El Faro Stablity


#21

The process used by the CG in ruling that converting the ship from RO/RO RO/CON was not a major conversion reminds me of Nancy Levenson’s analysis of the Challenger explosion.

With the El Faro the CG had the authority to make the call with regards to the conversion work but lacked the expertise. For that the CG had to depend on the ABS but evidently there was no formal process to fully evaluate the claims TOTE was making about the conversion.

TOTE’s argument, as would be expected, was legalistic, not technical.


#22

Not the orginal DEI but the new one, correct?


#23

I was of the impression that the original main deck (measuring deck) was retained throughout the conversions?
In that case the DEI and DFA would have been reduced, but until either one was reached there would be no effect on stability. The range of stability would obviously be reduced though.


#24

The new one. Another effect that was not mentioned is that the angle of vanishing stability is decreased due to lower GZ values.


#25

I don’t understand how or why the load line got changed. It seems the load line was not changed when the ship was lengthening which was ruled a major conversion but it was changed when it was converted to carry containers? Is that right? I don’t recall having seen an explanation.


#26

Unfortunately, the stability criteria do not increase as the draft increases. While the righting arms and area under the curve may decrease, the same criteria has to be met from lightship to full load draft. As long as a vessel meets the minimum criteria, the vessel is ok to sail from a stability perspective. There is no legal way to require a ship to meet criteria over and above what is required by the Regulations, be it the CFR or IMO.

Keep in mind that the only applicable criteria was the USCG Weather Criteria and SOLAS damage stability from 1990. There was no applicable righting energy criteria for the EL FARO. None. Not when built. Not when lengthened and not when converted in 2005/6. The SOLAS damage stability was not updated until 2009, so that would never have applied, even though the USCG’s report showed the EL FARO did meet it on the ill fated voyage.

Would meeting more strict criteria be safer? Of course. Let’s take an example that’s closer to home. Look at the vehicle you drive. More than likely each seat is provided with a seat belt and a shoulder strap. Why? Because that is what the regulators have been deemed safe - the minimum level of safety to be met.

Now we all know that a 5 point harness is safer than a belt with shoulder strap. How many of you have retrofitted them on your vehicles? Think about those that drive around their kids or grandkids. If you know this would be safer and could save the lives of you and/or your passengers in an accident, why haven’t you spent the money to retrofit your vehicles with 5 point harnesses for each person? You have deemed it too much money to spend on the increasing the level of safety over and above what is required.

When you say that the owners should have gone above and beyond the required level of safety provided by the applicable stability criteria, you are expecting them to do what you haven’t done for yourself.

One last thought. The vessel sailed for 40 years under it’s applicable stability criteria without a loss until she was put on a collision course with a hurricane. Everything that is built (cars, truck, ships, trains, planes, buildings, dams, etc.) has a limit to the conditions it can withstand. I don’t care if the vessel was built in the 70s or last year, ship stability criteria are not developed with the thought of running into the eyewall of a hurricane.


#27

I must have seen an explanation somewhere, but I cannot find it again.
Now, I just found this principle:

From TOTE’s submission to the NTSB, appendix B, page 16, by Prof. Charles Munch:

In 2006, the vessel was again modified, including: removing spar deck, strengthening of the main deck to carry containers on deck, and adding permanent ballast for stability (which allows the carrying of containers on deck), and increasing the load line draft by two feet.

The modifications were not deemed a major conversion. Thus, stability requirements from 1992 continued to apply to the Vessel. The impact on stability was the requirement to add permanent ballast to the vessel so that the desired number of containers could be carried on deck. Added permanent ballast allowed the vessel to meet required GM criteria. FEU capacity was increased by 232 and the RO/RO capacity was reduced by 40 FEU. Total change is an increase of 192 FEU.

PS: The Marine Board’s Final Report, page 55, states:

“…in 2006… and an additional 4,875 long tons of iron ore fixed ballast in the remaining two
pairs of double bottom ballast tanks.”

This is nearly double the weight that would increase the draft by two feet…


#28

Yes that is correct, if I calculate well 4875 long tons alone stands for almost 3.9 feet draft. I cannot explain this, bit of a mystery. The only thing I can think of is that the ship had, before taking on the iron core, a positive draft of 1.9 foot.


#29

I don’t understand what is meant by max draft. My max draft is just a bit over 10 metres, that is max draft as per the ship’s particulars.

RO/RO cargo is not very dense, A normal full load is 8.5 - 8.7 meters or so. The deepest I’ve ever been is 9.2.


#30

In commercial ship operations, the ship will usually quote the mean draft as the vessel’s draft. However in navigational situations, the maximum draft, usually the aft draft, will be known on the bridge and will be shared for instance with the pilot.


