First of all I would like to express my sympathy for the situation You have got yourself in. I am not going to give You advise, what to do as this is a lawyer’s job and I am not such.
For starters here is a link to WMU webinar, which landed in my news feed on my FB account and upon watching it i have figured, it may be of some interest to You -especially part III .
Myself and may be other participants of this forum may not agree with all what the panellists have said but generally i think it is the best so far from the legal point of view, what has been aired on the legal issues involving Ever Given -your case included .
First watch the whole thing and listen carefully and do not get discouraged by foreign accents 
Now when you are done let me quote one of the commentators here:
quote:
However, some knowledge of our legal systems suggests, that the reasons for this unilateral decision, to declare a “General Average”, may be challenged by the big and wealthy “losers”.
end quote
He is damn right and not only big and wealthy losers can do it but smaller fish can do it as well if they “band together”
Some participants may declare me a roving lunatic propagating such an idea but i will tell them " hold your horses" fellas and consider the following :
I find it difficult to understand, why all legal gurus including those in above webinar and those participating in different forums and panels( Splash247 for example) , do not mention that clearly , that G.A. (general average) is not a sacred cow and can be challenged and butchered easily if claimants /challengers can prove unseaworthiness of the vessel .
Of course the burden of proof rests with them to do it but the cases history can show it can be done. Example : CMA CGM Libra case , which is now flying to the Supreme Court as Owners contest Honorable Judge Tiare decision to declare the said vessel was unseaworthy - hence the G.A. test failed miserably .
The reason of Libra unseaworthiness may be shocking to Old Salts here but it was badly prepared , inadequate PASSAGE PLAN , which was in addition badly executed by the ship master. I will skip further details.
Surely Ever Given had to have a Passage PLAN , which surely contained " points of no return" such as Suez anchorage , surely it had to contain master deliberations on the risks his vessel takes given it’s physical dimensions versus dimensions of Suez Canal with or without strong winds , surely it had to contain Under Keel Clearances calculations/deliberations with particular focus on the SQUAT EFFECT , BANK EFFECT and other risks . Surely the vessel had Safety Management System where such procedures were written and should be complied with.
Surely it had to contain info from all available sources on the bridge like B.A NP Pilot books , Guides to port entries, , ships routeing and ocean passages of the world - the WHOLE SHEBANG. And i am damn sure the master should be familiar with SCA Rules of navigation or at least have some rudimentary knowledge of it’s contents regarding not only the transit speed and limits but rules regarding tug assistance when required and how it is arranged.
And if he did not have this knowledge prior transiting this peculiar area where pilots pray during navigation and consume huge amounts of ice cream and read newspapers , then surely there had to be management SMS procedure how to make sure their masters get this knowledge ASAP and document it as per ISM mantra.
I can rattle on and on but i hope others here will join rattling as well and chip in and/or contribute.
One can find the Libra verdict on the web and read the Judge reasoning . Honestly i do not agree with all the arguments and would rather believe the master was incompetent as suggested by an Australian lawyer and Master Mariner in his analyses of the case.
The issue of seaworthiness has been expanded hugely in the last 50-60 years and includes not only technical prowess/condition of the vessel but also competence/skills of master and/or crew, certification, adherence to ISM Code( Solas) , vessel management system , industry advise and many other things as the case history proves.
I have and have read many books on the issue including Gard P & I Guide to Shipmaster - there is a nice chapter on seaworthiness there and in many publications issued by top 10 P& I Clubs this issue was digested quite frequently and made public during the last 20 years.
From all this literature I regret to observe that nowadays, with all this ISM and SMS and all this bureaucratic bullshit , proving unseaworthiness looks like a walk in the park. One needs only skilled lawyers and guys/consultants who know the current systems inside out. Follow the CMA CGM Libra trail.
Need to shut up and split now but honestly if I was in Your shoes I would go for the jugular. I find it interesting that nobody clearly says who is the OWNER as per ISM definition . My gut feeling it is BSM and I know those blokes .They made me master in 1995 on their container ships.
Remember : that class certificates offer to all parties concerned in the adventure including master , the presumption of seaworthiness not a guarantee and the devil is in the details, which are best uncovered by judges and their brethren of maritime advisers/consultants.
If You have any questions You know where to find me. Cheers .