3. Construction Requirements

3.1 Hull Construction

3.1.1 Regulatory Requirements

3.1.1.1 The following regulations and standards apply to the hull design and construction of tugs:

  • Tugs ≤ 5 GT:
    • Small Vessel Regulations, Part 5 Section 521, Part 6 Sections 601 and 602
  • Tugs > 5 GT:
    • Hull Construction Regulations, Part VIII (specific to tugs)
  • Tugs of all sizes:
    • Hull Construction Regulations, Section 7 for Structural Strength
    • Hull Construction Regulations, Part VII Section 86 for Bulwarks and Freeing Ports
    • Marine Machinery Regulations, Schedule IX
    • Marine Personnel Regulations, Part 3, Division 3, Section 329

3.1.2 Additional Guidance

3.1.2.1 There is no TC regulation that defines in a quantifiable manner the scantlings required for a tug. The requirements of a Classification Society are recommended as general direction in this regard. For vessels undertaking Sheltered Water voyages or Near Coastal Voyages, Class 2, Limited, the ISO 12215 Small Craft – Hull Construction and Scantlings standards series may be used but the appropriate wave height design category must be considered. The side framing should be additionally strengthened as a minimum by the percentages stated in Classification Society Rules.

3.1.2.2 In general, tug owners find that the rugged service of tugs demands that the side strength of tugs should be considerably in excess of Classification Society Rules.

3.1.2.3 Note that on vessels of less than 24 metres in length, watertight doors could be of hinged or sliding type. Some owners may choose to install sliding watertight doors to allow the doors to be remotely operable from above the main deck similar to what is required in the Hull Construction Regulations section 111 for vessels of more than 24.1 metres in length.

3.2 Intact Stability

3.2.1 Regulatory Requirements

3.2.1.1 The following regulations and standards apply to the Intact Stability requirements of Canadian tugs:
 

  • Tugs ≤ 5 GT
    • Small Vessel Regulations, Part 6, Section 601
  • Tugs > 5 GT:
    • Hull Construction Regulations: Part VIII Sections 105 to 107 for inclining experiment and stability book requirements
    • Stability, Subdivision and Load Line Standards – TP 7301, STAB 1 for inclining experiment requirements, STAB 2 for stability book requirements and STAB 3 for intact stability criteria

3.2.1.2 Particular attention should be paid to the Hull Construction Regulations, Part VIII, 105-107 and the Stability, Subdivision and Load Line Standards – TP 7301, STAB1-3, pertaining to the requirements for the minimum intact stability criteria for tugs, and to the requirements for the data, methodology used and conditions to be included within the stability documentation.

3.2.2 Additional Guidance

3.2.2.1 It must be noted that by virtue of their very operation, tugs are subject to large external forces from the towline connections to their tows. The impact of these external forces is not presently considered in the referenced TC regulations. Owners are therefore strongly advised to apply the requirements for towline stability as defined by Classification Societies or other regulatory agencies such as the Australian Transport Council and its National Standard for Commercial Vessels - Part C Design And Construction - Section 6 Stability - Subsection 6A Intact Stability Requirements – Annex F (http://www.nmsc.gov.au/) to verify that a new design is safe for the intended towing task.

3.2.2.2 If a tug is to be engaged in any escorting duties, its intact stability should be thoroughly assessed for compliance with the Escort Towing Stability requirements of a major Classification Society. At present the criterion has been published by DNV, GL, and BV.

3.2.2.3 If a tug is engaged in other operations such as carrying deck cargo or lifting, the stability shall also be assessed accordingly. Appropriate operating conditions, limitations or notes to the master should be added to the stability booklet. For lifting operations refer to the Australian Transport Council National Standard for Commercial Vessels - Part C Design and Construction - Section 6 Stability - Subsection 6A Intact Stability Requirements – Annex E (http://www.nmsc.gov.au/) or other equivalent standards.

