Plimsol disc (load lines). Landing the vessel and determining its draft using the deepening marks. Drawing of the location of the deepening marks.

Control over the landing of the vessel during operation is carried out according to brands of recesses. In contrast to settlement, which is measured from the theoretical main plane of the OP (i.e., from the inner surface of the outer skin ), the recess is measured from the lower edge of the horizontal keel (i.e., takes into account its thickness).

Recess marks are applied on both sides in Arabic numerals in the area of ​​the midship - frame, on the stem and stern in the area of ​​the bow and stern perpendiculars and they indicate the recess in decimeters.

The layout of the recess marks on the ship's hull is shown in Fig. 3.4.

Rice. 3.4. Determination of sediment by depression grades

1. Calculation of vessel draft by deepening marks

Vessel draft T(d) is the distance measured from the OP, i.e. the upper edge of the horizontal keel to the waterline at the midships - the frame of the ship T m , and also on the nasal T n and stern T To perpendiculars.

Deepening the vesselT at is the distance measured from the lower edge of the horizontal keel to the waterline, measured from the indentation marks marked on the sides of the vessel in the midship area and the bow and stern perpendiculars.

It is obvious that the ship's draft T different from the deepening of a vessel T at by the amount of correction and is calculated using the formulas:

T n =T Well – δ g.k. + l n ∙ tgψ;

T To =T ku – δ g.k. + l To ∙ tgψ; (3.3)

T m =T mu – δ g.k. + l m ∙ tgψ,

Where δ g.k. – thickness of the horizontal keel, m;

l n , l To , l m– distances from the recess marks to the midsection and bow and stern perpendiculars, m;

ψ – trim angle, degrees, determined by the formula:

(3.4)

Values l n , l To , l m – positive if located forward of the perpendiculars and amidships and negative if located aft. These values ​​are given in tabular form in the ship's documentation (Table 3.1). The scheme for determining sediment by depression marks is shown in Fig. 3.4.

Table 3.1. Distance of recess marks from perpendiculars and midsection

The recess marks are welded in the form of stripes and Arabic numbers in decimeters, and

then applied with black or white paint depending on the color of the side. The height of the numbers and the distance between them are 10 cm.

1. Calculation of vessel displacement

Calculation of displacement and its geometric characteristics of the underwater part of the hull is carried out according to the theoretical drawing of the vessel during its design, and for practical calculations during the operation of the vessel - according to the ship's technical documentation, consisting of hydrostatic curves, Bonjean scale, drill, cargo scale, tables, etc.

These documents allow you to find numerical values ​​of quantities for any

Load line - a sign of maximum draft, applied on both sides of a sea vessel in the middle of its length (load waterline). The load line is depicted as a circle intersected in the center by a horizontal line, which shows the maximum permissible draft of the vessel in sea water (in summer time in the temperate climate zone), and a series of horizontal lines showing its maximum immersion in the sea or river depending on the time of year and area of ​​navigation.

English sailors call the load line the Plimsoll disk, which, based on the rules of the international convention, is applied to the sides of every merchant ship launched if its tonnage exceeds one hundred and fifty register tons. Such a freight line was first proposed by Samuel Plimsol, an Englishman and brewer from the city of Derby, who had nothing to do with shipping.

The following load lines are used:

• summer load line – L (S);
• winter load line – W (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).

For each ship, the load line is marked according to international rules, which are mandatory for all maritime powers in the world. Therefore, the shape of the load line is the same everywhere. The only difference is in the letters. The designation of the organization that assigned the load line is placed above a horizontal line passing through the center of the sign ring (Plimsoll disk). Register of Shipping designation Russian Federation- RS, L and R "Lloyd's Register", A and B - "American Bureau of Shipping", etc.

There are load lines for timber carriers, passenger ships and sailing ships.

The load line corresponding to the season must not be submerged in water during the entire period from the moment it leaves the port until it arrives at the next port.

Ships with load lines marked on their sides are issued an International Load Line Certificate for a period of not more than 5 years.

Each ship carries a freeboard certificate, and if the draft is greater than allowed by the load line, then its captain has no right to go to sea. In the event of overload, the port authorities responsible for the vessel's departure have the right to demand the removal of excess cargo and even detain the vessel in the port.

The dredge marks should never be confused with the load line, as they serve only to measure the actual bow and stern draft at a given time.

Application

According to the international convention on load lines, a ship is prohibited from going to sea on international flight unless it has been marked with a load line and has not been issued an International Load Line Certificate or, where appropriate, an International Load Line Exemption Certificate.

This Convention applies to all ships except:

• warships,
• new ships less than 24 meters (79 feet) in length,
• existing ships of less than 150 gross tonnage,
• pleasure yachts not engaged in commercial transportation,
• fishing vessels.

Nothing in this Convention applies to ships navigating exclusively:

a) along the Great Lakes North America and along the St. Lawrence River within the limits bounded on the east by a straight line drawn from Cape Rosier to Cape West Point on Anticosti Island, and then by a straight line drawn from Anticosti Island in a northerly direction along the meridian of longitude 63° West,

b) in the Caspian Sea,

The load line provisions are based on the 1966 International Load Line Convention. The load line provisions apply to every ship that is assigned a minimum freeboard.

Freeboard is the distance measured vertically at the side at the midpoint of the ship's length from the top edge of the deck line to the top edge of the corresponding load line.

Freeboard deck- this is the uppermost continuous deck, not protected from the effects of sea and weather, which has

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 a ship is fixed by applying on each side of the ship a deck line mark, a load line mark and deepening marks marking the highest drafts to which the ship can be maximally loaded under various sailing conditions.

