Maybe interesting for our former pilots:
The Icelandic Investigation Authority publishes a report about the cruise ship ‘Norwegian Prima’ manoeuvring in the Reykjavík harbor in strong winds, on May 26, 2023… and the good luck they finally had.
The report >>>
Urs,
Fascinating report on human factors. The Master was comfortable, based on his limited experience, to sail in up to 35 knots whereas the Pilot suggested delaying the sailing.
What is interesting is that with a combined 17,000 hp on the bow and 44,000 hp with two aft pods she could not be held in that wind strength and relative direction.
All over wastewater issues……
To be fair to the Master…….
“ The vessel’s safety management system did not identify any maximum wind speed limits for manoeuvring and there was no effective impact assessment available to the bridge team of the loss of power or any component during a manoeuvre at a given wind speed.”
I find this last statement interesting to say the least. Once again there is a level of culpability to be sheeted back towards the owners/operators.
They were dead lucky. Had the Master not requested the tug, it may have been a different outcome.
While conducting the investigation,
investigators used data from Norwegian Prima’s voyage data recorder and footage from CCTV cameras to recreate the event using specialist software. A video of this part of the voyage was created and can be seen
here:
Interesting video, thanks.
I don’t know anything about the authority of pilots in different ports; therefore I refrain from judging something, I am only surprised.
From the report, there are three turning places, A, B and C.
‘A’ is inside the port, considered too small to turn the ship.
‘C’ is far outside with no obstacles, it was proposed by the pilot, but refused by the master.
‘B’ is just outside of the port’s breakwaters with not much more place than inside, but more exposed to the wind. The master insisted…
As for the ‘cleaned wastewater’ problem:
Cruise-ships voyage always with the same draft.
Then they must adapt their draft continually to the shrinking fuel and provisions on board.
They are equipped for this, at least to keep the ship upright for the passengers on the roulette tables…
KC,
Thank you for this…….it paints a definitive and damning picture. Nearly took the bricks twice.
The swing position and pod demand inputs, under those meteorological conditions, were interesting to say the least.
Edit: For it’s size and windage, this vessel appears to be underpowered both in thruster and pod capacity. For example……
Norwegian Prima 293m LOA ….THRUSTERS 10,000 hp/ PODS 44,000 hp
Oasis of the Seas 360m LOA….THRUSTERS 29,700 hp/ PODS 81,000 hp
I remember a conversation with a Master, whilst Piloting a passenger vessel, who claimed that the new buildings were being designed to handled a sustained 45 knot beam wind.
The video of the tug attempting to push the bow around with 2.5kts of headway and the resulting wash coming from it says it all. Too much headway (which also kills the bow thruster’s effectiveness). In marginal conditions with a high-windage vessel, you’re not helping yourself with that.
The stern should have been held into the wind for as long as possible, with minimal longitudinal way through the water, keeping the pivot point relatively aft and allowing the tug and bow thruster maximum leverage. There is no need to “rush” the stern around. The wind will eventually help/take care of that.
I’ll bite my tongue a little bit when it comes to cruise ships (podded ones in particular) and the things they ordinarily get away with simply because they have so much power. This was a bit too close of a call though. Glad it was investigated.
The decision/pressure on the Master to sail in marginal conditions is another matter.
This is from the report.
The pilot’s preference was to depart stern first and swing near circle C but master and pilot opted to swing near circle B.
Forecast at the time were 27-31 knots, with higher winds expected off-shore. Winds increased from 15-28 kts during unmooring to 35-55 kts at closest approach to shallow water.
Always make decisions off the ‘Wind Gusts’ part of Windy and not just Wind.
This will make a good BRM case study for both pilots and masters, especially on cruise ships where the master or staff captain typically does the docking/undocking.
To me, the winds, and forecasting of, were less of a factor than those of the human ones. The pilot and master were not on the same mental model over something that is fairly basic shiphandling and has been addressed in the past on this forum in other incidents: speed control plus understanding (and manipulation) of the pivot point.
From the report:
The pilot’s mental model was that forward momentum needed to be limited to a speed of around 3 knots to maximize the effectiveness of Norwegian Prima’s bow thrusters and the ability of the tug to push.
The master’s mental model was that Norwegian Prima’s azipods were the best option to lift the bow - whilst the effectiveness of the bow thrusters (and tug, I would add) was lost due to the forward speed, there was a greater sense of control and reduced leeway.
