Motor Yacht

Overview

A motor yacht is a powered cruising boat carrying living accommodation: a saloon, sleeping cabins, a galley and a head, driven by inboard engines rather than sail. This 52-footer rides a planing GRP hull, so at speed the bow lifts and the boat skims on its aft sections instead of pushing through the water displacement-style. Twin turbo-diesels turn separate shafts and propellers, which also lets the helm steer and pivot using differential thrust. The whole boat is built up from the GRP Composite Hull, a one-piece molded fiberglass shell stiffened internally and capped by the deck and superstructure moldings.

Power comes from two independent drivelines. Each Diesel Driveline string is a Marine Diesel Engine coupled through a Marine Gearbox to a Propeller Shaftline that exits the hull and turns a bronze propeller. The boat is held on course by Hydraulic Steering working twin rudders behind the props, and maneuvered in marinas by the thrusters in Pumps & Thrusters. Everything aboard runs off the Electrical System system, topped up underway by engine alternators and at anchor by the Diesel Generator. The crew lives in the Interior and drives from the helm using the Navigation Electronics suite.

How it works

Diesel fuel from the tanks is filtered, raised to injection pressure and sprayed into the cylinders, where compression ignites it; the turbocharger packs extra air in to raise output. The expanding gases drive the pistons and crankshaft, and the marine gearbox reduces shaft speed and selects ahead or astern through a wet clutch. The propeller converts that rotation into thrust, and its reaction against the water pushes the hull forward. A raw-water pump draws seawater through a strainer and a heat exchanger to carry engine heat overboard, keeping the freshwater coolant loop in range.

Electrically, the Electrical System system runs a low-voltage DC house bus charged by the alternators and the genset, with an inverter making AC for domestic loads and a shore inlet for dockside power. Float-switched bilge pumps keep the hull dry, the windlass in Ground Tackle sets and weighs the anchor, and the chartplotter, radar and autopilot in Navigation Electronics handle position, collision avoidance and hands-off course holding.