Resistance and propulsion of ships, Slides of Marine Engineering

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VARIOUS METHODS OF

REDUCING WAVE

MAKING RESISTANCE

By

Thalapathy Vigneshwar

M. TECH ( Naval Architecture and Ocean Engineering)

Objective of this presentation

• (^) Students attending this lecture will get a brief idea on various

methods of reducing wave making resistance.

• (^) Wave making component is major component of resistance at high

speeds. It is important to study this component of resistance in detail

and methods of reducing it.

• (^) Because if resistance experienced by ship decreases, power required

to propel the ship forward will reduce and there will reduction in fuel

consumption of ship leading to environmental safety and ship owners

operating profit.

Forces acting on ship while

cruising?

• (^) VERTICAL FORCES:

1. Total weight acting down at centre of gravity
2. Total buoyancy( up thrust) acting up at centre of

buoyancy

• (^) LONGITUDINAL FORCES:

1. Resistance acting against the direction of motion.
2. Thrust acting along the direction of motion when

trying to push forward.

SHIP RESISTANCE:

Resistance is the opposing force exerted on the ship hull against the

direction of its motion.

• (^) Ship resistance is a complicated phenomena, there are several causes

of ship resistance.

• (^) Problem simplified by dividing total resistance into independent

components, neglecting mutual interaction.

• (^) Understanding of various components of resistance is important since

they are used in ship engine powering calculation, and for optimizing

ship resistance to reduce fuel consumption.

Components of ship resistance:

Wave formation around ship:

Kelvin wave pattern.

Various methods of reducing wave

resistance:

Bulbous Bow

• (^) Hull form optimization

Reducing angle of entrance and run.

Smooth shoulders.

Bow