Frigate Helge Ingstad Design - Damage Survivability

The Norwegian investigation team blames the Spanish shipyard Navantia for the sinking of the frigate KNM Helge Ingstad (F-313) after colliding with an oil tanker on November 8. The Commission of Investigation of Transport Accidents claims to have discovered a “critical” design failure of the ship by the Spanish shipyard. However Navantia has not received the report nor has been able to participate in the investigation. Naval military experts question the Norwegian version and stress that the accident was due to negligence. That commission is clearly clairvoyant since the wreck has not even been lifted yet, a rather premature and unprofessional conclusion.

The watertightness of the compartments guarantees that, in case of hull damage, it does not flood the rest of the ship, causing it to sink. According to an annex to the preliminary report, the flood affected three compartments: the aft engine room, the accommodation of the crew on deck and the store room. Water went from engine room to the gear box through the hollow of the propellers as they were not hermetically sealed and so it was quickly flooded. The crew found that water from the aft generator room was running into the gear room via the hollow propeller shafts and that the gear room was filling up fast. From the gear room, the water then ran into and was flooding the aft and fore engine rooms via the stuffing boxes in the bulkheads. This meant that the flooding became substantially more extensive than indicated by the original damage.

If this is true the yard surely has to answer for a few things. On the other hand the Norwegian Navy should have been on the alert also. Was there a Class involved?

The Nansen class frigates were billed as ‘unsinkable’ due to its construction with 16 water-tight sections designed to keep the warship ‘intact and operable’. Where have I heard such a statement as ‘unsinkable’ before?

I’ve been watching this with bemusement. According to the press, water was allowed to pass between water tight compartments by way of “the hollow prop shafts”. I assume that they mean the shaft tunnels, but it’s hard to tell. AFAIK, this stems from a Navy source rather than the preliminary report, and no sensical technical information has made its way into the media. When confronted with the idea that hollow prop shafts caused progressive flooding, the shipyard union representative scoffs at the stupidity of it all, which seems to me like they’ve only been contacted by the media so far. Fun and games.

I don’t think anybody is blaming them for the sinking, but if the rumors are true that construction flaws allowed free communication between watertight compartments, it’s still kinda serious.

This state of affairs reflects very poorly on anyone who had anything to do with the ships. Of course, the surveyors carry a much greater part of the blame than any yard worker. If anyone did notice such a glaring flaw without making it known where it counts, it’s grossly negligent.

Part of the problem with the Norwegian Navy is that it has shrunk to a point where it can hardly keep its head above water. It’s hard to maintain a high level of competence throughout the ranks when you’re working with such a tiny pool of active personnel, as generational overlap becomes smaller etc. The way these frigates were acquired and operated has bordered on the outright scandalous, with budget overruns, delivery delays and ships being nonoperational for extended periods of time because they “forgot” to allocate funds for spare parts. I shit you not.

As someone recently pointed out, for the past decades our government decided on a larger defense force than they have funded, and we now reap what we have sown.

Where were the Norwegian Naval Architects? Norwegian owners represetitives at the yard during construction? Norwegian surveyors? Did the ship’s officers discover these defects and report them up the chain of command? Why not?

And here I thought that only the US Navy was totally incompetent, and only the US Government throws away ridiculous amounts of money to shipyards for defective designs and poorly constructed ships with massive cost overruns.


There are three types of ships! Ships that carry passengers, ships that carry cargo and ships that carry weapons to destroy the enemy. Forget fishing boats, yachts, etc. Here I discuss the first three types.

Ships that carry passengers, aka passenger ships shall survive one or two compartments up-flooding and 100% of the persons aboard shall have a seat in a davit launched lifeboat and life raft in an emergency requiring abandon ship in 30 minutes. Compare Costa Concordia 2012. All was the fault of the Captain that 32 persons drowned and the ship was a CTL.

Ships that carry cargo and less than 12 passengers, aka merchant ships, shall have lifeboats for them and crew but there are no damage stability/survival requirements. Compare Exxon Valdez 1989. All, incl. the oil spill, was the fault of the Captain asleep in his cabin.

Warships are completely different. There are no safety rules for them. Only idiots, aka sailors, work on them and they are supposed to swim ashore after being hit and sunk in action by the enemy. Compare Bismark 1942. All the fault of Adolf Hitler.

I have been involved with all three types in my 50 years career in shipping and I have witnessed plenty incidents. Easiest is to blame the Captain but we never did it.

In this case the King of Norway, the Owner, must decide what to do with his incompetent sailors on KNM Helge Ingstad!

Regardless of why, if they had stabilisers extended, that could explain why the HI got holed below waterline. The lack of water tightness between compartment could case her to flood and list enough to get so low in the water that the above waterline damages caused by the anchor finished her off.

I don’t get why? Why is it so big deal whether HI had stabilizers fins extended or not?

Also I don’t get. Didn’t they have built in bilge pump on board? Some high efficiency pumps just for emergency? It is military ship so should it should be expected the hull might get punctured by enemy fire after all. Why 130+ trained men on board could not form bucket brigade just long enough to plug hollow shaft propeller? Did they didn’t care? Were they afraid the ship capsize?

Heck, I even myself took part in bucket brigade not far off Öland.

