RIASSUNTO
INTRODUCTION
The ESARC is a multipurpose geological and geophysical survey ship for deep waters and rough sea conditions, the main feature of which is the use of flexodrilling. The USSR has ordered one of these vessels from SERETE, a French engineering company. The tasks that can be performed by this vessel are as follows: establishment of profiles of the sea bed to a depth of 2,000 ft; work by divers in saturation diving conditions to a depth of 800 ft; drilling of wells with a maximum depth of 170 ft and core sampling for civil engineering studies; and drilling of wells with a depth of more than 650 ft and core sampling for the establishment of geological maps. For this type of drilling at a maximum water depth of 650 ft, the drilling fluid can be returned to the surface. The maximum water depth for drilling is 2,000 ft.
TECHNICAL DATA
The major features of this vessel are:
(Information available in full paper)
The ESARC carries 26 tons of water, 1.30 tons of fuel, and 44 tons of powder in bags. This leaves 84 tons available for additional equipment and fluids.
The hull has a central well for coring and drilling operations. The walls of this well are lined by a waterproof coffer dam that rises up to mid height between decks, becoming wider to form a cellar deck for storage of the wellhead and the vibrocoring drill.
All crew quarters are air conditioned.
THE VESSEL POWER PLANT
Electricity is supplied by four diesel alternator units with a power of 1,075 hp and an additional 150-hp unit. In normal operation, three units are enough to provide the necessary power, and the fourth is on standby or undergoing maintenance.
DYNAMIC POSITIONING
The ESARC is equipped with a dynamic anchoring installation that allows it to remain in place in water depth of 2,000 ft under the following conditions, using both its main propulsion units and its dynamic anchoring thrusters: wind force, 40 knots; gusts of 60 knots not exceeding 20 seconds; and current of 2 knots.
Using only its dynamic anchoring thrusters for a steady wind of 27 knots with gusts of up to 4D knots and a current of 2 knots on the entire section of water, the position of the ESARC indicated by the spot of the inclinometer must remain in a circle with a radius of 20 ft for a depth of .3.30 ft, 2.3 ft for a depth of 660 ft, and 59 ft for a depth of 2,000 ft.