Transverse tunnel thrusters
The achievement of operational economy has become essential in all sectors of shipping. Reduction of costs depends not only on cruising speed at sea, but also on faster turn-around times and the ability to navigate in busy shipping lanes and crowded ports.
For these reasons nowadays the use of transverse tunnel thruster application is a must as it remarkably facilitates the ship evolution when manoeuvring in narrow waters or at low speed. This solution allows an appreciable safety and is time-saving, the use of tug boats being no longer necessary. Since the beginning of the ‘60s Fincantieri has acquired experience in the production of controllable pitch propellers and being a qualified builder of high performance ships, can offer a product of high efficiency and reliability, designed for an easy arrangement and maintenance on board.

Low noise
All rotating components of fincantieri thrusters are statically balanced and the blade shape is studied in order to achieve low levels that are required nowadays. Skewed blades are manufactured by fincantieri to meet the requests for propellers with low noise level. The surface finish of the blades and the propeller hubs are designed so as to delay the formation of fouling as long as possible; therefore they reach better efficiency and a lower noise level.

Suggested thrust
Expected ship rate of turn with suggested thrust.

Underwater radiated nooise
To cope with the requirements of low acoustic signature typical of naval or oceanographic research vessels, fincantieri is manufacturing, since more then 20 years, tunnel thrusters fitted with special hatches to completely close the tunnel when the thruster is not in operation. 

	TYPE OF SHIP	THRUST REQUIREMENT FOR AREA ABOVE WATER LINE N/sqm	THRUST REQUIREMENT FOR AREA BELOW WATER LINE N/sqm
	Tugs, supply vessel	50-70	70-90
	Seiner, special purpose vessel	50-80	100-120
	Tanker, bulk carriers cargo vessel	50-80	50-70
	Ferries, passenger vessel bulk carriers	50-80	100-140

Materials
The choice of the right material ensures a long life in underwater service and an optimisation of propeller components design due to its high mechanical properties.
A stainless steel coating covers the tunnel inway and prevents local erosion of the blades.

Installation
Fincantieri thrusters can be supplied either in a standard tunnel or in a tunnel manufactured according to special shipyard requirements. It also supplies loose thrusters with the relevant procedure to install them in a tunnel manufactured by the shipyard.

Types
Fincantieri has developed two transverse tunnel thrusters designs: 
• HMF type with fixed pitch propeller
• HMC type with controllable pitch propeller
Both types use a flexible coupling to connect the e/motor to the bevel gear (with case hardened toothing) used to transmit power to propeller.