Radar.. should we make more use of it?

[Nostrodamus]

Like a lot of boats we have an expensive integrated radar system fitted.
I have to say it is probably one of the most underused pieces of equipment on the boat, probably due in part to it's power consumption.

It goes on in fog or poor visibility or occasionally at night. Apart from that it becomes the poor relation and forgotten about.

I know it probably does a lot more that I use it for and in the right hands is an invaluable piece of kit.

So how often in a year will you put your radar on and to those who know how to use it properly what can you use it for apart from looking for other ships and obstacles in bad weather.

 

[Tomahawk]

I use it all the time, but it takes a lot of learning to work out now to use a radar.. Can you make effective use of the EBL and VRM? Then we go to true motion, relative motion, north up, course up!!

My prefered use is in true motion, north up with MARPA tracking targets aganist the chart overlay..

It is very comforting to have a radar shadow that lines up with the coast line on the cahrt... It confirms my chart datum is correct and I am where I think I am...


lovely

 

[Nostrodamus]

I use it all the time, but it takes a lot of learning to work out now to use a radar.. Can you make effective use of the EBL and VRM? Then we go to true motion, relative motion, north up, course up!!

My prefered use is in true motion, north up with MARPA tracking targets aganist the chart overlay..

It is very comforting to have a radar shadow that lines up with the coast line on the cahrt... It confirms my chart datum is correct and I am where I think I am...


lovely

Must have gone on the Polish forum by mistake as I have got to hold my hands up and say I have no idea what you are talking about.

 

[Tomahawk]

Must have gone on the Polish forum by mistake as I have got to hold my hands up and say I have no idea what you are talking about.

Polish lesson

EBL Electronic bearing line
VRM Variable Range Marker
MARPA something like Mini Automatic Radar Plotting Aid

Cahrt.. My bad typing

 

[Piers]

Like a lot of boats we have an expensive integrated radar system fitted.
I have to say it is probably one of the most underused pieces of equipment on the boat, probably due in part to it's power consumption.

It goes on in fog or poor visibility or occasionally at night. Apart from that it becomes the poor relation and forgotten about.

I know it probably does a lot more that I use it for and in the right hands is an invaluable piece of kit.

So how often in a year will you put your radar on and to those who know how to use it properly what can you use it for apart from looking for other ships and obstacles in bad weather.

For collision avoidance, the simplest way to use radar is set to North up (like your chart); relative motion, and to use the Electronic Bearing Line (EBL) which is the elecronic version of your mark 1 eyeball watching to see if the target boat is on a constant bearing to you which shows if there's a risk of collision.

In fog, as you know, all the usual col regs go out of the window, and a different set comes into play. One critical thing to know is the opposing target's aspect, for which true vectors are needed which will show you which way the vessel is pointing.

So, check regs (rule 19) and practice with your radar in good vis, so you have confidence when using it in fog.

Finally, do treat MARPA with caution. I suspect your radar is fed with GPS COG and SOG which in any tide or wind will give eroneous data. Just us the EBL instead.

Have fun! One of the best books on the use of radar was written by the (now deceased) Robert Avis. Simply written, so easy to follow. Worth its weight in gold.

 

[Nostrodamus]

Thanks Piers.
I do need to learn more about radar. It is fitted and all I know is what I have discovered from the small Manual that came with it, ie turning it on and off.

 

[Sailfree]

Always use it on X channel and on Head up.

I use MARPA but for Raymarine system I can get my head round difference between SOG/COG and over water for collision avoidance. Surely the other boat is SOG/COG as well and you hit by being over the same piece of Ground!

Can anyone explain it to me please.

I know the MAIB criticised the Moody that had the collision in the channel for having it set up on SOG/COG.

 

[wadget]

Always use it on X channel and on Head up.

I use MARPA but for Raymarine system I can get my head round difference between SOG/COG and over water for collision avoidance. Surely the other boat is SOG/COG as well and you hit by being over the same piece of Ground!

Can anyone explain it to me please.

I know the MAIB criticised the Moody that had the collision in the channel for having it set up on SOG/COG.

I tried to explain it here. Its not a great explanation but I'll look it up and explain it better later.

http://www.ybw.com/forums/showpost.php?p=3883585&postcount=8

 

[Sailfree]

I tried to explain it here. Its not a great explanation but I'll look it up and explain it better later.

http://www.ybw.com/forums/showpost.php?p=3883585&postcount=8

Thanks but I still dont understand!!

Yacht has a course over the ground, boat has a course over the ground. When they occupy the same spot over the ground they have collided!!

If I try Option B:-

Yacht has a course over the ground, boat has a course relative to yacht. When they occupy the same spot over the ground they have collided!! On MARPA the bearing will remain the same? and distance diminishes until collision.

