An emergency tow concept is a plan designed to ensure the timely arrival of efficient salvage tugs in the event of a casualty, before it becomes in a situation where it is not possible to tow it free of charge or only at the cost of severe environmental damage. For this reason, Canton Salvage and Towage Co. Ltd. has developed an EMERGENCY TOWING VESSEL (ETV). There are three stations for the ETVs, Yantai, Shanghai and Canton - on each station one Vessel is placed.
Tuzhong - Class
Emergency Towing Vessel
Displacement:
1.014 t light; 1.048 t standard; 1.691 t normal; 2.205 t full load
Dimensions:
Length overall / water x beam x draught
218,93 ft / 208,33 ft x 38,06 ft x 14,93 ft (normal load)
66,73 m / 63,50 m x 11,60 m x 4,55 m
Machinery:
Diesel Internal combustion engines plus batteries,
Electric cruising motors plus geared drives, 2 shafts, 3.907 shp / 2.915 Kw = 18,20 kts
Range 32.000nm at 12,00 kts
Bunker at max displacement = 1.157 tons
Complement:
13 - 17
Cost:
£0,364 million / $1,457 million
Distribution of weights at normal displacement:
Armament: 0 tons, 0,0%
Machinery: 95 tons, 5,6%
Hull, fittings & equipment: 419 tons, 24,8%
Fuel, ammunition & stores: 677 tons, 40,0%
Miscellaneous weights: 500 tons, 29,6%
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
3.392 lbs / 1.538 Kg = 263,5 x 6 " / 152 mm shells or 1,6 torpedoes
Stability (Unstable if below 1.00): 1,03
Metacentric height 1,3 ft / 0,4 m
Roll period: 14,3 seconds
Steadiness - As gun platform (Average = 50 %): 62 %
- Recoil effect (Restricted arc if above 1.00): 0,00
Seaboat quality (Average = 1.00): 1,24
Hull form characteristics:
Hull has raised forecastle, rise forward of midbreak
and transom stern
Block coefficient: 0,500
Length to Beam Ratio: 5,47 : 1
'Natural speed' for length: 17,39 kts
Power going to wave formation at top speed: 62 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 20,00 degrees
Stern overhang: 3,94 ft / 1,20 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 18,31 ft / 5,58 m
- Forecastle (20%): 17,06 ft / 5,20 m (12,47 ft / 3,80 m aft of break)
- Mid (50%): 12,47 ft / 3,80 m (9,84 ft / 3,00 m aft of break)
- Quarterdeck (20%): 9,84 ft / 3,00 m
- Stern: 9,84 ft / 3,00 m
- Average freeboard: 12,17 ft / 3,71 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 51,6%
- Above water (accommodation/working, high = better): 89,1%
Waterplane Area: 5.494 Square feet or 510 Square metres
Displacement factor (Displacement / loading): 245%
Structure weight / hull surface area: 47 lbs/sq ft or 231 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0,88
- Longitudinal: 3,56
- Overall: 1,01
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is cramped
Good seaboat, rides out heavy weather easily
Misc. Weight: 500tons
Towing equipment - 100tons
Salvage crane - 50tons
High-capacity pumps - 50tons
Submarine rescue apparatus/chamber - 50tons
Fire Fighting equiment - 50tons
Subsidiary low-speed towing diesel - 50tons
Stowage - 100tons
Deep Stowage:
15000sm @ 12kn: 340tons
First Aid & Operation room: 100tons
Hospital (20 Persons @ 5 tons): 100tons
Workshops: 100tons
Crew complement reduced for commercial service