Draft marks
Draft marks (depression marks)
signs on the outer plating in the bow, stern and amidships of the ship, applied at some level from the keel to determine the draft of the ship. Draft marks - numbers or letters with a height and a distance of 100 mm between them. The magnitude of draft fore and aft can be determined only by knowing the distance of each draft mark from the keel (given in a special draft mark layout)
Edwart. Explanatory Naval Dictionary, 2010
See what "Precipitation marks" are in other dictionaries:
- (Draught marks) see Load line. Samoilov K.I. Marine Dictionary. M. L .: State Naval Publishing House of the NKVMF of the USSR, 1941 ... Marine Dictionary
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On cargo ships, the determination and calculation of draft are required for various purposes. For example, to determine the mass of loaded or unloaded cargo, to give the ship a given trim, etc. The ship's draft is measured on the bow, stern and middle marks of the deepening.
Groove marks these are numbers and horizontal lines welded on both sides of the ends of the hull and in the midship area. The draft of the vessel in the area of marking is equal to the vertical distance from the lower edge of the figure to the lower edge of the keel. In everyday work, the term “remove precipitation” is used to measure the settlement, i.e. determine the draft of the vessel by the marks of the deepening, or determine the draft by measuring the height of the freeboard.
Indentation marks are painted white on a dark background or dark on a light background.
Marking of recess marks can be performed:
In the metric system (Arabic numerals), the draft is measured in meters - while the height of the numbers and the distance between them (along the perpendicular to the main plane) is 100 mm.
In the English system (Roman numerals), the draft is measured in feet (1 foot = 0.3048 m. There are 12 inches in one foot, 1 inch = 2.54 cm). In this case, the height of the numbers and the distance between the numbers (along the perpendicular to the main plane) is 0.5 feet (6 inches).
If both systems are used on the ship, then on the port side of the mark, the indentations are applied in Roman numerals, and on the starboard side in Arabic numerals.
It should be noted that the accuracy of the calculations associated with them depends on the accuracy of sediment removal. Therefore, navigators must learn to shoot precipitation under various unfavorable conditions: poor lighting, roughness, snow, ice, poor visibility of marks due to a large viewing angle or poor coloring of marks.
In addition, it is necessary to acquire the skills to measure the freeboard height at the locations of the deepening marks. From the measured freeboard, the ship's draft at the measurement site is also calculated.
An example of sediment removal on the English and metric marks of the recess is shown in Figure 1.
English system Metric system
Settlement measurement by depression marks
The shape of the extremities of the ship's hull does not always allow marking recess marks on the bow and stern perpendiculars. Therefore, for the convenience of removing the sediment, they are applied at a certain distance from the corresponding perpendicular.
The bow mark is applied either on the bow perpendicular or aft of it.
The stern and middle indentation marks can be applied both forward and aft from the corresponding perpendicular.
Sometimes part of the mark of the recess is applied on the perpendicular, and the other part of it at some distance from it.
Figure 2 shows an example of the layout of the recess marks relative to the bow and stern perpendiculars and the midsection of the vessel. Typically, ship diagrams indicate the distance between the mark of the recess and the corresponding perpendicular. Since in all calculations related to determining the ship's landing and determining the mass of cargo from drafts, drafts on perpendiculars are used, the drafts taken on the marks of the recess must be corrected with appropriate corrections in order to correspond to the drafts on perpendiculars. To correct the precipitation taken on the marks of the recess means to “bring” them to the corresponding perpendiculars. To do this, use the formulas that are given in the article "Bringing sediment to perpendiculars."
An example of the layout of recess marks.
Symbols used in Figure 2:
KVL - Constructive waterline corresponding to the ship's draft according to the summer load line.
ln– Distance of the nasal mark of the recess from the nasal perpendicular.
lav- The distance of the middle mark of the recess from the midsection.
lcr– Distance of the stern mark of the recess from the stern perpendicular.
The load line provisions are based on the 1966 International Load Line Convention. Load line provisions apply to every ship to which a minimum freeboard has been assigned.
