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Old 04 June 2003, 09:30   #1
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Radar on RIBs

I see that JK appears to have radar on his Ribcraft.

Many have concerns over getting "zapped" by what I believe are microwaves (unless you know different), whether on RIBs or on flybridge boats. Those that don't have probably already been "zapped"!

I have a vague recollection that the exposure to radiation is inversely proportionate to the square of the distance from the antenna and that the rays are actually very short pulses, rather than continuous. There may even have been suggestions that the risk is no greater than from a mobile phone.

Does anyone know how safe/dangerous it really is, given the proximity of the helm/navigator to the radome?

I am thinking of this in connection with a proposed Ribcraft 5.45, to be used for cruising.

Does the lack of height make the radar horizon so close as to render the kit almost useless?

Thanks for your thoughts!

Chris.
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Old 04 June 2003, 11:11   #2
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Chris, For what it's worth ,we have a JRC Radar already fitted on our 5.85 Ribcraft . The manual recommends that you keep 3 - 4 metres away from the transmitter ( could be tricky ! ). It apparently has a working range of 16 miles max to 25 metres min. I believe it was specifically put on there to watch out for fast ferries flying about in the mists of the Solent. I'm sure you will get some more specific info from experienced users.
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Old 04 June 2003, 11:25   #3
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Another advantage to being short.

I am 5'8

Advantages of being Short

1 you don't bang your head (less brain damage)
2 The air is thin up their so tall people get less oxygen to the brain
3 You head is not in the clouds
4 You don't get zapped as much by radar
5 Lower centre of gravity
6 You can stand behind a consul with more shelter



CJL you must wish you were shorter
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Old 04 June 2003, 12:05   #4
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I think as long as you position the RADAR correctly, you are OK. It doesn't blast out a pulse like some sort of electronic bomb, more a narrow beam.
I am also speaking out of shear ignorance here when I say I have never heard of anyone being hospitalised with a zapped brain because of RADAR. So it must be alright (mustn't it?).
Here is a piccie of my boat with an indication of the beam angle and direction. As my physog is normally about inline with the top of the windscreen, and underneath the radome, theoretically what remains of my brain, is quite safe!
There are a lot of threads here (do a Search) on RADAR which tells you the pluses and minuses. Basically, if you can afford the kit and the space on your boat, get it.
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Old 04 June 2003, 12:22   #5
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Re: Radar on RIBs

Quote:
Originally posted by Chris Murray
I see that JK appears to have radar on his Ribcraft.
Just a few things

1 It's a Ribtec not a Ribcraft
2 It's not mine any more
3 It was a dummy box, not a real radar!

Radar seems to cause a lot of worry. As far as I can tell it's about as dangerous as having a mobile mast at the end of your road. That will worry some people more than others!

John
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Old 04 June 2003, 13:55   #6
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Radar RIBS

Hi We had Radar fitted to one of our training boats recently sold.

Some thoughts !

We had a JRC 1000 fitted which is a nice little unit with a small but effective radome suitable for mounting on a RIB.

The JRC 1000 screen unit is NOT ( I think) suitable for a RIB as we had terrible problems with internal screen fogging despite a full console cover which went on each night to protect the electronics.


We also had abysmal / non existant service support from JRC and their agents who did not want to know us after the sale.

We mounted the radar on a specially designed frame above the helm position out of the fresnel zone. See attached pic of Ally Cat or look at our website www.powerboat.org for pics.

Even at a height of over 2 metres it was more of a toy than a practical tool at sea Ranges of one to 5 miles depending on wave height. However on the large Shannon lakes and wide river sections it was quite good and lots of fun ( when you could see the screen ! Ranges of up to 12 miles.

Important when you design the dome mount, that you realise that RIBs on trailers sometimes have a different attitude ( Nose pointing to sky or water) to RIBs afloat. Your dome could end up pointing at the sky whereas a better attidude is tilted down slightly 5 to 10 degrees.Be sure your boat is afloat when positioning the dome base plate.

Best wishes,

Stuart
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Old 04 June 2003, 14:01   #7
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Ooops here is the pic that should have been on the last posting.

Stuart
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Old 04 June 2003, 14:48   #8
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Hi folks

We here is my 2p's worth

Input from 2 people, myself and another eng at work who trained as a marine radio & radar officer at Fleetwood.

The vertical beam width on most small boat radars is about 25 Deg, so you need this you need this to work out if you in the target area.

When I asked Lee what he thought, his reply was "im not going near a active radar, 1.5Kw or not!!" Even though the pulses are very short they are very repetative and of quite a high power.


I have considered fitting a radar and have come up with the following

a) I wont fit it unless all persons, when seated or stood are clear of the theretical beam width.

b) I considered fitting a higher mount to acheive this but it gets quite high and the G forces etc would be greater the higher it got.

c) I have considered angling the radome up at the front so the front beam is almost level, whlile this would decrease the range a bit would help keep the beam over peoples heads.


Anyway at present i am leaving radar, I belive it only usefull in poor vis, so we will just try and avoid poor vis (Thats done it,its months of fog now ) and dont belive the possible risks are clear enough to just give it a go

Also regarding Stuarts post, I belive the RIB needs to underway when you workout whats level as some RIB's mine included sit level underway but very stern down when stopped. But also be aware if it that bad to need radar you wont be doing 40Kts, well maybe not.

Regards Gary
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Old 04 June 2003, 15:12   #9
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As Garygee says, make sure you point it in the right direction. For me, a bit low rather than high.

If you're worried about your brain, mount it higher. The raydome is not so heavy.

Is it worth fitting? Without a doubt, yes. You'll use it for spying all sorts of dangers that, without one, you just wont know exist. You will have to learn how though.

In poor visibility, it'll become your friend. You might even find yourself speaking to it - and you might even find yourself stroking it after it gets you home in a pee souper!

JW.
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Old 04 June 2003, 16:02   #10
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I agree with the last few points.

When fitting our radar I decided on the boat being in displacement mode for max effectiveness as you won't be doing 40 knots when you really need radar.

We had no problems with mounting the small radome up above the console. The small domes are quite light although as can be seen from the effective range figures shown small dome equals small performance.

Tried to attach pic to these emails without success but pics of Ally Cats radome fit can be seen on www.powerboat.org. This was high enough to be safely clear of every one . Remember that radar is 360 degrees ! So tilting the beam up at the front tilts it down at the back into the people sitting behind it. i really feel that you cannot really fit it to a RIB A Frame as it will also be too low to be effective and will zap people aboard. I really think that the only option is to fit it as we did on an over console frame a few feet safely above everyone.

Best wishes,

Stuart
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