Wave impedance. Pursuit of speed at sea

/ pirates, merchants, in order to manage to sell goods on time and escape from pirates, pirates to catch up with merchants, mercenaries, to be in time to complete government tasks on time, and, of course, to the rangers to successfully complete everything at once.

Ship speed calculation

Speed \u200b\u200bis one of the most complex characteristics and depends on a number of parameters, the main of which, of course, is the nominal speed of the engine, on which various effects of acceleration and deceleration are superimposed.

Slowing Effects

Overload

The large mass of the ship, equipment and cargo that it carries in the hold can lead to a decrease in speed. In this case, the deceleration coefficient fluctuates from 1 to 0.333   and is calculated by the formula:

Thus, with a ship weight of 2000 coefficients. will take its minimum value and will not decrease with further mass growth.

Overheat

Broken engine

Acceleration effects

Equipment

Some samples of acrylic equipment or enclosures may give bonuses (or fines) to speed in the form of an integer, rather than a coefficient.

Fast and furious

Gaalistra of time

A stimulator that makes the brain work several thousand times faster and, in addition to bonuses to skills, increases the speed of the ship by a third, thereby adding a coefficient to the speed formula 1,3 .

Artifacts

• Psi accelerator of matter   - using its own powerful consciousness allows the engine to use the physical laws of psi-space. By implementing some of these laws, the engine significantly increases speed. In the first and second parts of the cosmos, it adds +100 units speed, in КРHD the integer bonus has been replaced by the coefficient - 1,2 , i.e. the bonus is 20% .
• Coplanator   - Self-extracting set of additional nozzles that are connected due to one unused gun compartment. Thanks to a freer release of energy into outer space, the speed of the ship increases. Gives a permanent bonus +100 units to speed.

Speed \u200b\u200bcalculator

• BS \u003d engine speed
• SW \u003d speed reduction due to overload (0.333 to 1)
• SE \u003d decrease in speed due to overheating (0.5 to 1)
• SBE \u003d speed reduction with a broken engine (0.6 or 1)
• H \u003d product of all acceleration factors
• FS \u003d the sum of all speed bonuses (including from acrin)

Changes in the speed calculation mechanism in KRHD

• Penalty from a broken engine increased to 70%
• Slowing effects are superimposed according to the formula:

• Pure effects (flat) are superimposed before scaling
• All speed reduction, below 200 comes with an 80% penalty
• All speed increase, above 1000 comes with a 30% penalty
• All speed increase, above 1500 comes with a 50% penalty
• All speed increase, above 2000 comes with 80% penalty

Examples

Notes

The pursuit of records is not alien to the sea routes. A flight from Europe to North America by plane takes only a few hours, while the fastest ship needs to spend three and a half days to cross the ocean. If we talk about transport ships of today and the near future, then they still move much slower than the fastest passenger ship 25 years ago. Only in 1973, a merchant ship reached a record speed of 33 knots. However, this figure today is as little characteristic of the average level of speeds achieved in the merchant marine fleet, as in previous years. The average speed of vessels is much lower than this maximum achieved by single vessels, and there are reasons for this. The increase in speed, although it leads to a reduction in the time of transportation of goods, is financially very expensive. VFM ships reach speeds of not more than 60 km / h. With increasing speed, the costs of building a ship and its operation increase significantly. The expediency of increasing the speed is also determined by the duration of ship parking in ports. From the point of view of economic efficiency, an increase in speed will be justified only if at the same time improvements to the processing technology for ships in ports are carried out to reduce parking time. Navy ships also maintain this trend, and their speeds range from 50 to 60 km / h. And these speeds are enough for the effective performance of combat missions.

"Peter the Great" has a speed of 57 km / h.

"Moscow" maximum cruiser speed - 60 km / h.

Varyag has a speed of 60 km / h.

The “persistent” destroyer speed is 62 km / h.

"Admiral of the Fleet of the Soviet Union Kuznetsov" speed - 53 km / h.

The submarine "Yuri Dolgoruky" surface speed is 28 km / h, submarine speed is 53 km / h.

4th generation multipurpose nuclear submarine “Severodvinsk”, submarine surface speed - 30 km / h, submarine - 57 km / h.

The patrol ship Tatarstan of project 11661 (Cheetah) is the flagship of the Caspian flotilla. The speed is 52 km / h.

Corvette "Clever." The speed of the corvette reaches 50 km / h.

So, the desire that began in the 60s to increase the efficiency of dry cargo vessels by increasing their speed was not successful. Qualitatively new conditions arose only after the introduction of containers for the transportation of general cargo. In combination with the creation of special kits for container transshipment, this led to a sharp reduction in the downtime of container ships under cargo operations and provided the necessary prerequisites for increasing the speed of transport ships. Fleet ships are very expensive anyway. Despite this, the speed of ships has gained great importance in the competition in the global freight market, especially for linear vessels. High speed is considered a sign of high competitive ability and serves the appropriate shipping company to gain or maintain prestige; this phenomenon inherent in capitalist production relations contributes to the squandering of social labor. Operating costs that increase rapidly with increasing speed are superimposed on the cost of the transported goods. This is justified only when transporting valuable general cargo, where high freight rates can pay off due to faster delivery. As for dry and liquid bulk cargoes, because of their lower cost, they cannot withstand large margins on transport, otherwise their further processing will be economically disadvantageous. Therefore, among high-speed vessels, only container ships, horizontal-loading vessels, refrigerated vessels and lighter carriers can be found, that is, mainly ships intended for the transport of valuable piece goods, but not tankers and vessels for transporting bulk cargoes. Note that recently, tankers for transportation of liquefied gases have also been included in the number of high-speed vessels. This type of transport represents a particular problem, which will be considered later. Increasing ship speed, however, is not a purely economic problem. The faster the ship, the sharper the contours it should have. Large hulls that extend from the extremities of the vessel almost to the midship frame itself lead to a very uncomfortable form of ship holds in terms of cargo storage during loading or to large cubic losses in comparison with slower vessels of similar sizes. At the same time, it is the containers that make very high demands on the cubic capacity of ship holds.

