Quayside Cranes and Cargo Handling
See also Appendix One - Canals, rivers and coastal shipping for more information on coastal shipping, river and canal barges (includes a description of standard markings and flags used) and Appendix One - Fishing boats and ports for more on the fishing industry and port facilities. Dock side cranes are discussed below but also see Wagon Loads & Materials Handling - Materials Handling - Hoists and Cranes and Materials Handling - Crane Hooks and Lifting Aids for more on cranes and cargo handling gear.
People consider dock cranes to be a problem, and the modern type with its tall tower and lightweight construction would be difficult to produce convincingly. Not all docks used their own cranes of course, in smaller ports the ships would use their own derricks or deck mounted cranes. Cranes of various kinds have been fitted to ships since the 1960's but as already mentioned for general cargo work the traditional ships 'derrick' is better.
The two examples shown below are suggested as the best option for modelling, both being quite straightforward to construct (the Ratio OO scale lattice mast LNER signals are handy for this kind of thing in N). The small crane on the left is a hydraulic crane, on the right a larger electric type, both were in service in the early 1930s and both types were still in use in the 1950s, later in the case of the electric example.
Fig ___ Easy to model dock cranes
Docks used every type of crane available, including man-powered, hydraulic, steam and electric types. Small hand powered and steam rail mounted cranes were used for quays with no fixed cranes, they came in handy for unloading barges or small coastal craft and for moving larger items about the dock area. If using a steam crane, such as the one in Liverpool's Albert Dock Museum, don't forget the coal bunker somewhere nearby.
The problem of reaching over ships sides generally lead to tall cranes, however there were alternatives, the example below is sketched from a small self propelled steam crane in use on Fleetwood Docks. The jib is arranged as a dog-leg, suitably reinforced, there were several such cranes at Fleetwood and presumably similar cranes would be seen in other docks where the quay was narrow.
Fig ___ Quayside mobile steam crane
Weymouth Quay (served by the GWR) had in interesting arrangement where the quay was built up to form a platform along the dock edge which allowed goods to be easily loaded into vans. There were a number of small cranes mounted on this platform and this arrangement makes a pleasantly different model. Each year this small port handled about ten thousand tons of early potatoes and about twelve thousand tons of tomatoes all being imported from the Channel Islands.
Fig ___ Small steam cranes
The larger quay-side crane was generally a quick acting machine, generally with quite a small capacity (men were used to load up the crane and this restricted the advantages of larger equipment).
General purpose dock cranes, either electric or hydraulic, were originally standardised to handle 30 cwt. Some larger steam cranes were rated at two or three tons. A standard feature was level luffing, which meant the load stayed at the same height as the jib was raised or lowered. There were various methods used to achieve this, most subject to patents, however there was a series of articles in The Engineer magazine dated Aug 26th and Sept 2nd of 1927 which discussed these in considerable detail.
Most dock cranes built up to the 1930's could reach out about thirty feet from the quay wall. As ship size increased in the 1940's this increased to fifty feet and by the 1960's a reach of ninety feet was not uncommon. For modelling purposes we can reduce the length of the jib quite a lot whilst still retaining the general look of the prototype which makes for a more robust model.
More modern tall dock cranes appeared in the 1930's, most of these were electrically operated and most could safely lift up to three tons, although they were still loaded up by hand so except when lifting large single items the typical load was a lot less. In the 60's five ton cranes started to become more common but soon after this the container appeared and by the mid 1970's the general purpose cargo ship was becoming rare.
One space-saving arrangement used in real life had an overhead gantry supported at the landward end by a rail set on the side or even on the roof of the transit sheds, technically this is called a 'half portal crane' (a full portal type has both rails on the quay). The illustration below shows such a design. This gantry arrangement was not uncommon and in the 1980's there were essentially similar electric cranes in use in Bombay.