Suitable for the season, it should not be immersed in water during the entire period from the moment it leaves the port until it arrives at the next port. Ships with load lines marked on their sides are issued an International Load Line Certificate for a period of not more than 5 years.

The following load lines are used:

summer load line – L (S);

winter load line – W (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 placed above a horizontal line passing through the center of the sign ring (Plimsoll disk). Designation of the Register of Shipping of the Russian Federation - RS.

There are load lines for timber carriers, passenger and sailing ships.

Designed to determine the draft of the vessel, they are applied on the outer plating 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 numerals is 20 cm) and determine the distance from the effective waterline to the lower edge of the horizontal keel. Until 1969, the markings of the recess on the port side were 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 load scale is a table for determining displacement (deadweight) based on the calculated or measured average draft of the vessel. It is usually calculated for two densities of water: sea - 1.025 t/m 3, fresh - 1,000 t/m 3.

To use a load scale, it is necessary to draw a horizontal line through a known value (for example, draft) and remove the values ​​of interest (for example, displacement).

On cargo ships, 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 draft of the vessel is measured at the bow, stern and middle marks of the depression.

Recess marks these are numbers and horizontal lines welded on both sides of the ends of the ship’s hull and in the midsection area. The draft of the vessel in the area where the mark is applied is equal to the vertical distance from the lower edge of the number to the lower edge of the keel. In everyday work, the term “removal of precipitation” is used to measure settlement, i.e. determine the draft of the vessel by the marks of the recess or determine the draft by measuring the height of the freeboard.

Recess marks are painted white on a dark background or dark on a light background.

Marking of recess marks can be carried out:

In the metric system (Arabic numerals), draft is measured in meters - the height of the numbers and the distance between them (perpendicular to the main plane) is 100 mm.

In the English system (Roman numerals), draft is measured in feet (1 ft = 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 (perpendicular to the main plane) is 0.5 feet (6 inches).

If both systems are used on the ship, then on the left side the indentation marks 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 take photographs of precipitation under various unfavorable conditions: low light, waves, 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 height of the freeboard at the locations of the recess marks. Based on the measured freeboard height, the vessel's draft at the measurement location is also calculated.

An example of sediment removal on English and metric recess marks is shown in Figure 1.

English system Metric system

Measuring draft by deepening marks

The shape of the ends of the ship's hull does not always allow the marking of recesses on the bow and stern perpendiculars. Therefore, for the convenience of removing 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 recess marks can be applied both forward and aft from the corresponding perpendicular.

Sometimes part of the recess mark is applied on the perpendicular, and the other part at some distance from it.

Figure 2 shows an example of the arrangement of recess marks relative to the bow and stern perpendiculars and the midship 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 landing of a vessel and determining the mass of cargo by drafts, drafts on perpendiculars are used, the drafts taken on the marks of the recess must be corrected with appropriate corrections so that they correspond to the drafts on the perpendiculars. Correcting the sediments taken on the depression marks means “bringing” them to the corresponding perpendiculars. To do this, use the formulas given in the article “Reducing precipitation to perpendiculars.”

An example of the arrangement of recess marks.

Symbols used in Figure 2:

KVL – structural waterline corresponding to the draft of the vessel along the summer load line.

lн– Distance of the nasal mark of the recess from the nasal perpendicular.

lsr– Distance of the middle mark of the recess from the midsection.

lcr– Distance of the stern mark of the recess from the stern perpendicular.

3.1. Determination of bow and stern draft values:

m.

3.2. The bow, stern and average drafts determined above correspond to the calculated values ​​at perpendiculars. If it is necessary to check the correctness of the calculation after loading the vessel, you should take the values ​​of the draft on the marks of the vessel's recesses - from the left and right sides (visually). The resulting settlement values ​​on the marks will differ from the calculated settlement values ​​on the perpendiculars due to the following factors:

– the location of the recess marks does not coincide with the position of the perpendiculars;

– marks of recesses are applied to the hull of the vessel, while repeating the spatial curvature of the shape of the contours of the vessel at the extremities;

– the presence of a deflection arrow from the general bending of the body;

– a significant change in the shape of the waterline relative to the calculated one in the presence of trim;

– the actual value of sea water density differs from the accepted value.

Therefore, the values ​​of the drafts taken from the markings of the recesses are recalculated to the values ​​​​at perpendiculars (based on data from the ship's documentation), after which corrections are introduced to the displacement determined on the load scale for the average draft, taking into account all of the above factors:

a) correction for water density

where ρ f is the actual density of sea water, t/m 3 ; ρ – density of water on a load scale, t/m3; D– displacement determined by the load scale, t;

b) correction for trim

,

Where q 0 – number of tons per 1 cm of precipitation, t/cm; x f 0 – abscissa of the center of the waterline area, m; M diff – moment differentiating by 1 cm, tm/cm;

c) correction for body contours at the extremities

,

where is the distance of the bow mark of the recesses from the bow perpendicular, m; is the distance of the stern mark of the recesses from the stern perpendicular, m;

d) correction for body bending

where is the hull deflection arrow, cm (for this calculation, for educational purposes, we accept cm).

Thus, the final displacement value is obtained by summing the value determined from the load scale and amendments to it. This final value must coincide with the value calculated when drawing up the ship's cargo plan.

3.3. Recalculation of precipitation on perpendiculars to precipitation on marks:

where is the trim angle of the vessel; A– distance of the nasal mark of the recesses from the nasal perpendicular; b– distance of the stern mark of the recesses from the stern perpendicular; With– distance of the middle mark of the recesses from the plane of the mid-frame.

(m)

3.4. Calculation results for the vessel's landing after loading as of departure: