sector lights

[martinworswick]

I'm working my way through the rya navigation book and i understand what basic red, white and green sector lights are for but on some of the charts around my local area there are sector lights with multiple repetitions of these lights and i can't see what the white sections are trying to guide you through.I've tried searching on here and google and can't find any information so i guessing i'm searching the wrong term.Can anyone explain what lights like these mean or what they're called so i can do some more searching.

[knotstogo]

Sector lights can be used individually or in series. Individually, a sector light might be used to guide a vessel into or away from a port, perhaps to avoid shallow water. In series, sector lights can provide a path around obstacles such as reefs or islands, to or from some point.

In the third image you provided, I drew a path to show you how two sector lights might be used to navigate between the islands of Omø and Agersø, from the northwest. It appears that there are also buoys in the area, along that path that would help a navigator confirm their position.

Without the charts, I can't provide much more local information but I hope that helps.

[TrentePieds]

Martin,

I may be way off track, but the fact that you are taking an RYA course in combination with your name might suggest that you are an ex-pat Englishman. So the question presents itself: How good is your Danish:-)?

Charts are compiled and published by a government agency called "Geodatastyrelsen". Go here: Søkort.

Geodatastyrelsen doesn't sell at retail, but has a distributor in every port in the land. There you should be able to find a sheet containing nothing by the legend for Danish Charts. You'll have discovered already, I'm sure, that Danish Aids to Navigation differ in some respects from those used elsewhere. So get the Legend for the Charts.

The reason for the complicated sector lights is the complexity of the navigable channels and the confusing way they branch, and often shift, due to the often very shallow waters. When I sailed in Denmark sixty-odd years ago, we just "felt our way" :-)

On your screenshot is shown the little island of Omø. and because it is an island in quite shallow water, there are several ways to get to her. These several ways (channels) are denoted by the white sectors. So even just in your imagination get yourself into one of those. Once you are there, the usual rules hold: If white turns to red (which is equivalent to seing another vessel's port side light) you turn to starboard which (which is equivalent to passing "port to port"). This will bring you back into the white sector. If white turns to green (which is equivalent to seeing another vessels starboard side light) your turn to port because doing that is equivalent to "going under the other vessels stern" and that brings you back into the white sector.

So just focus on the "cluster" of red,white, green for the channel you are in. If green turns to red. and if red turns to green with no intervening white, you are passing from one cluster to another, and you apply the standard rules to the new cluster you are now in.

But passing from one cluster to another may mean that you are moving across water too shallow for your vessel, so if you decide to do so, do keep your sounder going :-)!

Held og lykke :-)!

TP

[martinworswick]

Originally Posted by knotstogo

Sector lights can be used individually or in series. Individually, a sector light might be used to guide a vessel into or away from a port, perhaps to avoid shallow water. In series, sector lights can provide a path around obstacles such as reefs or islands, to or from some point.

In the third image you provided, I drew a path to show you how two sector lights might be used to navigate between the islands of Omø and Agersø, from the northwest. It appears that there are also buoys in the area, along that path that would help a navigator confirm their position.

Without the charts, I can't provide much more local information but I hope that helps.

some of the combinations like the one you pointed out are fairly straightforward and easy to understand,the more i'm looking at the charts i can see some of what the other sectors are for but for others i'm just scratching my head.
The screenshot below is a larger scale of the same area

[martinworswick]

Originally Posted by TrentePieds

Martin,

I may be way off track, but the fact that you are taking an RYA course in combination with your name might suggest that you are an ex-pat Englishman. So the question presents itself: How good is your Danish:-)?

Charts are compiled and published by a government agency called "Geodatastyrelsen". Go here: Søkort.

Geodatastyrelsen doesn't sell at retail, but has a distributor in every port in the land. There you should be able to find a sheet containing nothing by the legend for Danish Charts. You'll have discovered already, I'm sure, that Danish Aids to Navigation differ in some respects from those used elsewhere. So get the Legend for the Charts.

