Nelson & His World

The Plimsoll line limiting the load carried by merchant ships was introduced as late as the 1860s.

Were there any regulations or unofficial 'understanding' about limits on the loads carried by warships in Nelson's day?

Tycho,

The Plimsoll line is the waterline marked on merchant ships, to show the level at which cargo may safely be carried. Since its inception is has progressed a great deal from the original circle with a line through it, and in more modern times has also shown a vertical bar with markings for the waterline in different parts of the world. This delineates water salinity and the levels at different seasons, to which a merchant ship may safely be loaded.

I don't believe warships have never used this system, using instead a method based on water displacement, although I believe a New Zealand vessel is about to be the first warship to be marked with a Plimsoll line. More reliance is placed the vessel's draught and the draught markings at bow and stern, which are of some antiquity and which were traditionally marked in roman numerals. I say traditionally, since many merchant ship use modern figures, although I think warships still prefer the old method as being easier to read.

Back in Nelson's day I'm sure there were some rules and a great deal of understanding about the loading of a vessel. Being a sailing vessel, it would have been important to get a ship in the best sailing trim as possible, which meant that any weight, such as stores, ballast and even guns were moved around periodically to achieve this. Ships usually drew more water at the stern and presumably the crew would also have been a factor, as was the height of the lowest gundeck above the waterline.

As Devenish has stated, warships have never used a Plimsoll line but have relied on Draught Marks, figures painted in the bows and stern measured in feet from the keel. It was (indeed it still is) a requirement for the draught marks to be checked regularly.

I have certainly come across the ship’s draughts recorded in logbooks, particularly after taking on stores.

This is pure surmise on my part, but I suspect there would have been little opportunity to overload a warship from the point of view of safety. Warships were designed to carry an enormous weight, and I am not sure that adding a little more load into the limited space left would have made much difference. It was all about the guns, which were heavy in themselves, but also demanded a large quantity of shot, and a crew of about seven men per gun, who took up a lot of space and whose weight was significant in itself, but more importantly needed a large quantity of provisions, particularly water (and beer). The fact that the guns were carried above the water line (for obvious reasons!) meant that a large weight of iron and/or shingle ballast was needed as a counterbalance for stability, and to ensure the ship did not heel so much that the gun ports disappeared under water. This was of course in addition to the ballast needed because of the enormous weight of the masts, sails and rigging. With the ship designed to carry all that, I doubt that it would have been much problem topping up the little remaining space in the holds with a bit extra. I may be talking through my hat – if so, please tell me.

As Kester says, I think captains may have been more interested in the sailing trim. Prize money would have been a great incentive to keep the ship in the best trim possible, and certainly a disincentive to overloading. Some captains definitely paid a great deal attention to the distribution of ballast and the stowage in the hold, in order to get the best out of their ship. While Captain of the frigate Andromache, Mansfield made immaculately detailed drawings of the distribution of iron and shingle ballast and the stowage of water barrels in the hold. There was 75 tons of iron ballast, consisting of 525 pigs, and 112 tons of shingle ballast. A complete load of water was 78 tons (without beer). He recorded the best sailing trim to be 16 feet 8 inches draught fore, and 17 feet 4 inches aft, thus as Kester says with 8 inches more draught at the stern. His attention to detail seems to have paid off. While part of a squadron of four frigates, he is recorded as having left his companions far behind in a chase on more than one occasion. But it did get him into the odd spot of bother. On one occasion he engaged a Spanish line of battle ship unsupported for an hour before the other frigates and his commander caught up and called him away. On another occasion he unfortunately got into a fierce fight with an Algerine corsair who refused to identify himself.

Lightening a ship too much could be a problem too. I have just been reading an account of the Foudroyant (Captain Jervis) capturing an American rebel privateer in 1777 on the coast of Cornwall after a long chase (they eventually ran aground to try to escape ashore). During the chase, they had thrown overboard guns, water and ballast to try and speed up the ship, but Jervis recorded that after the capture it had been very difficult to get the ship safely into port.

I have recently come across an account of Sir Richard Strachan altering the sailing trim of the Caesar, a month or two before he captured the remnants of Dumanoir's squadron after Trafalgar. William Richardson in his journal (published as 'A Mariner of England') describes how while sailing, the men were sent aft to witness a punishment and 'the keen eye of our captain soon saw how our ship started ahead' with the extra weight at the stern. All hands were immediately set to trimming her more by the stern until 'we got her down to three and a half feet deeper than she drew forward, and by doing this she beat everything we had in company with us'. In the chase of Dumanoir's squadron, it took several hours for the rest of Strachan's squadron to catch up with him.

This is a very interesting and informative exchange. I suppose the point is that the cargo carried on merchantmen was variable in weight and bulk so that marks of some kind were necessary to ensure the vessel was not so overloaded that it produced a dangerously high waterline.
On warships, the quantity of stores, guns, men etc was fixed and predictable (although obviousy changed slightly as water and stores were consumed as Tony points out). As a result, they were designed with their 'ideal' weight in mind and were intended to float with a pre-determined draught and displacement. Ships of the line for example were built to ensure that the waterline was on average 5 to 6 feet below the bottom edge of the lower deck gunports, whereas in frigates the figure was 8 to 9 feet. The marks on warships were therefore presumably designed to enable adjustments to be made (as Kester says) to the trim - ie the comparative displacement of water at the prow and the stern which would determine both speed and response to the helm.

Brian

As an aside, these days the centuries old method of carrying solid weights when a ship is empty, or in ballast, to maintain stability has been substituted for by the use of water.

This has many advantages, it is easily pumped on board – and around the ship between various tanks – when the cargo has been offloaded, and can just as easily be pumped off again when the vessel is to reload with another cargo. I believe it is also possible to flood only that part of the ship which is empty of cargo. By this method the trim of a vessel is also easily rectified. Another advantage is that the propellors are kept below the waterline and thus operating more efficiently than with the old methods, where the blades often broke the surface.

However, as with most things, there is a down side, since it seems that this system of ballasting is partly responsible for moving various harmful marine organisms around the world to apparently detrimental effect. I came across this site:

http://globallast.imo.org/index.asp

What a pity I missed that! Here's a bit about 'Coast' and Plimsoll.


http://www.thisisbristol.co.uk/news/Dra ... ticle.html

Though 'plimsolls' or sneakers are called 'daps' in Bristol!

I hadn't realised his bust had been moved. I don't go into nearby Bristol often as it is full of terrifying, insane drivers. ('Traffic lights advisory only' says my other half.) Plimsoll's bust used to be down on the waterfront with a plaque naming him 'The Sailors' Friend' - as indeed he was. There was a lot of re-building in the Cumberland Basin for the Millennium so I suspect they moved him then. Poor old Bristol was bombed flat in World War 2, of course, and the hideous post-war rebuilding made a bigger mess than the Luftwaffe. The millennium gave an opportunity to get rid of the monstrosities and rebuild once again but it's a disgrace that they removed Plimsoll in the process. I think the waterfront is a much better home than a museum.

On another tack, Bristol was a centre of the slave trade in Nelson's day, as well as the main port for sugar and tobacco. How politically incorrect can you get!!!!

Another useless but interesting fact: old maps show Bristol as 'Bristowe' or 'Brigstowe'. It acquired its final 'l' as a result of the odd Bristol dialect which adds an 'l' to words ending with a vowel. E.g. 'I'll draw you a sketch map of the areal [area]'; or 'That's a good ideal' [idea].