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Mast Head lights and assumed distance

STOL71

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17 Sep 2014
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312
Crossing the English channel under sail at night with only a tricolour at the mast head. Tricolour about 10 - 12 meters above sea level. Could the watchman of a passing ship not assume a much larger distance of my sailing vessel (< 20 m length) due to the elevation of my tricolour and am I putting myself in danger?
 

Boathook

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Surrey & boat in Dorset. Both have pubs
I suspect that they will see you on radar before they see any light. The average visible range of a yachts navigation light is only a few miles i believe due to the power and that the lenses are normally scratched as well.
 

TernVI

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Depending on the ship, your masthead light may still be well below the watchkeeper's eye level.
 

Aeolus

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Unless you're very close by, all a watchman would see is the light. I don't think he would be able to judge its height above the water nor guess its distance.
 

Ian_Edwards

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I wouldn't rely on been seen by a large passing ship with only a masthead trilight.
I wouldn't attempt a night crossing without and AIS B or B+
And, I'd be happier with a radar responder like a dual frequency Sea Me or Echomax in addition to the active AIS.
On my Quantum Radar, I don't see another yacht until it's within a 2nm radius, and then it's a blip which comes and goes as the vessels roll. A big ship radar will be better, but I don't know by how much.
As the visibility comes down, the trilight is more or less useless, but the big ship will see the AIS and the big blip on the screen as the responder returns a pulse at the same frequency.
 

johnalison

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I wouldn't rely on been seen by a large passing ship with only a masthead trilight.
I wouldn't attempt a night crossing without and AIS B or B+
Oh dear. I've been doing it wrong all these years (until about seven years ago).
The Southern North Sea or Channel may be busy, but the risk of collision is not huge, given that you can see the ships even if they can't see you. I don't think that anyone should be discouraged from setting out in a well-found boat that complies with the regulations, even if they haven't the fortune or resources to have radar and AIS class B as we have.

I would put the range of seeing a yacht on my radar at about 2.5 miles, with the gain at average setting. I also have SeaMe, and would hope to be seen by a ship at five miles or so, but in any case, the combined use of ship radar and both of our visual lookouts should be adequate, even if they can be improved.
 

ghostlymoron

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Shropshire
Could the watchman of a passing ship
Watchman?
They are a thing of the past I suspect.

gary
Surely big ships are still obliged by law to keep a lookout by all means and would be taking more care than in less trafficked areas. I've sometimes called ships to check whether they've seen me and been told they've been watching me for the last half hour. I've never had radars or a is (too expensive) but I have had an echomax passive reflector.
 
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Sandy

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On the Celtic Fringe
I wouldn't rely on been seen by a large passing ship with only a masthead trilight.
I wouldn't attempt a night crossing without and AIS B or B+
And, I'd be happier with a radar responder like a dual frequency Sea Me or Echomax in addition to the active AIS.
On my Quantum Radar, I don't see another yacht until it's within a 2nm radius, and then it's a blip which comes and goes as the vessels roll. A big ship radar will be better, but I don't know by how much.
As the visibility comes down, the trilight is more or less useless, but the big ship will see the AIS and the big blip on the screen as the responder returns a pulse at the same frequency.
How I have managed to survive crossing la Manche all those times I will never know.
 

Ian_Edwards

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Oh dear. I've been doing it wrong all these years (until about seven years ago).
The Southern North Sea or Channel may be busy, but the risk of collision is not huge, given that you can see the ships even if they can't see you. I don't think that anyone should be discouraged from setting out in a well-found boat that complies with the regulations, even if they haven't the fortune or resources to have radar and AIS class B as we have.

I would put the range of seeing a yacht on my radar at about 2.5 miles, with the gain at average setting. I also have SeaMe, and would hope to be seen by a ship at five miles or so, but in any case, the combined use of ship radar and both of our visual lookouts should be adequate, even if they can be improved.
But life moves on, and sailing is all about managing risk, and I think that adding aids like AIS and radar responders significantly reduce the risk for relatively small amounts of money, compared to the cost of owning a boat, and the cost of getting it seriously wrong doesn't bear thinking about.
I'm not shy about taking risk, in the late 1950's, my father and I set off across the Irish Sea in a 22ft yacht, with a compass, a hand bearing compass and a pair of binoculars, and successfully sailed around Ireland. Because that's all that was available at the time, but I wouldn't do that now, you simply don't need to take that risk. And I've recently sailed single handed across from Milford Haven to Penzance in 25 to 34 knots of wind, starting and ending the passage in the dark, using AIS, Sea Me and Radar, but I wouldn't have undertaken the passage without them.
 

Boathook

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Surrey & boat in Dorset. Both have pubs
I wouldn't rely on been seen by a large passing ship with only a masthead trilight.
I wouldn't attempt a night crossing without and AIS B or B+
And, I'd be happier with a radar responder like a dual frequency Sea Me or Echomax in addition to the active AIS.
On my Quantum Radar, I don't see another yacht until it's within a 2nm radius, and then it's a blip which comes and goes as the vessels roll. A big ship radar will be better, but I don't know by how much.
As the visibility comes down, the trilight is more or less useless, but the big ship will see the AIS and the big blip on the screen as the responder returns a pulse at the same frequency.
I wonder how many of the big ships actually look at their AIS screen unless it is an integrated system. There was a discussion a few years ago about AIS and big ships and the fact that a lot just transmitted but rarely looked at the screen preferring to use radar. Maybe things have moved on, but how many of us / them replace a system just because it is old ?
 