The power plant’s power required for the ship’s movement grows approximately in proportion to the third power of the ship’s speed. To achieve a speed of 18 knots, a modern 14,000-ton dry-cargo vessel costs about 8,100 kW, and a container ship that is only three times as large in carrying capacity requires 85 thousand kW to reach a speed of 30 knots. Along with the need to install such powerful engines on board the vessel, it is also necessary to provide for the possibility of placing fuel reserves for them. If we dwell on this example, it turns out that a dry cargo vessel will need “only” 1300 tons of fuel for one voyage to East Asia, while the container ship mentioned above will have to carry almost 11 thousand tons of fuel if it does not replenish its supplies on the way, and calls at intermediate ports are associated with inevitable loss of time. In connection with a further increase in the requirements for the speed of transport ships, it can be assumed that the increase in speeds will be restrained not only by the increase in the cost of building and operating ships, but also by certain technical and physical aspects of this problem. The upper theoretical speed limit of any vessel will obviously be reached when all its useful payload is used up for the mass of engines and fuel reserves. But for merchant ships this option is unacceptable. In fact, why should a ship go on a flight if it does not carry any payload? However, nothing else will happen if, for example, you set the task to design a vessel with a full carrying capacity of 10 thousand tons for sailing on a line with a length of 10 thousand miles at a speed of 40 knots. The carrying capacity of such a vessel is only enough to accept the fuel reserves necessary for the operation of a power plant with a capacity of more than 75 thousand kW. With empty holds and 10 thousand tons of fuel in the double bottom and other compartments, this vessel will begin its voyage as a tanker, and will arrive at its destination with empty fuel tanks. In practice, however, this will not come to this, if only because the size of ships is growing at the same time. This favorably affects the upper limit of the capacity of the power plant, which can be put on the ship, but, on the other hand, requires a constant supply of cargo in quantities sufficient to load such large vessels.

In addition to the above considerations of a mass-dimensional nature, there is another hydrodynamic limit for the speed of transport vessels, associated with a sharp increase in wave drag. This follows from the fact that, starting from a certain speed value, the resistance of the water to the movement of the vessel grows so much that any further increase in speed is associated with an excessive increase in resistance. So, for example, with a further increase in the speed of a large 40-knot dry cargo ship by only 1 knot, a significant increase in the power plant capacity is required - up to 40%. But such an increase in speed would be too expensive. Hence there is a speed limit for all ships floating on the surface of the water. The maximum speed in accordance with physical laws depends on the length of the vessel and has a different value for vessels with full formations and with sharp contours. Forecasts of the highest achievable speed are made, of course, only for displacement vessels, which, in accordance with the law of Archimedes, displace as much water as they weigh. These forecasts do not apply to hydrofoil and hovercraft, to gliders, or to hydrofoils. Although the speeds that are currently being laid down in projects of high-speed vessels with sharp contours always turn out to be lower than the extreme values, nevertheless, a tendency is quite distinctly observed: high-speed displacement vessels must simultaneously be large in magnitude. Thus, forecasts of speed growth should also take into account the size of the vessels. The lengthening of the vessel from 300 to 400 m, for example, although it increases the top speed by 6 knots, it simultaneously increases the ship's carrying capacity from about 40 thousand tons to 70 thousand tons. Such a container ship is designed to carry about 3,000 20-foot containers. All of these containers should be delivered to the port as soon as possible for loading onto the ship and removed as quickly from the port after unloading. One cannot but note the difficulties of storing such a large amount of valuable cargo.

In 1973, the first transport ships were launched at a speed of 33 knots. In Japan, studies are underway related to the construction of a 35-node container ship. It is possible that by the end of the century the speed of container ships in some cases will reach 40 knots. However, to come to such speeds, even greater scientific and technological achievements are needed. Sharp increases in oil prices and, as a result, for fuel have a significant opposition to the increase in ship speeds. Since 1973, fuel prices in international shipping have increased several times. Therefore, now (and in the future) when choosing ships, fuel prices can serve only for purely indicative economic assessments. In this regard, it should be noted that faster vessels, as a rule, are not the most economical. It is noteworthy that the fastest vessels are owned by state-subsidized shipping companies. Military considerations are decisive in this case, as important military functions are entrusted to high-speed transport vessels as part of the US global strategy. The influence of these circumstances on international shipping in the design of container ships and horizontal loading vessels precludes the choice of an optimal speed from an economic point of view. The competition of capitalist shipping companies leads to an overestimation of the speed of such vessels. In contrast, the research work leading to the achievement of higher speeds by reducing water resistance and increasing the efficiency of marine power plants meets this. The most commonly used means to reduce water resistance is the nasal bulb, which gives the maximum effect with moderately sharp contours: with very sharp contours, the nasal bulb gives about 5% power savings, with more complete ones up to 10-15%.

The increasingly wide range of ship hull coatings offered by the paint and varnish industry reduces corrosion and fouling of the hull, which also leads to some, albeit small, reduction in friction resistance. A much greater effect can be expected in the future from the injection of air and the injection of high polymer solutions (as far as environmental considerations allow) into the boundary layer between the body and water. The effect will come when the costs of these activities will be paid off by the benefits of them in the form of saving power and fuel. It is still difficult to say when this will happen. To reduce the resistance, the correct choice of the ratio between the length and width of the vessel is of great importance, especially now, when there is a further increase in the speeds and sizes of ships. All this serves one purpose - the maximum possible reduction in the power of ship power plants. For a displacement vessel of the usual type, moving at the interface between two media - water and air, a speed of more than 40-45 knots is hardly achievable. If high speed is required, it is necessary to use new methods of ship movement. This does not mean, however, a simple departure from the now accepted form of the hull. The hull of the vessel must leave the interface and move in only one environment. There are two ways to do this: down, under the surface of the water, or up, above it. In both cases, the impedance should disappear. Indeed, above or below the surface of the water, the ship can move faster, speed limits lose force. hydrodynamic wave ship

It is expected that the transition from single-hull to multihulls will also lead to an increase in speed. In principle, however, any increase in ship speed is associated with a significant increase in power. Interestingly, the nature of the increase in power with increasing speed is very different for ships of different types. The superiority of one type of hull over another is always associated with a specific speed range. If at first we get distracted from the problems associated with the choice of main engines, then for the future, in terms of achievable speeds, we can propose the following new classification of ships:

• - Displacement single-hull vessels moving on the surface of the water, in a semi-submerged state and below the surface;
• - Displacement vessels with two or more hulls, moving on the surface of the water and in a semi-submerged state;
• - vessels with hydrodynamic forces of maintenance: planing and hydrofoils;
• - hovering vessels: hovercraft with aerostatic support force and ekranoplanes with aerodynamic support force.

For all vessels of an unusual type, the hull of which is either placed above the surface of the water or lowered under the water, the wave resistance disappears, which is the dominant part of the total water resistance for ordinary displacement vessels. In fact, such maximum speeds were achieved (or envisaged in the projects). Underwater transport 50-60 knots Semi-submerged multihull 50--80 knots On hydrofoils 60-100 knots. Hovercraft 80-200 knots.

These speeds are significantly higher than conventional merchant ships. The range of speeds between transport aircraft and the merchant marine fleet will be filled, at least in part, by hydrofoil and hovercraft. In any case, ideas about the prospects for the development of these two types of vessels go very far. Although heavy projects, weighing many thousands of tons, hydrofoils and hovercraft with speeds of about 150 knots and even more than 200 knots are recognized as technically feasible, however, their construction remains unrealized, since there is no socially determined need for this. It can be assumed that the implementation of such projects will require decades, during which great achievements in other areas of transport are inevitable. In the future, high demands will be made on the efficiency of maritime transport. However, will it be possible, with the help of previously known technical means, to create ships that can satisfy the wishes of the clientele of maritime transport? An increasing level of specialization of ships and an increase in their size create the prerequisites for sea transportation of goods with a minimum cost of funds. Automation of ship production processes in combination with their high reliability will also contribute to increasing the efficiency of ships. But is this enough? Will there be a problem for the future marine fleet to meet the new, still unknown needs of society? Apparently, it will be so. The unresolved question is whether the Navy will in the future be able to satisfy the requirements of high-speed transportation of valuable goods. Already, aviation is an alternative to transoceanic ship transport. Achieving high speeds is the most important promising task for all international shipping. This refers not only to the transport of valuable goods, but also expanding ferry services and tourism.

