Ship Handling Flashcards
What is the wheel house poster?
The wheel house poster contains a summary of the propulsion system fitted to the ship and the results of the ships manoeuvrability at sea trails. It also contains:
- Ships particulars
- Steering particulars
- Draught at which data was obtained
- Anchor chain length
- Propulsion particulars
- Thruster effect at certain conditions
- Draught increase
- Turning circles at max.rudder angle
Tell me about a right-handed propeller?
- A right-handed propeller is one the rotates in a clockwise direction when moving ahead.
- A right-handed fixed propeller moving ahead, the bow will cant to port and stern to stbd
- A right-handed fixed propeller moving astern, the bow will cant to stbd and stern to port
Explain the turning short round manoeuvre?
Step 1 = If the ship is proceeding on the stbd side of the channel, cross to port and the true will be made to stbd.
Step 2 = The turn to stbd should be initiated by an initial kick ahead, with wheel hard to stbd. This will result in the pivot point moving forward towards the bow.
Step 3 = Before the ship gains headway the engine is stopped and wheel amidships.
Step 4 = The wheel is kept amidships and engines given a kick astern. The bow will cant to stbd and stern to port.
Step 5 = Before ship gains astern motion engines are stopped and wheel is placed hard to stbd, will a kick ahead.
What is interaction?
As a ship moves, it displaces the water around it causing a hydrodynamic interaction between ships passing or when a ship is navigating in close proximity to a bank or shoal.
There are three situations involving hydrodynamic interactions:
- Head-on encounters
- Overtaking situations
- Interaction in narrow channels
What is squat?
Squat is a hydrodynamic effect on the ship when the the depth of water is less than twice the draught of the ship. The flow of water around the vessel will also increase in speed, meaning the water flow causes a reduction in water in the vicinity of the ship. This fall in water level results in a loss of UKC known as squat.
What factors affect squat?
- The ships speed
- Type of bow
- Position of the longitudinal centre of buoyancy. If the LCB is aft, squat by stern would be expected and if LCB is forward, then squat by head would be expected.
What is the formula for squat?
Open water = BC x V2 / 100
Confined water = BC x V2 / 50
What is the block coefficient formula?
BC = displacement of the ship / L x B x D
What is the definition of confined waters?
Confined waters mean an area of the sea where the width of the safely navigable water is not more than 2 miles, such as a strait, considering the draught of the vessel and water depth.
