OUPV / Six Pack Captains License Course

DECK GENERAL - Boat Handling

Deck General

Boating Terms and Handling

*Safety and Deck General will be combined on the final exam for a total of 50 questions with a 70% needed to pass.

Stability is the ability of a boat to right itself. This is always a major concern to the prudent boater. High weight tends to destabilize while low weight (ballast) tends to stabilize. Slack water, scuba gear, and passengers should be secure. Proper trim is necessary for safety, fuel economy and stability underway. You are responsible for the safety of your passengers.

The capacity plate should be adhered to including maximum horsepower and safe load capacity.
Rolling is a rotational movement of a vessel to either side. The roll period is the time it takes a vessel to go from one extreme heel to the other side and back again. Tender (top heavy) means the roll period is long due to overloading. A stiff vessel rights itself quickly and is stable. It is important to load and unload a vessel evenly.

Pitching is a fore and aft rocking motion, or the rise and fall of the bow of a vessel as it proceeds through the water.
Yaw is when the bow of the boat swings to the starboard or port when going down a wave. Following seas most often causes yawing.
Broach is when the vessel swings wildly parallel to the waves. Safe speed is required at all times, including turning your vessel without broaching. When you turn, be aware of slippage. To cross a wake slow down and cross at a 45 degree angle. This technique is called quartering the seas. You are responsible for your wake.


Abaft is in the direction towards the stern of a vessel.

Quarter is the section located abaft the beam on either side.

Windward is the direction from which the wind is blowing.

Lee (Leeward) is the side of the vessel sheltered from the wind.

Bearing is an object’s direction in relationship to your vessel. Bearings can be visual or by radar or radio.

Athwartships is at right angles to the fore and aft centerline or keel of the vessel.

Vessel Parts and Measurements

Beam is the width of the vessel. Abeam is 90 degrees from the keel.

 is the forward (pointy end) of a vessel

 is the aft end of a vessel.

 is the right side of the vessel.

 is the left side of the vessel.

 is the vertical distance from the waterline to the top of the deck.  High freeboard is subject to wind.

Waterline length
 is the length of the vessel in the water.

Length overall is from the bow stem to the transom.

 is the underside flare of a vessel.

 is from the waterline to the lowest portion of the vessel, including propellers and rudders.  The minimum depth of water that a vessel will float is what the vessel is said to “draw”.

 is the widest part of the vessel at the deck level.

is the upper edge of the side of the boat (gun wall).

is transverse part of the stern.

Displacement – the weight of water displaced by a vessel afloat.  Displacement is different in salt water than in fresh water.

 – the total weight of a vessel immersed to load line, including cargo, mail, water, fuel, stores, passengers, crew, baggage and personal effects.

Gross Tonnage
 – total enclosed space using 100 cubic ft./ton (LxBxD/100).  For sailing vessels use 50 percent of the answer and for power vessels use 66 percent of the answer.  The USCG uses gross tonnage for documentation and certification of vessels.

Net Tonnage
 – gross tonnage less the engine space, fuel compartments, crews’ quarters, and spaces having no cargo capacity.

Docking and Undocking

Never approach the dock faster than you want to hit it!

Advanced planning is the key to docking sucessfully.  Factors that affect docking and undocking include wind, current, maneuverability, sea conditions, traffic density, and weather.  Practice docking and undocking to become proficient.  Slow speed during berthing is absolutely essential.  The berth should have sufficient water and be free from floating or sunken debris.  Make a mental note as to whether the  berth has a solid face or open pilings, as this will determine how water moves through or around the pier.  A vessel will maneuver more easily alongside an open faced pier because the water moves more freely under it and does not build up on the face.  Usually the most important line to get in place is the after-bow spring line.  It is important to secure the vessel against damage caused by the wake of another vessel.

When clearing a berth, make sure the engine and steering are working properly before disengaging the lines.  Make sure you retrieve all lines and anchor, if used.  Make sure all hoses, power lines, gangplanks, and any other connection to shore are disconnected prior to taking off the mooring lines.  Always check the direction and strength of the wind and currents.

Never attempt to fend a vessel off a dock or pier by using a hand or foot.  Always use a fender.  Keep the appropriate size fenders handy and place them in the most appropriate location.

When mooring with on-dock winds approach the dock parallel to it with fenders in place.   Ensure that the vessel has no fore and aft movement when contacting the dock.  When mooring with off-dock winds, the approach should be made at a sharp angle or 45 degrees or more.

Keep the stern away from danger.  If the propellers and rudder become damaged, the vessel becomes crippled.  If the stern is free to maneuver, the vessel will be handle difficult situations.  Except when using a stern spring line to assist in maneuvering, never tie down the stern of a vessel while maneuvering since it restricts movement.  When more precise control is needed, try to keep the vessel’s heading into the wind or current.