With a strong beam wind, you can’t always “lift” the bow by putting the stern in the downwind direction. Careful watching of the COG vector on the video during this (which is based on a GPS antenna located above the bridge, ie. representing the bow’s motion) shows that the bow never gained any true motion to port once headway increased over 2.5-3 kts. Lifting requires the ability to laterally move both ends together and while the stern is quite easy to lift, the bow, whether by thruster or tug or both, is quickly overwhelmed if excessive headway is put on. Headway not only reduces the hydrodynamic effects of the tug and thruster but also moves the pivot point forward. It’s a double whammy to lateral control of the bow.
The extended “bonus” is that should you still not be able to hold the ship against the wind, settling down into something (like a rock) would result in a relatively small puncture rather than ripping the entire side of the hull open Costa Concordia style. These guys were fairly close to doing the latter.
Once the headway got to 4+ kts, the tug (and thruster) was really not doing anything. Now you’re committed to driving hard ahead and hoping to clear.
A podded ship really has no excuse for not being able to lift the stern while not gaining headway as would a conventional ship with a single 35 deg rudder and fixed prop. Patience is required to hold the ship against the wind and creep along, keeping control of the bow until sea room allows for some leeway as speed is brought up (quickly).
Without local knowledge of the conditions, reliability of forecasts and typical patterns, it’s hard to remotely judge the decision to sail (though the pilot clearly had concerns) but I feel this could have been done safely if not for the excessive headway that was imparted in the latter part of the turn.
Something that I would also add is that cruise ships can develop windage forces that are in excess of those that are purely calculated from the area alone due to a condition sometimes called the “ice cube tray” effect. Basically, all of the balconies and other cutouts in the superstructure can “capture” the wind in a way that exceeds forces that would be encountered in an equally-sized smooth sided ship (like a PCTC). Think a large spinnaker with a deep shape vs a flatly trimmed jib. This is especially true with the wind on the quarter.
Could not agree more.
This report is flawed……there is absolutely no reference to the second near grounding.
According to the report it was the pilot’s preference to depart stern first and swing in relatively open waters (Circle C on the chartlet) Captain instead opted to swing just off the breakwater which was exposed to westerly winds and shallows on both sides.
How would that have worked out at “B” had winds increased the way they did while the ship was backing there instead of turning?
I’d assume the ship being equipped with with a bow thruster and two aft pods it’d have considerable power and control running astern, especially compared to a conventional prop/rudder ship.
KC,
Here is what you can do with high windage, 350m LOA, 19,000 hp thrusters and 55,000 hp pod total.
Could the Norwegian Prima have safely manoeuvred stern first into open water prior to swinging? I believe so with the view that you had the 85t BP tug in attendance and stern way was not excessive allowing the tug to push up on the port shoulder. A combination of thruster/ tug push allied with pods partially thrusting stern to starboard should have tracked the aft pivot point quite safely.
This, of course is conditional upon the competency of the individual on the sticks………
Seems to me they would have been better swinging bow to starboard and into the wind, that would have been good seamanship wherever they decided to swing.
IMO, given the layout of the breakwater and channel, they made the correct decision to back the stern into the wind. What was lacking was keeping the stern upwind and controlling the headway as the ship came out of the turn, resulting in the bow being much farther downwind than desired and the subsequent challenge in moving the whole ship laterally upwind. Of course, waiting to do the maneuver when further offshore would have afforded even more room.
Most ships, including cruisers, will want to naturally back into the wind with sternway (more precisely, with the pivot point aft, the bow gets pushed downwind, in this case, helping the turn to port). You can see that as they initially approached the breakwater, the thruster was being worked to starboard to keep the swing from starting prematurely. Also most likely was why the tug was kept on the port bow for so long.
If they had decided to turn the bow into the wind, they would’ve had to kill most, if not all, of the sternway before swinging and perhaps even have to give a shot ahead. It would be an “unnatural” and probably more challenging maneuver, requiring more power at the bow to push it into and around the wind. A major portion of shiphandling is using the elements and present movement/momentum to your advantage. Turning the other way would have been the antithesis of that.
Another thing you sometimes see, especially in newer ship/boat handlers is a desire to always be “doing something”. During delicate maneuvers in tight spaces or challenging environmentals, sometimes you need to recognize the requirement to be patient and let the ship do what it’s doing. So long as things are going the right way (even if slowly), that may mean not touching a control or giving a command for an extended period of time. It’s possible the master thought the bow was “taking forever” to come around so he would just help it by starting to drive out of there. Seeing that he was on his first job as master, this may have been an unconscious factor.
