Tugs
Getting to know our Workhorses

Tugs are very important part in any harbor maneuvering. Today we will strive to know this important team member in detail and how to safely and effectively use them.

 

 

We will divide this large topic into following sections:-

  1. A typical tug layout and parts of tug

  2. Types of tugs- Their limitations

  3. Effective usage of tugs

  4. Safety precautions when using tugs- Interaction, Girding etc.

 

 

A typical tug layout and parts of tug

 

The ability of tug to handle such a large pulling or pushing force vis-à-vis its size is due to its deep draft and heavy in bottom part (very low VCG).

A typical tug is powered by 2 variable speed diesel engines powering the 2 fixed pitch propellers mounted onto azimuth which can be rotated 360 degrees using hydraulic mechanism.

Tugs bow (stern in case of tractor tugs) is additionally strengthened and fitted with fixed fenders like W-fender, tube –fender, U-fenders made of hard rubber. This Hard rubber is supplemented by installing a softer layer of tyre fenders (Usually discarded Aircraft tyre or Hydra tyre)

 

Once tugs engines are started, initially they are allowed to run at idle rpm for few minutes, then propellers are clutched with the engine shaft, and then RPM can be varied as required and direction of thrust can be controlled by rotating the Azimuth (Z-peller). Z-peller rotation is mostly hydraulic actuated.

If tugs is fitted with FIFI (firefighting system- Pumps upto capacity 2400 CubM/Hr), there will be either 2 pumps which can be clutched with engine simultaneously with propeller or in case of single fire pump, one of the engine will need to be declutched and to clutch the fire pump. In such case tug will need to be maneuvered with only 1 propeller until FIFI system is being used.

 

Operation in case of power failure:

In case of Auxiliary engine failure, tugs have adequate battery back up to continue maneuvering for another 1 hour to 3 hour.

Typical 65 ton BP ASD tug GA plan and Particulars:

  • Length: 32m

  • Breadth: 12m

  • Draft Max: 4.7m

  • Displacement in Full load condition: 620 ton

  • Class Notation: DNV X 1A1 Tug Escort (n.V) FiFi 1 E0

  • FO Capacity: 118 ton

  • Fresh water capacity: 24 ton

Main Engines: 2 x Caterpillar 3516 BHD, 2 x 1920 kW = 5225 hp, Maximum speed 13,5 knots

  • Auxiliary engines: 2 x 269 kW Caterpillar C9 DI 1 x 83 kW Caterpillar C4.4 DITA

  • Bow Thruster 1 x 150 kW (Bow thruster is provided on only few of tugs)

  • Propulsion 2 x Z-Peller or Schottel

Towing equipment

  • Aft. towing winch: (break cap 130 T) Double drum 800/400mtr 52mm steel wire

  • Ford towing winch: (break cap 130 T) 1 drum 180 mtr 76 mm Ultraline

  • Emergency wire/Storage reel 650 mtr/52mm steel wire

Anchor handling equipment

  • Towing pins: MKB Fork Towing Pin System (FTP box) Stern Roller 3m x 1,3 m

Communication & Navigation

  • Navi Sailor 4000 ECDIS MFD, Transas

  • GMDSS A3 (sailor 5000)

  • 2 x Radar JMA with ARPA

  • Autopilot

  • Gyro Compass or Satellite compass +repeaters

  • Magnetic comp

  • DGPS 1

  • MF/HF Radio DSC

  • 2 x VHF DSC

  • 2 x VHF Handheld

  • Navtex · Epirb · Sart · Lrit · Ais

  • Speedlog

  • Echo sounder

 

Firefighting capability: FIFI system IRS AGNI class notation, Ex: AGNI-1(2400 cub m/ hr), Diesel driven portable emergency fire pump.

Oil Spill response Equipment’s: Oil Boom, OSD 5 ton, OSD spray booms, Hydraulic operated Skimmer,

LSA: Rescue boat with crane davit, Life rafts

ASD Tug- showing various parts of tug

Tractor Tug showing Towing arrangement on Aft (No Winch, Only loose towing rope used by taking turns on bollard).

Now we will move to next part of topic i.e. Types of tugs and their limitations( Click on this link)