But how can the running time be reduced if the possibilities for increasing the speed of ordinary type ferries are almost exhausted? Will these transport tasks be assigned to helicopters or, say, airships, or will the operation of high-speed hydrofoil and hovercraft ships prove more economical? Completely new, unusual challenges arise for maritime navigation in connection with a more intensive use of the northern sea routes. Ships that make their way through the Arctic ice with the aim of involving this part of the Earth in the sphere of economic activity are the forerunners of the ships of the future. Today it is still almost impossible to foresee what requirements sea production of marine raw materials will make to shipbuilding and shipping, the importance of which will increase more and more. From our point of view, future engineering structures designed to extract marine raw materials on the surface of the sea, below its surface or on the seabed, as well as floating concentration plants, floating stations for liquefying natural gas and other floating enterprises should look extremely unusual. Naturally, in this promising production process at sea it will be difficult to draw a clear line between ships and other industrial facilities. However, these and other issues will inevitably have to be addressed, since we are talking about the courts of tomorrow. New challenges lead to new technical and technological solutions. Along with all the improving vessels of the ordinary type, vehicles of a new, non-traditional type will also contribute to the solution of future transport problems at sea.

UDC 656.6 Kostenko Victoria Nikolaevna Odessa National Maritime Academy, Faculty of Navigation on Sea and Inland Waterways 2 year, group 1221

Head - Assoc. Siryachenko V.F., Department of Theory and Device of the Ship

WAYS TO INCREASE THE SPEED OF A BOAT SHIP

Sea and ocean water areas, covering 2/3 of the Earth’s surface, have been the natural transport arteries between island and coastal countries for many centuries. Sea transport remains the main mode capable of providing large cargo flows between the continents, and the development of the mineral and biological resources of the oceans further enhances the role of the marine fleet. However, the speed of transport ships has changed little over the past centuries, and no longer corresponds to the pace of development of the modern economy.
In search of ways to increase speed, attempts were made to separate the vessels from the surface of the water and thus avoid speed limits. However, displacement vessels are still the most practical, economical and comfortable. Therefore, it is necessary, as far as possible, to eliminate their inherent disadvantages or, in extreme cases, put up with them.
  Displacement vessels experience significant water resistance and, having reached speeds of about 40 knots, can no longer significantly increase speed (and economy), even if the power plant’s power is significantly increased. Therefore, the problem of increasing the speed of the vessel cannot be solved without considering each type of resistance that it faces.
  A hull moving in water experiences resistance to water and air, which impedes its movement. Air resistance can be neglected. Water resistance is the sum of the friction, shape and wave drag.
  Newton’s old idea is known, which describes the pressure exerted by the shock layer on the hull of a ship. Using its content to determine the resistance force, the calculation formula is adopted as follows:

Studies have shown that the dependence of the ship’s impedance on speed is not quadratic, and for different Froude numbers the coefficient k 1 varies within 2< k 1 <3 в зависимости от угла входа действующей ватерлинии.
  A significant part of the engine power is spent on overcoming an important part of the resistance - friction of water on the hull.
  Currently, there are many methods, ideas and projects aimed at managing the boundary layer in order to reduce turbulence, from traditional to exotic.
  The main traditional method is the docking of the vessel with the obligatory cleaning of the underwater hull and coating it with antifouling paints.
  Exotic development of methods for reducing friction resistance is currently quite a lot.
  For example, the addition of chemicals. The results of a test conducted in 1968 on the English minesweeper Haibaton are known, when a very weak solution of polyoxyethylene was constantly released from the bow of the vessel during the course. The friction resistance of the boat due to this decreased depending on speed and excitement by 22-36%, engine power saving was 12-20%. However, fuel economy did not cover polymer costs.
Curious, however, in some ways impractical, an air lubrication system may seem, the principle of operation of which is based on reducing the resistance between the hull of the vessel through the use of air bubbles created under the hull. During tests conducted in 2010 on a Yamatai cargo ship, it turned out that the bubble system allows you to save 10% of fuel, taking into account the energy consumption for the operation of air compressors.
  Also, scientists from the United States created a coating based on the principle of dolphin skin. To start the cleaning mechanism, you need to apply an electric pulse to this material or increase the pressure exerted on it. Then it wrinkles, while the biofilms fixed on its surface, and eventually fall off themselves.
  An interesting direction is the design of vessels with recesses (holes on a streamlined surface) using the phenomenon of movement of a golf ball. It is known that the vacuum mark left by a ball with holes is less than that of a regular ball, and its braking is weaker. Therefore, it can be assumed that the design of vessels with recesses in the hull can help make the vessel more efficient by significantly reducing its friction resistance.
  Another exotic area is the creation of a super-hydrophobic surface of the vessel based on the natural model of water fern salvinia molesta.Researchers believe that by reproducing the mechanism by which salvinia molesta   leaves dry from the water, it will be possible to save up to 10% of fuel during the operation of ships.
  The second component of the impedance is shape resistance; in some types of vessels (especially barges) it can be up to 50% of the impedance. Therefore, today an important task is to design the optimal shape of the hull. When finding the optimum length of the hull, for example, it must be remembered that low-speed vessels, the resistance of which consists mainly of friction, are advantageous to build relatively short, and high-speed ones - elongated.
  However, the main obstacle to increasing the speed of displacement vessels is wave resistance, since with increasing speed it increases approximately in proportion to the fourth degree.
  The search for ways to reduce wave resistance was carried out in various directions and gave rise to numerous assumptions, many of which turned out to be fantastic and impractical, and some very important and promising.
The idea of \u200b\u200bthe nasal arrangement of the mover came from the Austrian engineer Victor Schauberger. The bow and stern propellers were proposed to rotate in different directions. The water circulating with the help of screws has the shape of an elongated torus, and the movement of the vessel should have been due to the friction of this torus with the surrounding water. But, unfortunately, this idea did not find its practical application in shipbuilding due to the fact that the "active nasal bulb" is inconvenient in operation - it makes it difficult to maneuver, and also make it difficult to return anchors.
  At the heart of the fin mover is the “ridge course” used by most fish and cetaceans. The translational movement of the fish is ensured by a peculiar effect arising from the oscillations of the caudal fin, which, as it were, slides from the “cheek” of the water wedge. In the case of a sufficiently fast (pulsed) application of force from the fin side, a water wedge acquires the properties of a solid, i.e. The wedge accelerator plays the role, from which the elastic flexible fin slides. This hypothesis was tested in practical use by G. Bowlas and G. Semenov on models of catamarans with fin propulsion, as well as researchers at Komsomolsky-on-Amur State Technical University.
  However, in our time, the most practical and generally applicable way to reduce wave impedance is to use interfering devices, which include airborne boules, nasal bulbs and hydrofoils.
  Calculations show that to increase the speed of the ship at the same power of its power plant, it is enough to increase the area of \u200b\u200bthe bow contours, which can be done using the bow bulb.
  If it is absent, flow separation occurs near the bow of the vessel, and with the installation of a bulb, the average flow rate flowing around the underwater part of the hull decreases to such an extent that the viscosity decreases.
  It may also be promising to use a double bulb on combined vessels.
  As tests of large vessels showed, the decrease in impedance due to the use of such forms of the nasal extremity was 15%. It should be noted that the resistance is significantly reduced not only when the vessel is moving in full load, but also in ballast runs with low rainfall. This means that the effectiveness of the bulb is maintained even when it approaches the surface of the water.
In conclusion, it should be noted that by choosing the optimal shape of the bow of the hull, you can significantly reduce the cost of power to overcome wave impedance. However, at present, wave formation remains a complex and adverse natural phenomenon, which the designer cannot but take into account.

