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Ballast Stones

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While living in Florida, I accidentally became friends with a salvage diver and started doing repair work, etc. on his equipment. Two years later, I learned that he was actually a 'treasure' diver. I left Florida 9 years ago, but we're still friends to this day. I don't work on his equipment anymore, however. While living in Florida, he once told me something about what he looks for when searching for old wrecks in last known areas where those wrecks supposedly went down. "BALLAST STONES!" He claimed that these types of stones will be unlike the shapes of any natural stones found in the area. They will also be strung out over a distance, leaving a trail from the point in which the ship first hit a reef, buckled in heavy seas, etc. "'Follow the stones' and find a wreck, maybe... but not always!" The finding of ballast stones only proved that there was indeed a vessel that lost its ballast at that location. Nothing more. Once the ships guts were spilled, the ship, itself, could easily be shifted to 'god knows where', along the ocean floor, due to strong currents, hurricanes and hundreds of years of time. That being said, for whatever it's worth, makes me wonder about Ballast Stones, in general. They seem to be smooth, roundish, oft times 'elongated' stones that spent tens of thousands of years chilling out and being polished in rivers located close to the shipyards. I'm also thinking that maybe it's only the 'largest' of those ballast stones that are ever found leading to the actual discoveries of old wrecks. In donning my 'engineers' cap... I'd think that the largest and heaviest stones would be placed close to the keel, and as the stones are piled up and moving 'away' from the keel, the stones would become smaller, lighter and eventually serve a purpose more needful in 'fine-tuning' level stability than actual ballast. I'm probably dead wrong on this, but lacking any true data on the old world science of weights and balance, for 18th century sailing vessels, I have no choice but to use my imagination and guess. If I'm guessing correctly, how were the stones used for 'fine-tuning' secured in place and kept from moving/shifting in heavy seas? I'm sure that some of you folks are far more savvy to this ballast stone 'thing' than I am, so let 'er rip! Tell me what you know about 'Ballast Stones' and how I can best replicate something that resembles historic accuracy. I don't want to use gravel intended for fish aquariums to represent ballast stones in my sectional models! 😫                   

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In the 18th century there were two types of ballast. The permanent ballast was usually pig iron bars in various sizes. Occasionally old cannon were also used. The ballast was stowed on either side of the limbers (drainage channels)  each side of the keelson. Above this was shingle ballast. As you describe, these were smooth, rounded stones - usually from a sea beach, not a river. This was moveable and the lowest tier of stowage (usually barrels) were bedded on the shingle.

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Many years ago while touring the Balclutha in San Francisco I learned of another type of ballast stones. Ships sometimes filled empty cargo space with mill stones - cylindrical stones with a hole along the center axis that were used for grinding grain. These could usually be sold in areas that were developing and had a growing population. If the stones hadn't sold and the ship was loading a more valuable cargo the stones could be dumped overboard to make room.

 

Apparently the bottom of San Francisco Bay is littered with mill stones!

 

 

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From an economical perspective, commercial sailing ships used two types of ballast, the one that was permanently required to make the ship stable and the other to make up for a lack of cargo in order to keep it stable. The room in the hold is valuable, so you would keep the amount of ballast to a minimum. Some traders got away with no or little balast, while others, such as the tea-clippers needed lots of it, but could justify the loss of cargo space due to the high price the commodity they were transporting would fetch.

 

An important consideration for balasting was the availability of the respective material, its cost and also how easy it could be brought on board or discharged again. Sand was a cheap temporary option in many regions, but you ran the risk that the pumps got clogged. Harbours usually had an area, where sand-ballast was allowed to be thrown over board. Violation of these rules could entail hefty fines in some harbours, as it could lead to silting up the harbour.

 

Whenever possible, the temporary ballast was some material that could be sold at the destination harbour, so being something like a high-density, but comparatively low value cargo. I have two examples:

 

- many houses in the Caribbean are built from bricks that came from Europe as ballast; on the (formerly Danish) US Virgin Island these are called 'Flensborg Stone', after the town of Flensburg in Germany, which belonged in personal-union of the reigning house in the 18th and 19th century to Denmark (until 1864); there were many brick-factories around the Baltic coast in this area.

 

- the streets of most towns around the southern Baltic coast are paved with big slabs of igneus rocks (e.g. granite), which came from Scandinavia in the timber ships to counteract inter alia the deck-loads of timber.

