Ex. 8. Try to summarize the main facts from the text in few sentences.

Revision

For Independent Studying

Ex. 9. Read the text and recollect the basic principles of shipbuilding in different historical epochs.

TEXT 5B

EVOLUTION OF SHIPBUILDING

PART I

It is known that ancient ships were under construction by navigators and the designing of a new ship was always done, taking into account future mode and area of navigation. The ancient seafarer-shipbuilders had to give the much greater attention to safety of storm navigating, because rowing paddles are not suitable as movers even at temperate wave roughness, and the squall heavy wind the sail arms become into a source of serious danger. Much attention had to be paid also to the contours of the hull to give additional floatation and stability to the vessel especially in stormy conditions.

The basic features of contours of the hull, which provided storm non-sweep of the top deck, were following:

1) Low surface board that was not perceiving careening pressure of a wind, and wide hull ensuring good rolling stability;

2) Rounding form of the middle ship frames provided static rolling stability, and a low center of gravity allowed the hull easily to be kept on an inclined surface of a wave. It was necessary for maintenance non-sweeping of the middle top deck;

3) The narrowed and high V-figurative frames near of stern and astern promoted dumping of pitching. During pitching these frames pushed the water aside, creating dynamic conditions of non-sweeping on the bow and back decks;

4) The vessel was made symmetric concerning a bow and stern that was a main condition of non-resistance of sea wave phenomena. For keeping of a rate along of wave (i.e. along wave fronts - when the hull did not cross wave ridges), it appeared by sufficient effort of oarsmen on oars.

Such form of the hull well used properties of wind though the long storm at ocean made the unpredictable approach of a wave to the hull and complicated maneuvering with the purpose of evasion from a wave. Group character of wind excitement may cause large "crest of the tenth wave". It was necessary for helmsman to see to the hull of a vessel to be kept by along to a wave, keeping a deck parallel of wave surface. Non-sweep of deck in this mode of navigation was provided, even if height of the “tenth wave” in some times exceeded height of the hull of a vessel. It was a fascinating and beautiful navigation, as the vessel could completely immerse in abyss, then for an instant appear at top of a wave perfectly safe!

 

PART II

In Scandinavia canoes, or dugouts, capable of sea travel appeared in the Stone Age, some 7000 years ago. Their long narrow hulls be Pic. 19. Stone Age dugout

 

came the basic design used for all northern ships up to and during the Bronze Age. By the Iron Age, some 2500 years ago, Pic. 20. Iron Age canoe of planks canoe design changed. Hard

iron tools allowed ship builders to use planks and a clinker design. It proved so successful that it is still inuse today. These boats, which the Viking design closely resembled, held twenty oarsmen and were very seaworthy. A century or two before the Viking Age began, a key development occurred in the design of ocean going open canoes that has lasted even into modern ship building times. It was the

Pic.21. Ocean going canoe

addition of a keel. The keel added greater stability to the ship and enabled it to travel straighter through the water than ships without keels. More importantly, the keel's solid construction gave the canoe the ability to carry a sail.

So, the perfection in the design, structure and materials used in Vikings ships was not the result of one shipbuilder or the work done in any one year of the Viking Age. Like most technologies, Pic. 22. Viking Dragonship

it was the result of many years of improvements to an existing design. In the case of Vikings ships, it was the result of slight changes made over six thousand years that began with a simple Stone Age dugout. All the Viking ships were based on the same design: overlapping planks, solid keel, matching bow and stern and open deck.

 

PART III

For protection of trade vessels against pirates, Saxons in north, and Illirians in the south, Romans created easy and high-speed sailing-oar ships, liburnes, which are considered to be the prototype of Mediterranean galleys, existed up to XVIII centuries. The purpose of this project was to put achievement of the maximal speed, and as a consequence new operational requirement force seriously to reconsider the conception of seaworthiness and safety of navigation.

On Mediterranean galley bulb was already not present, as it obviously

did not maintain test on Pic 23. Mediterranean galley

propulsive quality and ma neuverability of ship.

In bow part of the hull the large completeness of contours was kept, and its components were made larger, as the absence of bulb essentially reduced stabilization of bow extremity and the aft superstructure. Thus, the opportunity of storming by a bow on a wave was kept on counter roughness and resulted in increase wave sweeping. Nevertheless, the ship builders reduced height of a bow deck and essentially increased sail surface of quarterdeck.

Trimming the hull by the stern, installation of sternpost and small completeness of concave branches of stern frames allow putting the center of board resistance of the hull on one vertical with the center of sail surface of Latin sails. It is necessary for achievement of stability in a movement under sails and also makes effective work of stern rudder.

 

PART IV

Approach of epoch of great discoveries and colonial expansion can be characterized by construction of the ships in the best way adapted to long ocean navigation under sails. Taking into account the small tonnage of the ships of Columbus and Magellan, it is necessary to recognize true perfection of a ship science of that time, to note a harmony in a combination of the architectural and fluid-mechanics decisions; and also accuracy in laying-out of sailing arms and its complete conformity to features of hydrodynamics of the hull in conditions of navigation on roughness. Certainly, the crew of these small vessels could not completely rely on active use of sailing arms in an opposition with storm elements.

Pic. 24. A full-rigged ship (XVII cent.)

Therefore determining role in maintenance of safe navigation again was played with the special form of the hull, where the contours and surface architecture provided a mode of the minimal interaction with energy of the storm sea.

The advanced aft superstructure displaced the center of sail surface to aft, and large width and completeness of bow frames replaced a center of gravity and center of displacement in the bow part of the hull. Thus, on a wind the hull behaved similarly to "weather vane", providing storming by a bow on a wave without a going.

