DHT Bronco is the latest addition to the tanker herd

DHT has a clearly defined approach to managing the tanker cycle, and its latest scrubber-equipped addition fits the bill

The newly launched DHT Bronco and the soon to be delivered DHT Mustang are prime examples of the large tankers we can expect to see in the post-2020 global sulphur cap era. The 317,975 dwt DHT Bronco is fully equipped with scrubbers and ballast water management systems (BWMS) and DHT Holdings has committed to having 14 VLCCs scrubber- and ballast water treatment-ready by the start of 2020. DHT Bronco is a key element in that strategy.

DHT Bronco was launched from Hyundai Heavy Industries’ shipyard at Ulsan on 5 May and was delivered to DHT on 27 July 2018. The cargo arrangement of the VLCC is constructed around five central cargo tanks with five pairs of side tanks and two slop tanks. This includes transverse swash bulkheads which are arranged in the side cargo oil tanks. The double hull structure includes a double bottom with five pairs of ballast tanks. The double bottom is continuous throughout the cargo tanks, pump room, and engineroom area.

The engineroom structure is built mainly to the transverse framing system and the cargo area is constructed from a longitudinal framing system. The stern frame and the stern tube are fabricated with steel plates and from weldable cast steel. A full spade rudder was specified, and the neck bearing is arranged at the lower end of the rudder trunk.

Hull cathodic protection is provided by a Cathelco impressed current cathodic protection system, with a mean current density for the underwater hull area of 35 mA/m², rising to 120 mA/m² for the rudder and 600 mA/m² in the propeller area.

All the tanks are fitted with access points, and the structure has been built with high tensile steel in key areas. The hull has been constructed to meet the requirements for a 25-year North Atlantic design life, as per the Common Structure Rules (CSR). It features shell plates that are gradually tapered in thickness from midship to ends and bottom forward to strengthened for rough seas.

Jotun supplied the tank coatings and the cargo tanks are coated with KCC shop primer, followed by a coating of Jotun’s Jotacote Universal N10 epoxy paint. The ballast tanks also use Jotun product, in this case Jotacote Universal HF002 epoxy paint with sacrificial anodes.

All the piping, joints, valves, nuts and bolts in the hull and engineroom are specified in accordance with Korean and Japanese industrial standards. All the piping in exposed areas is clamped with SUS316L-specification U bolts with Teflon coating, in accordance with the owners’ standard.

"The tanker has been constructed with worldwide trading in mind and joins a fleet of 26 VLCCs owned and operated by DHT group"

The cargo control console and cargo valves were provided by Nakakita of Japan and feature integrated cargo and ballast water control simulation on the console. All the cargo and ballast valves are hydraulically operated from the cargo control console. DHT Bronco has a maximum loading capacity of 20,500 m³/hour and a discharge rate of 15,000 m³/hour.

A SAAB remote level gauge system enables ship staff to continuously monitor the tank volume during cargo operations.

Shinko Industries of Japan supplied cargo and ballast pumps. The cargo pumps are rated at 5,000 m³/hour, with two sets of cargo eductors running at 600 m³. The ballast pumps are rates at 3,000 m³/hour.

An Alfa Laval ASQ-180H inert gas generating system supplies 100% of the required capacity for cargo tank inerting, and there are two auxiliary inner gas generators with a capacity of 50% each. The total inert gas generating capacity is 18,750 m³/hour

The tank cleaning system is a conventional Scanjet set up, with a fixed-type tank cleaning machine provided to each cargo tank. Tank cleaning machines are of the single nozzle (programmable) or twin nozzle (non-programmable) type and are driven by the force of the washing liquid flowing through the system.

BWMS retrofitting

The retrofitting of BWMS is currently something of a hot topic, with several companies specifying BWMS for nearly new tankers.

This fate has been avoided by DHT as DHT Bronco was specified with BWMS at an early stage. The vessel is equipped with the Hyundai Hi Ballast (filter + electrolysis type) BWMS with capacity of 6,000 m³/hr. The BWMS is operated with two ballast pumps (one steam turbine and one electric motor) rated 3,000 m³/hr. DHT reports that the main reason for selecting the Hi Ballast system over alternative solutions was reduced energy consumption (maximum 240 kW). Moreover, Hyundai HI Ballast is already in service on DHT VLCCs and has proven very reliable.

The main engine is a Hyundai MAN B&W 7G80ME-C9.5-HPSCR with high pressure selective catalyst reduction, as per Tier III NOx requirements. The main engine nominal rating is 32,970 kW at 72 rpm.

The daily fuel oil consumption at NCR for the main engine was specified at around 65.6 tonnes per day, based on marine diesel oil of 42,700 KJ/kg without the scrubber in operation. However, during the sea trial main engine consumption was found to be about 68 tonnes of HFO per day at NCR.

The auxiliary engines consist of two HiMSEN Hyundai 7H21/32, with an output of 1490 KW at 900 rpm. The scrubber is an Alfa Laval Pure SOx Exhaust Gas Cleaning system for the main engine, auxiliary engines and the boilers, with a scrubbing dilution ranging from 3.5% sulphur down to 0.1% sulphur.

In normal seagoing operation the scrubber operates on the exhaust gases of the main engine and the two auxiliary engines. In port, the scrubber also washes the exhaust from one boiler and the two auxiliary engines.

During sea trials with different engine loads, auxiliary engines and boilers in operation the scrubber was found to meet the performance requirements for SECA/NECA/2020 global sulphur cap.

The boilers consist of one Alfa Laval composite boiler and two Aalborg OD (KBSD3000 and KBM150) rated at 40,000 kg/hour.

