2.6 Docking, Undocking & Line Handling

Docking Is Exam Seamanship, Not Just "Park the Boat"

Q160 Deck General treats docking, undocking, and line handling as professional shiphandling: geometry of lines, effect of current and wind, and what happens when you heave on one lead without the others. On a Master Less Than 100 GRT platform with a Certificate of Inspection (COI) and paying passengers, the same answers also protect people on the rail and crewmembers on the bitts.

Best Timing: Slack Water (and Against the Set When You Cannot Wait)

Slack water—the brief period of little or no tidal/current stream between flood and ebb—is the preferred window to dock or undock when the schedule allows. With little set, prop walk and rudder do what you expect, fenders stay where you put them, and spring lines take predictable loads.

When commercial schedules force you into a running current:

• Prefer an approach against the current (or against the stronger of wind and current) so you keep steerage at low speed and can check way without being swept past the berth.
• Approaching with a strong fair current often leaves too much uncontrolled momentum; reverse may not stop you in time before the next piling.
• In a river with strong current and light wind, textbooks and Q160-style items favor stemming the current into the berth.

Wind on a high-sided dinner boat or whale-watch cabin acts like a second current. If wind dominates, treat the windward/leeward problem the same way: keep control by pointing into the stronger force when that is safe for traffic and the pier layout.

Breast Lines vs Spring Lines

Know the lead, not just the name printed on a training diagram.

Springs control fore-and-aft surge. Breasts control the gap to the dock. That one sentence ends most Q160 line-identity traps.

Coming alongside with residual headway

As you land with slight headway still on, the line normally used first to check surge ahead is a forward spring led aft from the bow (or forward fairlead) to a bollard aft of that lead. When the spring comes taut, ahead motion is checked and the hull can be walked alongside with rudder and small engine orders. A breast line alone is a poor substitute for checking headway—it mainly pulls the side toward the pier.

Secured alongside, tending to surge ahead

If the vessel is already alongside and begins to surge ahead, the line designed to check that motion is the aft spring (leads from forward on the vessel to a dock point farther aft, resisting ahead motion). Do not answer "breast line" for fore-aft surge questions.

Effect of Heaving on a Bow Breast Alone

A classic exam and real-world trap: the deck crew heaves hard on a bow breast (or bow line led nearly abeam) while after lines are slack or not yet fast.

What happens: the bow is pulled in toward the pier. With the bow fixed and no after restraint, the stern may swing out (or walk out under prop and current). You end up bow-in, stern-out—awkward for passengers at the gate and hard on bow fenders.

Correct habit: heave breasts in pairs or with springs and after lines tended so both ends come in together. If only one end can be worked first, the master should plan engine/rudder to control the free end—not rely on a single breast to "suck the whole boat in."

Springing On and Springing Off

Springing means using a spring line under controlled strain as a fulcrum while engines and rudder walk the hull.

Springing on (onto the berth)

1. Get a spring fast early (often a forward spring led aft).
2. Put controlled strain on the spring.
3. Use ahead or astern and rudder so the free end walks toward the pier (for example, ahead on a forward spring with outboard rudder can tuck the stern in, depending on leads and screw).
4. Pass remaining lines once the side is parallel and fenders are working.

Springing off (leaving the berth)

1. Single up to the working spring(s); take in breasts that would hold you in.
2. Strain the spring and use engine/rudder so the bow or stern opens off the pier.
3. When the end is clear of the dock face, cast off the spring and proceed—watching for traffic and prop wash against other vessels.

Springing replaces brute force and reduces the need for dramatic reverse walk in tight marinas. It is also safer for line handlers because loads are planned, not sudden.

Current, Wind, and the Approach Plan

Build a brief mental checklist before every landing:

1. Set and drift of current relative to the pier face
2. Wind direction and vessel windage (empty upper deck vs full load)
3. Traffic and room to abort
4. Which side to and whether prop walk helps or hurts that side
5. First line to go out (usually the spring that checks the dangerous surge)
6. Passenger and crew positions: clear of snapback zones, not on the rail in the impact zone

If wind and current fight each other, honor the stronger force for the final approach angle, then use lines early so the weaker force cannot open a gap after you think you are secure.

Master 100 Dock Approaches with Passengers

Command on a COI small passenger vessel adds non-negotiable layers:

• Announce and stage: deckhands on stations before the approach, not after the bow is already at the pile.
• Minimum way: passengers interpret a hard landing as poor seamanship and it can cause falls on wet decks.
• Fenders placed for the contact point you will actually hit first (often the shoulder or midships, not the bow stem).
• Synthetic line snapback: stand clear of bights and the likely recoil path; figure-eight turns on bitts, never a foot in a coil.
• Gate and embarkation control: do not open the passenger gate until the vessel is secure and the master (or designated person) says so—surge can still open a gap.
• Undocking with people aboard: same standard; a rushed cast-off with a fair current can pin a fender or part a late line.

Worked scenario

You are landing port-side-to on a flood that sets you down-pier. Right-hand single screw. Plan: stem the flood so you approach against the set; shallow angle; early forward spring led aft to check residual headway; short reverse to stop and walk the stern in; pass after spring and breasts before allowing passenger movement. If the crew heaves only the bow breast, stop them—correct the stern with engine and after lines, not more bow breast alone.

Exam framing for Q160

Memorize slack water preference, against the current for control, breast = alongside / spring = fore-aft, forward spring checks headway on landing, bow breast alone → bow in, stern out, and springing as engine-plus-line technique. Passenger-vessel stems still use those same definitions; the extra layer is line safety and controlled landings under a master's duty of care.