Freeboard is the vertical distance measured along the side at the middle of the ship's length from the upper edge of the deck line to the upper edge of the corresponding load line.
Freeboard deck- this is the uppermost continuous, not protected from the effects of the sea and weather deck, which has
permanent means of closing all openings on its open parts and below which all openings in the ship's sides are provided with permanent means for watertight closing.
The freeboard assigned to the ship is fixed by marking on each side of the ship a deck line mark, a load line mark and recess marks indicating the maximum draft to which the ship can be loaded to the maximum under various navigation conditions.
Corresponding to the season, it should not be immersed in water during the entire period from the moment of leaving the port until arrival at the next port. Vessels bearing load lines are issued an International Load Line Certificate for a period not exceeding 5 years.
The following load lines apply:
summer load line - L (S);
winter load line - З (W);
winter load line for the North Atlantic - ZSA (WNA);
tropical load line - T (T);
load line for fresh water - P (F);
tropical brand for fresh water - TP (TF).
The designation of the organization that assigned the load line is applied above the horizontal line passing through the center of the mark ring (Plimsol disc). The designation of the Register of Shipping of the Russian Federation is RS.
Distinguish cargo lines for timber carriers, passenger and sailing ships.
Designed to determine the draft of the vessel, applied to the outer skin of both sides of the vessel in the area of the stem, sternpost and on the midship frame.
The recess marks are marked with Arabic numerals 10 cm high (the distance between the bases of the numbers is 20 cm) and determine the distance from the current waterline to the lower edge of the horizontal keel. Prior to 1969, portside indentation marks were marked with Roman numerals, which were 6 inches high. The distance between the bases of the numbers is 1 foot (1 foot = 12 inches = 30.48 cm; 1 inch = 2.54 cm).
The cargo scale is a table for determining the displacement (deadweight) from the calculated or taken average draft of the vessel. Usually it is calculated for two water densities: sea water - 1.025 t/m 3 , fresh water - 1.000 t/m 3 .
To use the load scale, it is necessary to draw a horizontal line through a known value (for example, draft) and remove the quantities of interest (for example, displacement).
landing called the position of the vessel relative to the calm surface of the water. In the general case, the landing of the vessel is determined by parameters that fix the position of the vessel relative to the surface of the water or the position of the waterline relative to the vessel.
Fig.5 Landing of the vessel.
If the diametral plane is inclined at some angle to the vertical plane, then this parameter will be the angle θ, which is called bank angle (Fig.5 a); if the plane of the midsection - the frame is inclined at some angle with respect to the vertical plane, then this parameter will be the angle ψ, called trim angle (Fig.5 b).
The landing of the vessel in the general case is determined by three parameters:
D- average draft(midship draft), m;
Df- trim(difference between bow and stern draft D f = d n – d c), m;
-θ – bank angle– (inclination of the ship in the plane of the midship frame), deg.;
The trim angle is related to the trim D f:
tg ψ \u003d (d n - d c) /L = Df/L
With the adopted coordinate system, the trim on the nose is considered positive (ψ > 0), and the angle of roll to starboard (θ> 0) .
The following landings are possible:
A. The ship sails straight and straight on an even keel (θ = 0, ψ = 0). In this case, the landing is characterized by only one parameter - the average draft. d.
B. The ship sails straight but trimmed (θ = 0, ψ ≠ 0). In this case, the landing is characterized by two parameters in one of the following combinations:
Medium draft d and trim angle ψ ;
Medium draft d and trim Df;
Precipitation by the nose d n and stern d to, measured respectively on the bow and stern perpendiculars.
The above parameters are interconnected by the following dependencies: ψ ○ = 57 0 ,3(d n – d c / L) ; d \u003d (d n + d k) / 2
IN. The ship sails on an even keel, but with a roll (ψ = 0, θ ≠ 0). In this case, the landing is characterized by two parameters - the average draft d and bank angle θ .
G. General case of landing (the vessel floats with a list and trim). Landing is characterized by three parameters in one of the following combinations:
d, ψ And θ; d n, d k And θ; d , Df And θ.
