Can Microwaves See in Fog?

[StugeronSteve]

Time to buy the radar thingy. Does the panel think that I should ditch the Furuno (Navionics) plotter and replace the whole shooting match with a radar/plotter (too many eggs in one basket), or run the plotter alongside a conventional (and cheaper) radar? Where should the display go? Answers on a postcard please. I can't afford a repeater at this stage, so should the display go at the nav station, or on top of the steering pedestal. I know that the rotary airer whirling jobs, favoured by the dark siders, are out, but they do look useful for drying shower towels on windless days. So should the dome go up the mast for greater vis, or on a pushpit pole to fry the helmsman (and his parrot), and reduce mast top weight? Or maybe I should just blow the dosh on a new kite and get a microwave to cook the seagulls.

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[Twister_Ken]

This post betrays a fetishistic fascination with electronics.

Spend the money on a new leadline and sextant, my boy. And if there's any change, a cask of salt beef and a box of hard tack.

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[vyv_cox]

Participants in the PBO study last year agreed that the combined radar/plotters, even those with 10 inch screens, were too small for serious use. My radar is a 7 inch and I would agree that using it half size could be very difficult. I find that using separate plotter and radar in the same heading mode, north up or course up, is an excellent compromise. Having the GPS talking to the radar gives further advantage as the next waypoint is also shown on the radar.

Advice I received when buying mine was that any height disadvantage in having the scanner on a pole compared with up the mast was pretty much negligible. Mine is on a pole, making it much easier to install. It seems to be perfectly adequate there for sail yacht purposes.

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[pandroid]

Taking the microwave afloat could be dangerous. Not only can microwaves not see in the fog, but the wife would complain everytime she needs to thaw out the leg of beef.

We've got one of these sexy plotter/radar thingys. The overlay is a lovely tool, and MARPA sounds impressive. In practice, even with the Smart Heading Sensor, the MARPA is often wrong, and I've found I turn the plotter off when I'm using the radar, or at least put them side by side.

Contrary to what the big ship brigade say, who all have 21 inch screens, I find my little 7 incher to be fine. (Its not what you've got....) We went from Bornholm to Sweden this year in thick fog (twice) when the locals were wimping out as too dodgy. The radar even picked up a pot-marker! We wouldn't have even thought about it without the radar



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[Talbot]

Went through the same thought process - decided on seperate instruments (eggs/baskets!!) Strongly recommend that they are sited so that you can see them from the helm. The cheaper radar (bw display) does suffer from poor daylight vision when the sun is shining, however you normally only need radar when in poor vis, so the reflection problem is then insignificant. Siting of radar is dependant on how you want to use it. If you are only interested in ensuring that you see big ships, then site it on a pole. if you want to pick up low lying land at a distance then up the mast is better. for example with a target height of 5 metres, the radar up a pole (3m) would give you a max range of 7.7nm, if it was up a mast (7m) your range would be 10nm.
the weight of the scanner is also dependant on size. For most sailing boat applications, the 15" scanner is perfectly acceptable, 10" and 18" are at the top and bottom end of acceptable, and the 24" total overkill. thus if you were concerned about weight and cost the 10" JRC is definetly one to investigate.

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[jimi]

Agree with Talbot ... IMHO radar is only of serious use on a cruising boat if it's visible at the helm, particularly if sailing shorthanded. Have a look at my set up when we're in Cherbourg.

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[Mirelle]

Yes and a radar set can fry you!

(a big one, that is!)

Professional mariners have arrived at no conclusion about whether and how radar should be overlaid on an ECDIS chart display (there was a high powered two day conference on electroni integrated bridge systems in London last week!) and the present majority view is that the radar plot should be available separately.

I suggest we mere yotties follow suit!

I think the radar is most useful at the helm position, assuming you can see it and won't clobber it. Keep the chart plotter at the chart table.





