trafficked shipping channel in my TI.
It was a clear, sunny day...I still felt like a frog trying to cross a Freeway! It's amazing how fast a large ship can move up an "empty" channel.


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