Docking, undocking, anchoring

Question 1

Wind effects

Answer 1

• 30 knots of wind exerts same force as 1 kt of current

PG 130

Question 2

Trim and Ballast

Answer 2

• Try to ballast with stern down for these reasons

1. better directional stability
2. rudder and prop more effective
3. less stopping distance
4. twists less when backing
5. less rudder and counter rudder required

• Drag is more important than bow down for windage

Pg 140

Question 3

Left hand and variable pitch props

Answer 3

• Left handed propellers should be handled opposite of right handed ‘
• Variable pitch prop ships often have right handed turning props which means the prop turns in the same direction whether going ahead or astern. The pitch is what actually changes. This means the prop is turning clockwise when backing and should be handled as a left handed propeller.
• There is no standard for these ships

Question 4

Turning in a basin

Answer 4

• Keep stern in deep water
• take off all way prior to turn
• turn to starboard for prop walk if backing needed
• place pivot point where you know ship will clear shallows or obstructions. No diameter of basin
• Put swinging end of ship in favorable current
• start turn at up current end of basin

Pg 151

Question 5

Deep water anchoring

Answer 5

Depth of over 100ft brake may not be able to slow the anchor. In this situation engage the wildcat and lower the anchor almost to the bottom before dropping. You will be required to hold the ship in position longer

Pg 170

Question 6

Sea Room rule of thumb

Answer 6

Rule of thumb- A ship turning at a constant engine speed in deep water (more than 1.5x draft) will be about 3 to 3.5 ship lengths ahead of her starting point, and about 1.5 ship lengths to port or starboard after turning 90 degrees. The ship will continue around and be about 1 ship length ahead of the starting point and 3.5 ship lengths to port or starboard when 180 degrees from original track. As water depth decreases distances increase. When depth almost equals draft distances will be doubled. Pg 178

Question 7

Anchoring and shiphandling (general)

Answer 7

• when a ship has slight headway the bow will be steadied by the anchor and not shear either way
• When rudder is applied while an anchor is dropped and being dragged the pivoting moment will increase. This is a result of deliberate rudder not simply the anchor alone
• It also does not matter which anchor is dropped because both are close enough to the centerline

Question 8

How much chain when manuevering with an anchor

Answer 8

• Let go only enough chain to let the anchor grab and the break loose and drag. It must not dig in
• In an emergency you do not want enough chain let go for the anchor to actually dig in and hold. It is unlikely the chain and brake will hold in an emergency. The desired amount is just enough to catch and release to slow the ship without breaking any ground tackle Pg 192

Question 9

Docking with the anchor

Answer 9

• Drop the anchor well prior to docking and with less chain than you think you need. Come ahead slowly and pay out small amounts of chain until the anchor catches and releases as desired. Then follow these steps to dock

1. Ease ahead toward berth adjusting RPM and rudder to maintain speed and heading
2. Reduce RPM so the ship loses headway
3. Use rudder to change angle of approach
4. When you have the desired angle increase RPM to move closer to the berth
5. Reduce RPM to let bow settle into the berth. Use rudder to work stern in

Question 10

Holding in a channel with the anchor

Answer 10

1. Anchor is let go with about a shot of chain.
2. The engine is used ahead only to maintain heading while the ship loses headway.
3. When the ship is dead in the water slowly come ahead on the engine and pay out chain until the anchor holds against the engine.
4. Heading can be maintained by the helmsman

Pg 197

Question 11

Twin Screw Vessels

Answer 11

• Twin screw ships with a single rudder handle very poorly (like water soaked logs). Twin screw ships with conventional or variable pitch props, twin rudders and thrusters handle very well.
• Twin screw ships with a single rudder often handle better with the engines out of gear than with the props turning. The flow of water over the rudder is not disturbed by the water from the prop. When the props are turning the turn is also slowed by the wide spread props