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Because if they have stabilisers extended when hitting against the side of a loaded Sola TS that could rip open a fairly large hole in the side below waterline. The damages caused by the anchor appears to be all above waterline at normal draft and even keel.

Maybe you remember the Hurtigrute Nordlys that had a fire in the engine room but started to flood and nobody could figure out why and how to stop it?
When the Dutch Salvage master got on the scene he quickly found the cause. It showed up that she had had the stabilisers extended and nobody remembered.
When she was brought roughly alongside the wharf in Aalesund the stabilising fin hit the wharf, causing substantial flooding into the cargo hold and car deck.
Here she is, with a substantial list, while they were searching for the leak:

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A most probable contributive factor !

Yes, but … we have seen photos of empty the TS Sola undergoing repairs in the Gdańsk earlier in the thread and there are no marks of the stabilizing fins (finnmarks ? :slight_smile: ) on the hull of the Sola. It seems draught of the empty oil tanker that about 6m according to Ship SOLA TS (Crude Oil Tanker) Registered in Malta - Vessel details, Current position and Voyage information - IMO 9724350, MMSI 248020000, Call Sign 9HA4480 So there could be the hidden damage. However, here seems to be no attempt to repair underwater parts of Sola TS, what would suggest there is no such an damage.

I don’t KNOW if HI had stabilisers, but IF she had and IF they were extended (as I believe to have seen in some news report) that COULD explain why there were flooding in the first place.

Maybe you have an answer to the following:
How could damages inflicted by the anchor of Sola TS cause flooding?
There are no signs of damages to the bulbous bow and no other protrusions below waterline on the sides of either vessel.

Why no damages to Sola TS below waterline??
I don’t know if there are, or at least we haven’t seen any pictures showing any damages, or scratches. She has not been docked yet AFAIK(??)
Or could it be that the fin got ripped off without causing any damage, or leaving much marks, on the tanker??


There are different types of roll stabilization systems used for ships, passive and active. Active fins can reduce the roll with 90% but it puzzles me why the HI used the probably active fins when sailing in the relative calm water of a fjord. Seen the slack attitude as shown in navigating the ship they probably forgot about switching them off after returning from the TRIDENT JUNCTURE 18, NATO’s largest high visibility exercise since 2015 with Norway and Iceland serving as Host Nations. Still in the party mood. What a way to end the exercise by a Host country, a true anticlimax.

I sailed on a couple of passenger ships with active fins but for us the crew we did not particularky like them because of the jerky movements the ship made which made walking on the decks uncomfortable. On one occasion one of the fins broke off so then we felt better. A disadvantage of active fins is the increase of the water resistance, reason enough to switch them off or rather retract them if they are of that type and not really needed. A question of basic seamanship.

Interesting article here at TheDrive We Have The First Official Report On Norway’s Sunken Frigate And It Isn’t Pretty

Some photos, looks like the door for the torpedo tubes was ripped off, as an additional source of water entry.

A post was merged into an existing topic: Tanker Sola and Norwegian navy frigate Helga Ingstad collide off Norway

From this illustration it appears that the Nansen Class has stabilsing fins abt. 2/3 aft:
If those were extended it is VERY likely that there have been contact with the side of Sola TS as they passed each other AFTER the damage caused by the anchor was inflicted.

I cannot find any other explanation for the initial flooding. (??)

The torpedo tubs are situated at main deck level.

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So the starboard anchor of M/T Sola TS, fitted 6 m above waterline on the protruding bow flare of the tanker and probably >10 from the centerline contacted KNM Helge Ingstad (HI) starboard deck house/aft side above the waterline in a collision (angle <20°) and ripped open the HI side say over 30 meters and 4-5 meters … above the waterline. It may have lasted 5 seconds. Soon after HI lost propulsive power.

I must say that I cannot understand how a fairly small buckle in HI above waterline could cripple HI in so short time. The HI underwater hull was not touched by Sola TS!

So why did the HI main engines stop so fast and where did water flood into HI to sink it?

Anyway, this incident confirms again the BIMCO 1994 findings (presented to the IMO) that most collision damages are only above waterline! IMO, USCG and many maritime authorities thought before that that in collisions at sea the side of any ship was sliced from bilge to main deck, bla, bla. But in fact, in 75% of all collisions only the side above waterline of the ship being hit was affected (as in the HI incident). So in 75% of all collisions, no ship sank. Same applies to oil tankers. So 1994 I suggested to the IMO that it was better that oil tankers put their collision protection above waterline to prevent oil spills in such events. 100% agreed! But when my design to do it was approved by the IMO 1997, USCG informed that such tankers were not allowed to enter US ports. And there we are today.

We don’t know yet whether there was any damage below the waterline, but presuming you are correct, wouldn’t HI have had a significant rolling input from the collision? Once the HI rolled back, then the above-pictured gash would have been below waterline, perhaps long enough to impart a permanent list, dooming the vessel.
Another possibility is that the HI had her stabilizers deployed, and the collision tore the starboard one out, holing the hull. Damage to the M/T Sola from hitting the stabilizer might not show in the pictures we’ve seen.
Just speculation, mind you :slight_smile:

See the other HI thread re: stabilisers: