Wake Low Capsizes Ship - this is a new one for me

[James Marinero]

Seems I'm not up to date on the latest research - and realities!

Freak 'Wake Low' Storm Capsizes Vessel, Stirs Up Hurricane-Force Winds

 

[Bajansailor]

Some basic info about her on Marinetraffic -
SEACOR POWER (Platform) Registered in USA - Vessel details, Current position and Voyage information - IMO 8765682, MMSI 367527630, Call Sign WDG3592

She is a 'lift boat' with 3 enormous spud legs for winching herself up high out of the water - one of the legs is partially visible in the photo in the linked article that shows her capsized.
She has a gross tonnage of 2,276, is 51 m. long, and 31 m beam, so a length / beam ratio of slightly more than 1.5. This should make her very stable - but seems not when you have those enormous legs sticking up when you are underway in hurricane force winds.

Here is a good article about lift boats (and mentioning Seacor Power) from a naval architect's perspective.
https://www.wdsu.com/article/what-is-a-liftboat-a-naval-architect-explains/36123835#

 

[Tomahawk]

Not good.

 

[Deleted member 36384]

I have sat off Fouchon for 10 hours waiting to enter the bayou in about a F8, to cross the bar. It is very shallow with a short, steep chop. These boats are not that stable (the ability to return to the upright position) as they are low sitting in the water, have large surface areas and usually lots of weight well above the waterline. My employer uses many of them. Last year in Nigeria, similar environment, one rolled over after shipping water from a steep chop and being overloaded; a few lives lost. The reason they have the legs is more to make themselves a stable work platform, fixed in position, along side the many wellhead platforms, rather than elevate, although some can do that. They are used for lots of stuff: fuel store for the works, office and canteen, personal transport, base for mobile cranes and equipment movement. The facilities they serve are unmanned with minimum equipment. These vessel sail in and out to service them and are very low cost in a competitive market.

 

[Stemar]

100% hindsight and, of course, you've got to see the bad weather coming, but would it improve the stability to lower the legs when things get nasty? They wouldn't have to touch bottom - indeed, there may be advantages to staying afloat as it may allow marginal ability to manoeuvre.

 

[dom]

How tragic - a terrible loss.

Re @Stemar: these lift vessels have low AVSs and as I understand it, there's no obvious mechanism for materially improving stability and safety. However, in this case, your suggestion is a good one, in fact, going the whole hog and dropping them right down to the seabed and then jacking the vessel up.

The danger with this apparently is when a big wave catches the vessel in the midst of jacking:
Lift boats like Seacor Power are offshore workhorses but not designed for rough weather

There's a lot of questions to be answered re these vessels, which a subsequent expert investigation will no doubt do.

RIP to those poor lost souls

 

[DJE]

100% hindsight and, of course, you've got to see the bad weather coming, but would it improve the stability to lower the legs when things get nasty? They wouldn't have to touch bottom - indeed, there may be advantages to staying afloat as it may allow marginal ability to manoeuvre.

They're probably at their safest standing on the seabed with the hull jacked up clear of the waves.

 

[MystyBlue2]

Can't predict mother nature, Even if we think we know her and how to read her!

Look at volcanic activity...There's 54 Volcanoes world wide erupting simultaneously as we speak!!

She does what she wants and the best we can do is dodge the destruction the best we can.

 

[Deleted member 36384]

Self Elevating vessels have environmental limits for the jacking operation and when jacked up: wind loading, wave size and frequency, water current. The stresses can exceed the drive mechnisms, braking mechanisms and locking method for the jacking systems, as well as the design stress for the legs and hull penetrations that they run through.

In the conditions forecast, it is likely that the vessel would have had to jack up it's legs and move off location as it would not have been rated at elevation for the wind speeds. I doubt that lowering it's legs would have worked nor would the vessel be safe in the elevated condition at these wind speeds. Leg collapse is a reasonable risk when these vessels are subject to loads outwith their design constraints.