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 Very interesting, Wefalck! Very interesting, indeed!! Enlighten me further! How would the ship's captain know 'exactly' how much ballast to take on... and how to properly distribute the various weights of those ballast materials in order to create desirable sailing conditions/situations for a particular cargo/journey, in various weather conditions, seas, etc.? Let's go to extremes on this one. Let's talk Tea Clippers. Their cargo would be rather light, as compared to heavier loads of other trade goods, thus requiring a great deal more ballast, to achieve proper 'weight and balance' for the upcoming voyage. Clipper ships were also the old world equivalent of modern day racing vessels, seeking speed, per se. That being said, they had to take this into consideration when loading ballast... as the lower a ship rides, in the water, the more 'upright' the ship will ride, thus maximizing the amount of energy that can be generated and effectively utilized by her sails (a ship laying over on her side bleeds off a great deal of energy, while also exposing more surface area, upon the dense water, via the hull, which creates added drag and slows the vessel down). Would a clipper ship captain, looking for speed, opt for a heavier ballast load thus achieving a more 'upright' attitude, riding lower in the water, or prefer a lighter load of ballast that would allow the ship to ride higher and also list more dramatically, in high winds, intentionally bleeding off a certain amount of energy? Either way, I see a lot of stress being imposed upon the masts and sails as well as drag upon the hull. Seems like a "Catch 22" to me, but I'm sure that was some sort of a happy medium, science, and/or general 'rule of thumb' involved with this. Interesting stuff!

 Anyway... back to where my thoughts began with this reply. "How did the ships Captain determine how much ballast to take on, and how to properly distribute the weight?"              

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Other than the minimum required ballast that would not be removed.  The cargo itself becomes the ballast.  You can look at the ship during or after the ship is loaded to see what her draft and trim is.  A ship would normally be trimmed so that she was a little heavier aft.  If more ballast is necessary after the ship is loaded you could always add some and/or shift cargo around to provide the proper trim.  When the cargo was off loaded the ship would take on a new cargo (hence, not much change to ballast requirements) or if returning empty (this was called sailing in ballast) additional ballast my be loaded to stabilize the vessel.  

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There are whole books on ship stability, performance and loading.

 

Just a few additional observations:

 

- the behaviour in sea of a ship depends on how far the centre of gravity of the ballast plus load is below the centre of gravity of the hull; the lower the stable the ship is, but also stiffer, i.e. it works harder in the sea and more strain is put on the rig.

 

- the ship designer strived to keep the wetted surface (up to a point) and the hull speed more or less the same at all angles of heeling in order ensure equal performance.

 

- the loading of the ship was the responsibility of the captain and perhaps the suprecargo; until the later 19th Century there were no obligatory rules for the remaining freeboard (although there has been 'Lloyds Rule' since the 1830s) and the Plimsoll Mark was not introduced compulsary until the end of the century; the captain would also decide by his experience with the ship on the trim, i.e. the difference in draught forward and aft; the trim influence the maneurvrability under sail and the performance when heeling.

 

- load, centres of gravity and trim are only one set of parametres that determine the overall performance of a ship in the sense of the duration of passages; a keep variable here are the experience, knowlege and intuition of the captain that lets him choose the right route at the right time of the year; there are many examples for (theoretically) slower ships to make shorter passages; the books by Lubbock for instance are full of such stories.

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When considering the Tea Clippers (a very short time span of about 2 decades from ~1845-1869), one must first discount all of our "modern" conceptions of stability and wind effects, wetted area calculations and so forth and consider the situation through the lens of contemporary nautical architecture.

 

The essential components of calculating displacement (that is, determining the volume of the submerged portion of the hull at the desired load waterline) were fairly well known.  Determining the as-built weight of the empty cargo vessel was likewise able to be estimated reasonably well, although the actual weight was better known after launch by calculating the displacement volume once the intended ballast, masts and so forth were installed (variables in size of various timbers used, actual weight of each timber that could vary based on the moisture content, number of spikes and so forth during construction made an accurate estimate difficult at best).  Once the displacement weight was known, the difference between empty and fully loaded displacement volume provided the weight (actually, mass) available for cargo, store and crew.  There were standard estimates for stores and crew based on length of the voyage, so subtracting those gave the cargo capacity.

 

Bored yet?

 

Knowing the amount of cargo being transported (outbound was generally trade types of merchandise and goods purchased by the owneres to sell in China then purchase tea).  Ballast (preferably something which could be sold, but not always) was then loaded as druxey noted prior to the cargo.  Once at sea, particularly for a new ship, it was not uncommon for the captain and sailing master to shift masts (adjust the rake) and ballast for desired sailing qualities.  As stores (food, water, cooking fuel) were consumed, ballast would again be shifted as needed to maintain the optimum trim as percieved by the skipper.

