What is this symbol on the charts?

[Alaskan Sea-Duction]

So I do not understand the red, green, yellow circles around lighthouses islands and rocks.

 

[gaston]

Seen this before and believe it indicates the inner zone that the lighthouse light cannot be seen

 

[koliver]

Or, The red zone is where the red can be seen, where it is occluded by the rock behind, is left blank.

 

[twistedtree]

They are light sectors, showing the arc where the light is visible or not. They are another indication of where you are. If you can see the light, you are in the arc. Otherwise you are outside it. A good example would be a range light. They indicate where you should be in a narrow channel. They vary a bit, but typical would be white if you are in the channel, red if you are off to port, and green if you are off to starboard.

Chart zero is a good read, and good reference to have on board. It is the key to all the official cartography, and downloadable from the USCG for free.

 

[dhays]

Or, The red zone is where the red can be seen, where it is occluded by the rock behind, is left blank.

That would be my assumption but that is only a guess. I have an old copy of Chart 1 here are home and can't find any reference to it. The current edition of Chart 1 is on the boat.

 

[Hawgwash]

They are light sectors, showing the arc where the light is visible or not.

You nailed it.
I wonder if Alaska offers an accelerated USPS course.

 

[Hawgwash]

Or, The red zone is where the red can be seen, where it is occluded by the rock behind, is left blank.

You too.

 

[Hawgwash]

BTW Tom, the yellow indicates a white light. White doesn't stand out on the chart.
A true sector light shows all 3 with white being safer water.

 

[Crusty Chief]

Light Color

Thanks all for the explanations. We were on Toms boat mapping out tomorrow's trip and I was pretty sure it had to do with the light house or lights.
Your explanations, as usall are great.

We leave tomorrow from Juneau for Ice Straights, we gotta land a few Halibuts.
First stop hopefully is Swanson Bay then on to Hoonah with a couple hours hunting for Butt off of Pleasant Island.
Wish us luck.

Cheers

 

[ktdtx]

If you go by Excursion Inlet please let me know if the Ocean Beauty plant put the public dock back out this year. They took it out of the water the end of last August.

Thanks
Ken

 

[Crusty Chief]

Ken,
Was great to meet you two in Ketchikan, where are you guys now? Did you make it to Kalinin Bay? Any luck yet on the Kings?

 

[psneeld]

The colors that are used, are conform to the IALA Maritime Bouyage system that is designed by the*International Association of Lighthouse Authorities:

white - this sector is in the middle of the safe channel
red - indicates the*port*edge of the channel for vessels approaching the light source
green - indicates the*starboard*edge of the channel for vessels approaching the light source.

A ship that is sailing in safe water and then sees the red (or green) color of the light has to make an alteration in course.

https://en.m.wikipedia.org/wiki/Sector_light

 

[ktdtx]

We have decided to pay someone who knows what they are doing to find some fish around Petersburg. Our visitors arrived yesterday and we hope to get them off to a good start.

 

[Hawgwash]

Anyone have the NOAA Chart number that corresponds with the two plotter pictures? I'd like a better look, just for curiosity.

 

[rochepoint]

Anyone have the NOAA Chart number that corresponds with the two plotter pictures? I'd like a better look, just for curiosity.

Chart: 17316...........

 

[sbu22]

Twisted - think you're referring to Chart 1? https://www.nauticalcharts.noaa.gov/mcd/chart1/ChartNo1.pdf

 

[Hawgwash]

Chart: 17316...........

Thanks Mike. How did you come up with that so quickly?

Looking at the plotter screenshots, distance was not evident and I needed a look at a smaller scale to put it in perspective.

No distance and no current direction, a novice, relying solely on the teachings of RRR and looking at the two reds could get confused, if not in trouble.

But, looking at the chart you provided puts about 14 NM between Pt Sophia and Pt Couverden with the reds visible for 4 & 5 NM.

You may have encountered a spot out in the area of Shute & Morseby Passages where there are something in excess of 15 visible lights, some of which have duplicate characteristics. A challenge in the dead of night.

That example and the large scale plotter images above, prove the need to be up on all this stuff AND look at the big picture.

 

[rochepoint]

Thanks Mike. How did you come up with that so quickly?

HI Hawgwash, just typed Hoonah in the NOAA chart search........

 

[Hawgwash]

HI Hawgwash, just typed Hoonah in the NOAA chart search........

Oh for CS. I missed the "n".
Hooah!

 

[twistedtree]

Twisted - think you're referring to Chart 1? https://www.nauticalcharts.noaa.gov/mcd/chart1/ChartNo1.pdf

Yes, you are right. Too much time with computers where counting starts with zero

 

[Alaskan Sea-Duction]

Thanks everyone....