Lake and River Shipping Industry Terminology

Air Draft

Vertical distance from the waterline to the vessel’s highest fixed point. Critical for clearing bridges, power lines, and lock structures on rivers and canals, and varies with water level and trim.

-Our air draft is 21.5 m—won’t clear the railroad bridge at today’s river stage. -Lower the mast to reduce air draft before the next bridge. -The charter party lists an air-draft restriction in the canal.

AIS (Automatic Identification System)

VHF-based transponder system that broadcasts a vessel’s identity, position, course, and speed. Used for collision avoidance, lock scheduling, and traffic services on rivers and the Seaway.

-Confirm AIS Class A is operational before departure. -The lockmaster sees us on AIS and will prep the chamber. -Use AIS data to refine the ETA to the grain terminal.

ATB (Articulated Tug-Barge)

A tug and barge mechanically linked by an articulated connection, operating as a single unit. Offers ocean/coastal capability and is common for bulk liquids/solids on lakes and near-coastal rivers.

-The asphalt ATB calls Thunder Bay on Friday. -We need an ATB with 80,000 bbl capacity for the move. -The ATB handles better than a conventional tow-and-wire in locks.

Ballast Water Management

Operational and regulatory measures to prevent invasive species transfer via ballast water (e.g., treatment, exchange, saltwater flushing). Strict reporting applies for Great Lakes/Seaway traffic.

-Commission the ballast treatment unit before Seaway entry. -Submit the ballast report to Seaway traffic control. -We performed saltwater flushing before entering the Lakes.

Bollard Pull

A tug’s static pulling force, measured in tonnes of force. Used to match tug power to tow size, currents, ice escort needs, and lock maneuvers.

-The tow requires at least 30 t bollard pull. -Book a 50-ton bollard pull tug for the lock transit. -Bollard-pull trials are scheduled after the retrofit.

Bunkering

Taking on fuel (often truck-to-ship or barge-to-ship in inland trades). Requires fuel quality documentation, spill prevention, and compliance with sulfur limits in ECAs.

-Truck-to-ship bunkering will happen at the river terminal tonight. -Use 0.10% sulfur fuel while operating in the ECA. -Sign the bunker delivery note and retain the sample.

Cabotage

National laws reserving domestic waterborne transport to national-flag, crew, and often build (e.g., U.S. Jones Act; Canada’s Coasting Trade Act).

-A foreign-flag tug can’t perform cabotage on the Mississippi. -Apply for a coasting trade waiver for the project cargo barge. -The charterer asked for a Jones Act-compliant ATB.

Canal Lock

A gated chamber that raises or lowers vessels between water levels on canals and rivers; lockage time impacts schedules. Core to the St. Lawrence Seaway.

-Expect a two-hour lockage at Eisenhower Lock. -Ensure fenders are ready before entering the canal lock. -Our ETA depends on lock maintenance windows.

Charter Party

The contract of carriage (voyage, time, or trip) that sets freight, laytime, demurrage, cargo terms, and responsibilities. Often supplemented by local rider clauses.

-The charter party is on GENCON with Great Lakes riders. -Laytime starts per the NOR defined in the charter party. -Add an ice clause to the charter party.

Deadweight Tonnage (DWT)

The maximum weight a vessel can safely carry, including cargo, fuel, stores, and crew. Key for bulk loading plans and draft compliance.

-This laker is 28,000 DWT at Seaway draft. -We can’t load to full DWT due to air-draft limits at high river stage. -Freight is quoted per metric ton up to 95% of DWT.

Demurrage

Agreed liquidated damages payable when loading/unloading exceeds allowed laytime; common in barge and voyage contracts.

-Barges ran on demurrage during the flood closure. -We negotiated a lower demurrage rate but stricter laytime. -Despatch applies if we finish early; demurrage if we overrun.

ECDIS (Electronic Chart Display and Information System)

A certified electronic navigation system using official ENC charts. Inland/River ECDIS variants integrate river depths, notices, and RIS data.

-Update ENC cells on ECDIS before the shoal transit. -Switch to inland ECDIS layer for the Danube RIS sector. -ECDIS shallow contour alarm—check UKC.

Emission Control Area (ECA)

IMO-designated zones with stricter fuel sulfur and NOx limits; the North American ECA includes the Great Lakes–Seaway.

-Use 0.10% sulfur fuel while in the ECA. -Verify EIAPP certificates for ECA compliance. -Log the fuel changeover at Seaway inbound.

Freight Rate

The price for carriage, quoted per ton, per barge, or lump sum; often includes fuel adjustment factors and seasonal/ice or lock surcharges.

-Spot freight is $18/mt for ore upriver. -Our tariff adds an ice premium to the base freight rate. -Index the freight rate to diesel price.

Great Lakes–St. Lawrence Seaway System (GLSLS)

Binational waterway linking the Great Lakes to the Atlantic via locks and canals (e.g., Welland Canal, Seaway locks). Central to North American inland shipping.