List of materials used:
1. Shapiro L.S. The fastest ships. - 2nd ed., Revised. and additional - L .: Shipbuilding, 1989. - S. 28-39.
  2. Gilmer T.S. Design of a modern ship / E.A. Budyakovsky, A.O. Viglina, E.A. Shirokova. - 2nd ed. reslave. and add. - L .: Shipbuilding, 1984. - S. 142-159.
  3. Korotkin A.I. Myths and reality of hydrobionics. - SPb .: MorVest, 2012.88 s.
  4. Basin A.M. Speed \u200b\u200band controllability of ships. - M.: Transport, 1977 .-- S. 71-74.
  5. Donnelly K.J. Reduction of Ship Resistance through Induced Turbulent Layers. - F .: Master of Science in Ocean Engineering, 2010 .-- 65 p.
  6. Semenov G. Catamaran with fin mover // Boats and Yachts. - Vol. 169. - M .: Tsar, 1999. - P.54-55.
  7. Chizhiumov S. D., Belyaev V. A., Kuznetsov D. S. Projects of fin movers. - Komsomolsk-on-Amur State Technical University, 2012 - S. 57-63

L. M. KRIVONOSOV

Hydrodynamic modes of movement and the corresponding types of contours

A small high-speed vessel, as it "picks up" speed, passes the navigation mode first, and then the transitional mode; only after that it begins to glide. The main practical difference between these modes is that during each of them the vessel consumes an unequal amount of power for one kilometer per hour to increase speed.

This is because the forces supporting the vessel (Archimedean support force, hydrodynamic lifting force) and resistance to movement (friction, wave, vortex), change their value in each of the three modes according to different laws of hydrodynamics. The change of these laws does not occur suddenly - at the borders of regimes - but gradually and moreover, either faster or slower; therefore, the resistance and position of the vessel on the water (draft and trim) also change gradually, with accelerations and decelerations. As can be seen in fig. 1, when changing the transitional swimming mode, the resistance growth slows down, and then - when entering the planing mode - it again accelerates.
When the vessel moves in the sailing mode, as can be seen from Fig. 1, trim varies slightly; then, at the beginning of the transition regime, it increases significantly, after which it slowly falls again.

Fig. 1. The curves of resistance and trim angles of a harmless glider with a displacement of D \u003d 0.83 tons

As speed increases, in the planing mode, the trim angle continues to decrease.

The average initial (stationary) draft during the passage of a vessel of all modes decreases several times.

Simultaneously with the change of modes, the picture of wave formation during the movement of the vessel also changes. Calm wave formation while the vessel is moving in the sailing mode as it approaches the transitional mode is gradually replaced by violent wave and spray formation created by the bow of the bottom; at the same time, the water is completely detached first from the transom, and then from the sides of the vessel. The regime of pure gliding is characterized by relatively weak waves, but strong jets and splashes break out from under the bottom.

If the vessel intended for planing is designed correctly and has an engine of sufficient power, then you can easily calculate the speed at which changes will occur, according to the formulas:

In these equations, the velocity v is expressed in meters per second, and the displacement V is in cubic meters.

For convenience, the calculation of the values \u200b\u200bin Fig. 2 shows the corresponding schedule.

Fig. 2. Chart for calculation

Fig. 3. The curve of the effective power of a harmless glider with a displacement of D \u003d 0.83 tons

Therefore, if some vessels are intended for movement on a sailing mode, for others the transitional mode is calculated, and for the third - planing mode. At the same time, contours are attached to each vessel, allowing it to be better used for the specific mode and to spend as much as possible specific power, i.e., power per kilogram of displacement.
  For the sailing regime, the most rational are the so-called round-bottom (round-bosom) contours (Fig. 4), which provide a well streamlined shape of the ship's hull and are designed only for Archimedean support force.

Fig. 4. The rounded contours of a tourist boat (length 12.2 m; width 2.9 m), designed for the swimming mode.

Vessels intended for transient traffic are often attached with flat keeled contours (Fig. 5), which have high keeledness, transom stern and sharp cheekbones along the entire length. For ships designed for this mode of movement, combined contours are also used: flat keel in the stern and rounded in the bow. On ships with such contours, the hydrodynamic lifting force is added to the Archimedean support force as the cruising speed increases, as a result of which the ship on the move is partially displaced from the water, and its sides are almost not surrounded by water.

Fig. 5. The plane-keeled contours of a large tourist boat 12.5 m long, calculated non-transitional mode.

Figure 6. Flat-pitching contours of a walking glider (length 4.0 m; width 1.5 m).

Fig. 7. The contours of the bottom of a single-handed glider.

Transient flow around the bottom occurs partially along the bottom and partially across. The general direction of flow is at an angle from the keel to the cheekbones.

The contours of planing vessels are made flat or curved-keeled with a pitch angle decreasing from bow to stern to zero and, on average, smaller than for transition vessels; cheekbones - always sharp along their entire length, feed - transom (Fig. 6). Sometimes, on the fastest gliding vessels that are not intended for sailing, one or more ledges, called redans, are made about the middle of the length across the bottom (Fig. 7).

The contours of planing vessels are designed to ensure that the vessel on the move is supported almost exclusively by hydrodynamic lifting force and only to a very small extent by Archimedean force.

Elements of the contours of planing vessels and their significance

Flat bottom.   To create a hydrodynamic lifting force, a completely flat bottom is very beneficial, but such a bottom, even with slight excitement, experiences very strong impacts on the surface of the water, eliminating the possibility of normal operation of the glider. At higher waves, when the bottom of the majority of the Jews is sometimes torn off from the water, the impact of the flat bottom on the water becomes so strong that it can lead to the destruction of the structure and the accident of the vessel.

