Sivadath k.s

UT-KOCHI

APPANDAGE
&
TYPES

Appandages :something which is attached or mounted in the ship's hull is known as appandages

Eg: rudder,propeller,Skeg,Bilgr keel,Bow thruster,Zinc anode,Stabilizer,etc

1: RUDDER

A vertical blade at the stern of a vessel that can be turned horizontally to change the vessel's direction when in motion.

Rudder angle is upto 35 degree

Trammel gauge( L shaped instrument) is used for checking rudder drop

TYPES OF RUDDER

Balanced rudde

Semi-balanced skeg rudder

Full skeg rudder

Spade rudder

Balanced rudder

Open stern frame with a bottom pin which is a sopport bolt or pin with a bearing.

The upper bearing is inside the hull.

Mainly used in tugs and single screw marchant ships.

Semi balanced skeg rudder

Also known as a horn rudder or a marine rudder. The movable part of the rudder is supported by a fixed skeg with a pindle at the bottom of the skeg.

Full skeg rudder

An unbalanced rudder, the rudder is supported by a fixed skeg with a pindle at bottom.

Applied manily to large sailing yatches but also applied as hydro planes on under water vechicles.

Spade rudder

A type of sailboat rudder that is fastened only to the rudderpost and not to the keel or transom.

applied extensively to single and twin screw vessels including small power crafts,yatches, ferries, warships and some large marchant ships.

Also employed as sub-marines and other under water vechicles

2: SKEG

A brace that extends from the rear of the keel to support the rudderpost.

A skeg (or skag) is a sternward extension of the keel of boats and ships which have a rudder mounted on the centre line. The term also applies to the lowest point on an outboard motor

3:STABILIZER

A gyroscopic device used to stabilize the rolling motion of a ship

A device for making something stable.

stabilizer fins are generally rectangular in shape and are attached in pair on each side to provide the necessary balance to the ship. The size of the fins depends on various factors such as the ship's breadth, length, displacement etc. However, compared to the size of the ship, the size of the fins is relatively quite small.

4:BILGE KEEL

It is used to reduce a ship's tendency to roll.

Bilge keels are employed in pairs (one for each side of the ship).

A ship may have more than one bilge keel per side, but this is rare.

Bilge keels increase hydro-dynamics resistance to rolling, making the ship roll less.

5:SACRIFICIAL ANODE SYSTEM

metallurgy an electropositive metal, such as zinc, that protects a more important electronegative part by corroding when attacked by electrolytic action

The anodes are usually Zinc or Aluminium.

Zinc anode

6:PROPELLER

A marine propeller is a propulsion device which converts the power transmitted from the engine into a thrust force to propel the vessel.

CHARACTERISTICS

It consists of a number of identical twisted blades usually 3-5 equally spaced arround the hub or boss. The hub or boss is mounted on the propeller shaft. The hub of the propeller is fitted at one end of the propeller shaft by means of a nut.

Propeller is made up of mainly manganese bronze, stainless steel and phosphorus bronze.

TYPES OF PROPELLER

Pitch of the propeller ;pitch of the propeller is the apparant distance moved by the propeller on its axis on one rotation of the propeller.

Fixed pitch propeller

Variable pitch propeller

Ducted propeller

Skeg propeller

Fixed pitch propeller

Fixed pitch propeller has fixed blades which are integral with the propeller boss.

The blades are fitted at an angle which gives a permanent pitch for the propeller.

Variable pitch propeller

A controllable pitch propeller (CPP) or variable pitch propeller is a type of propeller with blades that can be rotated around their long axis to change their pitch.

If the pitch can be set to negative values, the reversible propeller can also create reverse thrust for braking or going backwards without the need of changing the direction of shaft revolutions.

It is provided with detachable propeller blades.

The blades are mounted on a angular slotted sliding block house in a hollow hub.

A pitch control rod is attached to the angular block.

Ducted propeller

A ducted propeller, also known as a Kort nozzle, is a propeller fitted with a non-rotating nozzle.

It is used to improve the efficiency of the propeller and is especially used on heavily loaded propellers or propellers with limited diameter.

which is shaped like a foil, offers advantages for certain conditions over bare propellers.

Skeg propeller

High propulsion performance.

Variable straights distribution.

Low noises and vibrations levels.

Reduction of the fuel consumption .

7:BOW THRUSTER

Bow thrusters are type of propellers, which are smaller in size and which help in better maneuverability of the ships at lower speeds. They are generally used for maneuvering the vessel near the coastal waters or while entering or leaving a port. Bow thrusters help in assisting tug boats in berthing the ship without wasting time.

8:BULBOUS BOW

A bulbous bow is a protruding bulb at the bow (or front) of a ship just below the waterline. The bulb modifies the way the water flows around the hull, reducing drag and thus increasing speed, range, fuel efficiency, and stability.

SONAR

SONAR(SOund Navigation And Ranging) is fitted bottom of the hull.

Used to detect sub marines, ice-bergs, fish school and other under water objects.

An echo-sounder is also fitted bottom of ship's hull.

Used to measure the depth of sea.

Reference;

class4exam.com/mmd

dictionary.reference.com/browse/skeg

www.thefreedictionary.com/Stabilizer+

www.brighthubengineering.com/naval-architecture/47686-types-of-ship-stabilizers-fin-stabilizer

www.masson-marine.com/en/propeller-cpp-and-fpp

www.olds.com.au/marine/maximizing_propulsion

www.propulsionnaval.com/eng/productos-skew.php

www.cathodicme.com/sacp.html

www.marineinsight.com/tech/auxiliary-machinery/bow-thrusters

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