USS Fitzgerald collides with ACX Crystal off coast of Japan

[DeepSeaDiver]

Click to enlarge.

[Heiwa]

Well, I remain surprised that seven persons drowned and that three watertight compartments were upflooded due to leakage by collision. As the damage has small longitudinal extent only one watertight compartment was probably upflooded, so I assume two other compartments were progressively flooded through open, watertight doors.
But why would seven persons drown? Why didn't they escape up to open decks? Why were they trapped down below? It would be interesting to see a layout of the decks where crew drowned. Were the escape arrangements as per ordinary passenger/ferry ship standards?

[Heiwa]

Thanks!

[oildrop]

Do not hang your guts out too much - as the Japs use to say -

[Tupsis]

What puzzles me is that three watertight compartments reportedly flooded following the collision even though the damage caused by the bulbous bow is very localized. Even if it had hit a transverse watertight bulkhead dead-on, it should have not flooded more than two compartments. To my knowledge, naval ships do not have watertight doors below the damage control deck, meaning that either a second transverse watertight bulkhead was damaged following the collision - perhaps indicating more serious global deformations in the hull - or there was a minor error in reporting and spaces within the same watertight compartment (but on different decks) were referred to as being different watertight spaces. I doubt there were watertight subdivision in the vertical direction.

When discussing watertight subdivision, escape arrangements etc., keep in mind that this is a front-line combat vessel, not a civilian ship. Instead of IMO, SOLAS etc. regulations, it is built according to US Navy's own standards which take into account for example the fact that every crew member receives continuous training for damage control, escape etc. I don't wish to speculate how the seven crew members died, but the fact that there were no more casualties proves that the crew, as a whole, had been properly trained.

[Heiwa]

Thanks. The Japanse today are different, though.

[Heiwa]

As I recall it (1970), warships (except submarines) had no watertight doors of any types (hinged, sliding, bolted covers) in any transverse hull bulkheads. To move from one watertight compartment to another you had to climb up to the main deck into the superstructure, deckhouse, etc, and from there down below again. There were no internal stairways anywhere. Sloping ladders were the rule.

External doors/hatches from superstructures/deckhouses were not only weathertight but also gas tight to pass poisonous or radioactive areas.

Internal openings in the maindeck between hull and superstucture/deckhouse were sometimes fitted with hatches to isolate the top from the bottom. When these hatches were closed, any person escaping from below had to open the hatch from below ... one way or other. But only when ordered to do so.

[TEFLing]

Those images define the collision impact angle, only one of which can connect the bow & bulbous bow to the two respective areas of damage indicated. An angle of 20-30 degrees appears consistent with the photos. I think you have to make the impact rather glancing & oblique to fit the port side of the bulbous bow -- plausibly at the line of apparent removal of marine growth as observed above -- forward of the main above-water impact point, against the rearward edge of the underwater hole:

[Urs]

...perhaps indicating more serious global deformations in the hull - or there was a minor error in reporting and spaces within the same watertight compartment....

Some articles of the USNI or other Near-Navy sites mention that the Fitzgerald has not only a hole below the waterline, but she is also ‘twisted’ or ‘warped’. I do not know if they are writing about millimeters or centimeters; meters would probably be visible on the pictures.
However, to twist a destroyer would ask for terrible forces. A grazing contact with a nearly parallel course could not be the origin; the angle of impact must be much higher.
During the first seconds, the momentum of the containership against the blocked destroyer (blocked by the opposite mass of water), transforms, seen from the destroyer, into a lateral force component and an advancing force component. Only a high angle of impact would result in a high lateral component.

What is happening to the frames and thus, to the watertight compatments, when the hull is twisted…?

[Tellarian]

+1 For twisted.

I was once on a reefer and we were swamped by a 40 - 50 for wave in the deep S Atlantic. speed went from 18 knots to zero.

Creased the main deck with two distinct kinks of 3 - 4 inches.

Temporary repairs included welding railway lines as longitudinals on deck, not pretty but it worked.

