Plimsoll Line

julian anstis
3rd June 2005, 17:51
Daft question but one I would like to know the answer to....

#1 Can anyone explain to me how the exact position of the Plimsoll line is determined on a ship.

#2 Is it ever used as such, if so in what respect.

3rd June 2005, 18:06
Rather than try to give an all-embracing reply in twenty lines or less, can I suggest you just open up google and do a search on Plimsoll Line. That Plimsoll dude was a great man, and generations of seamen have owed their lives to him.

Is it ever used ? Well yes. We once had a huge panic because we'd loaded a maximum cargo of oil up the gulf for a European Port with the old man assuming that we'd go to Rotterdam to discharge. Trouble was we got orders for Nynashamn in Sweden. We didn't have the bunkers to get there, and if we bunkered in Gib we'd have been below our Winter North Atlantic marks. Such was the panic that we slowed down and secret arrangements were made to bunker us at dead of night at sea off Gibraltar so that no one noticed. So it was definitely taken seriously.

Having said that we saw a Pilgrim ship in the Red Sea that had been overloaded to the extent that her paint was washed away and discoloured almost to deck level.


julian anstis
3rd June 2005, 19:10
Dave....have I missed something or correct me if I am wrong but if it was taken that seriously......why the need to bunker at the dead of night so no one noticed.......

3rd June 2005, 19:23
Good point

3rd June 2005, 19:51
Dave....have I missed something or correct me if I am wrong but if it was taken that seriously......why the need to bunker at the dead of night so no one noticed.......

It was taken seriously by the authorities and I'm sure most of the blokes on board wouldn't have been too happy to know about it. As ever the company and their henchmen had the commercial imperative to put profit first. They were prepared to risk this evasive action rather than bunker elsewhere or more than once.

I wasn't in a position to blow any whistles because my sources of the same information were twofold and one of them was covered by the secrecy of correspondence. If I'd had anything to say at the time, I'm more than sure it would have been alleged to be a breach of the latter.

She didn't sail from Gib below her marks that were applicable there, but would have been when we got 'round the corner'. It wasn't by some massive life threatening amount but was nonetheless an infringement.

Has that clarified it or made it even more convoluted ??

3rd June 2005, 20:19
I think we can safely say that Plimsoll was a true friend to seamen. The adoption of his marking of a ship was to save many hundreds of lives and stop unscrupulous owners, agents and Captains from seriously overloading ships and putting them and their crews in serious danger.

Basically a ship could only be loaded to the Plimsoll marks. These indicated a safe loading condition for the area of the world the ship was in, the season of that area and whether or not the ship was in fresh or salt water. Should a ship exceed the Plimsoll marks, then the owners, the agents and the Captain are in very deep Stow High In Transit as it is a Criminal Offence to exceed Plimsoll marks.

I remember as a Cadet having to paint the marks and boy did you need a steady hand which was not always very steady after a run ashore the previous night.


julian anstis
3rd June 2005, 20:50
Much clearer now thanks...........have tried Google but still cannot find out how the exact point of the Plimsoll Line is determined.........I guess it must be down to rather clever mathmatics...and X marks the spot.

3rd June 2005, 20:54
The Merchant Shipping Act of 1875, which established the marking of a load line on every cargo ship, was meant to stop practice of sailing with deliberately overloaded "coffin ships", to quote Samuel Plimsoll. These ships were intended to sink so that the owner could collect the insurance, with no regard to the crews.
This act was evetually followed by the Merchant Shipping (Load Lines) Act of 1932, revised in 1968 and ammended in 1990. The 1932 act was also the start of the International Convention that set the loading rules.

To confuse matters further, according to my college notes for ship construction quote:
The minimum freeboard is based on the volume of reserved buoyancy which may be regarded as safe depending upon the service of the ship and the conditions in which it is intended to sail. It is initially dependent on the length of the ship, with corrections made (+or-) for variations in form, sheer and camber, together with reductions for the Reserve Buoyancy of Superstructures above the Bulkhead deck. The calculation gives the summer load line marked S and circle with a horizontal line through it (the original Plimsoll Line)." It doesn't tell you what the calculation is.