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[Evadne]

I'm with Ken. (Taps out pipe, dims oil lamp and lays another strand in the tarred hemp splicing.) You should look where you're going, not at a screen. If you can't see through the fog with your eyes and use a radar, be sure that more than 50% of the blobs on your screen can't see anything and don't have radar (i.e. me), or ignore it (i.e fishing boats and coasters). That's excluding the ones that you thought were boats but are in fact unusually reflective pot markers, lost PWCs or baco-foil coated seagulls. And don't even think about the stealth vessels that you can't see (20-knot stinkies, according to a recent letter in YM or PBO).

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[tcm]

I use radar every single time i go out. This is to check it is working - and for that it has to be reasonable viz to check that everything that is there in vision is also on the screen. You also get quite good at knowing how far away things are, and how 1/4 of a mile looks. Yes, the boat is a stinkie and it has the whirly thing but too high up for drying/frying clothers i think.

Also, since the whirtly thing is a "telltale", then i think on biggish boat it wd look a bit bad if i whammed into anything and aha the cops or whoever find that the radar wasn't on. maybe.

In total fog, radar is all you have got, so eyes need to be able to see it, so best at the helm imho. Often best to have more than one looking and pressing buttons for discussions as to which blob is what.

overlay of radar and gps plotter is total rubbish imho: you need chart (and hence chart plotter) in north up mode, but your vision (and hence radar needs to be) in "course up". So the overlay is a gimmick imho.

I have dual colour screens at which you can have radar, chartplotter, sounder seabed graph thingy, tv/dvd and overlay. You can only overlay chartplotter and radar, not the blimin CNN news of course, dummy, though that might be fun. I default to radar on one and chart on t'other. The tv display option and the overlay are only for showing off to mates in a marina. Likewise, they are colour - which is not at all necessary imho apart from TV. Charts are pretty much monochromatic, and so are radar blobs. As above, all you need to be sure of is that evertthing in vision in good viz is on the screen.

With only a bit of practice you can count the number of seagulls behind the boat from the radar screen. Unfortunately, my set has no device for then zapping them but i agree it wd be handy. But then i spose anything else in that sweep wd also get zapped so the sails might get a bit melted too? Test this by putting the sails in the microwave first, i suppose. But then, the seagulls wd fly away would they, whilst only partly cooked.?..





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[andyball]

Drifting somewhat.....though there's a genuine question at the end :My Dad's got an old 70's microwave that has got less & less powerful over the years, though if you double the cooking time it works perfectly ok. Soooo..do old radars gradually lose range over years of use?

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[FlyingSpud]

Re: Yes and a radar set can fry you!

See the benefit of a radar at the helm, but how do you do this with tiller stearing?

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[StugeronSteve]

Thanks guys. Confirms my original thoughts. Stand alone radar, pedestal mounted colour display with the option of a chart table repeater if needed and funds allow. Think I'll go for the mast mounted dome as I do have this silly phobia worry about the possibility of frying myself and shipmates. Suppose it's going to mean another battery and a smart alternator controller. Still it's only money.

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[Mirelle]

Er, yes....

that's precisely the problem that I have myself. Which is one reason why I potter on without a radar - other reasons being that the bigger, more expensive, sets are much better and I cannot afford them; I need to buy a new engine first, etc. etc.



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[FlyingSpud]

Re: Er, yes....

Sounds familiar, I’m glad I’m not the only one

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[tome]

Andy

A radar magnetron loses sensitivity over the years and eventually needs replacing, just like your dads microwave.

Tom

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[tome]

Jim

I see a problem with instruments at the helm when using the autopilot. My instruments are located above the companionway with the radar at the chart table (it's a steam powered CRT so has to be protected). With the AP on I can hide under the sprayhood and see all, presumably you can't do this with your set up?

Just a thought
Tom

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[jimi]

Tom, you're absolutely right, however I'd take the view that I'd rather be at the helm in poor visibility also keeping a sound and vision watch ready for instant action.

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[andyball]

tvm Tom- there must be some with very limited range still in use.

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[tome]

I should have added that I always lurk in the coiled spring position! You're right, but poor viz is usually bloody cold, and with my recent success at weight watchers I feel it a lot more these days.

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[tome]

Yes it will still work, but won't tune as well and you'll get intermittent tracking of targets.

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