Fig ___ Electric dock crane
This illustration is loosely based on two electric cranes built by Stothert & Pitt Ltd. and installed at Southampton in 1893 (I based the gantry on an example in Australia as this is easier to model). These were I believe the first electric dock cranes in Britain and I understand at least one survived until about 1953. The suggested basis for the crane cab is a cut-down Peco refrigerator van body, this as a bit wide but saves you having to make the curved roof. The gantry spanned two tracks and on the original there was a space about one track width between these, there were quays with tracks with one, two and even (rarely) three tracks running under such cranes. A picture of the original cranes will be found in the book 'Southern Wagons Vol.2' (see Bibliography) if you wish to make a true replica.
Pola offer a 'mobile crane' as a kit (reference number XXX), unfortunately this features a fixed jib arrangement which although not uncommon in factories is unusual on such a modern looking crane when used on a dock side. John Ahern's famous Madder Valley layout had a similar crane in his Madderport docks but I have not yet traced any photographs of such fixed jib cranes in any British docks. The prototype of Mr Ahern's crane may have been a type used for hoisting coal wagons over a ship or barge, lowering them down and tipping them into the hold (this reduces breakage of the coal). One option is to replace the jib with a Ratio 'OO' scale LNER lattice signal mast (or an etched type if you have one to hand). This would be pleasantly intricate and reflects more closely the 'spidery' appearance typical of dock side cranes.
The base of the Pola crane is a bit large for the crane itself but it can be cut down, and if you are doing that anyway you might consider converting it to the building-supported design. This leaves you with one set of spare legs but a similar stationary crane is also available (catalogue number 248) which could be used to make a second crane. Personally I feel it is easier to build them from scratch as shown in the sketches.
The hydraulic crane was common in docks from the mid 19th century, Sir William Armstrong's firm built the first hydraulic cranes on a Newcastle quayside in 1846, using water supplied from the local water mains. As mains pressure was low and often unreliable it was common practice to install an 'accumulator tower' (often the tallest building on the docks) in which a steam engine pumped water into a pressurised reservoir. This then fed a hydraulic main which supplied the machinery in the docks. Smaller cranes and hoists were often fixed in position, but quay side cranes needed to be positioned to suit the ships hatches and for this they had rail mounted cranes which could be set up and connected to the main. Unloading a sea going ship might take a couple of weeks and once set up the crane did not change position. The docks were all heavily bombed in the Second World War and the damaged hydraulic cranes were typically replaced by more modern electric types, but a few survived into the 1960s I believe.
The sketch below shows three variants on a standard design of hydraulically powered crane used in docks throughout Britain and abroad. The tapered base under the jib housed the 'jigger', which had pulleys to either side of the central ram (hence the pyramid shape of the base). For more information on jiggers see also Appendix One - General Information - Engines and prime movers
In use the cranes were positioned on the quay and connected to the hydraulic mains, they did not move along the quay when working. On the left is a type with a fixed jib used at Butlers Wharf in London, I have altered it slightly to raise the gantry enough for railway wagons to pass underneath but other than that the illustration is closely based on a photograph. The crane is off-set on the gantry, mounted toward the quay edge end. The two examples shown on the right are based on a type seen in Penarth docks which appears to have a jib that can be raised and lowered. These are easier to model as the jib can be a length of H section Plastruct. The jib assembly on all three cranes is mounted on a rotating base on top of a simple tapered base. On the London crane the cab rotates with the jib, the Penarth cranes had the cab mounted on one side of the base (there were some cranes, similar to B, which had the cab mounted on the side of the mast rather than fixed on the side of the base as shown). Note the fixed drum shaped counter-weight on arms at the rear of all these cranes. The rough construction diagram for type B was prepared for my Godson many years ago but type C requires less room as the siding passes underneath it, not to one side (there was another variant with straight sides as B but with the arch for railway wagons as on C, this is easier to model but takes up a lot of room).
Fig ___ Hydraulic dock cranes
For a layout you may find it is easier not to model the quay itself, instead having a 'transit shed' with the railway sidings running along the near side and the far side representing the quay. To 'set the scene' a crane or two should be visible above the top of the shed and the example below left is a fairly easy option. The long lattice jib can be represented using a lattice signal mast (in N you can use the Ratio OO scale tall lattice signal mast kit for this). There is room inside the shed for a motorised belt which can be used to raise and lower the load (add some weight to the load and use fine fishing line for the cables), or swing the jib.
