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Old 23-04-2018, 18:31   #1
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Topmark meaning of special mark buoy

Dear all,

My oral examiner requested me to describe a Y can-shaped light special mark buoy. I answered the light colour, flash frequency, can colour, purpose, etc., to him. His follow up question was the differentiation of having cross and do not have the cross topmark of the special mark.

I failed on review with examiner by my not sure answer. He would not give me an answer and suggested me to study other books. I check with many books, there are not especially to talk to this point.

BTW, what the difference from Y can-shared buoy and Y cone-shaped buoy.

Please help 🙏🙏🙏
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Old 23-04-2018, 19:16   #2
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Re: Topmark meaning of special mark buoy

Cans, square top, green, river right. Nuns, cone top, red, river left. Left and right match the port and starboard lights, and are from the perspective of a barge floating down the river. In channels that do not have a clear upstream and downstream direction, one is chosen by the authority that sets the buoys.

Yellow special mark buoys are shaped -- can or nun -- appropriate to their location in the channel (left or right). They are rarely seen in the waters I visit.

See page 6, the legend, of the U.S. ACOE nav chart for the upper Mississippi river. It's free, a search should turn up a PDF.

The cross is just a grid for the letters so you can match them with what's on the chart. No cross, no letters, guessing it would be the only yellow buoy in the area so no need to differentiate, or perhaps a private marker. It may vary by jurisdiction.

As an aside, I once had a friend of a friend who was red/green colorblind and couldn't differentiate the channel markers. I mentioned the difference in shape to them, and while they had noticed the different shapes, they never realized that they had the same meaning as the colors.
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Old 23-04-2018, 20:30   #3
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Re: Topmark meaning of special mark buoy

Quote:
Originally Posted by Jammer View Post
Cans, square top, green, river right. Nuns, cone top, red, river left. Left and right match the port and starboard lights, and are from the perspective of a barge floating down the river. In channels that do not have a clear upstream and downstream direction, one is chosen by the authority that sets the buoys.
That's assuming the OP is in IALA Buoyage Region B - since he hasn''t put a location in his profile, we can't assume that

As for the OP's question, I've never come across a rule as to whether a special mark should or should not have an X topmark.
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Old 23-04-2018, 20:37   #4
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Re: Topmark meaning of special mark buoy

Is the OP Canadian?

I've found a couple of Canadian references that say "Cautionary, scientific and anchorage buoys may display a yellow 'X' topmark", but nothing from anywhere else in the world.
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Old 23-04-2018, 21:33   #5
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Re: Topmark meaning of special mark buoy

I have taken the exam in HK for 5 times. They treat the examination very serious after incidents. 100% correct answer is the passing mark, so poor me to take the exam.

Some peoples took me that the cross is for prohibited area.

I define that the cross will show both of the prohibited area and limited access area, or prohibited area only?
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Old 23-04-2018, 22:05   #6
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Re: Topmark meaning of special mark buoy

Quote:
Originally Posted by ftkl View Post
I have taken the exam in HK for 5 times. They treat the examination very serious after incidents. 100% correct answer is the passing mark, so poor me to take the exam.

Some peoples took me that the cross is for prohibited area.

I define that the cross will show both of the prohibited area and limited access area, or prohibited area only?
Definitely does NOT indicate a prohibited or limited access area, even in Hong Kong.

Here are two Hong Kong Special Mark notices, neither of which impose any restrictions on access and which display yellow X topmarks:

https://fairplay.ihs.com/ports/artic...ew-light-buoys

https://fairplay.ihs.com/ports/artic...t-buoys-change
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Old 23-04-2018, 22:33   #7
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Re: Topmark meaning of special mark buoy

After a lot of exercising of my google-fu, My answer would be:

There is no difference between special marks with and without an X topmark. The topmark is optional on a special mark.
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Old 23-04-2018, 22:40   #8
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Re: Topmark meaning of special mark buoy

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Originally Posted by StuM View Post
After a lot of exercising of my google-fu, My answer would be:

There is no difference between special marks with and without an X topmark. The topmark is optional on a special mark.
Yes, the rule is also X topmark is optional, but the officer looks like unsatisfied to my answer
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Old 23-04-2018, 22:49   #9
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Re: Topmark meaning of special mark buoy

Quote:
Originally Posted by StuM View Post
Definitely does NOT indicate a prohibited or limited access area, even in Hong Kong.

Here are two Hong Kong Special Mark notices, neither of which impose any restrictions on access and which display yellow X topmarks:

https://fairplay.ihs.com/ports/artic...ew-light-buoys

https://fairplay.ihs.com/ports/artic...t-buoys-change
In this scenario, quoted by the "Mardep report" where submarine outfalls with diffusers are installed. Mardep remind all vessel coxswain to take precaution action.

So , X topmark has been shown.

It is possible that don't show the top mark?
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Old 23-04-2018, 22:51   #10
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Re: Topmark meaning of special mark buoy

Officer said, I ask you the difference, Of course, they have difference between them.

So, I want to cry
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Old 24-04-2018, 09:54   #11
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Re: Topmark meaning of special mark buoy

U.S.A

Bifurcation..... I had my students remember what to do when approaching a bifurcation or preferred channel.

Example "Triangle, red over green.

Look the the top color of the buoy or day mark, as well as the shape .

the top color ( red ) it will be a triangle day mark. treat the top mark like a normal red navaid and you know red right returning, so keep the red navaid, to your starboard side. the preferred channel is to port.

Top color is Green it will be a square. Treat it like a normal green buoy or daymark, Keep it to your portside when returning. Preferred channel is to starboard.

No getting confused with top and bottom red over green or green over red.
Keep it simple.

However, just FYI, when you are cruising, in some nations, RED RIGHT RETURNING IS WRONG. Know the navigational rules where ever you are sailing.

In Tahiti, they have some quite different navaids and day marks to keep you off the reefs and shoal areas. Important to know those navaids and what they are telling you.

Fair winds and following seas
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Old 24-04-2018, 10:06   #12
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Re: Topmark meaning of special mark buoy

To the OP...

I just re read your original post .

Where are you sailing ? I have never seen a y shaped navaid, but we do not sail rivers or lakes .

Anyway, the post that I replied with concerned top marks in the U.S.A , and are what I described, so perhaps that will assist you in those circumstances when approaching a preferred channel in United States waters.

I have no clue as a Y shaped navaid.

You have received great scoops from the other poster. You are all squared away. All is good.
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Old 24-04-2018, 14:33   #13
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Re: Topmark meaning of special mark buoy

Quote:
Originally Posted by Lihuedooley77 View Post
...

Where are you sailing ? I have never seen a y shaped navaid, but we do not sail rivers or lakes .

...

I have no clue as a Y shaped navaid.
Apparently he's in Hong Kong.

It's not Y shaped. Y = Yellow

i.e "Yellow can-shaped" and "Yellow cone-shaped"
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Old 24-04-2018, 14:39   #14
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Re: Topmark meaning of special mark buoy

Quote:
Originally Posted by Lihuedooley77 View Post
However, just FYI, when you are cruising, in some most nations, RED RIGHT RETURNING IS WRONG. Know the navigational rules where ever you are sailing.
There, fixed it for you.

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