Design of a Catamaran Sounding Vessel for Operation in the St. Lawrence

Abstract

CCG Laurentian Region currently operates three vessels whose primary function is the sounding of dredged navigation channels in the St. Lawrence from Montreal to Gap Gribane, 15 km downstream from lle d'Orleans. The vessels also provide services as far out as Rimouski and into the Saguenay. These vessels sound, on an annual basis, some 120 km2 of surface area. Due to its association with Seaway dredging in which some 0.3 million m3 of material is removed annually, this sounding activity has to be carried out with an accuracy greater than that normally associated with hydrographic charting. CCG Laurentian Region specialists have brought together current off-the-shelf sounding and position-keeping equipment which comprise a sounding mission system capable of onboard real-time data processing compatible with significantly higher sounding speeds than the 10 knots of the existing fleet. The existing fleet, which comprises two 18 m catamaran vessels and the shipping channel maintenance vessel Nicolet, is now approaching the end of its economic life and is scheduled for replacement. The replacement program comprises two catamaran vessels designed to sound at 18 knots, thus providing full area coverage in the 8-month operating season from mid-April to mid-November. This paper presents some of the challenges represented by the mission requirement and the engineering solutions incorporated into the vessel design.