3.3 Damaged Stability and Subdivision

3.3.1 Regulatory Requirements

3.3.1.1 The following regulations and standards govern the requirements for the subdivision of tugs and the consequent damaged stability characteristics (applicable to tugs > 5 GT):

  • Hull Construction Regulations, Part VIII Sections 104 & 107 for compartment down-flooding

3.3.1.2 Particular attention should also be paid to the Hull Construction Regulations, Part VIII, pertaining to the requirement for positive freeboard and stability to remain after filling (down-flooding) any compartment aft of the machinery space which is accessible from the main deck. Note specifically that this is not a damaged stability equilibrium flooding condition, but one that assumes the complete flooding of a space below deck from above. Compliance with this requirement must be demonstrated by calculation at the design stage and incorporating the results of the inclining experiment after completion. Refer to the Stability, Subdivision and Load Line Standards – TP 7301, STAB 3, for the requirements for the data, methodology used and conditions to be included within the stability documentation.

3.4 General Outfitting

3.4.1 Regulatory Requirements

3.4.1.1 The following regulations and standards apply to the design and construction of tugs with respect to the configuration and layout of all crew accommodation, common and storage areas, and the means of safe access and egress thereto in particular:

  • Tugs > 5 GT:
    • Hull Construction Regulations, Part VIII;
      • Section 110 to 128 for Openings requirements,
      • Section 140 for Non-Skid Surfaces and
      • Section 141 for Exterior Storm Rails.
    • Towboat Crew Accommodation Regulations
      • Sections 6 – 10 for Layout of Accommodation Spaces
      • Sections 11 – 14 for Construction of Accommodation Spaces
      • Sections 15 – 18 for Sleeping Rooms
      • Sections 19 – 21, 33-34 for Dining, Recreation and Galley Spaces
      • Sections 22 – 32 for Sanitation Requirements
      • Sections 35 – 36 for Storage Requirements
      • Schedule I for General Safety
      • Schedule III for Deck Coverings
  • Tugs of all sizes:
    • Hull Construction Regulations, Part VII;
      •  Section 84 for Means of Escape,
      • Section 86 for Railings and Stanchions, and
      • Sections 94 to 96 for Notices and Markings
    • Maritime Occupational Health and Safety Regulations (see 3.4.1.4)
      • Part 2 for Access arrangements and General Safety
      • Part 3 for Crew Accommodation
      • Part 4 for Sanitation
      • Part 6 for Medical Care
      • Part 7, 9 & 10 for General Personnel Safety

3.4.1.2 Particular attention should be paid to the Hull Construction Regulations, Part VIII, and the Towboat Crew Accommodation Regulations pertaining to the requirements for the location, size and outfitting of accommodation spaces.

3.4.1.3 Particular attention should also be paid to the Towboat Crew Accommodation Regulations pertaining to the requirements for domestic systems, including, but not limited to, potable water, scuppers and drains.

3.4.1.4 Vessels with employees that are covered by federal health and safety legislation will fall under Part 2 of the Canada Labour Code (Section 123) and the Marine Occupational Health and Safety Regulations. Most vessels that operate only within the limits of a province will have employees that are covered by that province’s health and safety legislation.

3.4.1.5 For the services to be provided to living spaces on tugs (greater than 5 GT), refer to the following:

  • Ventilation:
    • Hull Construction Regulations, Section 126,
    • Towboat Crew Accommodation Regulations, Section 42
  • Lighting:
    • Towboat Crew Accommodation Regulations:
      • Section 41 for emergency lighting
      • Schedule IV for lighting levels
  • Access and Egress:
    • Hull Construction Regulations – Part VIII
  • Wash places:
    • Towboat Crew Accommodation Regulations; Section 22
    • Maritime Occupational Health and Safety Regulations (MOHS) Section 46 (see 3.4.1.4)
    • Note that the MOHS regulations apply to tugs of all sizes.