At the other end of the scale you may wish to model a side dock, used only by lighters and barges. To show this is part of a larger docks a hydraulic crane helps to set the scene and the example below right would serve. As the base is low the jigger is mounted on the rear balance arms behind the mast (I have tinted it red for clarity - For more information on jiggers see also 'Appendix One - General Information - Engines and prime movers').
Both these cranes have the operators cab mounted on the side of the mast.
Fig ___ Larger and smaller hydraulic dock cranes
Where regular heavy loads were anticipated a large fixed crane or two might appear. The large crane shown below was sketched from a photograph of the GWR's London Brentfod Dock in the 1920's found in Janet Russel's book GWR Company Servants. As this crane is crane is anchored to the dock it does not require the counter-weight. There were two cranes at Brentford, the second was basically the same but had a heavier jib and a pulley type heavy-lift hook. They were used for off-loading 'lighters' (a kind of large barge) which had taken on cargo from a ship at anchor in the river.
Even in sailing ship days a larger vessel alongside the quay could be several feet higher than the quay side. The curved jib on the Fairbairn crane was designed to reach up and over the side of ships moored alongside. An example of the Fairbairn type, built by Stothert & Pitt in 1876, still exists at the Princes Wharf Museum in Bristol.
Fig ___ Large hydraulic crane and Fairbairn crane
Not all dock cranes were large and complicated, the sketch below shows a simple type of electrically powered crane dating from about 1910. This was a fixed crane the original was on a quay on the Rochdale canal used to unload bales of cotton from large barges and lighters towed by steam tug from Manchester docks.
Similar cranes were also used in docks serving coastal craft, a steam powered machine of essentially similar appearance but with a heavy square section wooden jib was used at a dock in Wales to hoist loaded coal wagon over the holds of ships and tip them.
The examples shown below are preserved in the former docks at Manchester, an area now redeveloped as offices. These have comparatively short jibs as the size of ship using the port was limited by the size of the locks (most were in the 1-2 thousand ton range). Quayside rail mounted cranes of this type would serve for layouts set between about 1955 and the present day.
Fig ___ Manchester docks electric cranes
The sketch below shows a large wharf crane with something called a 'horses head' level luffing gear which was common on larger dockside cranes (those used for heavy loads, not for general cargo work). This extension allowed the lift to be brought close in to the base of the crane without lifting the main jib almost vertical and provided greater 'reach' when extended (see also the section on Wagon Loads and Materials Handling - Lifts, hoists and cranes'). The example shown (scanned from a 1930s book on engineering) is a very big crane, the only times I have seen cranes of this size has been in dry docks. The example on the right is closer to those I remember from my own time at sea, these had the level luffing gear working onto the gearing of the cables. A large crane such as this would serve in a major docks from the 1930s to the present day and to model these in N Gauge the LNER lattice mast available from Ratio in their OO signals range makes a good starting point. For the base you can use Plastruct or you can cast about for kits that can be bashed, for example a water tower on tubular metal supports can be effectively cut down to suit, adding the side frames and wheels gives ample clearance for wagons passing underneath. A crane with a long jib such as shown would be seen on a river berth, it allowed the crane to reach over a lighter or two. Many quayside cranes had shorter jibs, those in an enclosed dock were usually much shorter (see the photos of the Manchester docks cranes above) but the tall crane with its long jib is very suggestive of a quayside.
Fig ___ Electric dock crane with level luffing using horses head extension
The larger cranes usually had the cab in the centre as shown above right, with the jib split and running to counterweights on either side of the cab (the crane driver must be able to see the load). I have had success using the Ratio OO scale LNER lattice signal masts for crane jibs in N but these cannot be used for this type of crane as the mast requires considerable widening at the base. One alternative as used on real dock cranes is to offset the cab to one side as shown below left. Another alternative, if using a signal post, is to mount the jib on top of the crane, the example below right (based on one in Bristol docks) has this arrangement with a small 'cab' on which the jib is mounted set above the main driving cab.