The Aalborg OC-TCi 2,950 kg/hour composite boiler uses a KBM150 burner. This composite boiler is only used during the port stay when no cargo operations are taking place. The boiler relies on the waste heat (exhaust gas) of the main engine, which should be sufficient for domestic purposes during normal sea-going mode.

The auxiliary boilers are only used for discharge operations in port, for cargo tank inerting and tank cleaning. The boilers are configured for the exhausts to exit via the funnel and through the scrubber.

During sea trials the scrubber was found to meet the performance requirements for SECA/NECA/2020 global sulphur cap

Alfa Laval supplied the fuel system, which consists of Alfa Laval centrifuges that have a capacity of 5,700 litres per hour and can handle oil types of up to 700 cst / 50-degree C with a separation temperature of 98° centigrade. The centrifugal separators monitor various parameters to enable a flawless separation and have a water transducer to monitor the water content in the oil outlet. The configuration of the fuel system allows a range of fuels, including HFO/ULSHFO/LSMGO for the main engine, auxiliary engines and boilers, in conjunction with the Alfa Laval Purification system for HFO & MGO.

As a safeguard, the vessel is fitted with a huge LSMGO bunker tank, as contingency in case of a failure of the SOx scrubber system.

The fuel oil lines are configured with separate HFO and LSMGO lines to handle the challenges of the 2020 sulphur cap; one boiler can fire on HFO with 3.5% sulphur, in line with the SOx scrubber, and the other boiler can be fuelled with LSMGO for cargo tank inerting while at discharge operations. The boiler control system in designed such that it can be controlled in automatically, with one boiler in master control and other on slave mode. The slave-mode boiler will follow up the master boiler and cuts in and out depending on demand.

The propeller is a Hyundai design keyless bore propeller (Wet type) with an aerofoil section weighing 76.5 tonnes. The four-blade propeller was fabricated in the Hyundai foundry/propeller shop from nickel aluminium bronze material and has a diameter of 10.4 m and a pitch of 7.55 m. In addition, DHT Bronco is fitted with a bulb and a Hyundai- Pre-Swirl duct for energy saving.

The steering gear is supplied by Yoowon-Mitsubishi. The YDFT-530-2 model was chosen for its compact construction and high reliability. The steering gear comprises two rams and four cylinders and a Rapson-slide type. The design incorporates two variable displacement pumps, one of which is stand-by.

The steering gear is controlled by a Tokyo Keiki autopilot (model: PR-9340A-DM-SS2) and incorporates an emergency control in the steering gear room.

Deck equipment includes two HHP-type stockless 27,000 kg anchors attached to a Macgregor windlass, with a capacity of 84 tonnes at 9 m per minute. There are two sets of anchor chains of 412 m each with 14 shackles.

There are 11 MacGregor 30T X 15 m/minute mooring winches, including one dedicated to single-point mooring. DHT Bronco is equipped with two hose-handling Oriental cranes (SWL 20 T), one 10-tonne SWL Oriental deck crane and one three-tonne SWL Oriental deck crane.

The bridge is equipped with two radars (1 X-Band and 1 S-band) with integrated ARPA functions and an inter-switching facility. The vessel has two independent sets of ECDIS (JRC 9201) with a robust system for obtaining and maintain permits/licenses which allows paperless navigation. The engineroom controls are duplicated on the bridge and in the bridge wings. The vessel has been fitted with two gyro compasses and one magnetic compass, which continuously transmit the heading to the steering system when navigating the vessel on autopilot. There is a voyage data recorder on board for accident investigation and training purposes.

With safety a paramount concern, the vessel has been fitted with CCTV monitoring systems in eight locations, including the bridge, with a feed going to the master’s cabin among other locations. The shore office has access to the system, enabling them to check on the vessel and its compliment at any time.

The communications system consists of three VHF radios, 1 MF/HF, 2 INMARSAT-C stations (LRIT is incorporated in one of them), a V-SAT system, FBB 500 and other small units. These units ensure vessel GMDSS, as well as routine communications irrespective of location.

DHT Bronco is classified by ABS and registered in Hong Kong; all DHT Holdings vessels sail under the USA flag. The P&I club is Gard and the technical manager is Goodwood Ship Management in Singapore, a company 50% owned by DHT Holding.

The tanker has been constructed with worldwide trading in mind and joins a fleet of 26 VLCCs owned and operated by DHT group. Sister ship DHT Mustang is due from the same yard later this year and the two newbuildings mean the fleet has an average age of only six years, compared to the VLCC fleet average of seven years.

Most of the DHT VLCCs are trading spot at the time of writing and this is influenced by management’s strategy towards the tanker market cycle.

DHT has a clear strategy when it comes to managing the tanker cycle

DHT Bronco is currently reported to be on a US$17,000/day, nine-month time charter to an unknown Chinese charterer. Clearly, this rate is far below capex and opex requirements, but is in line with current market norms.

DHT has ordered 12 scrubbers from Alfa Laval and has secured US$50M in funding from its banks to cover the cost of retrofitting them. The financing is structured through an increase of the existing US$300M secured credit facility entered into in Q2 2017.

The increased facility will bear the same interest rate equal to Libor + 2.40% and is available immediately. Quarterly repayments will consist of US$2.5M commencing Q2 2020, aligned with the implementation of the 2020 sulphur cap and resulting anticipated economic benefits.

All seven banks in the existing facility participated in the increased facility: Nordea, ABN Amro, Danish Ship Finance, DNB, ING, SEB and Swedbank.

With the support of its banks and the new fully-2020 ready additions to the VLCC fleet, DHT looks well-placed to weather the likely chaos associated with the implementation of the new fuel regulations.