Tug & Workboat
Workboats including many type of merchant vessel such as harbor supply boats, multicats, landing crafts and etc. that traffic daily in a harbor or coastal area. These vessels generally work with 2 – 6 crew, who have many different duties according to workboat field of occupation such as offshore wind farm service, fish farm service, port construction, Dredging support, offshore energy platform service, crew transfer, anchor pull out and restoration, buoy supporting, geotechnical research, mapping and etc. in fact workboat means some boat with variety duties that gather in one boat and usually their navigation area are near coastal and harbor, therefore most of work boats have low draft and suited for shallow water or inland water way. Multicats or multipurpose vessel known as a workboat with varieties duty in offshore zone that typically equipped with powerful offshore cranes and towing winches and have large deck area for operation. In order to better operational condition, most of new workboats equipped with dynamic positioning system that help captain to keep the boat in a certain location in sea or river current.
Marinnor Company able to design and built any workboat with any auxiliary equipment and facilities. Marinnor Company in accordance with its expert and experience on light ships, focus on workboats under 24m length. Marinnor company design the workboat base on three important criteria: 1- Ergonomic design 2- Operational condition 3- Tailor made design. Construction steps explain in Gantt chart and generally according to boat complexity and construction technique it may take between 4 to 7 month delivery times.
According to existing multicats, some features of these vessel shown below:
The following figure shows the category of tug boat :
According to above flowchart tug boats have three types base on propulsion system: 1- Screw propeller 2- Azimuth thrusters 3- Voith Schneider. Tug boat have 5 types according to navigation area and operational condition: 1- Sea tugs 2- Ice class tug 3- Push boat 4- Escort tugs 5- Harbor tugs.
Tugs duties varies according their type as follows:
- None propelled vessel need tugs for transfer for example: all kind of barges, pontoon, floating structure and etc.
- Large vessel in harbor need tugs for mooring and berthing operations for example: container ship, oil tanker, balk carrier and etc.
- Supply fuel oil, water and ships requirement is alternative duty of some tug boats
- Tug boats can have some duties as a salvage boat to recovering a vessel or its cargo
- Tug boats can have some duties as an ice breaker
- Tug boat can have external firefighting facilities for harbor or ocean accident
There are three type of tug boats according to their power:
- Small tug boat: main engine power up to 500 horse power
- Medium tug boat: main engine power between 500-3500 horse powers, power to tonnage ratio between 4.0–9.0.
- Large tug boat: main engine power up to 27000 horse power, power to tonnage ratio between 2.1 – 4.4.
As above mentioned the ratio of power to tonnage very high proportional to other type of ships that between 0.35-1.25.
In the following advantages and disadvantages of varies propulsion system will be explained.
Diesel engine is usually the main power source for this propulsion system. This propulsion system is compose of main engine, gear box, shaft, propeller, duct and rudder. Tug with this type of propulsion system usually divided in 3 type: 1-Single screw propeller 2-Twin screw propeller 3-Triple screw propeller. Tug boats usually have 2 type of propellers: 1-Fixed pitch propeller (FPP) 2-Controllable pitch propeller (CPP). CPP propellers able to change the pitch angle of propeller blades in order to access optimum propeller efficiency in different condition.
- Easy construction and maintenance
- Low cost
- Maximum efficiency for towing ship port to port
- Good towing performance when towing on a line
- Need a gearbox for backward motion
- More cavitation phenomena
- Less stability
- Less maneuverability
- Low astern power
Diesel engine or diesel generator usually the main power source for this type of propulsion system. This propulsion system is compose of main engine or generator, gearbox, shaft, azimuth thruster, propeller and duct. Azimuth thruster can rotate in any direction, so there is no need to rudder in order to change in vessel direction or maneuver. The azimuth thruster and screw propeller have same position is vessel stern.
- Good stability in turning
- High bollard pull
- Easy maintenance and repair
- Low draft equal to conventional propulsion system
- Bad side stepping movement
- Capsizing possibility at aft towing condition
- Danger of encounter to external object
- More complex control system
- Limited to towing in forward condition
Voiith Schneider Propulsion system is composed of some vertical blades and a circular plate that rotating around and axis. According to blades and circular plate direction, thrust direction will be change, so this type of propulsion system no need to any rudder in order to maneuverability
- the propulsion system can provide thrust in any direction without waste of energy
- fast response in maneuver condition
- low possibility of capsizing
- good performance in any speed
- optimum movement in port and starboard direction
- no need to rudder for maneuver
- Less bollard pull proportional to azimuth propulsion system
- High cost of buy and maintenance
- Complexity in maintenance and repair because of the position of this propulsion system
- Low handling performance because of lower arm between center of gravity and thrust effective point
- High heeling angle when pushing a vessel from side
- High risk of damage due to crash with sea bed (high draft)
- Need expert master for navigate the boat
Marinnor is able to design and build any type of tug and work boat in accordance with customer requirements base on any of IACS members or local classification society.
Marinnor Tug & Workboat
16m Multicat Service Vessel
Hull Material: Marine Steel
Length O.A: 16.4 m
Beam O.A: 6 m
Max. Draft: 1.7 M
Main Engines: 2×500 hp(1800 RPM)
19m Tugboat (2000 hp)
Hull Material: Marine Steel
Length O.A: 19 M
Beam O.A: 7.3M
Max. Draft: ~2.2 M
Main Engines: 2×1000 hp Diesel