Ocean guardian bearing failure

did this REALLY require the NTSP.? This happens on occasion when the size of the bearing are not read by the mechanic. not untypical for crankshaft bearing journal to be turned over the life span of the crank.
Honestly! doesn’t the NTSB have anything better to do.

I was asked to join the NTSB but as I found out its at your own expense for the most part. members are subsidized by their corporate employer at least they were when i was asked. being a small business I couldnt afford it no matter how impressive it would have been to my resume

while i have aways been impressed by the aircraft aspect of the organization it appears that the marine aspect is like the definition of an attorney. “someone that goes in after the battle and bayonets the wounded”

On May 27, 2022, the supply vessel Ocean Guardian was conducting a sea trial in Shilshole Bay when its no. 3 diesel generator engine suffered a mechanical failure, resulting in an engine room fire that caused $1.1 million in damages. No injuries or pollution were reported.

Full report here: https://www.ntsb.gov/investigations/AccidentReports/Reports/MIR2308.pdf

The chief engineer inspected the area near the engine and found a crankcase door had been ejected from the engine block and part of the engine block had been “sheared away.”


Major marine casualties may include any one of the following:

  • the loss of six or more lives.
  • the loss of a mechanically propelled vessel of 100 or more gross tons.
  • property damage initially estimated to be $500,000 or more.
  • a serious threat, as determined by the Commandant of the Coast Guard with the concurrence of the NTSB Chair, to life, property, or the environment by hazardous materials.


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Great Photo’s! looks like a 16 cylinder cat. tossed the rod through the block. Ive seen this many times. Biggest problem now is cutting the deck open and getting the engine out.
while you may be able to stitch up the block, roll out the crank & rebuild it in place i would want it line bored which may require it to be removed. could open the thread but i wrote it down and will look at the particulars.
Again, is this REALLY all The NTSB has to do!

looks more like case of “shit happens” and pretty routine from where i come from.

No. But it’s their job. They also investigate shrimp boats that sink at the dock.

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Everything is routine until it catches on fire, I guess.

Complete loss of propulsion and having to be towed in right out in Shilshole is fairly NTSB worthy. Cat’s seem to be more prone to cause fires with major crankcase failures, not sure why. The rep will tell you it’s because everything is built so good they build more heat prior to catastrophic failure but they get paid to say stuff like that.

Surface paint fire

The surface paint was burning in the bilge?

I’m pretty sure that’s an engine oil fire.

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A little unusual that the auto shutdown didn’t operate before it got that far engineer shut down the engine

Engine oil fire in the bilge is very unusual must have been diesel in the bilge
Oil fire from tossing a rod is not common with this type of damage

NTSB just parrots what they were told they don’t have the expertise to do a real investigation

If you have ever worked up in Seattle then you would know about the good old boy network up there. I used to get sent up there all the time from San Francisco primarily by insurance companies to investigate losses of this nature
The USCG and NTSB are no match for an experienced port engineer
Hawaii is the same way. Anytime I wanted to get warm. I could always get work in the sandwich islands

I only did a quick skim of the report, but I didn’t see mention of an oil mist detector/splash oil monitor. Was one not required due to the engine displacement? If fitted would it have caught this before the explosion? The modern versions are pretty sensitive to bearing failures.

3516 do have an auto shutdown, you would think alarms would have went off shortly after the bearing spun and or when the rod went through the block. circumstances as described are very unusual when it comes to a fire in the bilge. should have been plenty of smoke from the hot oil in the sump from the high heat, but as described, it seems flaming oil entering under the bilge plates. i would image after a rebuild that there MAY be some diesel floating on the bilge water that might have ignited but to me its a little farfetched. I have had engine room fires from broken high pressure fuel lines. atomized diesel hitting hot exhaust surfaces and causing flames. but never for throwing a rod through the block.
as i have stated the USCG and NTSB are no match for an experienced port engineer with a “ripping good yarn”
anyway it was nice to speculate, the truth may never be known, and it just demonstrates the lack of experience of the “investigators” in this incident.

What 3500 series CATs have individual sensors for crank bearing temps?b

The 3600 series (largest made by CAT) don’t even have this feature.

Unless this is new instrumentation on the newer engines, please correct me if I am wrong.

Engines this size don’t typically even have oil mist detectors or “OMD”s. The OMD would have been the device to detect this failure as far as I can tell.

Your auto-shutdowns are typically overspeed, low oil pressure, and high-water temperature. Other sensors attached are more often alarms but not necessarily shutdowns, i.e., crankcase pressure.

For sure the 3618’s installed in high speed catamarans had main bearings temps.

Thats my experience when the block broke it should have shut down the engine way before the lube oil could ignite

Also oil mist detector if certain thresholds are met:

"SOLAS requirement for oil mist detectors – Engines of 2,250 kW and above or having cylinders of more than 300mm bore shall be provided with crankcase oil mist detectors or engine bearing temperature monitors or equivalent devices.” Chapter II-I, Regulation 47.2 (1981).

As per IACS M10.8 Oil mist detection arrangements (or engine bearing temperature monitors or equivalent devices) are required:

For alarm and slow down purposes for low-speed diesel engines of 2250 kW and above or having cylinders of more than 300 mm borefor alarm and automatic shutoff purposes for medium- and high-speed diesel engines of 2250 kW and above or having cylinders of more than 300 mm bore."

What you say is correct, but in the case of the Ocean Guardian the Cat 3516B’s are 1990 kW and 170mm bore. The requirement does not appear to be applicable.

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