Watching the video a few more times, I’m a bit confused as to some of the azipod movements. They’re usually setup to “pull” the ship but the recording layout seems to have that aspect reversed… unless Norwegian Prima is for some reason opposite of convention.
Also, as Ausmariner alluded to, the only way you can get away with even attempting something like this in those conditions is because of the large amount of power that these ships have, especially with the pods and their ability to rotate to any direction. Had this been a conventional ship using assist tugs the outcome would have been much different.
I still think the greater lesson here is the lack of mental picture agreement between the pilot and master. Lack of synergy on that has resulted in incidents even in dead calm waters with perfectly working equipment. The somewhat unconventional relationship that pilots and cruise ship masters have in most ports adds a challenge to that as well. It’s quite different than on cargo ships.
Now this is all my opinion and other pilots/masters can certainly disagree. It’s also really getting into some nitty-gritty shiphandling and judging that from recordings will never reveal the whole story. I also have exactly zero experience in Reykjavík.
It’s a common mistake not to do so. There’s no shame in backing out of an awkward situation and taking advantage of the pivot point aft instead of making things more difficult by trying to push the bow around with brute force. The pilot’s plan evidently was the correct one.
NWWaterman,
Yes, the display convention is clearly reversed and can be confusing until you get your head around it.
At the risk of being a patronising pr.ck I would like to say that I totally agree with every point that you have made in your last post.
I have downloaded the video and run it back and forward slowly watching the pod/thruster demands relative to SOG, ROT, position and vectors. In summary, I am mystified by some of the demands and will leave it at that.
The greatest challenge throughout my Pilotage career was dealing with passenger ships. Not the ship handling side but the human factors aspect whereby I dealt with, in most cases, a level of arrogance and constant retorts about the supply of tugs. The fact that the supply of tugs was a port requirement and not a Pilot requirement rarely mollified them.
In this particular case, the tug saved this young Master and hopefully he has accepted lessons from the entire incident.
Dear colleague,
You’re crossing the line of good taste.
On the vast majority of passenger ships, the principles of BRM are adhered to impeccably. This is evidenced by numerous comprehensive industry publications as well as individual opinions, including those on this forum.
If I were to be equally facetious, I would say that your posting video “Ovation of the Seas Napier Port January 5th, 2017” and comparing both maneuvering situations doesn’t exactly speak volumes about your experience.
Sirk,
Firstly, we are not colleagues……never have been and never will be. I am totally unaware of your bona fide……
I have noted some of your other interactions on this forum and offer no further commentary on that.
Nor am I crossing any line…… I am offering an opinion borne out of Piloting many large passenger vessels over 22 years with in excess of 5500 Pilotage Acts under my belt with no accidents. Some refer to it as opinion borne out of actual experience……
Yes indeed, the implementation of BRM principles on passenger vessels is on the whole first class but what has that to do with individual Master arrogance and resistance to documented Port procedures prey tell?
The attachment of the Napier video was a direct comparison with the proposition that the Norwegian Prima could have been manoeuvred stern first to open waters prior to swinging. Nothing more nothing less.
EDIT: Whilst on the subject of BRM, do you believe that we have witnessed effective and “impeccable” actions in the case of the “Norwegian Prima” incident?
With bow thrusters and tugs, I am sure they could have swung the bow through the wind, minimising the wind angle and then got onto a WNW’ly heading and started to quickly build up speed. They could have started to move ahead on the swing before the bow was even pointing at the breakwater if swung at A.
Speed is your friend on a windy day.
The problem with putting the stern through a strong wind is that you need an element of stern power to combat the wind and the effect of the bow swinging fast with the bow thrust and in this case tug tending to draw you ahead. If you then have stern way, it takes a long, long time ( at least it feels like!) to stop the vessel and start building up speed, all the time drifting to starboard in this case.
It should also be noted that in the latter stages in this case, trying to come to port to compensate for the leeway, things will only get worse before they get better.
This was the predicament they found themselves in:
As soon as the tug stopped working they lost ground towards the rocks. Using speed would have been a tradeoff as both tugs and bow thruster lose effectiveness.
Had they gone stern first to turn at point C, when the winds increased they could have steered upwind towards the windward side of the channel. In that case control of the bow would have been easier and would have mattered less.