 

For the voyage to England with the tea as cargo, generally shingle was loaded as additional ballast to compensate for the reduced weight of tea.  Clark (a former clipper ship captain) states that they carried some 200-300 tons of shingle when loaded with tea for the trip to England (Clark, Arthur H. 1911. The Clipper Ship Era : An Epitome of Famous American and British Clipper Ships, Their Owners, Builders, Commanders, and Crews, 1843-1869. New York : Putnam. http://archive.org/details/clippershiperaep00claruoft ).

 

There are a number of exceptional descriptions of the Tea Clipper era (some, as in the book by Clark, are available for download).  Here is a brief listing of some you may find of interest:

 

Brown, Daniel M. 2010. “The Need for Speed: Baltimore Clippers and the Origin of the First American Ship Type.” https://www.academia.edu/14330732/The_Need_for_Speed_Baltimore_Clippers_and_the_Origin_of_the_First_American_Ship_Type.
Davison, Darius. 1852. Progress of Naval Architecture ...: Being a Popular and Brief Explanation of the Principles and Advantages of Darius Davison’s New American Model, for Ocean Steamers, Clipper Ships, Steamboats, Yachts, Etc. Illustrated with Fifteen ... Wood Engravings. Containing, Also, a Communication in Relation to His New Engine and New Motive Power! And a General Explanation of His Plan for a Great Iron Ocean-Steamer, 700 Feet Long! Maximum Speed, 30 Miles an Hour! Baker, Godwin & Co., Printers. http://archive.org/details/progressnavalar00unkngoog.
Lubbock, Basil. 1984. The China Clippers. The Century Seafarers. London: Century Publ. [u.a.].
MacGregor, David R. 1993. British & American Clippers: A Comparison of Their Design, Construction and Performance in the 1850s. Annapolis, Md: Naval Institute Press.
MacGregor, David R., and Geoff Hunt. 1984. The Tea Clippers: Their History and Development 1833 - 1875. 2. ed., rev.Expanded. London: Conway Maritime Press [u.a.].
Montagu, Robert. 1852. Naval Architecture: A Treatise on Ship-Building and the Rig of Clippers ; with Suggestions for a New Method of Laying down Vessels. London: London : Colburn and co. http://archive.org/details/navalarchitectu00montgoog.
Whipple, A. B. C. 1980. The Clipper Ships. The Seafarers. Alexandria, Va: Time-Life Books.
 
With that, I shall now stop boring everyone.  Carry on and have a wonderful day!

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How would you shift ballast at sea ? It would be nearly impossible to get to it, given that the cargo usually was wedged in order to prevent it from moving around. This would require to open the carefully closed hatches at sea too - the hatches were covered by (double) layers of tarpaulin, nailed down in order to provide a water-tight closure. The only access to the holds were the very small cargo hatches.

 

There would be also no space, except the limited deck space, to store loads while re-arranging the hold ... this is different from warships, where more intermediate deck space was available and stores were taken out of the hold regularly. There the cooper would collapse barrels etc. cautiously for later re-assembly and re-use.

 

In the tea-loading ports there were experts that would carefully stow the boxes according to size and value (the most valuable in areas the least likely to be exposed to damage by water). The boxes were litterally hammered into place, I seem to have read in one of the books cited above. No chance to get them out at sea.

 

This tight storage on commercial ships made fires in the hold so dreaded. Very difficult to get access.

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On 12/2/2019 at 9:10 PM, Dr PR said:

Many years ago while touring the Balclutha in San Francisco I learned of another type of ballast stones. Ships sometimes filled empty cargo space with mill stones - cylindrical stones with a hole along the center axis that were used for grinding grain. These could usually be sold in areas that were developing and had a growing population. If the stones hadn't sold and the ship was loading a more valuable cargo the stones could be dumped overboard to make room.

 

Apparently the bottom of San Francisco Bay is littered with mill stones!

 

 

I've heard of ships carrying grindstones as ballast to places where they might be sold, but I've never heard of jettisoned grindstones being recovered over the course of my forty-plus years of familiarity with maritime archaeology in the S.F. Bay Area. During the last of the Nineteenth and beginning of the Twentieth Centuries, the large "ocean carriers," mainly four-masted barks and ships such as Balclutha, primarily carried grain grown in the Central Valley of California to Europe and, finding cargoes wanting on the return leg from Europe to California, required balasting. They would carry cobblestones quarried in Europe, called "Belgian block," that were off-loaded at San Francisco and used to pave the streets of the City. Many are still in place, though often now covered in asphalt. They are pulled up when streets are rebuilt and were once resold as construction material. I once owned a home with a twelve foot high living room wall built of them. Today, the City realizes their value and has an ordinance requiring all cobblestones removed from the streets to be retained for reuse by the City itself for historic restorations and the like.

Edited by Bob Cleek

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