Another disadvantage of a vessel with a completely flat bottom is very poor turning ability; after the steering wheel is deflected, it drifts to the side opposite to the rudder shift, describing a very gentle curve. This is because, after the steering wheel is deflected, the vessel, moving along the curve, experiences centrifugal force, which can only be balanced by the lateral resistance of the bottom; the flat bottom cannot provide sufficient lateral resistance. To eliminate this drawback, you have to put a special fin on the bottom. Therefore, a flat bottom, in its pure form, almost does not find application.

Keeled bottom.   To mitigate water strikes, the strongest in the bow, the pitching vessels are attached to the bottom with a pitching force greater in the bow and smaller in the stern. In this case, the deceleration of a vessel falling onto water when it encounters water occurs gradually, as the keel-shaped (wedge-shaped) bottom is immersed in water. If at a meeting with a wave immersion for 1 sec. decelerates more than 9.81 m / s, that is, if the deceleration becomes greater than the acceleration of gravity g \u003d 9.81 m / s2, then it is said that the ship is experiencing an overload of one g. Overload, equal to 5-6 g, a person tolerates very hard. A ship with a keeled bottom has good agility, since it provides sufficient lateral resistance to centrifugal force; with a certain profiling of the contours, such a vessel becomes very stable in circulation, which occurs with an internal bank.

The flat-keel bottom is devoid of the most important shortcomings of a flat one, however, with an increase in the pitching, the resistance of the vessel and the angle of its running trim increase, the lifting force decreases, and spray formation increases. The keel-shaped bottom is more difficult to calculate and produce than a flat one. Typically, to reduce drag and running trim, pitching is gradually reduced from the bow to the stern, and at the transom the bottom in the cross section is made flat. Too much keeving in the middle of the hull forces one to make very sharp changes in the pitching angle in the aft working (wetted during planing) part of the bottom, and this causes an increase in resistance; bottoms with the same average angle, but with a small difference in the bow and stern angles of pitching have less resistance. Such a difference in resistance is explained by the fact that for any sharp change in the contours during the transition from one frame to another, the flow should spend energy on twisting.

Curved keeled bottom. To reduce the height of the jets and splashes, breaking off the cheekbones, sometimes rising above the sides and filling passengers with a side wind, the part of the bottom closest to the cheekbones is bent very smoothly (for example, along an arc of a circle) (Fig. 8). Such a bend of the bottom also serves for a certain increase in the hydrodynamic lifting force, and consequently, a decrease in drag. When flowing along such a curve across the bottom, the mass of water acquires a centrifugal force directed upwards. After separation from the bottom, the water rushes down. Sometimes the bending part of the frame near the cheekbones is given a horizontal position (Fig. 9).

The magnitude of the hydrodynamic lifting force depends on the radius and location of the lateral curvature of the bottom (sometimes called the tunnel).
  Bending the bottom of the cheekbones to increase the hydrodynamic lifting force and reduce drag is often combined with a slight convexity of the bottom of the keel (Fig. 10).

This shape of the bottom is called curved-keeled. The curved-keel bottom can have a very solid construction, which is not afraid of strong impacts on the water. However, the curved-keeled bottom is less studied than the flat-keeled, so its resistance can only be calculated very approximately. Building a boat with a curved keeled bottom is also much more difficult.

Fig. 8. Profile with bends at the cheekbones (tunnels).

Fig. 9. A curved-keeled profile with a horizontal direction near the cheekbone.

Fig. 10. Curved keel-like profile with tunnels at the cheekbones and rounding at the keel.

Contours deployed on a plane.   In order to simplify the pattern and the process of attaching the outer skin of plywood or other sheet material, select contours deployed on a plane. With such contours, the bottom sheathing can be cut out from one sheet without resorting to cutting the sheets into narrow strips, punching or other similar techniques; the frames in their bottom part are slightly convex (Fig. 11). The quality of contours deployed on a plane is often no worse than more complex ones.

Fig. 11. Contours deployed on a plane: a - with a high cheekbone in the nose; b - with a low cheekbone in the nose.

The geometric method for constructing such contours is described in several special works.

Cylindrical contours of the bottom (monohedron). In recent years, some foreign authors recommend giving cylindrical contours to the wetted part of the bottom of planing vessels. The bottom of the stern frames with such contours have the same pitching angle and the same shape (Fig. 12). Bottoms with such contours, called "monohedron", have a constant angle of attack on the entire working part; in addition, the flow of water washing the bottom does not expend energy on twisting.

Monohedron contours somewhat simplify the construction of the vessel, allow more accurate calculations of resistance and do not exclude the possibility of giving the bow contours any shape. However, the experimental data confirming the above considerations are very limited and the number of boats built with contours of the monohedron type is small, although close to cylindrical contours of the aft part of the bottom are used very often.

Fig. 12. Cylindrical contours of the aft bottom (monohedron).

Edan bottom contours.   Redan divides the length of the bottom into two parts, turning the relatively long wetted area into two, shorter ones. An increase in the ratio of the width of the wetted bottom area to the length is advantageous in terms of resistance and lift. In addition, the wetted surface of the bottom, and hence the resistance value, is reduced due to the fact that the water “squeezed” by the redan downwards is torn off its edge and exposes most of the bottom behind the redan. The redan is positioned so that the center of gravity of the glider is between it and the transom, and the distance from the center of gravity to the redan would be 25-40% of the distance between the redan and the transom (Fig. 13). Accordingly, 60-75% of the total weight of the vessel falls on the redoded wetted platform, and 25-40% on the transom. The height of the redan should be large enough to allow air to enter the affected area. The redan form does not matter much in terms of; usually a redan slice is placed across the vessel in the plane of the frame.

Fig. 13. The location of the center of gravity on the edged glider.

Unedored gliders under the same load conditions in the regime of clean planing, as a rule, have less resistance than berez-data, but they are more sensitive to disturbance. During the planing mode, the short wetted part of the bottom in front of the redana very easily breaks away from the wave, after which the vessel rapidly falls, striking with great force on the water. Such rapid jumps of the vessel, called the “leopard”, significantly reduce the quality of the glider, as in order to avoid unacceptably large overloads they are forced to reduce the speed. This drawback makes edged gliders low-maritime and limits their use to swimming on inland waterways and in the coastal sea strip.

Accurate hydrodynamic calculation of edged gliders is much more difficult than that of harmless gliders, since when gliding, the aft of the bottom meets the surface of the water, distorted by redan. Determining the profile of this surface, the actual angles of attack, and the speeds with which the stern of the bottom meets the flow is a very difficult task. Therefore, the resistance of edged gliders is determined mainly by testing models or according to statistics of previously constructed gliders, and not by theoretical calculation. Three-point contours of the bottom. About twenty-five years ago racing gliders with a special hull structure appeared. The hulls of these vessels during the course in planing mode come into contact with water by three platforms of the bottom: two front, located at the sides of the vessel, and one back (Fig. 14).

