Yesterday was one of those days where I was fast walking, fast typing, fast dialing and fast talking all damn day.
There were challenges in the cargo load yesterday. Not our fault, thankfully, and then you know the children's game 'telephone?' There was that for instructions on fixing the problems, so that the three parties involved (me being one of them) had three different impressions on on dealing with the issue. It was an issue with the oil we were loading, and so one party made plans for a fix that didn't consider whether or not I could physically carry out the job on the HQ, my office trying to get in touch with me while I'm running in the house to do calculations or work on papers ( and then rushing outside to swing valves or run the cargo crane, etc etc,) and I'm trying to figure out if I can do what the customer OR my company asks, because I'm getting emails from the customer forwarded from our office, but the oil terminal is getting different emails and making plans too, that differ from mine.
What was stressful yesterday was trying to handle a multi-part plan involving multiple transfers of several kinds of oil and trying to ensure that the HQ is able to load and pump off these things without blending them, also without stressing the hull, and also being trimmed and having either no list or an acceptable temporary list or an advantageous list, but not a disadvantageous or an extreme list, and also the same for trim.
The HQ has pairs of tanks- port and starboard, no center tanks, and in all the tanks except my aftermost tanks, the suction point in the tank, where the pump sucks oil, is in the back of the tank, and close to the centerline of the barge. Since the generator house and part of the accomodations block sits above part of the aftermost tanks, the suction point of those tanks is in the front of the tanks.
Confusing, yes? Essentially it means that in order to drain my aftermost tanks, I have to have the bow lower in the water than the stern, and the deck sloping forward, but in all the other tanks, I have to have the stern lower than the bow, with the bow in the air. So with problems, and loading two grades of oil and also having oil on board for two ships (one ship gets some of both grades of oil, the other only wanted some of one grade). The problem was that I couldn't use our computer to calculate the list and trim during some of these moves during the load, as the loading program would instantly 'forget' the last movement when I tried to predict the effects of future movements to decide on the best way to set up the next movement. Simply put, the computer couldn't do what I needed it to do, and I had to rely on my understanding of how the HQ trims and lists based on the amount of oil and also where it sits. As an example, I know that 1000 tons of oil in my #1 tanks will shove the bow down this far and shove the stern up this far... but it's harder to predict how far the same mass in the #2 tank will push the bow down and the stern up because the hull is a lever- pushing at the end has a greater effect than pushing part way towards the center. Now, I know roughly how this will work, I've been on the current HQ for over a year. But I had to load just ONE tank for a time, to get a parcel of oil out of the way that was in the pipeline that we needed to use at the terminal. We didn't want this parcel so once we were loaded, I could pump this one ashore before we sailed... but I needed to use all my other tanks to do this job, so having the unwanted parcel would list us over one way, and then filling the other tanks would list us over the other way. So I had to load a large batch of oil in just one tank, and I had to decide which tank, and it would give the whole barge a list to one side, and depending on where I put it, I had to be sure I could completely drain the tanks- if we list to one side, we can't suck tanks on the 'downhill' side of the hull dry- the oil runs away from the pipeline. Plus, my aftermost tanks have to have a forward trim but all my forward tanks require we have an aft trim in order to suck dry.
now, another headache- one of my after sets of tanks is smaller than the others. Not the aftermost tanks, mind, but the ones just forward of them. I have two sets of tanks dedicated to carrying one product, an ultraclean fuel that can't be put in a tank with other grades of fuels. So the volumes involved, I have to completely load the small tanks aft and the other set of tanks up forward will be partially loaded. These tanks are not balanced against each other, either, the small tanks are towards the center of the aft end, and the forward ones are my #1 tanks, up in the bow.
Essentially it came down to writing everything down, step by step, then taking pieces of paper and writing the weight of oil in each tank, and seeing if I could do the next step, then the one after... for 10 steps... and THEN, to see if the results would allow me to get both grades of fuel off for the correct ships at the right time... so sometimes I had to pump the same product from one tank or another to get the bow up, and then to get the bow down, and then to get the bow up again... all without stressing the hull. And the stupid list from the product we were loading temporarily complicated that for sure.
In the end, it was a gut call, as the paper predictions and the computer couldn't model what I needed to do- too many variables. I knew that at two key points I would be VERY close to being out of trim, like a 1-in-5 chance, which is to say that I thought we might be OK, but we'd maybe, for example, be slightly down by the bow when I needed us to be bow up or flat, leaving oil in our tanks. This is not one of my regular customers' oil, so if we had a remainder on board, *someone* was going to have to pay for it to be returned to the owners' tanks. So an ROB was not acceptable, but I had to rely on my gut feeling a little bit, which is not cool at all.
In the end? I had two key points where I felt we'd be close on being in the proper trim.. One of them, where I needed us to be flat or bow up, I had almost 3' of trim with the bow up, and all that worrying I had tons of room for error. The other? I needed us to be flat or bow down- and we were flat, or maybe bow down by 1-2 inches... skin of my teeth stuff.
The math part and the load planning was actually a great exercise for my mind, as it's something I enjoy doing, and I'm ok at it anyhow. The playing telephone thing where I'm getting a message on a plan, and working one out, only to get another message from another party negating my plan, and then informing one party that the other wanted something different, when all the time everyone but me was talking to each other but not passing the same information somehow... it was stressful. I mean I'm no dummy, when things go sideways I request written orders, and really, if I had fucked up and sucked air because of a trim issue and couldn't empty my tanks, my company would have had my back given the chaotic nature of the order request and my need to use intuition rather than math at a few points.
And really, it worked out well- the discharges went smooth as silk. Unusually so, in fact, which was nice. It all left me a little fatigued, but I don't get paid to go to bed feeling rested, I suppose. I had the feeling this afternoon that I had been worrying too much, and if I'd just gone with my guy we'd have been fine. Perhaps there's a lesson there.
Is it physically feasible to have some deck mounted ballast tanks that you could pump some seawater into to accomplish that tilting you need? If not metal, maybe rubber or other soft construction/inflatable?
I'm guessing that your crane is too limited in capacity/location to essentially use a dip bucket to swing around to get the necessary trim change? Clearance to your customer may be a limitation on using it, even if the engineering is adequate.
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