3.4.2 Additional Guidance

3.4.2.1 Note that in addition to the regulations some vessels may be subject to union agreements with respect to the crew accommodation requirements, and in particular:

  • the location of sleeping rooms relative to the main deck
  • the size of spaces and amenities allocated per crew member

3.4.2.2 Although section 127 of the Hull Construction Regulations states the minimum strength requirements for windows in tugs, Classification Society Rules should also be consulted for more detailed requirements. Further, if the windows are in close proximity to winches or other towing devices, then suitable mechanical protection in the form of heavy duty screens or similar equipment should be provided

3.4.2.3 When air-conditioning services are to be provided to living spaces on tugs, refer to the following:

  • ISO 7547:2002 – Air conditioning and ventilation of accommodations spaces – Design conditions and basis of calculations
  • ISO 8862:1987 – Air conditioning and ventilation of machinery control-rooms – Design conditions and basis of calculations
  • ISO 8864:1987 – Air conditioning and ventilation of wheelhouse on board ships – Design conditions and basis of calculations
  • ANSI/ASHRAE Standard 26-2010 - Mechanical Refrigeration and Air Conditioning Installations Aboard Ship
  • ANSI/ASHRAE Standard 151-2010 - Practices for Measuring, Testing, Adjusting, and Balancing Shipboard HVAC&R Systems

3.5 Deck Machinery

3.5.1 Regulatory Requirements

3.5.1.1 Regulations and standards that contain references to the design, installation and operation of deck machinery on tugs are the following:

  • Tugs ≤ 15 GT:
    • Small Vessel Regulations – Part 5 – section 510 for basic tackle requirements and section 521 (tug specific) for means of emergency release of towline
  • Tugs > 5 GT:
    • Hull Construction Regulations – Part VIII (tug specific) Sections 131 to 138 for basic equipment functionality and safety features & sections 142-143 for chain lockers
    • Towboat Crew Accommodation Regulations (tug specific) – Schedule 1 with regard to routing hawse pipes through accommodation spaces
  • For all sizes of tugs:
    • Marine Machinery Regulations – Schedule VII, Part II, Div. 3 for windlass

3.5.2 Additional Guidance

3.5.2.1 In addition, it is recommended that the design and construction of the deck machinery be in accordance with the rules of a Classification Society to provide design guidance, establish design loads, and define allowable stresses for critical components.

3.5.2.2 Ground tackle (anchors, anchor chain, windlasses, etc.) for tugs should be selected according to the vessel size, its duty and service area. In the absence of any quantified TC requirements, refer to the Rules of a Classification Society. However, the nature of the tug duty may not warrant such equipment, or fitting it may actually constitute a hazard to safe operations on the working deck. For example, tugs performing only ship-assist operations within the confines of a port could, in certain cases, do without any anchors at all, or perhaps a smaller "throw-over" anchor in case of emergency. In this instance, further consultation with the Classification Society being used may be necessary.

3.5.2.3 It is strongly recommended that the design and construction of the towing machinery and related towing fittings such as towing bitts, towhooks, etc. be developed with reference to the requirements of a Classification Society to provide general design guidance and establish the most appropriate design loads, towline orientations and allowable stresses in each component.

3.5.2.4 The maximum allowable design load for any fitting to be used for towing should be clearly marked directly on that fitting.

3.5.2.5 If a tug is to be engaged in any escorting duties, its towing gear should be assessed for compliance with the Escort Towing requirements of a Classification Society.

3.6 Machinery and Systems

3.6.1 Regulatory Requirements

3.6.1.1 The following regulations and standards apply to the design and construction of the propulsion machinery and related shipboard systems on tugs (applicable to all sizes of tugs):

  • Marine Machinery Regulations:
    • Schedule I to III for boiler systems
    • Schedule IV and V for engines
    • Schedule VI for gearing, shafting and propellers
    • Schedule VII for steering systems, shipside components, and windlasses
    • Schedule VIII for remote control and monitoring systems (see Section 3.8 of these Guidelines)
    • Schedule IX for non-structural tanks, and plastic piping
    • Schedule X for steam, boiler, and cooling water systems
    • Schedule XI for compressed air and refrigerating gas systems
    • Schedule XII for fuel oil systems
    • Schedule XIII for liquid petroleum gas fuel systems
    • Schedule XIV for lubricating oil and hydraulic power oil systems
    • Schedule XV for bilge and ballast systems
    • Schedule XVI for general design specifications

3.6.2 Additional Guidance

3.6.2.1 In addition, it is recommended that vessels adhere to the published Rules of a Classification Society for the machinery requirements appropriate to the vessel's size, area of operation, and intended service.