The reason for the complicated sector lights is the complexity of the navigable channels and the confusing way they branch, and often shift, due to the often very shallow waters. When I sailed in Denmark sixty-odd years ago, we just "felt our way" :-)

On your screenshot is shown the little island of Omø. and because it is an island in quite shallow water, there are several ways to get to her. These several ways (channels) are denoted by the white sectors. So even just in your imagination get yourself into one of those. Once you are there, the usual rules hold: If white turns to red (which is equivalent to seing another vessel's port side light) you turn to starboard which (which is equivalent to passing "port to port"). This will bring you back into the white sector. If white turns to green (which is equivalent to seeing another vessels starboard side light) your turn to port because doing that is equivalent to "going under the other vessels stern" and that brings you back into the white sector.

So just focus on the "cluster" of red,white, green for the channel you are in. If green turns to red. and if red turns to green with no intervening white, you are passing from one cluster to another, and you apply the standard rules to the new cluster you are now in.

But passing from one cluster to another may mean that you are moving across water too shallow for your vessel, so if you decide to do so, do keep your sounder going :-)!

Held og lykke :-)!

TP

The assumption is spot on,the Danish is lets say-a work in progress!

Theres definitely a lot of shallow water around here,thannks for the explanation of the green/red sectors with no white section-that was going to be my next question.

I've added a screenshot below of my local area,my home harbour is on the bottom left,there's an area on the bottom right which is out in open water and suddenly its only a foot deep and most of the charts i have have multiple areas like that.

[TrentePieds]

I take it you keep your boat at Kragenæs, then ? :-) Not a whole lot of employment available in that part of the country unless your Danish is flawless, I wouldn't think :-). When I was still a Dane, automobiles were still scarce, and roads were primitive. The journey from Copenhagen to Kragenæs would have taken an entire day. I learned the basics in Odense Fjord where the shallows are even more extensive and treacherous. However, the tides are generally no more than a foot or so, so if you do touch, you swing out your boom, and having snugged up the topping lift you crawl out on the end of it. In the boats we sailed, certainly, that would heel us enuff to lift the keel out of the mud and set us sailing again. It might in your boat too :-). It's balm on wounded pride that the bottom is generally really soft mud or soft sand so the probability of having done damage is very slight.

As for Danish, some say that it is not a language, but a throat disease. I would think the reason for that opinion is the way Danes utter the sound represented by the letter "R". In case you haven't got your tongue around that yet, the pronunciation is exactly like the "R" in French spoken by a Parisian. That is the ONLY exception to the fact that there is NO "phoneme" in Danish that does not have the EXACT equivalent in English. The trouble Danish gives to native speakers of English derives from the unfamiliar way Danes combine the phonemes, and from the odd, unpredictable elisions. Not to mention the orthography, of course. As a native of Funen I find the Copenhagen accent difficult to deal with and downright unattractive. My native dialect of Danish, that of Odense, has a nasality and a tendency to "upspeak" that is almost identical to those traits in the speech of the West Midlands. So if you are a Brummie or a Scouse, you might try to emulate that dialect ;-) When I lived in Brum, I found that coincidence enormously useful.

But we were talking sailing, and even though our Mods are generally forgiving, if you'd like to talk language, drop me a PM.

Cheers

TP

[boatman61]

Green your on the starboard edge of the safe passage.. White your on the safe passage.. Red your on the Port side of the safe passage.. some light houses only have red and white.. if you start to see red alter course till you have just white again.

[knotstogo]

Originally Posted by martinworswick

some of the combinations like the one you pointed out are fairly straightforward and easy to understand,the more i'm looking at the charts i can see some of what the other sectors are for but for others i'm just scratching my head.
The screenshot below is a larger scale of the same area

Caveat: I am not an expert in navigation nor am I a qualified instructor. Whatever you learn in your courses supersedes what I am saying (hopefully, clearly) here.

That zoomed out screenshot gives a little more map to work with. I painted another route onto the screenshot as an example. In another screenshot, this route is labeled "Rute T" but here it seems to be labeled "Wag or Weg T", pardon my ignorance of the language here, I can't make out the labels very well.