johnalison

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But life moves on, and sailing is all about managing risk, and I think that adding aids like AIS and radar responders significantly reduce the risk for relatively small amounts of money, compared to the cost of owning a boat, and the cost of getting it seriously wrong doesn't bear thinking about.
I'm not shy about taking risk, in the late 1950's, my father and I set off across the Irish Sea in a 22ft yacht, with a compass, a hand bearing compass and a pair of binoculars, and successfully sailed around Ireland. Because that's all that was available at the time, but I wouldn't do that now, you simply don't need to take that risk. And I've recently sailed single handed across from Milford Haven to Penzance in 25 to 34 knots of wind, starting and ending the passage in the dark, using AIS, Sea Me and Radar, but I wouldn't have undertaken the passage without them.
I think that we should be careful not to discourage those who are either new to sailing or who can't afford all the gear that we ourselves think desirable. While I would not advise reckless navigation, and there is a certain minimum of equipment that should be considered obligatory, I would not think less of someone who set out with the same sort of gear that we did years ago. Yes, compass, radar reflector, life-jackets and flares and so on, but I would not assert that going to sea without GPS, AIS, or even VHF should be considered blameworthy.
 

Sandy

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using AIS, Sea Me and Radar, but I wouldn't have undertaken the passage without them.
I'd be interested to understand how AIS, SeaMe and Radar assisted with the passage?

I transmit AIS, it lives by the chart table and I never look at it unless I am interested in seeing where the big ship over there is going (I consider it more a tool for the CG should I ever hit the small button under the red flap or for friends and family to see where I am and get the first pint in at the bar). I don't have an Active Radar reflector (it is on my list of nice to haves) and the RADAR gets switched on twice a year just to play with/check it still works.
 

jamie N

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Fortrose
With my Echomax and GX2200, I've been able to see that 'another' vessel has 'pinged' me at 10NM, on the Echomax 'ping', and seeing the other vessel on the AIS receiver part of the GX2200.
This was with the Echomax on the pushpit at the stern, so not at height.
As with others, these are really nice to have bits of kit, that are (perhaps) more relevant to me given that I sail around the Northern & Western Isles; perhaps not.
If I didn't have them, I'd still sail in exactly the same manner and location.
 

duncan99210

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Winter in Falmouth, summer on board Rampage.
If you’re on watch on the bridge of a merchant ship, you may just happen to see the navigation lights of a small craft. It’s equally likely that you’d miss them altogether as they’re relatively low powered and are associated with no other lights to draw your eye to them.
However, watch keepers are much more likely to be focused on the radar and AIS displays, which are their primary tools for spotting other vessels in the vicinity. Your masthead light’s height above water will not lead them to get the range wrong: they’ll likely have already got you plotted on their displays and may take a look out of the window to see if they can see your lights, rather than spotting your lights and checking range on the radar.
 

Topcat47

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Solent, UK
I have a radar reflector mounted on my masthead, immediately under the masthead light. If the light isn't visible to a watchkeeper on the bridge, the reflector will appear on the radar (assuming anyone's looking at it). Personally, at night, I rely on my ability as a watch keeper and take early avoiding action if I consider it advisable. Been doing successfully like this for nearly 30 years.
 

garymalmgren

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Joined
28 Jan 2017
Messages
32
My comment about the lack of watchkeeping might seem flippant, but this thread brought back memories of a collision at sea about 3 years ago.
Location; The entrance to Tokyo Bay. (no need to stress how busy that sea way is)
Vessels ; US Fitzgerald ( modern US destroyer) MV ACX Crystal (modern large container transport)
Weather. benign
Time 2;20 am.

Crew on both vessels' simply didn't see each other. (with their eyes or any of the equipment aboard)
Not much chance of them noticing a yacht's navigation and streaming lamps.
gary
What we know about Navy destroyer's deadly collision with a container ship off Japan
 

Gwylan

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31 May 2007
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Moved ashore
AIS really is your friend.
Have it wired to the plotter, a careful watch and the alarm set at 5 miles seems to work in the Channel. At 20 knots an alarm for closest approach of 1 mile gives me time to think about what I am going to do.
Also my assumption is that I cannot rely on the other guy seeing me. Also in the Channel their options are severely limited. So it is my job to keep out of their way and not be a pain in the arse.

I have also seen on several occasions that boats have made small early changes to course that mean our closest approach stops being a bother to either of us. So some boats do run a good watch.

Also I do remember, to my shame, waking up in the cockpit on a solo night passage as I passed under the stern of a Spanish coaster. I could have wiped my nose on their ensign.
As we passed someone came out of the bridge and gazed over the stern in my direction. But I do not think either of us has seen the other one until that moment. That was pre AIS and plotters - well on my boat anyway.
 

STOL71

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17 Sep 2014
Messages
312
Thanks for everyone’s input. I’m aware of navigational aids available to me and other ships.
My question still stands: could the watchkeeper not misjudge the distance of an elevated masthead light? I am aware that in some countries there is the school of thought to discourage the use of the masthead tricolour and encourage the use of nav lights and stern lights closer to the waterline for that very reason.
 

garymalmgren

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Joined
28 Jan 2017
Messages
32
My question still stands: could the watchkeeper not misjudge the distance of an elevated masthead light?

Yes. Back on topic, Sorry.
To answer your quest. most definitely, yes!

gary
 
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