You are responsible for your vessel’s wake.  You can be responsible for damage to another vessel caused by your wake.  Always think ahead and don’t take chances.

With the rudder amidships.  The pivot point of a vessel is 1/3 of the distance from the bow in forward and 1/4-1/3 from the stern in reverse. 
Motors can be outboard, inboard/outboard, inboard and jet drive.  Single screw, right hand, backs to the port.  Twin screws have counter rotating props and have great maneuverability as they can be steered with the throttles.  If the vessel loses an engine the vessel can return home, but docking should be practiced ahead of time.

Propellers should be clean, balanced, properly installed, and sized.  Improper installation causes engine failure, vibration (cutlass bearing) and effects fuel efficiency.  Some important factors include the number of blades, the diameter, pitch and shaft size.  The diameter is the measurement of twice the distance from the center of the propeller’s hub to the tip of the blade.  The pitch refers to the angle the propeller’s blade makes in relation to the center line of the hub.  The basic function of the rudder is to direct the discharge current from the propellers to port or starboard to cause the bow to turn in the same direction.  The rudder is used in conjunction with the propellers in steering and handling a vessel. Head reach is how far your vessel will go forward until coming to a complete stop.  If your propeller has 26 degrees of pitch, it will advance 26 inches with each revolution of the propeller.

Advance and Transfer

You must always consider your vessel’s turning characteristics when precise piloting is necessary in an area with limited maneuvering space or when operating close to other vessels.  A vessel does not complete a turn instantaneously, but follows an arc that depends on the vessel’s length, beam, draft, trim, rudder angle, speed, wind and current, as well as other factors.  Advance is the distance the vessel continues to move in the direction of the original course before responding to a change of the helm.  Transfer is the distance the vessel moves perpendicular to the original course during a turn.  The amount of advance and transfer for a given vessel depends primarily upon the amount of rudder you use and the angle through which the vessel is to be turned.  This is extremely critical on large vessels, which is plotted for turns in confined waters to determine critical turning points.

Shallow Water Maneuvering

A vessel will handle differently in shallow water than in deep water.  As a vessel increases her speed, she sinks appreciably with respect to the surface of the water.  Squat is when the stern of a vessel settles lower in the water than the bow.  This would occur if the engine speed was increased in shallow water.  This can be dangerous in shallow water as the propeller, rudder, and hull are lower in the water and are close to obstructions on the bottom.  The water may eddy as it rushes between the bottom of the vessel and the bottom of the water, causing turbulence.  This can also cause a huge stern wave.

River Navigation

A vessel navigating along a riverbank will tend to sheer away from the bank because the bow wave acts as a cushion.  This is called bank cushion.  Along the side of a vessel close to the river bank, the velocity of the water increases as it is squeezed between the vessel and the bank.  This can pull the stern of the vessel towards the bank and is known as bank suction.  Together, the bank cushion and bank suction can cause a vessel to swerve out of control.  This is most noticeable when the draft of a vessel approaches the depth of the waterway.

Two vessels passing side by side when abeam will sheer towards each other.  Passing from astern your vessel will be sucked in toward the overtaken vessel. Thus it is extremely important that as the vessels approach each other, each vessel should be slowed as much as possible without losing control to reduce the effects of these forces.  When rounding a bend, it is important to know where the safe water is.

Rough Weather

Avoid rough weather, if possible.  However, rough weather should not necessarily be viewed as an emergency unless something goes wrong.  The vessel master should make all prudent and necessary preparations and provide leadership to prevent the situation from getting out of hand.  Try to quarter the seas and secure all passengers and gear.  Don’t run in the wave trough as it can cause the vessel to broach.  You can reduce yawing by moving deck loads aft, changing the trim, towing a drogue, or trailing a nylon line.  A sea anchor is used to slow a vessel’s drift and to keep her bow into the seas.  A sea anchor cannot hold a vessel in a fixed position or prevent drifting altogether.  A traditional sea anchor is conical in shape and is dropped over the bow.  It is secured with a heavy line.  Drogues are related to sea anchors and can also be used in heavy weather over the stern to reduce yawing.  A pooped vessel is one that takes water over the stern.  A vessel is said to pitch pole when it flips end over end.

Have everyone on board don a life jacket before the situation becomes dangerous.  Alter course to sheltered water or a lee, if possible.  Reassure the passengers and crew, giving them specific instruction to avoid danger and/or personal injury.  Pump bilges dry and check them often.  Storm oil, such as fish oil, can be used to calm the seas and prevent the seas from breaking.