Yno 235 - Mærsk Defender

A UT 756 Cable Laying Vessel built and designed to satisfy the general demands for cable laying world wide; and the general demands of the offshore industry for multifunctional offshore vessels. At delivery, the vessel was prepared for a possible later conversion to a platform supply vessel (PSV).

Yno 235 Maersk Defender

The UT 756 Cable Laying Vessel is built by Ulstein Verft AS; and designed by Ulstein Industrier AS dept. Ulstein International for satisfying the general demands for cable laying world wide; and the general demands of offshore industry for multifunctional offshore vessels.


2006: Renamed "Emerald Sea"

2017: Still active - IMO 9131163. Manager and owner is McDermott Canada, Dartmouth, Canada. 
Flag: Bridgetown. Barbados. The current vessel is a "Fast transit, dynamically positioned (DP 2) offshore construction support vessel with moonpool, carousel, saturation diving system and helideck".



Length over all approx. 96,00 m 
Length between pp 83,50 m 
Breadth moulded 20,00 m 
Depth main deck 11,40 m 
Design draught (3,0 m freeboard) 
Max. draught (2,7 m freeboard)


Ballast water 1830 m3 
Fresh water 940 m3 
Fuel oil 750 m3 
Heavy fuel oil (IF 40) 1300 m3 
Gross Tonnage (1969) International 5746 GRT 
Net Tonnage International 1723 NRT 
Deadweight at draught 8,4 m 7960 T 
Deadweight at draught 8,7 m 8450 T


The vessel is outfitted with machineryand provided with equipment in accordance with the latest rules and regulations of Lloyds Register of Shipping for world wide service with following class and notation: 
Lloyds + 100 A1 "Cable Laying Vessel" LMC, UMS, LNC (AA). dP (AM)


Speed loaded approx 14,0 knots 
Speed ballast approx 16,0 knots 
Bollard pull approx 100 T


Accommodation for 56 persons in total of which: 
- 32 single cabins 
- 12 double cabins 
In addition: 
- Galley/Mess/Dayroom/Videoroom/Gymnasiom 
- Office 
- Hospital 
- Washrooms/WC/Showers 
- Deck workshop


Cable Laying Equipment 
- One crane MCV2T, 2,5 tonnes at 20 metres 
- One crane KMCV 1301m 1,5 tonnes at 20 metres 
- One A-frame, 60 tonnes 
- One towing winch, 60 tonnes 
- One storage winch, 2 tonnes 
- One auxiliary winch, 36 tonnes 
- One capstan winch, 25 tonnes 
- One linear cable winch, 20 tonnes 
- One linear cable winch, 4 tonnes 
- Three linear cable winches, each of 2 tonnes 
- Four stern rollers


Rudder/Steering Gear 
- Two ULSTEIN High Lift Flap Rudders 
- Two ULSTEIN indenpendant electric-hydraulic 
- Steering Gears


Side Thrusters 
- One ULSTEIN Tunnel Thruster forward, 1103 kW 
- Two ULSTEIN Tunnel Thrusters aft, each of 736 kW 
- One ULSTEIN Swing-up Compass Thruster, 883 kW


Roll Damping System 
- One ULSTEIN Passive Stabilizing Tank System


- ULSTEIN Joystic 
- Dynamic positioning system according to DP (AM) requirements from LRS


- S-band and X-band ARPA radars 
- Two Gyro compasses 
- Autopilot 
- Log 
- Echo sounder 
- GPS navigator 
- Radio installation according to GMDSS-A3 with Inmarsat B and C 
- Three VHF radios


Deck Machinery 
- One ULSTEIN Windlass/Mooring Winch 25 tonnes 
- Two ULSTEIN Capstans 10 tonnes 
- Two ULSTEIN Tugger Winches 10 tonnes


Lifesaveing Equipment 
- One MOB-boat with one-armed davit 
- Four life rafts, each of 35 persons 
- Two life rafts, each of 25 persons


Machinery/Propulsion System 
- Two Krupp Mak main diesel engines, each of 3520 kW 
- Two ULSTEIN CP Propulsion System each of 3520 kW 
- Two ULSTEIN Reduction Gears with propeller PTO for shaft generators; 1800 rpm/1500 rpm, high speed 205 rpm. low speed 171 rpm


Electric Power Plant (450V AC - 60Hz) 
- Two shaft alternators, each of 3000 kVA 
- Two generator sets, each of 600 kVA 
- One emergency generator 85 kVA 
- Transformers, 2 x 80 kVA, 1 x 30 kVA (450/230V)


Electric Equipment 
- ULSTEIN Main Switchboard 440/220V 
- ULSTEIN Emergency Switchboard 440/220V 
- ULSTEIN Control Consoles and general Electrical Equipment 
- ULSTEIN Data Sound 
- ULSTEIN Microprocessor based Alarm System (UMAS) 
- ULSTEIN Brigde Alarm System


Liquid Cargo Discharge System 
- One fuel oil pump 
- One fresh water pump 
- One ballast/drillwater pump

Emerald Sea Previous Maersk Defender

The 'Maersk Defender' of today, currently named 'Emerald Sea'.