Fig ___ Electric dock cranes with offset cab (left) top hinged (right)
From the turn of the century it was standard practice to write the maximum safe load for the crane on the sides of the jib.
Docks - Cargo handling
NB see also the separate section on Wagon Loads & Materials Handling for more detail on equipment used in general cargo handling
Until fairly recent times the cargo had to be man-handled at several points on its journey, so shippers had to break down the loads in to suitable parcels. A standard item of ships and docks equipment was the cargo net, a square rope net about 10 foot to a side with a mesh about 9 inches square and with loops on the corners for slipping over the crane hook.
From the early 1920's docks, such as Liverpool and London, had large numbers of small electric run-about trolleys, these were about 7 foot long and 4 foot wide, running on 18 inch diameter wheels with the decking about 20 inches off the floor. These had a small platform on one end where the driver controlled the vehicle using small levers, there was usually a bulkhead or frame to protect the driver if the load shifted. Very similar types of run-about are a feature of large railways stations, and models were offered by most model manufacturers in the 1950's.
Fig ___ Run-about trolleys
A lot of goods were man-handled about the quay side and one small detail worth considering is a railway wagon with its side door dropped onto a barrel and a plank laid against the edge of the door to give access to a man on foot or a wheelbarrow.
Cattle were taken by rail to some docks specialising in this traffic. These had extensive pens which would require considerable room, even in N gauge.
Chilled meat was carried in ships from the 1900's, if you want to model these cut a model cow into right and left halves, cut off the head and legs just below the body and paint them white. These were (very) solid and a man can lift one at a time. To lift them from the hold of the ship they were generally laid on a wooden frame, which itself was in the centre of a cargo net. The railway companies used refrigerated and insulated vans and containers with hooks provided inside for these 'sides' of meat to hang on.
Butter has been shipped as a frozen cargo on ships since the turn of the century. The butter was shipped wrapped, in cartons, which often had light wooden battens attached to them for strength.
A lot of odd materials were shipped by sea, Britain at one time imported large quantities of dried dog droppings from Persia, this material being used for its high urea content in the preparation of leather (removing the hair from hides). These days synthetic Urea is shipped in place of the dog droppings, it is a white powder shipped in 80-100 lb bags or as 'prills' (small pellets) in covered hopper wagons, it is also sometimes shipped dissolved in water in standard steel drums. Urea, or carbamide, was and remains an important chemical, it was the first organic chemical to be synthesized (by Wohler in 1824) and it forms the basis for urea-formaldehyde resin from which the first plastics to be available in white, pastel and colours were produced.
The arrival of the 'Unit Load' concept in the 1950's produced the container and the pallet. The former can be lifted on and off ships using standard cranes (fitted with lifting frames) in smaller ports, but it is more usual to use specialised berths equipped with large gantry cranes (see Fig ___). Ships carrying containers range from large purpose built types (basically not a practical modelling prospect), right down to very small vessels, which might be converted from the Shell Welder tanker kit as discussed below.
The wooden pallet produced ships with side doors and ramps to permit fork-lift trucks to load and discharge them. Again these purpose built ships are not really viable for modelling, however palletised loads were, and are, carried in general cargo vessels and so would feature in a modern (post war) docks scene.
Docks - Coal handling
A lot of coal was shipped by sea, both exports and UK to UK movements, and colliers are an example of the specialised ship relying on shore gear to load and discharge them. One small point to note is that logically you would not have facilities to load coal into ships in the same port as equipment to land coal. The areas and chief ports associated with coal exports are illustrated in the map of the UK coal fields shown in Fig ___.
Coal was shipped in considerable quantities, justifying extensive dock installations devoted to nothing else, which tended to be vast sprawling affairs. Most of the rail wagons feeding them ran in regular circuits from pit to port and they were painted plain black with the colliery initials painted on the sides in white. This tends to make for a large and rather boring layout option, and you have the problem of removing the coal from the loaded wagons arriving from the pit so they can be returned empty.
