New dive support boat for Brazilian offshore market

APRIL 17, 2015—The DP-2 monohull shallow dive support vessel (SDSV) Sistac Victoria was recently delivered by shipbuilder SeaSafe Barcos Manufacturados S.A., Angra dos Reis, Brazil to Sistac Sistemas De Acesso S.A.

Designed by Incat Crowther in collaboration with SeaSafe Barcos Manufacturados and classed by RINA, the 42.5m x 9.3m Sistac Victoria will operate in the Brazilian offshore in support of Brazil state-owned oil company Petrobras. The SDSV has a draft of 1.85 meters and hull depth of 4.25 meters.

For its diving support operations, the Brazilian-flag SDSV’s aft working deck has integrated winches for ROV and dive bell launching and retrieving as well as a knuckle boom crane for handling deck gear and a small rescue/service vessel. The aft deck also features a lower platform at the stern to facilitate direct access to the sea by diving personnel.

Constructed of marine grade aluminum, the vessel has a landing area complying with Petrobras requirements for accommodating a crane-loaded man-riding basket, and for carriage and delivery of supplies and small cargo.

Diver safety and vessel maneuverability are paramount in the operation and were key factors in selecting four Hamilton HM 521 waterjets for propulsion. The vessel’s propulsion power is supplied by four Scania DI13 main engines that are rated at 410 kW each at 1,800 rev/min. They drive the waterjets via four ZF 665 gearboxes. The Sistac Victoria has a service speed of 11 knots and maximum speed of 13 knots.

Station-keeping and maneuverability are further enhanced by three 200 hp Thrustmaster model 30TT200ML tunnel thrusters. The thrusters are driven by electric motors whose speed is controlled by variable frequency drives (VFD), all part of Thrustmaster´s integrated solution package. Electrical power is supplied by four 375 ekW Scania DI13 generators.

Thrustmaster tunnel thrusters are of exceptionally robust design capable of producing lateral thrust under extreme load conditions in demanding offshore applications for dynamic positioning or for slow speed maneuvering of marine vessels and are available from 150 hp (100 kW) up to 5,000 hp (3,500 kW) with tunnel diameters from 30 in. (762 mm) up to 136 in. (3,455 mm).

All components in contact with seawater are constructed of marine grade aluminum, bronze or 316 series stainless steel to insure longevity and prevent galvanic corrosion. The thrusters do not require external cooling. Any heat generated by the gears and bearings is dissipated through the pod housing to the surrounding seawater.

The thruster pod housing is an aluminum casting and is bolted in the tunnel. The pod contains the propeller shaft, right angle gears, input shaft, bearings, and seals. The geometry of the pod housing is hydrodynamically optimized to minimize drag resistance.