The Freshwater Allowance in mm = Displacement / 4 x tonnes per cm immersion. This added to the summer mark gives the F.
Similar allowances are made for tropical and winter conditions, the rest is still too difficult for me to grasp.

29th November 2006, 23:36
From Lloyd's rules and regulations 1896/97' Merchant Shipping (Load Line) Act,1894.

John Rogers
30th November 2006, 00:16
There is a statute of Sam located in Bristol,which back in the old days had many ships sail as coffin ships.

Jan Hendrik
30th November 2006, 01:12
My avatar does of course reflect the importance of this safety mark and honours Samuel for the introduction of safety at sea.
The company I worked for uses all their advertising with the plimsoll mark.
Some of you may have seen glasses, ties, belts, cufflinks, any sort of advertising with the plimsoll, most of which comes from that company and I also added quite few of that stuff over the years even including wine labels.

30th November 2006, 08:18
Here the statue, taken in 2005 by Evert Sikkema;

30th November 2006, 11:14
never board a ship that has its plimsole line on the funnel i was told??? LOl

30th November 2006, 18:11
Was on a ship once that had had the Plimsoll marks changed - cannot remember why. Anyway - some time after we had been in drydock we discovered that the marks on both sides were at different levels. Caused a bit of a stir .....

Hamish Mackintosh
30th November 2006, 20:52
never board a ship that has its plimsole line on the funnel i was told??? LOl

Thats where "Kellies" was, wasn't it?

non descript
30th November 2006, 21:34
It is a relatively common occurrence to change the load line so that the vessel can comply with a particular deadweight restriction; e.g. some ports may restrict entry to vessels of: “less than 150,000 mt deadweight”, so arriving with a load-line showing she has 151,013 MT at Summer Salt Water is not going to be too impressive. As a result the Owner can apply to the Classification Society and have their vessel re-measured, so the full (certified) deadweight is, for example, 149,900 mt deadweight on a reduced draft.

Obviously the system only works for re-measuring to a lesser deadweight.... the idea of re-measuring to a deeper draft and size is somewhat contrary to what the good Mr Samuel Plimsoll had in mind way back in 1875...

Having re-measured the ship and obtained a new tonnage certificate, the only remaining task is to send the crew over the side and get them to kindly paint new load-lines.

This scenario may well have been behind the concept of the ship having to "have the Plimsoll marks changed" referred to above by xrm.

2nd December 2006, 11:17
He was certainly a great man and very determined, it took him years to get his law passed and actually enforced !

If memory serves correct ( I worked mostly on german coasters)
the reserve buoyancy is someplace around 20%, which is easy enough to figure on a single decker and a bit more complicated on a shelterdecker.
Since on a shelterdecker (assuming 1 between deck) the between deck is actually the maindeck and the ship can be downloaded to that deck level but not beyond, its obvious that if you did that on a single decker you'd have a U-boat LOL
As it was in the wintertime we seemed to be more underwater than above it lol
It gets even more interesting with "changelings" (convertibles). No, not MGB's ! LOL I never found a good translation into english for them.
Those are ships that have 2 measurements. 1 as single decker and 1 as shelter decker. I worked on 2 of those, for the most part they tend to end up working as one or the other and seldom get changed. The original idea was apparently to register the ship depending on the kinds of cargo available, ie lighter bulkier loads or simple heavy stuff. and as always manning requirements, fees and such where considered.

Summer and Freshwater line should give you the exact same tonnage.
So when you load 2000 tons in Cologne for instance by the time you get to the North Sea she'll float higher and vice versa

2nd December 2006, 20:41
AS a draft surveyor I can say many of todays management companies do not understand the load line regulations, ie that a vessel cannot be over her marks (plimsoll) at any part of her voyage. You may load in a tropical zone and enter a winter zone your draft has to correspond on that day not at arrival port. Many of the changes in plimsoll lines occurred when open shelter deck vessels were changed to closed shelted deck, take to long to explain but both dealt with profit at various times.