At larger coal ports loading ships was commonly accomplished from end-door wagons by having a tall tower equipped with a chute which could be moved about to distribute the coal evenly in the ships hold. In most ports the wagons were lifted up the tower and tipped, in some the towers were supplied by conveyor belts fed from wagon tipplers of various forms.
The towers in which the wagons were lifted up for tipping were called 'coal hoists', the last two in the world were at Cardiff Docks. These ceased operating in 1987, spelling the end of the standard steel 21 ton end-door unfitted mineral wagon on BR. There were still over a thousand of these wagons in use at the time and these were in the main sold to the National Coal Board for use in collieries. Cardiff had both hoists and conveyors, the former were built in the last century, the latter date from the early 1930's.
A variation on the coal hoist idea was used at Partington on the Manchester Ship Canal where two railway tracks ran from a raised area of ground to a tower on the bank. The loaded wagons were rolled out along the upper track by gravity, at the tower they were lowered to the chute and tipped, then rolling back out on the lower level and back to shore by gravity. The Partington coaling stage was for supplying coal for ships fuel, not to load ships with a coal cargo, however the basic principal is similar to the larger hoists used for loading colliers. The design of the standard N gauge coupler would theoretically allow an intrepid modeller to duplicate this procedure but emptying the wagons would not be a practical proposition. The sketch below is based on a tracing from a photograph taken in about 1900, there were a series of these hoists along the bank, and other quays on the opposite bank, the sketch is simplified to show the design of the hoist.
Fig ___ Coal hoist at Partington
There was at least one of the coal towers apparently well maintained at Partington into the 1970s, I am not sure what it was used for, possibly loading barges with domestic coal.
At smaller ports and river or canal coal berths where coal was loaded into barges the wagon did not need to be lifted to clear the side of the hold and a simple tipping platform was commonly used, usually fed from a wagon turn-table. These platforms came in various designs, there is a preserved example to be seen at Wigan Pier Museum which consists of a platform set into the quay wall with curved bars to hold the wagon wheels, the 'works' being hidden underneath the quay surface.
Where river berths were used, requiring a short jetty extending out from the bank a simple hinged platform rather resembling a drawbridge was sometimes used. Most of the examples of this type had an external frame to support the wires, pulleys and counter weight. The wagon would be rolled out onto the platform and the end door opened, once the man was clear the platform would be released and the weight of the loaded wagon would tip the thing over the ship or barge. Once empty a counter-weight enabled the staff to pull the platform back to the horizontal so the wagon could be rolled off again. These draw-bridge tippers were common in the small harbours on the banks of the Severn Estuary handling coal from the collieries of the Forest of Dean and there are several good illustrations on the books on the Severn & Wye Railway mentioned in the bibliography.
Fig ___ Coal tipper as used on the Severn Estuary
There were other variations, in one the wagon was tipped sideways against a wooden frame by a hydraulic ram, emptied through its side door (there was a gap in the frame to allow the door to open), the coal falling into a chute which fed down into the barge below. If the drop was substantial there would be a steel spiral track inside the chute so the coal would not break up due to the long fall. At some ports a heavy crane was used to lift a frame which could then be lowered into the ship or barge and tipped, again this was done to reduce the breakage. The frame is shown near vertical however when working the platform would never exceed an angle of about thirty degrees to avoid damaging the wheel bearings on the wagon. There were a row of these cranes at a wharf in Liverpool. Both these are shown in the illustration below.
Fig ___ Side tipper and coal crane
The tipping platform was quite a common feature at docks, usually associated with a rather large crane. The example below is,or was, a large electric crane in Hull docks, on this example the main platform remains level and a sup-platform tips the wagon. This is less complicated than arranging the main platform to alter its angle and allows the platform to e exchanged for a grab for bulk minerals coming the other way.
Fig ___ Crane with tipping platform at Hull docks
A 'coal staith' is a raised section of track which permits the coal to be tipped into the ship or barge via a chute. The wagon hoists of South Wales are technically staithes but the term is most often associated with the North East where ships and barges were often loaded from hopper waggons. These were sometimes run on a raised section of track on the bank but at the ports the staith would be a heavy timber structure to which ships tied up. In the photo below, dating from the mid 1950s, the staith is the pier like structure in the upper part of the photo, there are two in fact the outer run has two tracks, the inner has three.
