Technical stuff
The Suction valve / pipe definitely was blocked, a result of many voyages carrying cheap nasty crudes which are not suitable for COW. A few members of the crew spent a few hours unblocking it and then we checked the valve position indicator in the tank to ensure it corresponded with the light in the CCR. Now that tank is again to load cargo which cannot be used to COW so no doubt this will become a regular occurrence. The COW machines are only at the top of the tanks and are not of the programmable type. This ship is 13 years old now, making it the oldest in the fleet and has been placed on a run which usually carries thick crudes. So perhaps more regular tank inspections will be necessary in the future.
With regard to the cold ballast being in contact with the bottom of the cargo tank before cargo is fully discharged / COW completed - the ballast tanks on this ship are mainly of the "U" shape without any centre divide and therefore for stability reasons must be full to the level of the double bottom before cargo is fully discharged - I don't claim to be 100% correct here as the book explaining this was rather complicated! The heating coils were turned off a little early during the last discharge - and then quickly turned back on again as the cargo began to cool!
The Chief Mate is on his first trip in rank, as is the Captain and Chief Engineer, other than the 1st Engineer all other Officers are on their first trip with the company so everyone is learning!
posted by Rob @ 10:35 am
9 comments
9 Comments:
Ok Rob.
Everyone first tripping in their capacities - all learning.
That is a problem for sure - a certain sign of an industry in crisis - but they brought it on themselves in the first place.
Keep at it.
Actually a question was asked earlier on - ie did your cargoes fall into the LSWR category - No response was received.
From what you are saying - your cargoes fall quite close to that category if not in it.
Crapy crudes are often good crudes - they can contain more products for refining.
Am suprised your ship is not fitted with either programmable machines or bottom washers. Makes me wonder how she ever got COW certification in the first place.
Good luck - you is learning real fast - pity it has to be the hard way though.
Shipmaster (Ret'd)
Hmm - interesting stuff.
It does not sound like your ship was constructed to Chevron specifications. They were very high specifications - in the past.
Maybe Chevron lost interest in shipping some years ago now.
They certainly don't go out of their way to "trumpet" it on their website.
Deteriorating standards - thats off shore management, flags of convenience, agency manning etc. etc.
Sad days indeed.
Good blog though - it could make a big difference - in the long term that is.
Capt (Ret'd)
U shaped ballast tanks with no centre line subdivision. Thats a lot of "free surface" for sure.
There's room for design improvement,so it seems.
Notwithstanding that, and considering free surface in combination carriers of like size they can typically go to three slack holds max at any one time but no more, except in one case I can think of - which ship could go to four.
Would have thought your vessel could go to at least two slack - maybe not though. Some transverse stability calculations required there - but it does seem odd that she can,go to two slack DB's. Of course tanker men generally have no idea about transverse stability as they don't generally use it at all -learn it at college then forget all about it after that.
I'd be suprised if it wasn't possible to have two slack without fear of going to any angle of loll.
Could be wrong though - you'll have to check that out yourself by doing the appropriate calculations. Get the c/o to show you how - there should be sample stability calculation forms in the stabilty/hydrostatic data publications on board.
Just fill in the appropriate figures and do the maths as the forms should indicate. It's just addition, subtraction, multiplication and division at the end of the day - surely you can handle that. Just looks a bit complicated when you are not used to it - but it's not. Remember to calculate the apparent rise of G due to the slack tanks.So long as G does not rise above M you'll still have positive transverse stability.
Check it out, 1 slack tank, 2 slack tanks, 3 slack tanks etc and see what results the calculations give you.
I suspect you won't "go negative" transverse stability until 3 slack - but thats just a hunch - do the calculations and see for yourself. The C/O will help you - I'm sure.
How many subdivided cargo tanks athwartships does your vessel have ?
bss
So she is thirteen years old and the oldest ship in the fleet.
That means two things to me.
1. The Fleet is at least not what you would call ancient and decrepit.
2. The ship herself however is certainly no “Spring Chicken”. She has certainly reached her more delicate years, and if the truth were known is likely to be on a downward spiral. How rapid that spiral will be is largely dependent on the degree of neglect she is currently exposed to or equally, has been exposed to in the past. Only you guys on board can really determine that – no one else – although others may have some idea through “reading the signs” so to speak.
Should “Offshore Management” Flags of Convenience and Agency Manning have been involved over the years, then the outlook may be exceedingly grim, dependent on just who those parties have been. There are some really bad ones out there – and yes – even Chevron could be vulnerable to such types, although it is perhaps less likely than in the case of others I could mention.