Such a hull is essentially an ordinary harmless hull, in the bow of which one float (sponson) is attached from both sides. The bottom of these floats is adapted for planing and located below the bottom of the main hull, so when gliding, most of the bottom of the boat hull is above the surface of the water; the aft part of the bottom, adjacent to the transom and in contact with water, as well as the bottoms of the floats, serves as a working platform.

The meaning of the three-point system of contours is as follows. Under certain conditions, at high speeds, excessive width of the bottom harms, but it cannot be reduced for reasons of stability. In these cases, the desired width of the bottom is obtained by introducing two narrow floats spaced wide enough to provide the necessary lateral stability.

At very high speeds, the air flow falling under the bottom of the main body creates additional lifting force, which helps to reduce its resistance.

Fig. 14. Three-point circuit of contours; wetted areas are shaded.

Contours of the stern.   The main value of the hydrodynamic forces acts on the bow of the working area of \u200b\u200bthe bottom of the glider. The aft is of secondary importance in terms of drag and lift of the glider. However, poor feed sizes and contours can significantly increase drag and degrade the performance of the glider. So, too wide a feed can lead to washing the sides with a stream of water coming down from the cheekbones of the bow and especially large in transition. If the glider does not have a sufficient supply of power, it may not be able to overcome the "hump" of resistance and will not enter the planing mode. Too wide a feed has excessive lifting force and tends to break away from the water, which can lead to a “shaking” of the feed, and then to water strikes of the entire hull. This harmful phenomenon, called the loss of stability of the stroke, sometimes forces to stop the increase in speed despite the fact that the engine still has a significant reserve of power. A too large angle of attack of the bottom near the transom also leads to a loss of stability of the course, since the lifting force can exceed the weight per aft work platform.
  The contours of the aft bottom are of great importance when you want to reduce too large a trim angle on the go. The feed contours play a particularly important role in those cases when, "due to an too large angle of attack, the resistance of the glider during the transition mode (on the hump) may turn out to be so large that there is not enough power to switch to the planing mode.

Fig. 15. The limb of the aft of the bottom down.

Fig. 16. The convex bottom of the transom.

Fig. 17. Concave bottom at the transom.

To reduce the trim angles of the glider, the parts of the bottom closest to the transom give a smooth (often along an arc of a circle of large radius) bending downward, which increases the lifting force and, therefore, the stern emerges (Fig. 15), which reduces the angle of trim of the vessel. However, excessive bending leads to a loss of stability. Bending the bottom in the opposite direction, i.e. with a bulge down, can cause the feed to leak into the water and an unacceptable increase in trim.
To improve the turning ability of the glider, fodder frames are sometimes given convex outlines (Fig. 16); this form helps the vessel to tilt into the circulation, i.e., towards the turn. To increase stability on the course, part of the bottom near the transom is sometimes made concave inward (Fig. 17), but this significantly worsens the behavior of the gliders on the circulation.

Cheekbone shape.   In most cases, the cheekbone, starting with the transom frame, gradually rises (relative to the keel line) and ends at the stem or near it. Most of the cheekbone line is a straight or smooth curve, convex down. In those cases where the glider is designed for “calm water” and there is no reason to fear meeting large waves, the cheekbone is finished on the stem relatively close to the keel line (Fig. 18). This line of the cheekbone, convex down, is relatively easy to obtain, since the zygomatic stringer in this case does not require a large bend.

Fig. 18. Stingy, located low at the stem.

If meetings with large waves are expected, when it is necessary to reduce the speed and switch to the swimming or transitional mode, then the cheekbone in the bow is raised as high as possible, sometimes to the very deck; sometimes a cheekbone is attached to a kink or, more precisely, an inflection on one of the nasal frames. Starting from the inflection point, part of the cheekbone to the stem is made convex upward (Fig. 19), while the nasal frames are made V-shaped with a collapse (Fig. 20). As the lowering of such a cheekbone during the transition to the stern, large pitching angles in the nose decrease, and the frames can get double bent - bulging downward at the keel and bulging upward at the cheekbones. However, the cheekbone, which has a very sharp inflection, can collapse during head-on meetings with the wave.

Bending cheekbones are often made on redanne sea planes.

In the edged gliders, only the aft part of the bottom adjoins the transom; therefore, the cheekbones on the remaining length of the aft part are arbitrarily raised only in order to avoid washing out of the bottom and sides behind the redan with water.

Fig. 19. Stingy with an excess in the nasal. parts.

On small high-speed gliders, for example scooters, the so-called transverse bevel is made near the cheekbone (Fig. 21); such a bevel creates a plane inclined to the water along the cheekbone, on which, with a significant roll of the vessel during a turn, an additional hydrodynamic force arises that protects the vessel from capsizing. For the same purpose, on small racing vessels, the three-point scheme of the side of the nasal floats (sponsons) is also made inclined.

Fig. 20. The nature of the nasal frames with high cheekbone.

Fig. 21. Transom scooter with beveled cheekbones.

Elements of the bow affecting the spray. Passenger cockpit flooding and splashing is influenced by the shape of the bow of the bottom directly adjacent to the keel and the longitudinal outline of the stem. For example, the smaller the radius of the longitudinal, rounding of the stem, the greater the likelihood of water entering the body; transverse convexity of the bottom of the keel in the area of \u200b\u200bthe stem prevents splashing. The nasal V-shaped frames with a significant bending of the cheekbones downward “roll off” the oncoming wave to the side and down, which prevents the rise of water above the deck and splashing of the cockpit in a side wind.
  To prevent water from pouring into the hull, sometimes it is necessary to put the so-called breaker bars on the cheekbones and shields at the junction of the deck with the side.
  The contours of the sides. When designing contours, the designer always seeks to make the area of \u200b\u200bcontact between the body and water as small as possible, since this reduces the friction resistance. Therefore, if you can be afraid of washing the sides with water, then the sides of the stern are blocked up, i.e. the width of the deck is less than the width along the cheekbone. The side of the nasal frames, on the contrary, are always made with collapse (Fig. 20).

In order to simplify the construction, very often not only the bottom, but also the sides are made straight; such contours are called sharpy contours.
  The rest of the contours of the sides, as well as the slope of the transom, are chosen for architectural reasons.

Gliding vessels are very sensitive to changes in bottom shape; unsuccessful contours of the bottom can transfer the ship from the discharge planing to discharge floating. Therefore, when creating a glider, it is necessary to approach its contours very carefully, focusing on the experience of gliding, since there is still very little information to quantify in advance a quantitative estimate of a change in contours by calculation.

Influence of width, displacement and centering

Width, displacement and centering (the relative position of the center of gravity of the vessel along the length) for the resistance value of the planing vessel are no less important than the contours. However, it is not possible to quantify the effect of each of these quantities on resistance in the form of simple dependencies, since for a planing vessel all these quantities are interconnected. For example, a change in width inevitably causes a change in the trim angles on the fly, and therefore the length of the wetted surface of the hull, and this effect may be greater or less depending on the displacement and the pitching angles.