3.7 Electrical

3.7.1 Regulatory Requirements

3.7.1.1 The following regulations and standards apply to the design and installation of electrical systems on tugs:

  • For tugs ≤ 15 GT:
    • Small Vessel Regulations – Part 6, section 608
  • For all sizes of tugs:
    • Ships Electrical Standards – TP 127 for most requirements
    • Collision Regulations – (tug specific) Part C and Annex 1 for towing lights
    • Marine Machinery Regulations - Schedule VIII, Part I for generator set requirements
    • Navigation Safety Regulations – Part 4 regarding searchlights
    • Ship Station (Radio) Regulations – Sections 21 & 22 regarding radio station power sources
    • Ship Station (Radio) Technical Regulations – Sections 13 & 14 regarding radio station power sources
    • Towboat Crew Accommodation Regulations (tug specific)
      • Sections 39 to 41 regarding lighting
      • Schedule I, Section 7 regarding battery location
      • Schedule IV regarding light levels

3.7.1.2 The following regulations and standards apply to the operation and maintenance of electrical systems (for all sizes of tugs):

  • Safe Working Practices Regulations – Sections 61 to 68
  • Maritime Occupational Health and Safety Regulations - Part 15 (subject to applicability of Canada Labour Code, Section 123)

3.7.2 Additional Guidance

3.7.2.1 In addition, it is recommended to adhere to the published Rules of a Classification Society.

3.8 Controls, Alarms and Monitoring Systems

3.8.1 Regulatory Requirements

3.8.1.1 The following regulations and standards apply to the design, construction and inspection of the control, alarm and monitoring systems aboard tugs:

  • For tugs > 5 GT:
    • Hull Construction Regulations – (tug specific) Part VIII, Section 130 in regards to steering
  • For all sizes of tugs:
    • Marine Machinery Regulations – Schedule VII, Part 1, Division I & III in regards to steering
    • Ships Electrical Standards, TP 127 – Part I, Sections 21-22 in regards to alarms and control circuits

3.8.1.2 The vast majority of tugs operate with "Periodically Unmanned Machinery Spaces", and the requirements for this designation are clearly defined in the following (applicable to all sizes of tugs):

  • Marine Machinery Regulations, Schedule VIII, Part I Division I

3.8.2 Additional Guidance

3.8.2.1 In addition, it is recommended to adhere to the published Rules of a Classification Society.

3.9 Pollution Prevention

3.9.1 Regulatory Requirements

3.9.1.1 The following regulations and standards apply to the design and construction of tugs with regards to pollution prevention:

  • Vessel Pollution and Dangerous Chemicals Regulations
    • Part 2:
      • Division 1 - Oil
        • Section 14 - Containers or enclosed deck areas for bunkering operations
        • Subdivision 4 - Discharges of Oil and Oily Mixtures
      • Division 4 - Sewage
        • Subdivision 2- Equipment
      • Division 6 - Air pollution
        • Section 110 - Nitrogen Oxides (NOx) — Diesel Engines
        • Section 111 - Sulphur Oxides (SOx)
      • Division 8 - Anti-fouling systems

3.9.1.2 Note that the mandatory installation of oil filtering equipment, alarm arrangements and automatic stopping arrangements prescribed by section 12 of the Vessel Pollution and Dangerous Chemicals Regulations only applies to vessels of more than 400 gross tonnage. However for any vessel, the authorized discharge under Subdivision 4 can only be made if the discharge is processed through oil filtering equipment that meets the requirements of the regulations.

3.10 Composite Units

3.10.1 Regulatory Requirements

3.10.1.1 If a tug is fitted or refitted with the equipment to mate with a barge in an articulated-tug-barge (ATB) or integrated-tug-barge (ITB) configuration, the equipment must be appropriate for the service under the Marine Machinery Regulations (i.e. hydraulics) and TP127 (electrical components).

3.10.2 Additional Guidance

3.10.2.1 The hull should be built, or strengthened, for the usage of ATB/ITB equipment, and any additional equipment should be appropriate for the service. The applicable requirements of a Classification Society should be followed.

3.10.2.2 Transport Canada is currently reviewing the requirements applicable to composite units and will release additional guidance at a later date.