To control the ship's draft when its load changes, as well as to determine its trim, use recess marks . Marks of depression are applied on both sides of the vessel in the bow and stern, as well as in the area of the midship - frame. The height of the figures, measured according to the norms for the OP, is 1 dm (100 mm), the distance between them is also 10 cm, or 50 mm and 50 mm, respectively; when marking depressions in feet, the height of the digits and the spacing between them is assumed to be 0.5 feet (6 inches). Metric marks are applied in Arabic numerals, foot marks in Roman numerals (Fig. 6)
Rice. 6 Grades of depressions (sediment).
The deepening marks measure the overall draft, since the lower edge of each number shows the vertical distance to the lower edge of the horizontal keel. In addition, recess marks are not necessarily located on the ship's fore and aft perpendiculars.
The ship's documentation, which serves to assess the seaworthiness of the vessel, is calculated and built for draft, counted on perpendiculars from the ship's OP. Therefore, to obtain them, it is necessary to correct the settlement values taken from the depression marks using a special scale (Fig. 7).
In the absence of the specified scale, precipitation at perpendiculars is determined by the formulas:
d n \u003d d nm ± δ nm + (L / 2 - ℓ 1) ψ;d to \u003d d km ± δ km - (L / 2 - ℓ 2) ψ, Where: δ nm And δ km- distance from the main plane of the lower edge of the keel in the planes of the bow and stern marks of the recess (the sign "+" when the edge passes below the OP, the sign "-" - above the OP), ℓ 1 And ℓ 2 – the distance of the bow and stern marks of the recess from the plane of the midsection - frame.
On some ships, precipitation gauges are installed to determine the draft, the readings from which are automatically transmitted to the bridge.
Rice. 7 Scale linking precipitation on perpendiculars with precipitation on the marks of the deepening of the m/v “A. Safontsev.
Questions for self-control:
1. What parameters determine the landing of the vessel?
2. What landing cases are typical for ships?
3. Why, where and how are the indentation marks applied?
4. Is there a difference between the drafts taken from the marks of the deepening and the draft calculated in the ship's documentation, and what is it?
The provisions on the load line are developed on the basis of the International Convention on the Load Line of 1966. Load line provisions apply to every ship to which a minimum freeboard has been assigned.
Freeboard- the distance measured vertically at the side at the middle of the ship's length from the upper edge of the deck line to the upper edge of the corresponding load line.
Freeboard deck- this is the uppermost continuous deck, not protected from the effects of the sea and weather, which has a permanent means of closing all openings on its exposed parts and below which all openings in the sides of the vessel are provided with permanent means for watertight closing.
The freeboard assigned to the vessel is fixed by applying on each side of the vessel a deck line mark, a load line mark and recess marks indicating the maximum draft to which the vessel can be loaded to the maximum under various sailing conditions (Fig. 1). The load line corresponding to the season must not be immersed in water during the entire period from the moment of leaving the port until arrival at the next port.
Vessels bearing load lines on board are issued an International Load Line Certificate for a period not exceeding 5 years.
The following load lines apply:
- summer load line - L (S);
- winter load line - З (W);
- winter load line for the North Atlantic - ZSA (WNA);
- tropical load line - T (T);
- load line for fresh water - P (F);
- tropical brand for fresh water - TP (TF).
The designation of the organization that assigned the load line is applied above the horizontal line passing through the center of the mark ring (Plimsol disc). The designation of the Register of Shipping of the Russian Federation is RS.
Fig.1 Load line
There are load marks for timber carriers, passenger and sailing ships. The recess marks are designed to determine the ship's draft; they are applied on the outer skin of both sides of the ship in the area of the stem, sternpost and on the midship frame (Fig. 2).
Groove marks are marked with Arabic numerals 10 cm high (the distance between the bases of the numbers is 20 cm) and determine the distance from the current waterline to the lower edge of the horizontal keel.