You can give only a few comments that will help in cases where it is necessary to deviate from successful, proven values \u200b\u200bof width, displacement and centering.

1. Reducing the width of the bottom causes an increase in trim angles.
2. If the bottom width is chosen to be the most advantageous, i.e., it provides the least resistance, then without fear of disruption, planing can be changed by ± 25%, and the load by ± 40%.
3. If the width and load are chosen most advantageous in terms of resistance, then reducing the load even by a very large amount (which will entail a decrease in the trim angles) can increase the speed by no more than 5-10%.
4. When additional passengers are taken aboard, they should be located in the bow of the glider to prevent an increase in the angle of attack, which always tends to increase with increasing load.
5. Increasing the load to 20% of the most advantageous will very little change the ratio of the magnitude of the load to the resistance. A larger increase in load can cause the glider to transition.
6. Displacement of the central heating to the stern increases the resistance on the "hump" and reduces it in the area of \u200b\u200bthe beginning of gliding; in this case, the “hump" of the resistance curve shifts somewhat toward lower speeds.
7. The shift of the CT to the nose “smoothes the hump” and brings the section of the resistance curve following the hump closer to the horizontal.
8. When the load increases (without displacement of the central heating) by a small (up to 10%) value, the resistance increases in proportion to the load.
9. A significant reduction in load can lead to loss of stability at high speeds (especially for edged planes).
10. If for every horsepower of the engine power there is more than 30 kg of displacement, then planing is difficult to achieve.

Selection of the type of contours, numerical determination of resistance, power requirement and speed
  the course

The resistance value of a planing vessel is one of its most important characteristics. The power of the engine, which must be installed on the vessel, and the speed that the vessel with this engine can develop, depend on the resistance value.

If the dependence of the resistance of the vessel on the speed is known, then the determination of the required power and the selection of the propeller can be performed with great accuracy.

However, determining the resistance of a planing vessel at the design stage is not an easy task. A very accurate way to determine the resistance of a ship is to test the model in the pool.

Another way is to test a large-scale model (such models are called "semiconductors") in an open reservoir. This model, which can accommodate 1-2 people, is towed along the measured area by another vessel, while measuring speed and resistance. In the absence of a suitable towing vessel, the resistance of the semiconductor can be measured by a hydraulic flat cylinder (mass dose) inserted between. transom and foot of an outboard motor mounted on a transom.

Less accurately, the resistance value can be determined by calculation. Such a calculation is based on the results of tests in the test pools of a series of flat and flat keel planing plates. Each such plate is a kind of bottom of a planing vessel. Gliding plates are tested at different towing speeds, different loads and different positions of the center of gravity along the length (centerings). Each towing measures resistance, trim angle, and the length of the wetted area of \u200b\u200bthe plate. The results of such tests are processed and shown in the form of diagrams, by which, knowing the load, width, pitching angle and centering, it is possible to determine the resistance, trim angle and wetted bottom length for any speed. Calculation of resistance based on the test results of planing plates gives the most accurate result for planers with a flat or flat keeled bottom of cylindrical contours, since such contours are most similar to contours of tested planing plates. The calculation technique is not complicated, but requires certain skills and is not always accessible to the amateur.

However, building an amateur recreational tourist or sports boat does not always require accurate knowledge of resistance. In most cases, it is enough to only approximately determine the power necessary for a given glider to have a given speed, or to approximately determine the speed that the glider reaches with an existing engine.

For such approximate calculations, there are several formulas based on the test results of real gliders with different contours. Some of these formulas are based on processing the results of testing a series of models. If the designed glider according to its contours and loading conditions is close to those ships, on the basis of the tests of which the formula is drawn up, then a fairly accurate result can be obtained.

The first diagram to select the type of contours. After determining the required width and displacement. future vessel and choosing the desired speed you can choose the type of contours using the diagram (Fig. 22). To do this, calculate the value

D - displacement, t;

B - width, m;

and value

where v is the desired (estimated) speed, km / h.
  After finding the calculated value C on the horizontal scale of the chart, we rise up from it to the intersection with the horizontal drawn from the division corresponding to the calculated value F B. The position of the vertical and horizontal intersection points will indicate the type of contours at which you can achieve the best results.

Fig. 22. Diagram for the initial selection of the type of contours at a given width, displacement and speed.

I - region of edged witty contours; II - the area of \u200b\u200bunsharp witty contours: III - the area of \u200b\u200bround-bent contours.

It should be borne in mind that the vessels whose data were used to construct the diagram (Fig. 22) are among the larger high-speed vessels and have a length to width LIB of 4 to 7, and the position of the center of gravity at a distance of 35 ^ - 45% of the length of the vessel L from transom to bow.

Example 1
We intend to build a vessel with a length of L \u003d 6.0 m, a width of B - 1.5 m, a displacement of D \u003d 1.2 tons; the center of gravity can be located at a distance of x - 2.3 m from the transom; expected speed v - 36 km / h.

We calculate:

From the division of 0.38 "and on the horizontal scale we draw a vertical line to the intersection with the horizontal line drawn from the division of 2.59 of the vertical scale; the cut-off point of these two lines is located in the area of \u200b\u200bthe edged contours.
  The second diagram for selecting the type of contours.

Fig. 23. Diagram for selecting the type of contours for a given length, displacement and speed.

I - swimming mode; round-shaped contours; II - transitional mode; combined
  contours or sharp-edged with a large angle of biting; III - planing mode; without-
  sharp edged contours with a small knevatostn angle; IV - planing mode;
  Harmless or red-headed sharp-pointed contours with a small angle of biting.

In fig. 23 shows a conditional resistance curve of a vessel passing through all three driving modes in series. When using this diagram to select the type of contours, it is necessary to calculate the value of

V is the estimated speed, m / s; L is the length of the vessel (m), selected for structural reasons;

V-total displacement of the vessel, determined according to initial calculations, m3. The inscription on the part of the scale on which the calculated value falls indicates the expected mode and the corresponding contours. If the readings of the FL and FD scales are different, then this indicates that the length, displacement and speed are poorly linked to each other and at least one of these three values \u200b\u200bshould be changed.

Example 2
  We assume that the speed of the ship will be about 10 m / s; the length of the vessel is assigned L \u003d 5 m; displacement according to initial estimates V \u003d 2.5 m3.

1. Calculate the value

Values \u200b\u200bgreater than 1.28 on the upper scale correspond to the contours for planing vessels.

2. Calculate the value

A value of 2.74 on the lower scale corresponds to the bypass for the transient mode. It follows that one\u003e of the quantities we have chosen is incorrect. Suppose that we can reduce the displacement to V \u003d 2.0 m3; while we expect that the speed will increase to 12 m / s.

Now the values \u200b\u200bof both values \u200b\u200bcorrespond to the contours for the planing mode.

