Fig.16 Capsizing effect of a sailing keel

In sailboats, keels use the forward motion of the boat to generate lift to counter the lateral force from the sails. Sailboats have much larger keels than non sailing hulls. Keels are different from centerboards and other types of foils in that keels are made of heavy materials to provide ballast to stabilize the boat. Keels may be fixed, or non-movable or they may retract to allow sailing in shallower waters. Retracting keels may pivot (a swing keel) or slide upwards to retract, and are usually retracted with a winch due to the ballast. Since the keel provides far more stability when lowered than when retracted (due to the greater moment arm involved) the amount of sail carried is generally reduced when sailing with the keel retracted.

There are several types of fixed keels including: full keels, fin keels, winged keels, bulb keels, and twin keels or bilge keels among other designs.

III. Answer the following questions:

1. What parts does keel consist of?

2. What is a structural keel?

3. The keel is generally the first part of a ship’s hull, isn’t it?

4. What does the term “lay the keel” mean?

5. Does the keel surface on the bottom of the hull give the ship greater directional control?

6. What are the keels made of?

7. What types of fixed keels do you know?

IV. Translate the following sentences from English into Russian:

1. Canting keels can be found on racing yachts.

2. Structural keel is suitable with its massive scantling where grounding is possible.

3. “To lay the keel” means the beginning of any significant undertaking.

4. Keels may be fixed or non - movable.

5. Bar keels often being associated with open floors.

V. Comment on the usage of Passive Voice:

1. The flat plate keel is fitted in the majority of ocean – going ship and other vessels.

2. Duct keels are provided in the bottom of some vessels.

3. Keels are made of heavy materials.

4. The word “keel” is derived from Anglo – Saxon word “cēol.”

VI. Translate the text: “Gunwale”

The gunwale is a nautical term describing the top edge of the side of a boat.

Originally the gunwale was the "Gun ridge" on a sailing warship. This represented the strengthening wale or structural band added to the design of the ship, at and above the level of a gun deck. It was designed to accommodate the stresses imposed by the use of artillery.

In wooden boats, the gunwale remained, mounted inboard of the sheer strake, regardless of the use of gunnery. In modern boats, it is the top edge of the side where there is usually some form of stiffening.

On a canoe, the gunwale is typically the widened edge at the top of the side of the boat, where the edge is reinforced with wood, plastic or aluminum.

VII. Speak on types of a keel.

UNIT 15. BALLAST TANK

I. Master the active vocabulary:

a compartment – перегородка

to include smth – включать что – либо

forepeak tank – форпиковая цистерна

center of gravity – центр притяжения

the draft of the vessel – проект судна

to adjust – регулировать, устанавливать

stability – стабильность

to be light weight – иметь легкий вес

to submerge – опускать, погружать в воду

buoyancy – плавучесть

compressed air – сжатый воздух

to dive – нырять

discharged water – отработавшая вода

II. Read and translate the following text:

A ballast tank is a compartment within a boat or ship that holds water. A vessel may have a single ballast tank near its center or multiple ballast tanks typically on either side. A large vessel typically will have several ballast tanks including double bottom tanks, wing tanks as well as forepeak and aft peak tanks. Adding ballast to a vessel lowers its center of gravity, and increases the draft of the vessel. Increase draft may be required for proper propeller immersion.

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