Drive a Boat

Question 1

Interaction

Answer 1

As a ship moves through the water, it creates a hydrodynamic pressure field around the hull, which will interact with other ships, or fixed objects such as the quayside structures or seabed.

Question 2

Bank effect

influenced by?

Answer 2

When the stern of the ship is sucked into the bank.

The area of flow between the ship and the bank is reduced.
Venturi effect: when fluid is constricted, it decreases in pressure but increases in velocity.

Influenced by:
- Speed
- Proximity to bank
- UKC

Question 3

Bow cushion effect

Answer 3

When a ship approaches a bank or another ships bow, the water flow is disrupted, creating higher water pressure on the opposite side, pushing the bow away.

Question 4

Ship to ship

influenced by?

Answer 4

A strong attractive force
between two vessels due to the reduced pressure between the hulls.
The smaller of the two
vessels feeling the greater effect.

The bows of the two
vessels will tend to repel each other if they approach head-on

Influenced by:
- speed
- narrow channels
- shallow basins.

Question 5

Vessel overtaking

two possibilities

Answer 5

Option 1: The vessel
being overtaken may take a sheer into the
path of the other.

Option 2: when the vessels are abeam of one
another the bow of each vessel may turn
away from the bow of the other causing the respective sterns to swing towards each other.

Question 6

Standing moor

Answer 6

involves anchoring a vessel by dropping both anchors while the ship is stationary

For areas with strong crosswinds and/or tides

the vessel is moored between two anchors with reduced swinging room.

Question 7

Running moor

Answer 7

Method of anchoring a vessel while still moving forward.

the vessel is moored between two anchors with reduced swinging room.

Useful in waterways with strong currents

Question 8

Berthing

Answer 8

effect of wind and current

use of tugs?

windage area? best profile used in approach.

effects of transverse thrust

approach angle

which lines sent first

is the berth easily accessible

Question 9

Squat

Answer 9

• the apparent increase in draught due to the shallow water effect.

the acceleration of water flow beneath the ship’s hull when entering shallow water results in a drop of pressure underneath the hull of the ship.

since the weight of the ship is unchanged, the ship has to displace more water to support her buoyancy.

Question 10

Use of tugs

Answer 10

1. escort tugs: Escort and manoeuvre ferries and barges to their destination.
2. support tugs: Provide support services for offshore and towing operations. These tugs play a significant role in berthing operations.

Question 11

Turning short around

Answer 11

• a manoeuvre that involves turning a ship around in a short distance.
• take into account transverse thrust (which way the vessel prefers to turn)

*maritime equiv. of 3 pt turn.

Question 12

Mooring buoys

Answer 12

Is it the right size for my vessel?

Approach slowly and downwind

use of tender to attach mooring lines

Question 13

Bernoullis Principle

Answer 13

as the velocity of a fluid increases, its pressure decreases.

the venturi effect is a practical application of this principle.

Question 14

The mark of a great shiphandler is never getting into situations that require great shiphandling.

Answer 14

Ernest King

Question 15

Transverse Thrust

for a fixed pitch right handed prop?

Answer 15

• The tendency for a forward or astern running propeller to move the stern to starboard or port.
• Caused by the interaction between the hull, propeller, and rudder.
• More noticeable when going astern.

-for a fixed pitch right handed prop:
Ahead: bow swings to port, stern the stbd
Astern: bow swings to stbd, stern swings to port.