Fig ___ 'Coal staith' at a port in Northumberland
The example shown below is a staith on a river in the North East, sketched from a photo dated 1971, the chute can be raised and lowered to allow the barges to get underneath easily and to reduce the drop at the end to avoid breaking the coal.
Fig ___ River or canal side 'coal staith'
The approach track had a loop on it and lead up a slight gradient to the staith. The loco would push the rake until the end wagon reached the discharge point where it was emptied and its brakes applied, the loco would back off and the points at the top of the loop would be thrown, the wagon would then have its brakes released and roll back into the loop.
A variation on this approach was used at one coal loading point on the Grand Union Canal, here the wagons used tended to be conventional types and the bottom doors, assisted by man-with-shovel method was used. The railway lines were lower, which might make it an easier proposition to model, for a canal parallel to the track turnplates can be used as shown in the sketch.
Fig ___ Canal side 'coal drop'
Coal unloading is a much more promising side to the business from the point of railway modelling. The facilities, even if dedicated, can reasonably be small and compact. Colliers were unloaded by shore cranes using rattan 'coaling baskets' or steel tubs, both of which were filled by men working with shovels. The tubs were cylindrical and generally about 4 foot wide by 4 foot deep. They were suspended from a steel stirrup which was pivoted just above the centre line, so the tub could be easily tipped into the wagon. The coaling basket is not easy to describe, and would be tricky to model, for those with the nerve to try they are now sold at 'Habitat' type shops as 'log baskets'.
Fig ___ Unloading a 'Clyde Puffer' using a coal bucket
Even at dedicated ports, or dedicated berths in a port area or on a river, the facilities could be simple in the extreme. The sketch below shows a basic 'derrick type crane mounted on a river bank. There was a single track running in front of the crane with two more run behind. There were several such cranes on the berth, separated by perhaps ten wagon lengths. In this way a rake of wagons could be positioned and the first wagons loaded, the rake would then be shunted along and the next wagons in the rake could be loaded. For modelling purposes a pair of these cranes, mounted about six wagon lengths apart, would represent an acceptable compromise. The sketch was made from a photograph taken in the 1890's but the cranes probably lasted into the 1930's and possibly into the 1950's. Between two of the cranes was a proper crane, capable of slewing (swinging round on its axis), similar to the illustration shown in Fig ___ XXX above. This would justify the odd load of something unusual at the berth (the crane was a light affair so do not make the load too large).
Fig ___ Coal derrick as used at Poplar docks
The rail mounted steam cranes shown below were both railway company owned and both were used for unloading coastal craft or barges, the smaller example (actually a medium sized crane) employed a coaling bucket as shown above, the larger crane (sketched from a photo taken in about 1910) has a large grab. Both examples were photographed before World War One, by the 1920s such cranes often had a simple wooden or corrugated iron 'body' over the boiler and gearing. The figure shows the scale of both cranes (see also Wagon Loads and Materials Handling - Materials Handling - Lifts, hoists and cranes).
Fig ___ Medium and large railway owned steam cranes
Cranes equipped with grabs for unloading coal from smaller vessels were not a common feature of docks other than at specialised installations such as power stations, the coaling tub was much more common right into the 1940s. Berths handling purpose built colliers often had grabs by the time of the First World War but the cost of manpower remained comparable with the cost of maintaining the grabs until the outbreak of World War Two. Since the war specialised and rather larger bulk mineral carriers have replaced the smaller general cargo ships on this traffic and quays devoted purely to coal traffic have become the norm. These have specialised gantry cranes using grabs which feed onto conveyor belts and thence to stockpiles. The conveyor belt for moving coal and other bulk materials was in use from the later nineteenth century.
Docks - Bulk liquids (oils and latex)
The first purpose built ocean going steam/sail bulk petroleum oil tanker was built in 1886, 300 foot long and carrying 2,307 tons of oil in a single tank. By 1918 steam ships carrying 8,000 tons were in operation. By 1930 the 12,000 ton tanker, with triple expansion steam engines at the back and a small section of accommodation over the centre of the ship (to give the deck officers a better view forward) was standard.
