BCM SECTION C - SEAMANSHIP, NOMENCLATURE, STABILITY

Question 1

What is the “BOW”?

Answer 1

Front end of a boat, going forward is to advance from the stern to the bow.

Question 2

What is the “STARBOARD” side?

Answer 2

When facing the bow (forward) the starboard side is the “Right”

Question 3

What is the “PORT” side?

Answer 3

When facing the bow (forward) the port side is the “LEFT” side.

Question 4

What is ATHWARTSHIPS?

Answer 4

Line or Running from side-to-side of the boat. Left-to-Right.

Question 5

What is AMIDSHIPS?

Answer 5

Centerline of the Vessel

Question 6

What is STARBOARD BEAM?

Answer 6

The middle right region of the vessel (long side) that is between the Starboard bow and quarter.

Question 7

What is PORT BEAM?

Answer 7

The middle left region of the vessel (long side) that is between the Port bow and Quarter.

Question 8

What is OUTBOARD?

Answer 8

Action or reference that refers to the movement going from centerline outwards away from the vessel.

Question 9

What is INBOARD?

Answer 9

Action or reference that refers to the movement going from outside to centerline of the vessel.

Question 10

What is the STERN of the vessel?

Answer 10

The back or rear end of the vessel.

Question 11

What is the PORT QUARTER

Answer 11

If facing forward toward the bow, this is the back left corner side of the vessel at the stern.

Question 12

What is the STARBOARD QUARTER

Answer 12

If facing forward toward the bow, this is the back right corner side of the vessel at the stern

Question 13

What is the PORT/STBD BOW

Answer 13

This is the left and right side of the bow.

Question 14

What is the WINDWARD side?

Answer 14

The side where the wind is coming from. If the wind was pushing against the port beam/structure of the vessel, port would be the WINDWARD side.

Question 15

What is the LEEWARD side?

Answer 15

The side where the wind is going/transiting away from. If the wind in striking the port side and going to the starboard, then starboard would be your down-wind LEEWARD side.

Question 16

What are the (03) Hull Types?

Answer 16

Displacement
Semi-Displacement
Planning

Question 17

Define Keel.

Answer 17

the centerline spine of the vessel, this lowest part makes up the “backbone” of the structure and runs fore to aft. (front to back). Keels can be internal or external.

Question 18

Displacement is measured in?

Answer 18

Gross Weight Tons (GWT)

Question 19

What’s a Through-Hull fitting?

Answer 19

An opening on the bottom of the hull usually to intake raw water (salt water). i.e. would be Sea Chests, Speed logs, Machinery Cooling systems, CAPAC.

Question 20

(02) PRIMARY FORCEs that affect a boat’s stability

Answer 20

Dynamic (external)

Static (internal)

Question 21

Define/Describe DYNAMIC Forces. (Stability)

Answer 21

Dynamic Forces are EXTERNAL forces that act on the stability of the vessel.
i.e. Waves, Winds, Currents, Tide.

Question 22

Define/Describe STATIC Forces. (Stability)

Answer 22

Static Forces are INTERNAL “on-Ship” forces that act on the stability of the vessel. I.e. Persons, Cargo, Fluids in the Ship, Gear. ICE Build-up

Question 23

Define Center of Gravity.

Answer 23

The center point of the vessel in which the vessel plateaus to it’s natural rest.

Question 24

How does Center of Gravity change when weight is added or subtracted?

Answer 24

Center of Gravity follows the weight. If weight is added to the starboard side then the COG will shift right. If weight is removed it would shift left. This is what causes a “List or Lean”

Question 25

Define Buoyancy.

Answer 25

The UPWARD acting force of water being displaced against the bottom of the surface or hull in the water.

Question 26

Define Gravity in relation to Stability.

Answer 26

The opposing force acting DOWNWARD against buoyancy.

Question 27

Define Equilibrium

Answer 27

The state in which the UPWARD (Buoyancy) and DOWNWARD (Gravity) equal/balance out.

Question 28

What is LISTING

Answer 28

a PERMANENT lean in vessel caused by a vessel adding weight to one side. Examples can be all static weight sliding to one side, or flooding. This can be Dangerous and cause a vessel to capsize.

Question 29

General Features Boat Features that affect Stability

Answer 29

Some examples:
Rudder,
Stability Fins,
Sked, 
Hull design,
Buoyancy Collar Features,
Recesses to escape water,
Scuppers,
Baffles in tanks.

Question 30

Effects of Freezing Spray.

Answer 30

Freezing Spray can cause ice build-up which becomes a static force as it is directly adhering and acting as weight on the superstructure, causing the COG to shift to the weight and offset the natural stability of the vessel. This can cause capsizing.

Question 31

(02) Common Types of Keels

Answer 31

Bar Keel (external bar)
Flat-Plate Keel (internal framework)

Question 32

Describe a Displacement Hull.

Answer 32

Displaces the water, “pushes”. Operates at slow speed, strong stability. i.e. Sailboats, Barges, Tugboats. (Strongest Stability is Slow-Speed if towed)

Question 33

Describe a Semi-Displacement Hull.

Answer 33

Operates as a displacement at slow speed, yet will planning or rise above the surface of the water at higher speeds. i.e. common yachts, powercrafts, cabin crusiers. (more common)

Question 34

Describe a Planning Hull.

Answer 34

Strongest Stability and designed to normally operate at higher speeds. The hull will break the surface of the waterline easily with minimal to no displacement. (These vessels should not be operated or towed at slow speeds, due to the design is made to be most stable at higher speeds). I.e. High Speed Performance Vessels, Jet Skis aka PWC.