-Seaway Notices to Shipping affect the GLSLS opening. -Footers can’t exit the GLSLS due to lock size limits. -Ballast reports are mandatory in the GLSLS.

Gross Tonnage (GT)

A measure of a vessel’s internal volume, used for regulatory thresholds, dues, manning, and pilotage. Calculated under the 1969 Tonnage Convention.

-Pilotage fees are based on GT. -GT increased after retrofit, affecting inspection regimes. -The tug’s GT determines the audit scope.

HAZMAT (Hazardous Materials)

Dangerous goods requiring special handling, documentation, and response plans; governed by IMDG, U.S. 49 CFR, and Canada’s TDG rules.

-Class 3 HAZMAT requires 'NO SMOKING' signage. -File a Notice of Arrival for HAZMAT barges. -Segregate oxidizers from organics per the HAZMAT table.

Hydrographic Survey

Measurement and charting of depths and channel conditions (e.g., multibeam sonar) to support safe drafts, UKC, and dredging decisions.

-USACE survey shows a 0.5 m shoal near Mile 42. -Update the sailing plan after tomorrow’s survey. -Survey data supports a temporary draft restriction.

Ice Class

Classification notation indicating hull and machinery strengthening for operations in ice; influences routing, season, and insurance.

-Charter requires Ice Class 1A Super. -Non-ice-class vessels need icebreaker escort. -Premium applies for higher ice class.

Icebreaking Assistance

Escort and channel-opening services by icebreakers to maintain winter navigation; coordinated by Coast Guard/Seaway authorities.

-Form convoy behind the icebreaker at dawn. -Icebreaking schedule adds two days to transit. -Request track maintenance after the wind shift.

ISM Code (International Safety Management Code)

International standard requiring a Safety Management System, a Document of Compliance (company), and Safety Management Certificate (ship).

-Our ISM SMS audit is next month. -Bring the new ATB under our ISM DOC. -Incident reporting followed ISM procedures.

Just-in-Time Arrival (JIT)

Operational practice of adjusting speed to meet an advised arrival window, minimizing idle time and fuel at locks and berths.

-Adopt JIT to avoid queuing at the lock. -Updated ETA supports JIT speed optimization. -JIT saved 6% fuel on the river leg.

Keel Clearance

Distance between the keel and the riverbed. Critical in shallow channels where squat and heave can reduce clearance.

-Maintain 10% of draft as minimum keel clearance. -High speed reduced keel clearance due to squat. -We delayed loading to preserve keel clearance.

Laker

A Great Lakes bulk carrier, often a self-unloader, designed to Seaway or lake-only dimensions; 1,000-foot 'footers' trade only within the Lakes.

-The laker will load taconite at Two Harbors. -Seawaymax laker length is about 225.5 m. -A footer can’t transit the Welland Canal.

Laytime

Contractual time allowed for loading/unloading; expressed as SHINC/SSHINC, weather working days, etc.; overage triggers demurrage and early completion despatch.

-Laytime starts on NOR acceptance. -We used 18 of the 24 laytime hours. -Include an 'all fast' clause for laytime commencement.

Length Overall (LOA)

Maximum length from bow to stern. Determines lock fit, berth assignment, and tug requirements in confined waterways.

-LOA must be under 225.5 m for Seaway passage. -Berth 3 can’t accept our LOA—shift to Berth 5. -LOA and beam determine lockage configuration.

MARPOL Annex VI

International rules on air emissions (fuel sulfur, NOx tiers, ozone-depleting substances). Requires IAPP/IEEC certificates and logkeeping.

-Engines comply with Tier II under Annex VI. -Record fuel sulfur content per Annex VI. -Scrubber operation is logged as an equivalency.

Mate's Receipt

Receipt issued by the ship’s officer on taking custody of cargo before the bill of lading; notes apparent condition/quantity.

-Mate’s receipt marked 'wet damaged' protects the owner. -Broker needs the mate’s receipts for documentation. -No cargo loaded without a signed mate’s receipt.

Multimodal Bill of Lading

A through bill covering carriage across multiple modes (e.g., barge-rail-truck) under one contract of carriage.

-Issue a multimodal B/L for barge-to-rail grain. -Claims fall under the multimodal liability clause. -Customs cleared on the through bill.

Navigation Season

The period when a waterway (e.g., Seaway) is open to navigation, often curtailed by ice and used for off-season maintenance.

-Opening of navigation announced for March. -Schedule drydock during the off-season closure. -Ice buildup could shorten the navigation season.

Notice of Readiness (NOR)

Formal notice by the vessel when ready to load/discharge per charter terms; when valid, it starts the laytime clock.

-NOR tendered at anchorage per charter. -NOR rejected due to berth congestion clause. -Laytime countered from NOR acceptance.

OSRO (Oil Spill Response Organization)

Contracted entity standing ready to respond to spills; required under U.S. law for certain vessels and cargoes, including many inland trades.

-Update the OSRO agreement before bunkering. -Notify the OSRO per the response plan. -Audit confirmed OSRO coverage for the river fleet.