The oil was pumped ashore in thick (typically 8 inch) reinforced rubber hoses, usually into large tanks. A small ship might however be loaded from rail tankers in a small dock, and fuel was sometimes delivered either direct to the ship at the quay or into 'bunker barges' for transferring to ships. One point to note is that the rubber hose would be supported clear of the quay wall and/or ships rail, using a simple crane on the quay or a derrick rigged on the ship or barge. On larger purpose built berths the hoses were supported from a gantry to ease the job of hauling them on board the ship.
Fig ___ Oil hoses being used to bunker (refuel) a ship in the 1930s
Bulk (petroleum) oil cargoes might consist of oils of two basic types: Light oils - Including gasoline, white spirit, alcohol, kerosene or light gas oil (diesel) and Heavy oil - Crude oils, creosote, asphalt, lubricating oil. Fuel oil falls somewhere between these two, it is mainly composed of unrefined residues from the refining process and it is used in specially designed engines and for fuelling boilers. This stuff usually has to be heated so it will flow.
Non petroleum based oils shipped in bulk include vegetable oils (palm oil, kapok oil, linseed oil etc), whale oil, molasses, pilchard and herring oil and animal oils (such as neatsfoot oil, tallow oil and lard). These were usually shipped in barrels but by the later 1930s deep-sea general cargo ships would often carry consignments of these less dangerous bulk oils in built-in convertible tanks as part of their cargo. When not used for oil the tanks could be used for ballast (sea water) or fuel oil for the ship (the tanks required cleaning and a degree of preparation for loading the oil, and after discharge had to be cleaned again for their alternative purpose). Hence it is perfectly acceptable to have railway tankers delivering or receiving a bulk 'oil' cargo from a conventional cargo ship. The standard hose for loading and discharging these tanks was four inch diameter, the ships pumps would normally be used to pump the cargo ashore.
Vegetable and animal oils are classed as oils if they are liquid at normal temperatures or fats if they are liable to solidify at those temperatures, however the distinction is very blurred. Where the oil was likely to solidify, or become too thick for efficient pumping, steam heating was fitted to the tank - This was often removable to allow the carriage of other cargo. In the days before containers general cargo ships could be in port for weeks and had a substantial crew, so fitting and removing pipes, cleaning and coating tanks etc were practicable if tedious options.
All oils are more or less inflammable however vegetable oils are generally safe enough providing they do not come into contact with rags, textiles or fibres such as Jute, in which case they can spontaneously combust (a particular problem with linseed oil). In the book on rail tankers mentioned in the bibliography is a rectangular tank wagon liveried for the splendidly named 'Scottish Fish Oil & Guano Co.' which would make an interesting addition to ones wagon fleet. Fish oil is produced mainly from pilchards, the entire body of the fish is steam cooked and then pressed to extract the oil, the resulting solid waste is sold as 'fish meal' mainly as an animal food. Fish oil is an important material, chemically modified it is used in soaps, detergents, protective coatings, alkyd resins and since the late 1930's it has been used as the base for margarine and shortenings.
Bulk liquid latex could also be carried in a general cargo ship's tanks, although because this requires ammonia to prevent the rubber coagulating there were additional restrictions, the double bottom ballast tanks (running along under the holds at the very bottom of the ship) were unsuitable as the ammonia tended to leak out (in which case the rubber began to set and the actual hull plating had to be removed to get the stuff out). The 'after peak' tank at the stern of the ship also tended to leak as the ship moved, and proximity to the brass liner for the prop shaft also made this inadvisable. 'Deep tanks', lower down on the ships sides but accessible from the deck, and the 'fore peak' tank in the bows of the ship were however considered suitable for latex. When carrying latex the tanks would be coated with paraffin wax (they also required pressure relief valves to cope with ammonia being given off). I believe this material was pumped directly into rail or road tankers for transport to the works (almost all of which were located close by the docks). See also 'Lineside Industries - Industries associated with docks and harbours'.
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