Prior to 1969, the mark of the recess on the port side was applied in Roman numerals, the height of which was 6 inches. The distance between the bases of the numbers is 1 foot ( 1 foot = 12 inches = 30.48 cm; 1 inch = 2.54 cm).
The cargo scale (Fig. 3) is a table for determining the displacement (deadweight) from the calculated or taken average draft of the vessel. Usually it is calculated for two water densities: sea - 1.025 t / m 3, fresh - 1.000 t / m 3.
To use the load scale, it is necessary to draw a horizontal line through a known value (for example, draft) and remove the quantities of interest (for example, displacement).
Rice. 2 Groove marks 
Fig.3 Weight scale Rules for the technical operation of the cargo device
The chief mate, chief engineer, boatswain, 4th engineer and electrician are responsible for the technical condition and maintenance of the cargo gear.
- Each ship must have a Register of ship's lifting devices and relevant certificates, certificates, instructions.
- After repair or replacement of any of the non-removable critical structures of the hoisting device, parts of the hoisting mechanism, topenant winch, the work of the hoisting device is prohibited until it has been tested in the presence of the Surveyor to the Register.
- Blocks, brackets, hooks, swivels, chain weights, tees must have stamps and certificates.
- It is forbidden to use even a slightly unbent cargo hook. The cargo hook shackles must lock securely. Blocks should be inspected, disassembled, cleaned of dirt, rust and lubricated with grease. The pulleys of all blocks, the swivels of the cargo hooks must be well lubricated, spaced and rotate freely.
- Each ship with a vertical cargo handling method, having a cargo device, must be equipped and always have in the required quantity (in accordance with the supply schedule) serviceable slings and other cargo equipment that meets the requirements of the Safety Rules.
- Shackles used in place of cargo hooks must be with a pin held in place by a cotter pin or pin.
- Wooden blocks with cracks on the cheeks (to make the cheeks available for inspection, they should be scraped), a forging or a pulley, as well as with an unbent hook, a stretched bracket, with a worn dowel or a damaged bushing should be replaced immediately.
- All detachable parts and cables of lifting devices that are not related to lifting devices must be checked at least once every 3 months. If broken wires are found in the cable, it should be inspected monthly. The results of the inspection and the measures taken to eliminate the shortcomings should be recorded in the ship's log.
- All cables of the running rigging of the cargo device must not have splashes, creases and strains of strands.
- Changing the horizontal position of the cargo boom at maximum outreach with the help of guys is allowed when the ship has a list of not more than 5 ° and a trim of not more than 2 °.
- All lifting devices must be inspected before each use. Defects and measures for their elimination are recorded in the log book. The lifting device is put into operation only after the elimination of the detected defects.
- Work with twin booms (“on the phone”) and heavy booms shall be carried out in accordance with the Instruction drawn up for each ship and agreed with the Register. Simultaneous operation of a heavy and light boom of one mast is not allowed, unless it is provided for by the said Instruction.
- Each detachable part (block, swivel, etc.) repaired or installed instead of a defective one must have the Register's brand of a trial load test carried out in the shop, without which it is prohibited to use it in a cargo device.
- The ship's cargo gear shall be surveyed by the Surveyor to the Register and tested in his presence. The test reports must be sewn into the Register Book of the ship's load-lifting devices.
- If liquid ballast is required for any loading option, no manipulation of it during loading and unloading is allowed. However, if the information on stability, floodability and strength contains other instructions on the procedure for ballasting the ship with liquid ballast, these instructions must be followed.
- During loading, passage and unloading, fuel and water should be consumed evenly from both sides.
- When transporting goods on deck, the following basic requirements must be met:
- deck cargo must be stowed in such a way that there are passages safe for people with a width of at least 0.7 m to ladders, measuring and air pipes, fire posts, horns and fire extinguishers;
- all passages must be through (no dead ends).
- If timber cargo is carried on deck, these requirements should be met to the greatest extent possible.
- The fastening of deck cargo must be carried out reliably, but with the expectation that in a critical position of the vessel it would be possible to quickly release the lashings or, in extreme cases, cut them.