#31

That’s the actual draft, the deepest acutal draft is called “deep draft” If the drafts are F 8.5 m A 8.6 m then deep draft is 8.6 meters.

Max draft is listed on the ship’s particulars, on my ship it is about 10.01 meters. Max draft doesn’t change with load.

For the El Faro:
From NTSB p 134
Draft, full load (extreme) years 1975-2005 28’-1 1/16” (8.6 m)
Draft full load (extreme) years 2005 -2015 30’-2 3/8” (9.2 m)

NTSB p142
Actual Departure draft:
Fwd: 26 feet 9.9 inches (8.18 m)
Aft: 32 feet 4.5 inches (9.87 m)
Mid: 29 feet 8.3 inches. (9.05 m)

Actual departure Drafts: After the CargoMax values were corrected,the vessel’s departure drafts decreased at the aft mark to 32 feet 4.5 inches, at the midship mark to 29 feet 9.1 inches, and at the forward mark to 26 feet 9.9 inches. The calculated midship draft was 29 feet 8.3 inches.


#32

Maximum draft in my book is also called ‘deep load draft’ which occurs when the ship sinks to its Plimsoll line.

Could the maximum draft in your case be the ‘scantling draft’? This draft is usually greater than the deep load draft. This draft is based on the strength of the ship, it is calculated to how much draft the ship can be loaded and still the stresses on the ship will be in safe zone. Because of the low freeboard it is legally not allowed to sail with such a load. The load line drafts are not based on the draft that the ship can load, but rather based on the minimum freeboard we need to have at all conditions. Kind of theoretical draft with little practical use.


#33

When I am asked for max draft I take it off the particulars, in my case it’s called "Max draft (summer)

This is from the internet - max draft would be 12.77 meter

This is from Gard; - max summer.

image

In the case of the El Faro what is being called max sounds like the new result of having added more weight.


#34

Again from NTSB page 145

the freeboard was originally 14 feet 2.25 inches - 14.18 feet or 4.33 meters
After the 2005 conversion it was 12.08 feet or or 3.68 meters.

ABS surveyed the vessel in 2005 and issued the load line certificate. The simplest explanation is that they moved the Plimsoll marks.

image

From linkedin:

Freeboards may, from time to time, need to be re-assigned. Here are some instances where this may be necessary.

Vessel lengthening.
Change of vessel type.
Change of trade from Coastal to Foreign-Going and vice versa.

This is from the CG report - page 190 ,

9.1.2.4. Despite the apparent increase in cargo carrying capacity and increase load line draft which would result, the 2005-2006 conversion was not designated as a major conversion by the Coast Guard.

This is naval architecture, I don’t understand how load lines are calculated.


#35

For US ships the USCG’s Load Line Act is valid.

Freeboard table.

The most significant and governing parameter for calculating the load lines is the ship’s freeboard. American vessels were loaded to a formula based on “inches per foot of depth of hold” (the method used in Britain prior to 1890) until 1917 when the U.S. Shipping Board required adherence to British Board of Trade standards based on a set of calculated freeboard tables. Not until 1929 was the Load Line Act passed in the United States, more than a century after ship losses due to overloading became a recognized problem in the industry.

For more information on this subject go to this link:


#36

In my experience with RO/RO, with a full load the ship will never be “full and down”, just full but not down. I’d guess that with a full load of trailers the ship wasn’t close to max draft even with full bunkers and (water) ballast. That’s why the extra 4875 tons of permanet ballast (minus the weight of the water ballast replaced) would still leave available freeboard for the trailers and the extra weight of the containers.


#37

Slade’s book mentions the similarities to the Edmund Fitzgerald; the Coast Guard rasied the load line on that ship three times, weather worse than forecast, ship worn out and used up.

The El Faro was getting older, being loaded deeper than ever, changed the load line, taking bankrupt Horizon Lines’ cargo, loading three tiers of containers instead of one deck of trailers.


#38

I remember that one of the theories about the sudden disappearance of the Edmund Fitzgerald was that the ship in undeep water and very high seas slammed with tremendous force on the seafloor and immediately broke up.


#39

Mariners on the Lakes certainly believe that she bounced over a shoal in rough weather that she routinely cleared with a reasonable margin in calm weather. This supposedly resulted in massive structural damage and flooding. The wreck has been found and studied. I read about it years ago, but don’t remember a thing.


#40

Hubris of the CO was another similarity between the Fitzgerald and El Faro. Right up until she sank, nobody on the Lakes thought the “big boats” could be sunk by even the worst gales. McSorely was a known heavy weather Captain too who did not have the level of concern he probably should have for the conditions he was sailing into. That being said, it should be noted that the similarly aged Arthur M. Anderson was also out there in the same conditions and didn’t have much more to suffer than a foul ride and some topside damage.