The coincidence of driving modes on both scales does not mean that the selected values \u200b\u200bof displacement V and length L are the most appropriate.

For most good built boats, the values \u200b\u200bof V and L are such that the value

Chart for the initial selection of speed, engine power and the number of passengers walking gliders.

In the diagram (Fig. 24) horizontally the values \u200b\u200bof engine power are supposed to be installed on the ship, and vertically - the speed values \u200b\u200bthat the ship can reach. Each of the curve diagrams refers to different open-air pleasure craft planing planes of various sizes. This diagram can be applied at the initial design stage, when the dimensions of the vessel have not yet been determined; The diagram is based on data obtained on good factory-built boats.

Fig. 24. Chart for initial selection, speed and power and determination of the number of passengers.

Example 3
  1. Given a motor power of N \u003d 60 liters. with., draw from the appropriate division of the horizontal scale. vertical intersecting the curve corresponding to the boat with three passengers; the horizontal drawn from the intersection indicates that the boat can reach a speed of about 50 km / h.

2. Given the number of passengers - 5 people - and drawing from the points of the corresponding vertical and horizontal curves, we find the speeds that can be achieved by the vessel with engines of different power; for example: at N \u003d 60 liters. from. v \u003d 47 km / h; at N \u003d 100 l. from. v - 52 km / h, etc.

Diagram for determining the required engine power, achievable speed and permissible displacement of planes. In fig. Fig. 25 shows curves showing what speed can be reached by a planing boat, if so many kilograms of displacement will fall on each horsepower of the engine power. These kind of diagrams are very convenient for preliminary determination of the speed that can be achieved with the known weight of the boat and its engine power. These diagrams are also used for quick approximate assessment of the quality of the glider. To do this, lay on the chart a point with the values \u200b\u200bof D / N and v for a given vessel; if it is above the curve, then the boat is better, and if lower, it is worse than the "medium" boats, on the basis of which the curve is built.

Fig. 25. A diagram for the approximate determination of the required power, displacement and speed of pleasure and tourist harmless planing boats.

1 - tourist boats with a displacement of D \u003d 0.8-2.0 tons with a stationary engine; 2 - pleasure boats with a displacement of D \u003d 0.25-0.8 tons with an outboard motor.

However, such a diagram can be misleading if it is not known for which boats it is composed: large or small, with large or small displacement, with an outboard or stationary engine. For example, as already mentioned, the most favorable load for the boat can be quite significantly increased without much damage to the speed; this means that for the same boat, two different D / N values \u200b\u200bwill be obtained at the same speed.

In fig. 25 shows two D / N curves of v; the lower one refers to small pleasure boat ride-free planing boats with a powerful outboard engine, the other - to heavier travel-less touring planing boats with a stationary installation with a capacity of 50-100 liters. from. Both those and other boats are among the most successful.

Diagrams D / N by v can also be used for an approximate determination of the required power or for a rough estimate of the permissible displacement, if the power and the expected speed are known.

Example 4
  1. On a boat with a stationary installation, it is supposed to put an engine with a capacity of N \u003d 45 liters from.; estimated displacement D \u003d 900 kg. What speed can you expect?

We calculate

The horizontal drawn from the division 20 of the vertical scale intersects the upper curve in Fig. 25 at the point corresponding to the speed of travel v \u003d 42 km / h.

2. It is supposed to build a harmless glider (motor boat) with an outboard motor, with a speed of 30 mm / hour; motor power-10 l. from. What displacement can our glider have?

From division 30 of the horizontal scale we draw a vertical line to the intersection with the lower curve; draw the horizontal from the intersection point; this horizontal coincides with the division of DIN \u003d 32 on the vertical scale. Since N \u003d 10 liters. sec., the displacement of a motor boat can be about D \u003d 32 x N \u003d 320 kg.

Formula for determining the required power for a given width and displacement of the glider.

If the width and displacement of a harmless or unharmed planer of conventional contours are specified, then the power required to achieve this speed can be determined by the following formula:

where C is the coefficient, the value of which is determined by Fig. 26 or 27; D - displacement of the glider, t; v is the speed, to achieve which the power is determined, km / h; B - width along the cheekbone or along the redan, m.

Example 5
  Asked:

1. The contours are harmless.
2. Width then cheekbone B \u003d 1.6 m;
3. Displacement D \u003d 1.1 t;
4. The highest speed v \u003d 40 km / h.

Decision

1. To determine the value of coefficient C, we calculate the value

2. According to fig. 26 we find that a value of 31.6 corresponds to a value of C \u003d 0.095.

3. Calculate the value

4. Substitute the values \u200b\u200bin the formulas / to determine the power:

This formula is useful in that it allows in each case to identify the effect of changes in width and displacement on the required power.

It should be noted that this formula provides a very high propeller efficiency, so the resulting power values \u200b\u200bshould be slightly increased. The same is done when determining the power for edged gliders, using the diagram in fig. 27.

Fig. 26. A chart for determining the coefficient of harmless gliders.

Fig. 27. A chart for determining the coefficient C of edged planes.

Formula for the approximate determination of speed at a given displacement and engine power.

This formula allows, given the type of contours of the planing vessel, its displacement and power, to approximately determine the highest attainable speed:

where v is the highest achievable speed,
  km / h;

D - displacement of the vessel, kg;

N - power of the installed engine, l. from.;

C is a coefficient having a different value depending on the type of contours:
for small walking harmless gliders C \u003d 113;

For single-handed gliders C \u003d 130;
for three-point racing gliders C \u003d 152.

Example 6
  Walking glider, harmless, with a displacement of D \u003d 1200 kg. Motor power N \u003d 45 l. from.

It is required to determine the highest possible speed.

There are four ways to increase the ship's CPU.

First   - coprocessors ( Co-processor I )

Fourth Liquid Cooled Electronics I that reduce CPU consumption for all skill-dependent modules Electronics Upgrades .

You should start by studying the skill of electronics. If this does not help, install the modules.
  If this does not save - rig the ship.
  And only if this did not help - put hardwiring (implant).

FAQ How can I increase the ship’s grid?

There are four ways to do this.

First   - modules like asterisks ( Reactor Control Unit I ) or "light bulbs" ( Micro auxiliary power core i ).

There is a fundamental difference between these modules.

The asterisk increases the ship's power output by a certain percentage.
  A “light bulb” produces a fixed amount of megawatts.
  For frigates, whose total power grid rarely exceeds 60MW, it is better to put a light bulb.
  But on ships larger than a cruiser, it is no longer useful.
  Plus or minus 10MW with a total volume of hundreds does not solve anything.

Fourth - rigs (ship modifications) like Ancillary Current Router I

You should start by studying the skill of engineering. If this does not help, install the modules.
  If this also does not save, “rig” the ship.
  And only if this did not help - put hardwiring (implant).
  An implant and rigs are just in case of emergency, if the ship is very good, and the modules are good, but not enough power.