- At the sea crossing, the details of the cargo device must be securely fastened in a stowed way:
- arrowheads are well fixed in nests;
- the hooks of the cargo pendants are laid behind the deck eyelets (toes up with shackling), and the cargo pendants are tightly fitted on the drums of the winches;
- the lower blocks of the guys are laid out from the eyelets and laid at the spur of their boom, the lopars of the hoists are fitted, laid in the bay and suspended from the mast;
- the cargo pendant and the hoists of the guy wires are attached to the boom in several places with lines.
Safety precautions when working with a cargo device
Cargo operations belong to the category of work of increased danger. The safety regulations on the ships of the navy determine the requirements for the cargo handling of the vessel and regulate the safe methods of working with hatch covers during the preparation and operation of the cargo handling device, and the performance of cargo operations.
cargo compartment The places where the traction cables pass must be protected and the inscription "The passage is closed" should be made. It is forbidden to walk on the hatch sections during their opening, closing, as well as during partial opening.
Sections installed in a vertical position must be securely locked. Do not leave them unlocked, even for a short time. Any work in the space between the open hatch sections can be performed only with the permission of the officer in charge of the watch or the work supervisor. During the entire period of work between the sections, a sailor must be on deck, who must ensure that no one removes the stoppers from the hatch sections, does not connect the traction cables to the sections, does not turn on the hydraulic hatch control system.
It is forbidden to carry out any work on hatch sections that are not completely closed until a temporary railing is installed to prevent people from falling into the hold. Rails with posted prohibition signs should be used to fence off the deck in the places of transshipment operations from the side towards which the cargo is moving.
It is impossible to descend into unlit and unventilated holds. It is possible to re-carry lighting chandeliers suspended on the pins only when the voltage is removed and after all people leave the hold.
Persons participating in cargo operations are instructed on safety precautions before starting work. Qualified sailors and other crew members who have undergone special training and have special certificates are allowed to work on lifting mechanisms as a crane operator and winch operator, as well as as a slinger.
Only specially trained crew members at least 18 years old are allowed to work on heavy devices, whose names are announced by order on the ship after they pass the exam. Only qualified sailors may be appointed signalmen.
The winch or crane operator carries out all the signals given only by the signalman, except for the emergency stop signal, which must be carried out regardless of by whom and in what way it is given. Any misunderstood signal should be taken as a stop signal. The signal to lift the load can only be given after the slinger confirms that the load is properly lashed and the signalman is satisfied that the movement does not endanger people working in the hold or on deck.
Signalman It is forbidden to pass under the lifted load, to be on the line of movement of the load, under the boom, in the gap of the hatch, and also to descend into the hold or rise from it when lifting and lowering the load.
When working on winches and cranes, it is prohibited:
- allow uneven tension of all branches when lifting a load using multi-branch slings;
- adjust the slings when the load is on weight;
- unsling the load before it firmly stands on the gaskets;
- swing the load to lay it out of the range of arrows or a crane;
- lift a load with people on it or loose objects, as well as a load that is in an unstable position or laid down by other loads;
- pull, turn and stop a swinging load during lifting, moving or lowering without the use of special braces.
In addition, when working on winches and cranes, it is prohibited:
- to feed the cargo into the hold without a warning signal, if there are people in the hold;
- deliver cargo into the hold before the previously delivered cargo is removed from the hatch clearance and people move to a safe place;
- carry cargo at a height of less than 0.5 m from the ship's structures or objects in the way of cargo movement;
- leave the load in a suspended state at the end of work or during a break;
- leave unattended mechanisms that are under current;
- adjust the pendant by hand, wind it up alone or wind it around the winch drum during its operation.
The operation of the lifting device must be stopped in cases of violation of the correct operation of the brakes, the appearance of abnormal noises in the mechanism, damage to the cable, malfunction of switches and systematic operation of electrical protection systems.
During reloading operations with dangerous and flammable goods, in addition to the above, one should also be guided by the transportation rules established for them.
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