Patent ID: 9708032
Date: 2017-07-18
CPC Classifications: B63B,B63H,Y10T

Claim:
1. A method for at least one of disassembling and assembling an underwater section of a retractable thruster unit of a swimming vessel, the thruster unit including an upper gear detachably connected to a power source, said underwater section including a lower gear and a propeller, and an intermediate section with a steering tube connecting the upper gear with the underwater section, said vessel being provided with a well formed in the bottom of the vessel, into which well said underwater section can be retracted when the thruster unit is out of operation, said well being closed upwards with a covering plate, whereby in disassembling the underwater section, the method comprising the steps of: a) fixing a supporting cradle detachably to the underwater section from below, disengaging the upper gear from the power source, and lifting the thruster unit so that the underwater section is at least partly brought inside the well and locking the thruster unit mechanically in place in the lifted position, b) connecting auxiliary lifting means provided with lifting wires to the supporting cradle for supporting the thruster unit, c) draining water from the well by supplying pressurized air into the well, d) loosening the joint between the lower gear and intermediate section of the thruster unit, e) lifting the upper gear and the intermediate section further and locking them mechanically in place while the cradle is supported in place by the auxiliary lifting means so that a space is formed between the intermediate section and the lower gear, and sealing the intermediate section and the lower gear to prevent water from getting into them, and f) letting water to ingress into the well and lowering the underwater section down by the auxiliary lifting means, attaching the wires of a crane, detaching the lifting wires of the auxiliary lifting means, and picking up the underwater section with the crane.