If you look closely at the hi-res image, you can see the inflection in the side plating leading up and aft'https://news.usni.org/wp-content/uploads/2017/07/170711-N-WC492-027.jpg

[cthink]

I was looking at that last night and put these images together, and marked the area of the breach but I think the looks are deceiving a bit because they do not show the temporary repairs at the bottom of the destroyer.

With the release of the dry dock pictures several other questions emerged in my mind... Relative to your pretty good assessment in post #577, I noticed the horizontal distance offset between above and under waterline contact points (I marked in the following image). Prior to seeing the new pictures I was expecting those contact points to line up vertically. My guess is that the delta is at least 2+ meters.

This mismatch between (above/under waterline) contact points makes me believe that the first contact took place above the waterline, and that impact made Fitz lean/roll about 15-20 degrees to port, at which point the bulbous bow made it's way into the hull. My estimate is about 3.5 meters (11+ ft) of the bulbous bow penetrated and possibly lodged into the hull. This also explains the admiral's statement in the first press conference that the bulbous bow penetration almost reached Fitz's keel. I think it is evident in this picture that the steel plate welded/bolted to the bottom of the hull (without braces) is extending towards the keel (as a part of the temporary repairs).

All that said, it is possible that the bulbous bow may in fact saved the destroyer by carrying the vessel as opposed to chopping it up because the leading edge of the ACX's bow never got a chance to split the ship open. In other words, structural integrity of the hull above the waterline on the stbd side of Fitz was preserved (as you drew it on your diagram) with the gap between Fitz and the leading edge of ACx's bow between the contact points. My guess is that the bulbous bow was lodged into Fitz for some part of the 90 degree hard starboard turn ACX made, possibly with pretty violent dragging assistance from the Fitz (depending on the speed of Fitz at that point).
Here is the picture of ACX I used for my estimate for the size of the bulb transposing the distances from the draught line (each segment is 1 meter). The bulb looks to me about 4 meters long and it's radius is around 4 meters as well.

after/before.

Source for some pictures used: link

[rmurphy1966]

Thanks for the images. It helps visualize how three spaces were flooded without severely overthinking the issue.

[Heiwa]

It would appear that Fitz damages are (red) high above the waterline (caused by the Crystal bow flare) and (green - the patch) below waterline (caused by the Crystal bulbous bow. Unless a transverse bulkhead was damaged only one compartment could be up-flooded.
It seems the underwater compartment was forward of the engine rooms. If these were connected by watertight doors, and if these doors were open, three compartments could have been up-flooded.
It would be interesting to see a picture of the underwater damages prior the patch being fitted.

[Seago]

Whatever happened to the M.V. American Cormorant?

[Seago]

Why would those "watertight doors" have been open when underway?

[Chief_Seadog]

The Navy did not renew the American Cormorant's charter around 2004. In 2005 she was renamed Asian Atlas and traded commercially until 2014. Scrapped as the Atlas in 2014. By then she was pretty long on the tooth having been built as a tanker in 1975 and converted to a heavy lift ship in 1982.

[Heiwa]

Probably to facilitate the crew going to the toilet. Warship design is/was always quite simple. Two boiler rooms, two turbine rooms, guns on/below deck everywhere, where space was available with amo store rooms below, a wheel house with the old man's suite just below. Then there is not much space left for crew accommodation and sanitary facilities, so they are squeezed in on the double bottom, etc.

[Chiefluis]

I was stationed on a DDG, depending on the readiness level, the watertight doors throughout the ship were left open, even the doors leading to the weather decks were open, there were blackout barriers to prevent the escape of light, when the readiness levels changed, doors were then closed.

[Tupsis]

Were there watertight doors (hinged or sliding) on the main watertight bulkheads below the damage control/bulkhead/main deck? To my understanding, unlike civilian ships, naval ships don't generally have those, so moving from one compartment to another would require one to climb "over" the bulkheads.

Of course you don't have to answer if you consider it to be such information that shouldn't be posted online.

[Seago]

Thanks.