However, you guys are the guys on the spot so to speak – so your contributions are undoubtably the most significant of all. Don’t forget it – and remember always – you are after all an ambassador for Warsash – and that is the best of them all. Make sure you highlight that fact in all of your C.V.’s from this time forward – for that will pay dividends for sure.
At her current age keep a good eye on her internal structures – Framing, Webs, Stringers, Ladders etc. for they are likely to have begun the process of perhaps rapid deterioration. Ladders, Ladders, Ladders, inspections all rely on them – keep them particularly in mind – DON’T FALL, and always move slowly and carefully when you are inspecting tanks.
Always, Always, Always for that is where most danger lies.
And whilst I am at it – Gas Free just is not good enough –TANKS SHOULD ALSO BE CLEAN, - BEFORE A PERMIT TO ENTER IS ISSUED. Some may not like that too much – well that’s tough – Isn’t it ?
As for those dirty tanks, there is little doubt your ship requires, at a minimum, one bottom washer specifically targeting those suction.
If I were the surveyor, they’d be placed on notice of that, and they wouldn’t be sailing far, until they had done it. Five Inches of sludge – that’s just not good enough at all !!!!.
Commodore Bond. Feb 2nd 2007.
Well Absolutely !! – Commodore Bond.
It would appear that the vessel in question has been “COW defective” for all of her 13 years,
a matter which, in my view, reflects badly upon International Survey Standards.
Of course, perhaps that indicates more than anything else that the IMO is primarily concerned with minimum standards as opposed to best standards.
In the 13 years of the subject vessels life, who knows how many seafaring mortals have been exposed to that crude oil sludge, it’s gaseous, noxious & toxic content. Additionally, what consideration has been given to the potential for further human exposure to contaminating micro biological organisms material emanating from thousands of meters below the surface of the earth or sub sea surface.
Tanks should certainly be BOTH GAS FREE AND CLEAN BEFORE ANY ENTRY PERMIT IS ISSUED.
Human life appears to become progressively cheaper with the passage of time – valued now, it seems, at less than a barrel of crude oil sludge.
pp.
3rd Feb 2007.
Dear Rob,
YOU SAID:- quote:
"a result of many voyages carrying cheap nasty crudes which are not suitable for COW."
"unquote"
That young man is essentially utter garbage. You have, in previous posted comments been pointed in the right direction with respect to the problems experienced. Go over those advisory postings again, bring your commense sense factor into play, and next time you'll get better results.
Cowing is not just a matter of opening a few valves, it requires vigilence during the process. On deck your ears should tell you a lot in respect to machine performance whilst in the CCR diligent observation and intelligent interpretation of instrumentation displays will tell you how well the procedure is progressing - particularly those pressure and vacuum gauges - that is, if they are working and properly calibrated, which directly translates to "care and maintenance".
When you carry LSWR's - the thickest dirtiest of them all, then that vigilence/diligence is much more important - to ensure a satisfactory result. COW is incredibly effective if it is conducted properly and given the attention it requires.
Of course, that requires both people and equipment which "perform" as they should do.
Kindest regards,
Shipmaster (Ret'd)
"Technical Stuff"
Yes Rob, you are right.
A deck officer is a technical type job, especially on tankers.
Boyscout.
In reviewing recent "postings" on what has in effect become a highly technical blog with respect to COWing at any rate, one important factor has so far been missed.
Here it is:-
COW pressure - that must be optimised at all times during the process. Too often COW pressure is compromised in favour of manifold pressure during discharge. When you do that the effect can be such that you might as well not bother to crude oil wash at all. That is a classic case of "commercial pressure" seriously compromising the overall efficiency of good operating practice. All too frequently it is just not possible to maintaing both optimum COW and manifold pressure at the same time.
If you want to maintain clean seas, minimise pollution risks, care for the environment, care for your tanker (the list goes on) then preference should be given to the COW pressure when that operation is in progress. Therein lies the potential for another "battleground" - stand by what you know to be right - from the mariners perspective. Mariners do not pollute, they deplore it. It is the big end of town that does the polluting - Mariners just carry the can.
Give preference to COW pressure - the big end of town will just have to learn to wait. Discharge may be protracted a bit - but the trade off resulting from clean tanks is far superior, far more beneficial to all - than merely "impressive turn around figures".
Capt (Ret'd)
There are no cheap crudes Rob.
All crudes - if they are indeed crudes, are suitable for Cow.
Some don't respond as well as others.
LSWR - well cow helps, but not much.
dsd
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