Pilotage

Compulsory use of licensed pilots in designated waters. Great Lakes Pilotage Authority (Canada) and U.S. pilot districts govern coverage and fees.

-Pilotage is mandatory for foreign ships on the Lakes. -Order a river pilot for the tricky bend. -Pilotage fees are budgeted by district.

Plimsoll Mark (Load Line)

Markings showing legal loading limits for various water types and seasons; freshwater allowance applies on lakes/rivers.

-Load to the freshwater mark for the Lakes. -Surveyor verified Plimsoll line exposure before sailing. -Seasonal load line reduces allowable draft.

Port State Control (PSC)

Inspections by authorities of foreign-flag ships to verify compliance with international standards; serious deficiencies can lead to detention.

-PSC boarding is scheduled at Duluth. -Fix fire door defects to avoid PSC deficiency. -PSC database shows a clean record.

Rules of the Road (Inland Navigation Rules)

Statutory right-of-way, sound signals, and lights rules for preventing collisions on inland waters.

-One-whistle meeting per Inland Rules. -Display proper towing lights for a composite unit. -Sound the danger signal—stand-on vessel not responding.

Seaway Draft

The maximum allowable draft for transiting the St. Lawrence Seaway; varies seasonally and with water levels.

-Seaway draft is set at 26'6'' this season. -Trim to even keel to meet Seaway draft. -Cargo plan revised due to lower Seaway draft.

Self-Unloader

A bulk carrier with onboard conveyors and a discharge boom, enabling rapid self-discharge without shore gear. Dominant among Great Lakes lakers.

-Self-unloader can discharge coal at 4,000 tph. -No shore gear needed thanks to the boom. -Boom outreach limits which berth we can use.

SOLAS (Safety of Life at Sea)

The main international safety convention for ship construction, equipment, and operations. Many Seaway/ocean-going ships must comply.

-Lifeboat inspections per SOLAS Chapter III. -Vessels on international voyages must comply with SOLAS. -The SMS bridges SOLAS with ISM requirements.

Spot Charter

A single-voyage or short-term fixture at prevailing market rates; common in barge movements where demand fluctuates.

-Booked a spot charter for 10 barges of grain. -Spot rates spiked after the lock closure. -Owner prefers spot to time charter this season.

Tow/Towage

Service of moving vessels/barges by tug (pushing, towing on wire, or alongside), priced per hour or lump sum.

-Arrange towage for the lock approaches. -Tow size is limited to 15 barges on this reach. -Towage contract includes weather standby.

Turnaround Time

Total time from arrival to departure at a terminal; key performance indicator affected by berth productivity and lock delays.

-Turnaround time improved after adding a loader. -Ice delays increased average turnaround. -We target a 24-hour turnaround for salt cargoes.

Under Keel Clearance (UKC)

Required minimum clearance between the keel and the bottom, accounting for squat, heel, and river stage. Often set as a percentage of draft.

-Company UKC policy is 10% in rivers. -Shallow stretch needs speed reduction for UKC. -UKC calculation triggered a draft reduction.

UN/LOCODE

UN standard five-character codes for ports and inland locations, used in documentation and EDI.

-Use CADRY for Dryden, Canada. -Chicago’s UN/LOCODE is USCHI. -The manifest needs correct UN/LOCODEs.

Voyage Charter

Charter for a specific voyage at agreed freight, with laytime/demurrage provisions; widely used for bulk lake/river shipments.

-Signed a voyage charter for 30,000 mt of ore. -Laycan fixed 10–12 April on the voyage charter. -Despatch applies under the voyage terms.

VTS (Vessel Traffic Service)

Shore-based monitoring and advisory service that improves safety and efficiency; integrates radar, AIS, and VHF. Present on parts of the Seaway and major rivers.

-Check in with Seaway VTS at calling-in points. -VTS reported congestion at the lock. -Follow VTS speed advisories in fog.

Waybill

Non-negotiable carriage document common in inland barge trades; evidences the contract and cargo details.

-The barge waybill lists 1,500 short tons of soy. -Use the waybill number for terminal gate-in. -The waybill accompanies the tow’s paperwork.

Winter Navigation Surcharge

Additional fee to cover delays, icebreaking, and risk during winter operations on lakes and rivers.

-Apply a winter surcharge from December through March. -Ice-season premiums raised the all-in rate. -The charter includes a winter navigation clause.

X-band Radar

High-frequency marine radar (~9 GHz) providing fine detail for close-range navigation and lock approaches; complements S-band radar.

-Use X-band in rain clutter near the lock. -Overlay AIS targets on the X-band display. -De-ice the X-band antenna in winter.

Z-drive

Azimuth thruster capable of 360-degree rotation, common on towboats/tugs for superior maneuverability in currents and locks.

-The Z-drive towboat handles better in crosscurrents. -Training covers Z-drive handling in tight locks. -Retrofit to Z-drives cut fuel and transit times.