That’s one of the downsides to using your radar in ground stabilized mode. It doesn’t properly show you vessels that aren’t making way.
It’s pretty intuitive to me that a station keeping vessel is materially different from one adrift. This is especially clear when considering areas with strong currents, such as rivers and tidal races. Any vessel (DP or not) holding its position in a significant current will be progressing through the water in a consistent, predictable manner. There is thus a meaningful difference between station keeping and drifting, both for the purposes of academic discussion and collision avoidance.
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We have a winner.
-A vessel on DP is not making way, but it is underway.
-A vessel on DP, waiting or otherwise not working is not RAM.
-A vessel working while on DP is clearly RAM by the nature of her work.
No, it would not be feasible to hoist and lower day shapes between picks, that’s just silly.
This is simple stuff, it’s not meant to be complicated.
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I tried to explain that before but nobody listened to me either…
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The underway making way or not making way is only in the COLREGS wrt to lights / shapes and sound signals.
Seems like showing running lights when RAM implies higher ability to get out of the way but in the case of a DP vessel the opposite could be the case due to the nature of the work being done.
The clause “Due to the nature of her work” is very telling here.
Approaching a rig at night with a vessel nearby and for some reason I expect the vessel to get out of the way. The other vessel is near the rig, showing RAM lights and perhaps the working lights on… I don’t see how the running lights being off or on is going to tell me much.
If anything a DP vessel showing the running lights because it’s holding position seem more likely to confuse rather then enlighten.
Both the RAM and running lights should be on at the same time.
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Rule 27 (b)(iii) controls.
Rule 27—CONTINUED
(b) A vessel restricted in her ability to maneuver, except a vessel engaged in
mine clearance operations, shall exhibit:
(i) three all-round lights in a vertical line where they can best be seen. The
highest and lowest of these lights shall be red and the middle light shall be
white;
(ii) three shapes in a vertical line where they can best be seen. The highest
and lowest of these shapes shall be balls and the middle one a diamond;
(iii) when making way through the water, a masthead light or lights,
sidelights and a sternlight, in addition to the lights prescribed in
subparagraph (i);
(iv) when at anchor, in addition to the lights or shapes prescribed in
subparagraphs (i) and (ii), the light, lights or shape prescribed in Rule 30.
Are you talking about as a practical matter or a strict interpretation of the rules? As a practical matter I’d expect a working vessel to leave it’s running lights on. But the rules say this:
Rule 27 : Vessels not under command or restricted in their ability to manoeuvre
- (a) A vessel not under command shall exhibit:
- (i) two all-round red lights in a vertical line where they can best be seen;
- (ii) two balls or similar shapes in a vertical line where they can best be seen;
- (iii) when making way through the water, in addition to the lights prescribed in this paragraph, sidelights and a stern light
No requirement to have the running light on when not making way, but like I said I don’t see how, in the case of a DP vessel keeping station in a RAM situation, the fact that they are on or off, from a practical standpoint, conveys much information .
When holding position on DP the vessel IS “making way through the water”.
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I think I get your point from a practical aspect. Using cruise ships as an example, you have to look for the running lights amongst all the other blinding “working lights” onboard.
Yes, understood. Making way means though the water.
I saying wrt to the duties of the vessel required to stay clear the running light off or on don’ t convey much information. I don’ t see why the subject comes up.
It might be useful for collision avoidance in some cases as mentioned but not for gaining information as to the vessel’s status in the case of a DP vessel. For example port and stbd side is not meaningful.
I forget why it came up initially. Probably having to do with frequency of fog signal.
If a fog signal was required, you can’t visually see the vessel or it’s lights/day shapes. Radar interpetation comes into play. Just stay the fuck away if you don’t require that particular space for whatever reason.
The question in the OP was in regards to vessel RAM. Not able to stay the fuck away.
Yes ,you have reminded me of that before. Other elements and questions have entered since then. Fog being the latest. If there is a debate over what the vessel is in clear weather,it is even more difficult to confirm in low visibility. Stay the fuck away if you have any question as to what that vessel is or isn’t, especially in the fog… Is that bad advice sir? I think not.