Equipment of sternpost andcompleteness small of stern frames had allowed putting the center of board hydrodynamic resistance on one vertical with the center of sails. It was necessary for achievement of a steady movement under sails, and also raised an overall performance stern blade of a rudder

For achievement stability the ratio of length of the hull to width (3:4) considerably decreased. Nevertheless, for the sailing ship there was no necessity in wide and continuous on length to a deck. The use of the push-off-waves boards and the division of a deck by superstructures, rising in an aft, excluded hit on a deck large on weight of amount of water, providing preservation storm stability. The same inside tilt of boards reduced risk of sweep of a deck at a course of the ship under sails and with a large rolling, and reduced forces of yaw, as the hull got vertical symmetry of a rather longitudinal axis which was taking place along a waterline. If at a sight in a stern part, medieval ship was soaring above water, allowing a wind to twist it without the special efforts, the bow part of the hull was heavy anddeeply pressed in water. The shipbuilders of those times did not care at all about non-sweeping on going bow to waves. The unique protection was bowsprit, bowcastle and galune, which by first perceive a counter wave and deform its front, not allowing concentrating impact on bow deck.

 

PART V

In contours of the ships constructed at the end of the XIXth and in the beginning of the XXth century is possible to read of the conciliatory proposals between submission and an opposition before sea phenomena.

Bulbous bow had continued to serve for stabilization of the hull and preservation of stability on a course in conditions of roughness. Especially it was important for high speed of a motion, that bulb favorably

Pic.25. A cruiser hull design

had an effect for reduction of wave resistance on calm water. Sharpening of extremities and small completeness of surface volumes in a bow and aft promoted fastness on roughness and favorably had an effect for reduction of pitching and prevention of slamming.

The narrow hulls of the ships were under construction for achievement of high speed of motion. Narrowed width of a deck served to the purposes of preservation storm stability in the sweeps conditions. The inside tilt of boards also reduced yaw during rolling that provided preservation of the given course and speed in conditions of storm roughness.

Rather low board and small surface of superstructures gave the possibility to conduct the ship even in conditions of strong winds.

Similar principles of hull construction are still in use nowadays, especially in naval shipbuilding.

 

Ex. 10. Answer the questions:

1. What had to be taken into account while designing an ancient ship? 2. Where was the greatest attention given by the ancient ship-builders? 3. Say in brief what the basic features of contours of the hull were. 4. What may group character of wind excitement result in? 5. What was the main task of a helmsman while maneuvering in storm conditions? 6. What for the narrowed and high V-figurative frames near of stern and astern used? 7. How was the rate along the wave kept? 8. What are the disadvantages of paddles and sails as movers? 9. What became the basic design for all northern ships in ancient times? 10. What allowed the shipbuilders to use planks and clinker design? 11. When did the first seaworthy ships appear in Scandinavia? 12. What key development allowed the appearance of ocean going vessels and has lasted even into modern times? 13. What design were all Viking ships based on? 14. What was undertaken for protection of trade vessels and with what purpose? 15. What was used to trim the hull of the medieval ships? 16. What could the ship crew rely on in conditions of navigation on roughness? 17. With what could the hull be compared on a wind due to its special construction? 18. What were the distinguishing features of medieval hull construction? 19. What was the traditional ratio of length of the hull to width? 20. What was considered to be the unique protection against the waves on the full-rigged ships?21. What conciliatory proposals can be seen in contours of the ship constructed in the beginning of the XXth century? 22. What did the bulbous form of a bow serve for? 23. How did it appear to be possible to promote fastness and reduce pitching and slamming? 24. What helped to conduct the ship even in conditions of strong winds?

 

Ex. 11. Explain why:

a) the ancient seafarer-shipbuilders had to give great attention to safety of storm navigating and to the contours of the hull;

b) the hull had to be wide with low surface board;

c) the middle ship frames had a rounding form;

d) the vessel was made symmetric;

e) we can say that it was a fascinating and beautiful navigation;

f) the invention of keel allowed the appearance of ocean going craft;

g) there was a necessity of creation of easy and high-speed sailing-oar ships in the Mediterranean;

h) the medieval shipbuilders rejected the idea of hull bulb;

i) it was necessary to trim the hull and to raise the center of board resistance.

j) the epoch of great discoveries and colonial expansion caused great changes in ship construction;

k) medieval ship was soaring above water, if at a sight in a stern part;

l) the shipbuilders of those times did not care at all about non-sweeping on going bow to waves.

m) the hulls of the ships were made narrow in the beginning of the XXth century;

Ex. 12. Develop the idea:

1. Ancient ships were constructed by navigators themselves.

2. The basic features of contours of the ancient ship hull provided storm non-sweep of the top deck.

3. There were no essential changes in ship design until the XVth century.

4. The hull construction played a very important role in further reliability of a ship. 5. A stern part of medieval ship was soaring above water, while its bow was deeply pressed in it.

6. The conciliatory proposals between submission and an opposition before sea phenomena were followed in contours of the ship constructed in the beginning of the XXth century;

 

Ex. 13. Complete the sentences translating the missing parts into English:

 

1. Строительство судов в Скандинавии началось long before the Vikings came. 2. Этот дизайн оказался настолько успешным that it is still in use today. 3. These boats очень напоминали корабли викингов. 4. It was the result of многолетних усовершенствований и незначительных изменений made over six thousand years. 5. The Vikings built корабли различных форм и размеров. 6. Целью этого проекта ставилось achievement of the maximal speed. 7. Тhe ship builders reduced высоту носовой палубы and essentially increased площадь парусов в кормовой части.