Analysis of the Collision

For those interested, the following link, Lights to Port - Lights to Starboard, will take you to a webpage describing an objective forensic analysis that I conducted in 2008 dealing with the famous 1956 collision between Andrea Doria and Stockholm. The results of this analysis were first presented before a class on casualty analysis at the Maine Maritime Academy (MMA) in Castine, Maine in November 2008. There is also a link on that page to access the complete report which can be viewed in pdf format.
Sam: Do you know where I might find an image of the *propellor warning* board, mounted on the poop rail of Andrea Doria, that was salvaged by Bill Nagle?

Michael Cundiff

Arun Vajpey

For those interested, the following link, LightsToPort-LightsToStbd, will take you to a webpage describing an objective forensic analysis that I conducted in 2008 dealing with the famous 1956 collision between Andrea Doria and Stockholm. The results of this analysis were first presented before a class on casualty analysis at the Maine Maritime Academy (MMA) in Castine, Maine in November 2008. There is also a link on that page to access the complete report which can be viewed in pdf format.

I followed that link and read your report Sam. Really well laid out and makes the event interesting for those who have not followed it before. I like the unbiased analysis and conclusion.
  • Like
Reactions: 1 user

Arun Vajpey

Sam, I have read your exceedingly interesting article on the subject of the collision between the Andrea Doria and Stockholm several times in the past year. Accepting your analysis as correct, I would like to quote some lines from your KEY POINTS leading up to the collision and subsequent CONCLUSIONS. My own points are in italics and mentioned in terms of apportioning blame for the accident.


22:40 - Carstens-Johannsen orders a course change from 089° to 091° for Stockholm to further compensate for a northerly current drift.

22:45:30 - Stockholm is picked up on Andrea Doria’s radar at a distance of about 17 nautical miles bearing slightly to the right of the heading flasher.

22:53 - Andrea Doria is picked up on Stockholm’s radar at a distance of about 12 nautical miles bearing slightly to the left of the heading flasher.

22:56 - Carstens-Johannsen plots Andrea Doria at 10 miles bearing 2° to port. In reality, Andrea Doria was close to dead ahead

23:02 - Carstens-Johannsen plots Andrea Doria at 6 miles bearing 4° to port. In reality, Andrea Doria was only 2° to port.

My Point: Although Carstens-Johanssen seems to have made an error of 2-degrees in his estimation – which could be attributed to the Andrea Doria emerging from the fog – he at least spotted correctly that the other ship was to the Stockholm’s port at that stage.

23:05 - Capt. Calamai orders a course change of "4° to the left, nothing to the right" for Andrea Doria. The two ships are 3.6 miles apart when Andrea Doria comes on to a heading of 264° 30 seconds later.

My Point: How could Calamai explain this? If Carstens-Johanssen on board the Stockholm could see that the Andrea Doria was to his ship’s port (albiet not as much as he estimated), then it should be safe to assume that Calamai should have seen that the Stockholm was not very far from a head-on course. In that case, how can a 4-degree change of course to port (left) be justified as it would be directly against the International Maritime Regulations of both ships turning starboard (right) so as to pass each other port-to-port under such conditions?

23:09 - Carstens-Johannsen orders a 2-point starboard turn on Stockholm. Distance between ships now at 1.3 nautical miles.

My Point: At least this can be explained. As per regulations, when there was the risk of 2 vessels being close to head-on, each was supposed to turn to starboard, which Carstens-Johanssen did at that stage.

23:10 - Stockholm completes 24° turn. Lookout Johansson calls bridge to tell Carstens that he sees lights about 20 degrees to port.
Lights of the Stockholm starting to appear to Capt. Calamai and 3/O Giannini out on Andrea Doria's starboard bridge wing and to the lookout out on the bow. Andrea Doria's 2/O Franchini leaves the radar when hearing reports of lights being seen. The ships are now just 0.6 miles apart.

23:10:30 - Carstens hangs up the phone and goes out onto Stockholm's port bridge wing and sees Andrea Doria showing a green sidelight about to cross his bow from left to right. He orders full right rudder and goes to the engine telegraphs to signal full astern.
My Point: At that stage Carstens-Johannsen could not have done anything else. Already committed to and completing the starboard turn, he could only ‘hard-right’ further when he saw the Andrea Doria crossing his bows from left to right. Perhaps the ‘full astern’ order was questionable but with the two ships so close to each other by then, would it have made much difference?