Sorry if I am being thick.

Frankly I obey the rules except when they take me within 2mls of a big boats forward track then I go behind. I have read that you need to use speed and course over the water but wonder if the difference is small that with prudent keeping clear of big boys its not noticeable.

 

[johnalison]

I have been using radar for about 12 years but this year it was largely superceded by AIS for collision avoidance. I will continue to use it but I don't intend to upgrade my compass to enable MARPA, which in general use seems much inferior. I tried using MARPA a few times with my older compass, in still water, and it functioned OK but, except for non-AIS targets, it seems more cumbersome than AIS.

Not having big-ship experience, I normally set the radar to course-up which is a little steadier than head-up and roughly the same to interpret. I haven't found the overlay on the chart very useful but play with it occasionally. I have always used EBL & VRMs, though most of the time this has been to check against my eyeball.

 

[wadget]

Thanks but I still dont understand!!

Yacht has a course over the ground, boat has a course over the ground. When they occupy the same spot over the ground they have collided!!

If I try Option B:-

Yacht has a course over the ground, boat has a course relative to yacht. When they occupy the same spot over the ground they have collided!! On MARPA the bearing will remain the same? and distance diminishes until collision.

Sorry if I am being thick.

Frankly I obey the rules except when they take me within 2mls of a big boats forward track then I go behind. I have read that you need to use speed and course over the water but wonder if the difference is small that with prudent keeping clear of big boys its not noticeable.

I'll try again, so I'm not a great teacher of these things as its one of those things I learnt you shouldn't do but since passing my exams I've forgotten the reasons why.

The ARPA takes a series of ranges and bearing and combined with your own ships course and speed it will calculate the true course and speed of the target. Similarly if you were to plot a stationary object the ARPA would be able to calculate the rate and direction of the current affecting your ship. So by entering the course and speed over the ground you are in a way entering the same data twice causing the error.

But for this error to reach 2 miles is quite unlikely. However if you have a log and compass capable of interfacing with the radar that would be a better method.

 

[LadyInBed]

My prefered use is in true motion, north up with MARPA tracking targets aganist the chart overlay..

My understanding is that this only becomes usable on yachts if you have a good (expensive) fluxgate compass fitted, as the more basic ones as fitted with an autohelm don't react quick enough to the boats change of head as it bobs around on the sea, is that the case?

 

[sailorman]

My understanding is that this only becomes usable on yachts if you have a good (expensive) fluxgate compass fitted, as the more basic ones as fitted with an autohelm don't react quick enough to the boats change of head as it bobs around on the sea, is that the case?

Gyro compass

 

[robp]

Thanks Piers.
I do need to learn more about radar. It is fitted and all I know is what I have discovered from the small Manual that came with it, ie turning it on and off.

Definitely worth going on the relatively short course in order to ensure correct use.

 

[LadyInBed]

Gyro compass

Quite right Sir, thanks.

 

[KellysEye]

We only used it in fog in the UK, off Finisterre, the Portuguese coast and the Western Med, but worth the money.

 

[LadyInBed]

what can you use it for apart from looking for other ships and obstacles in bad weather.

Very useful for picking up rain squalls, especially at night.
Picking up channel sticks in low vis, though in truth, for me this function has been taken over by the chart plotter.

 

[Nostrodamus]

Very useful for picking up rain squalls, especially at night.
Picking up channel sticks in low vis, though in truth, for me this function has been taken over by the chart plotter.

Now to really show my ignorance... what does a rain squall look like on radar and can you tell anything else about it apart from it is a rain squall, also in general terms what distance setting is it best to have the radar on.
See totally ignorant... the less I know the less I have to worry about!

 

[LadyInBed]

what does a rain squall look like on radar and can you tell anything else about it apart from it is a rain squall

The squall will show a breath and depth so you can see how big it is.
You will see if there is more than one rain burst.
You can deduce which direction it is moving so if necessary you can steer around it.

in general terms what distance setting is it best to have the radar on.

I tend to have mine on 6 miles, occasionally going out to longer ranges to see what's about.
Another useful tip is to use the 'Short Track' function, not because you want to see the target track but to pickup and hold small intermittent targets such as Mobo's and small yachts without decent reflectors.

 

[Sybarite]

Like a lot of boats we have an expensive integrated radar system fitted.
I have to say it is probably one of the most underused pieces of equipment on the boat, probably due in part to it's power consumption.

It goes on in fog or poor visibility or occasionally at night. Apart from that it becomes the poor relation and forgotten about.

I know it probably does a lot more that I use it for and in the right hands is an invaluable piece of kit.

So how often in a year will you put your radar on and to those who know how to use it properly what can you use it for apart from looking for other ships and obstacles in bad weather.

Mine gets little use. Admittedly it's still in its box waiting for the next boat.