What do you call the liquid that remains in a ship's tanks when they are emptied?

Thanks for the interesting and informative detail Jehardiman.



A brief slightly off topic diversion on the subject of sounding, and words that have changing meanings in different contexts:



I was looking into the history of making early charts, in particular the laborious use of lead and line to systematically sound the depths, and sample the bottom. I was surprised to learn that the etymology of 'sound' in this context had nothing to do with acoustics, or indeed, being 'whole' and 'working properly'. It comes, apparently, from Old English/Norse 'sund' and is connected with 'Sound' meaning a large body of water, typically between two areas of land. 'Sund' also can mean 'swimming' or 'separated' as in 'torn asunder' and this fits with the body of water separating two bodies of land.

At the time, I was also interested in the Lancashire coast on Morecambe bay. I had naively assumed that a particular area took its name as a variation on Sutherland (south land) it being the most southerly peninsula on the north bank of the river Lune. However, clearly, Sunderland (point) its road cut off from the mainland at high tide, is the 'sundered' or 'separated land' or even the 'swimming land.'

 

Obviously, this is correct ... and in fact VOCs are far more dangerous when extant as heels in holds than full due to the oxygen factor. If you opened a hold slap *** full of a VOC, you could likely flick a match directly into the tank with little to no effect (depending on volatility, vapor pressure, updraft from the hold, size of vapor pad over the load, surface area of the heel in the hold, presence of absence of any inert vapors in, or as, the pad (like nitrogen, etc., etc., etc., on a case by case basis) ... and in fact, the match would in the vast bulk of such cases be extinguished by the liquid VOC. The odds of you doing so into a hold that's carrying a heel of some light and volatile flammable organic liquid and the balance of the tank holding VOC vapor and O2 are far, FAR less likely to be as forgiving. I mean, you don't want to do either, of course, but your odds of carrying out the former without disastrous effect absolutely dwarfs the same for the latter, depending upon the particular situational characteristics involved therewith.

 

Heel yes! I agree from the very bottom of my little black heart!

 

What do you call the liquid that remains in a ship's tanks when they are emptied?
This was the original question - looks like we are branching off topic or ...into a new -albeit somewhat related perhaps - one? - ie: VOC's, flammable materials etc.
So, you add volatile material (fuel) + oxygen (air) + ignition = fire. Sometimes this can be obvious, sometimes not. One case I heard of made the participants eligible for the "Darwin Award"

A fishboat had some repairs done to the hydraulic system but there was still some leaks that could not be located. The system was drained for pressure testing with some inert gas. Well, they could not find any nitrogen tanks so they hooked up some alternate gas that was handy....oxygen. Yes, after a short time there was a quite a 'bang'. Fortunately, no serious injuries or damage.

 

Not exactly. The crews love it. When I apprenticed in a bulk cargo ship, the crew would manually sweep every nook and cranny of the hold after discharge. It is called "bilge cleaning". They could manage to scrounge 10-12 drums of ore then resell it to a third party next time around.

In other ships, tanks sometimes are of bad design. As a surveyor, there is a residual FO remaining that cannot be sounded off. Up to 50 tons. The engine crew would open the manhole cover and use an auxillary pump to dry out the tank then sell it. Lots of money for them. Big headache for me as I could not figure the difference between how much was certified delivered and how much can be sounded off. Eventually the practice was discovered and the CE was fired along with some of the engine crew.

 

Perhaps calling it R.O.B. wasn't the wisest choice.

 

The liquid in a ship tank that can't be pumped with the normal piping system servicing the tank, due to the liquid being below the suction, is typically called the "tailpipe allowance" or "unpumpables". Often this is taken as being 2% to 5% of the tank total volume depending on the tank size and shape. A tank with a V bottom can be pumped down more than a tank with a flat bottom. It is the geometry of the tank, the position of the suction, and the trim and list of the ship that prevents all liquids being pumped out of a tank.

 

You Maritimers have a name for everything!

Well designed tanks may have a "sump" or catchment pocket built into them.
A recessed low-point to collect "stuff", concentrated into a smaller, more isolated space.
This can make for easier, more effective pump clean out.

 

Interesting discussion. Back in 1969 to 1971 I worked at Lockheed Shipbuilding in Seattle. (no longer exists) We were building LPDs. Each LPD had 101 tanks. Someone, (Me), had to climb down into every tank, measure the distance above the lowest point of the tank of the striker plate for the sounding tube, and the exact position of the air bell at the end of the capillary tubing for the tank gauge. I can tell you from first hand experience, in some tanks the amount of residual liquid that could not be measured (or pumped) was considerable. In smaller tanks it could be several hundred gallons. In the huge belly tank that held close to 100,000 gallons (water) it could be several thousand gallons. I don't remember any special term for the residual liquids.

 

@Ike Could have been worse.