Capt. Calamai sees Stockholm showing a red sidelight and her forward masthead light swinging out to the left of the higher aft masthead light. Calamai orders hard left rudder and calls for a whistle signal be given to indicate a turn to port.
My Point: At that stage hardening the starboard turn would have been Calamai’s only choice but if he had ordered a full astern instead of ploughing on at near full speed, was there a possibility that the Andrea Doria might have slowed just enough in those 30 seconds to avoid impact?

23:11 - Impact! The bow of Stockholm strikes into Andrea Doria just aft of the starboard bridge wing.


1. The choice of using an eastbound route putting Stockholm directly into the path of westbound shipping heading to New York just to save a little time and distance.

2. The failure of the Stockholm's Third Officer to call his captain or suspect fog when he could not see the lights of the fast approaching ship as it came under 6 miles almost dead ahead on his radar.

3. Dependence on an inattentive helmsman (Larsen, who was known to have a tendency to allow his ship to yaw a bit) to keep a steady course and provide accurate heading reports while the third officer was trying to plot the radar picture on Stockholm. This may also have distracted the Third Officer from concentrating on the approaching vessel once it appeared on the radar.

4. The failure of those on the bridge of Andrea Doria to plot the radar picture as the situation developed, and the lack of special training by those manning the radar.

5. A possible breakdown in bridge team management on the Andrea Doria as the Second Officer left the radar upon hearing that lights were becoming visible. Also loss of situation awareness by the OOW of Stockholm caused by a phone call distraction during critical moments.

My Point: In my opinion, while considering the levels of responsibility, the first 3 points of error by the crew of the Stockholm would be more than cancelled out with the more serious error by the crew of Andrea Doria of a failure to plot the radar picture as the two ships closed on each other. In the last 30 seconds or so, there were distracting factors on both sides.

Taking all above points into account, while there were doubtless errors made on both ships, it seems to me that those made by Captain Calamai of the
Andrea Doria were collectively more serious - ie that left turn against regulations in a tight situations and failure to plot the radar picture. (oddly enough, it reminded me of KLM Captain van Zanten's decision to start his take-off run without clearance from the control tower that led to that awful 1977 Tenerife runway crash). In my opinion therefore Calamai should accept 75% of the blame and Carstens-Johanssen the remaining 25%.
I personally don't like to assign blame percentages. But, I do agree that the accident could have been avoided if Calamai would have taken a significant (2 or 3 points) turn to port, much more than the measly 4° that he took, which would have made very clear to Stockholm that she wanted to pass green-to-green instead of the usual red-to-red for approaching vessels.. There was much more open water to the southward and not too much open water to northward at the time. Remember also that Andrea Doria was in dense fog all the time while Stockholm was in clear air and could be seen on radar only which only caused some confusion on Stockholm because they could not see the Doria's lights until it too late. Carstens-Johannsen saw Stockholm on radar and did not understand why he couldn't see her lights. He never thought that one vessel could be in fog while the other, his ship, was in the clear.
  • Like
Reactions: 1 user

Doug Criner

A number of years ago, we encountered the former Stockholm - with a new name and bow, of course. She was doing coastal-steamer cruises on the Norwegian fiords. Probably catering to Europeans on a budget. When we pulled into a port, our ship invited the old Stockholm's officers to come aboard for socializing and perhaps some refreshments. As I watched them climb up our accommodation ladder, they seemed happy to come aboard our ship. I can't remember the country of registry of the old Stockholm.

Arun Vajpey

Other than Sam Halpern's unbiased report, most others that I have read about the accident tend to hint (or more) that Carstens-Johannsen somehow misread or misinterpreted the radar data (even if they do not always claim that it was wrongly set) and so suggest that the accident must have been largely the Stockholm's fault. The same writers tend to wax lyrical a bit too much about the beauty and elegance of the Andrea Doria and how great Captain Calamai was as a captain. In fact, in some books and reports this business about the "floating art gallery" goes on to such an extent that anyone wanting to know about the accident in an objective manner can get quite annoyed to the point of feeling nauseated. I know that the AD was a beautiful ship but that is irrelevant as far as the event goes.

IMO, the nature of Andre Doria and the fact that it sank after being struck by the Stockholm which survived and is (AFAIK) still seaworthy albeit under a different name is making some people biased while analysing the accident.