11. Match English and Russian words.

1)	size	a)	главный
2)	enable	b)	буксировать
3)	main	c)	скорость
4)	move	d)	давать возможность
5)	flow	e)	посредством
6)	speed	f)	размер
7)	improve	g)	двигаться
8)	by means of	h)	улучшать
9)	tow	i)	поток

12. Translate the word combinations.

a)	1. the ship’s bottom, 2. the bottom of the ocean, 3. of great dimensions, 4. ship dimensions, 5. principal dimensions, 6. at the bottom of the sea, 7. large size, 8. the size of the ship, 9. seaworthiness of the ship, 10. her seaworthiness, 11. to improve seaworthiness, 12. to investigate the ocean bottom, 13. to be in motion, 14. the speed of the motion, 15. flow speed, 16. high speed, 17. both seaworthiness and dimensions.
b)	1.	these flows, a water flow, its flow, a good flow, it flows, this flow;
	2.	their speed, don't speed, its speed, he speeds, these speeds, its speed,
	3.	the water surface, its surface, it surfaced, it surfaces, their surfaces, these surfaces, they surface.

13. Read and translate the text with a dictionary. Ship Model Tests

Test tanks and water tunnels (гидродинамическая труба) are the most widely spread experimental constructions for investigating seaworthiness of ships. Test tanks are canals made of concrete and filled with water. Dimensions of these tanks are rather large: length is up to 1000 m and more, breadth – 18 m and depth – 8 m. In these tanks ship models of about 12 m long are tested. Models may be self-propelled and towed. In the first case the model moves by means of its own engine and a screw propeller (гребной винт), in the second case it is towed by a special carriage (тележка) or a tow-line cable system (тросовая система).

The test tank of the University is 36 m long, 5.5 m wide and 2.7 m deep. A special wave-maker (волнопродуктор) serves for producing waves on the water surface and there is also a false bottom (наплавное дно) for making water shallow. The ship models are 3 m long, their speed is 3 m/sec. During the experiments the scientists and students can watch and investigate models seakeeping (мореходность), make records of forces acting at the models, periods and amplitudes of motion, acceleration, etc. These experiments help improve ship lines (обводы) and seaworthiness.

The main function of the water tunnel is to experiment with screw propeller models and other kinds of propellers, wings and projecting elements of the ship. This tunnel is a closed contour where water is circulating. This tunnel is sometimes called a cavitation tunnel. In this case the system is used for investigating cavitation of screw propellers and other bodies when moving in water. The cavitation tunnel in the University is of medium size: the distance between its vertical axes is 5.7 m, between horizontal axes – 6.5 m; maximum diameter is 1 m, minimum diameter – 0.4 m, speed of the flow is up to 8 m/sec.

Both the test and the cavitation tunnels are up-to-date systems which enable scientists to make high-level experiments.