In my other post I said that a single sector light can be used to lead a vessel into a port (like so called lead-in lights) and a series of lights may be used to guide a vessel on a course. In this wide screenshot you can see that sector lights can be used for another purpose, to mark progress on a course. This way of navigating is sometimes referred to as a transit, using conspicuous landmarks or navaids to navigate on a course.

If you follow the magenta line, which is our course, I highlighted the white sectors with yellow. Notice how when we start from our southern origin, moving northeast, we have a white light astern and the further we go, a white light ahead at what I have labeled Point 3. To keep the proper course, that white sector light astern and ahead needs to remain so. If they turn red or green a correction is in order.

Now look what happens when we reach what I labeled Point 1. Here, we have our white light astern and ahead, and the sector light to our east, Osö, has turned from green to white. These three sector lights have now been used to mark a precise position on our course; we are using them as a transit.

As we progress to Point 2, our lights astern and ahead should remain white but the Osö light goes from white, to red, then green, and at last white again. There is also a lighted buoy at this point for further confirmation.

Passing Point 2 to Point 3, we have been keeping the sector light at Point 3 (I can't see its name) white, but Osö is going from red to green. Now when it goes green, we need to make a turn to port and observe sector light 4. To maintain our course away from Point 3, sector light 4 must remain green and 5 must remain red.

The basic idea I've tried to outline is that sector lights can be used to designate points when their beams intersect.

I hope this adds a little bit of understanding.

[hellosailor]

I'm wondering if some of those 180-degree sectors are simply blocked off so that you will only see them from "this side" of the light, preventing it from being seen as background clutter from "the other side" of whatever it is sitting on. Sometimes, just cutting the clutter so that one light can't be mistaken for another, makes life easier.

[TrentePieds]

Martin:

Knotstogo in #8 gives a very good augmentation of what I said earlier. The technique he describes so well is one I call "bouncing off the lights". Follow his trace from the northern end, heading south, and you will see that what I said regarding "which way to steer", when you see sector lights changing colour, will keep you in the channel, even as it wanders about.

The last leg of KTG's trace bears about 270ºT from Omø. Departing Omø on 180ºT, you will be able to see a green light all the way across the Belt. It is located on the island of Langeland, specifically near a little community about 3/4 mile inland, called Østerhuse. When the light bears about 4 points on your starboard bow it will change to white and you use it as a “lead-in” light for Østerhuse. The reason the lead-in is so narrow is that the shore at Østerhuse and for miles on both sides is treacherous, particularly in an easterly wind. It is very shallow and characterized by sand bars. The fisherfolk of Østerhuse in days of yore built a very long pier to reach out beyond the shallows, and provided you stay in the lead-in light you will just exactly hit the end of the pier.

All the best :-)!

TP

[martinworswick]

Originally Posted by knotstogo

Caveat: I am not an expert in navigation nor am I a qualified instructor. Whatever you learn in your courses supersedes what I am saying (hopefully, clearly) here.

That zoomed out screenshot gives a little more map to work with. I painted another route onto the screenshot as an example. In another screenshot, this route is labeled "Rute T" but here it seems to be labeled "Wag or Weg T", pardon my ignorance of the language here, I can't make out the labels very well.

In my other post I said that a single sector light can be used to lead a vessel into a port (like so called lead-in lights) and a series of lights may be used to guide a vessel on a course. In this wide screenshot you can see that sector lights can be used for another purpose, to mark progress on a course. This way of navigating is sometimes referred to as a transit, using conspicuous landmarks or navaids to navigate on a course.

If you follow the magenta line, which is our course, I highlighted the white sectors with yellow. Notice how when we start from our southern origin, moving northeast, we have a white light astern and the further we go, a white light ahead at what I have labeled Point 3. To keep the proper course, that white sector light astern and ahead needs to remain so. If they turn red or green a correction is in order.

Now look what happens when we reach what I labeled Point 1. Here, we have our white light astern and ahead, and the sector light to our east, Osö, has turned from green to white. These three sector lights have now been used to mark a precise position on our course; we are using them as a transit.

As we progress to Point 2, our lights astern and ahead should remain white but the Osö light goes from white, to red, then green, and at last white again. There is also a lighted buoy at this point for further confirmation.

Passing Point 2 to Point 3, we have been keeping the sector light at Point 3 (I can't see its name) white, but Osö is going from red to green. Now when it goes green, we need to make a turn to port and observe sector light 4. To maintain our course away from Point 3, sector light 4 must remain green and 5 must remain red.

The basic idea I've tried to outline is that sector lights can be used to designate points when their beams intersect.

I hope this adds a little bit of understanding.

thanks for that explanation,it makes things a lot clearer

[martinworswick]

Originally Posted by TrentePieds

Martin:

Knotstogo in #8 gives a very good augmentation of what I said earlier. The technique he describes so well is one I call "bouncing off the lights". Follow his trace from the northern end, heading south, and you will see that what I said regarding "which way to steer", when you see sector lights changing colour, will keep you in the channel, even as it wanders about.

The last leg of KTG's trace bears about 270ºT from Omø. Departing Omø on 180ºT, you will be able to see a green light all the way across the Belt. It is located on the island of Langeland, specifically near a little community about 3/4 mile inland, called Østerhuse. When the light bears about 4 points on your starboard bow it will change to white and you use it as a “lead-in” light for Østerhuse. The reason the lead-in is so narrow is that the shore at Østerhuse and for miles on both sides is treacherous, particularly in an easterly wind. It is very shallow and characterized by sand bars. The fisherfolk of Østerhuse in days of yore built a very long pier to reach out beyond the shallows, and provided you stay in the lead-in light you will just exactly hit the end of the pier.

All the best :-)!

TP

I'm having to read these explanations a couple of times whilst referring to the chart but its starting to make sense.
Thanks for the tip about getting unstuck should it be necessary-i'll remember that one.
I work in nykobing-the language isn't a problem as construction staff are hard to come by,theres a whole mix of languages on site

[knotstogo]

Originally Posted by hellosailor

I'm wondering if some of those 180-degree sectors are simply blocked off so that you will only see them from "this side" of the light, preventing it from being seen as background clutter from "the other side" of whatever it is sitting on. Sometimes, just cutting the clutter so that one light can't be mistaken for another, makes life easier.

I suspect you're right about the 180 sector lights. Sometimes they are narrower angles if there is higher terrain or if a channel is narrow in its approach. I noticed that some of the lights in the provided screenshots are occulted in patterns that help in their identification. In my area there are navigation lights and also an airport thrown in for fun.

Everything is blinking and flashing!

[knotstogo]

Originally Posted by TrentePieds

I learned the basics in Odense Fjord where the shallows are even more extensive and treacherous. However, the tides are generally no more than a foot or so, so if you do touch, you swing out your boom, and having snugged up the topping lift you crawl out on the end of it. In the boats we sailed, certainly, that would heel us enuff to lift the keel out of the mud and set us sailing again. It might in your boat too :-).

I really like that trick with the boom! I saw a video somewhere on YouTube that showed a crew that was doing something like that to pass under a bridge that wasn't high enough to get under otherwise.

The screenshots that were provided show some pretty shallow water. I looked up the area on Google Maps and it really seems like beautiful country!

Paul

[hellosailor]

I used to have vampire night vision and charts never confused me. But the first time, heading northbound to round Orient Point, on a pitch black moonless night (and racing, so there was no question of taking our time) I looked at all the lights (Fishers Island? CT? LI? the buoys?) and said "WTF?!" because it was like being in a Christmas tree display. In desperation I turned to the depth sounder, which we usually ignored, and it said "___" and that really did not amuse me. Went back to the charts, realized the main channel was over 200' deep and the sounder stopped at 199...and I said "THANK YOU" and learned to appreciate a depth sounder. Which told me pretty much exactly where I was, just by saying nothing.

Yeah, had a number of "WTF?!" moments with lights at night. I may not really trust GPS (or any instrument) but it has made naviguessing overall less stressful, most of the time.