First new AZT 2400 Class tugs from Robert Allan Ltd., for Fratelli Neri S.p.A.

August 30, 2007


In August 2007, the first two of a series of new high-performance, compact 24 metre ship-handling tugs, named “Porto di Livorno” and “Fratelli Neri” were delivered to their Owners, Fratelli Neri S.p.A. of Livorno, Italy  by the shipyard Rosetti Marino of Ravenna, Italy.  These tugs are the first of a new class of powerful ship-handling/escort tugs developed by Robert Allan Ltd., Naval Architects of Vancouver, BC.  Designated as the AZT 2400 Class, these tugs are true “Z-drive tractors” with drives located in the forward third of the hull length.

The Z-Tractor configuration has somewhat fallen from favour lately against the more usual Azimuthing Stern Drive (ASD) configuration, however for the operator that can accept the inherently deeper draft, this configuration has some attractions; namely slightly higher propulsive efficiency, and a more uniform thrust vector pattern around the compass.

In the case of the Neri tugs, the major design challenge was to put all the Owner’s operational requirements, including two line-handling winches plus a high-standard of accommodation for six crew into a compact and attractive package which offered good ship-handling and escort towing capabilities.  Under the design guidance of senior Naval Architect and Project Manager Dr. Oscar Lisagor, the Owner’s objectives have been well-fulfilled with these handsome and powerful little tugs.

These new tugs will be used in the port of Livorno, served by the Owners.  They are classed for both harbour and coastal duty.



The tugs were built to RINA Class notation “C ✠ Hull, C ✠ Mach, Tug, Fire-Fighting ship 1, Water-spraying, Coastal Area, ✠ SYS-NEQ-1, ✠ AVT-UMS and AUT-PORT, and ✠ Inwatersurvey”.
Particulars of the AZT 2400 Class tugs are as follows:


Length Overall
Beam, Moulded
Depth, Moulded
Draft, Maximum
Fuel Capacity
Potable water capacity
– 30.25 metres
– 11.00 metres
– 5.28 metres
– 4.85 metres
– <300
– 120 cubic metres
– 12 cubic metres


Propulsion comprises a pair of CAT 3516B diesel engines, each rated 2,100 kW at 1,600 rpm, and each driving a Schottel model SRP 1515 Z-drive with a 2,600 mm diameter fixed-pitch propeller through a Cardan shafting system.  This combination delivers a Bollard Pull of 69 tonnes ahead, 65 tonnes astern, and provides a free running speed in excess of 12 knots.

The AZT 2400 Class tugs are outfitted for a crew of six persons, in necessarily “cozy” but modern and well-equipped fashion.  The entire deckhouse is resiliently mounted to provide a low noise level in accordance with Italian registry regulations.

The main hawser winch is a double drum, hydraulic winch supplied by Kraaijeveld.



Electrical power is provided by a trio of CAT C.4.4 gen-sets, each rated 86 at kW, 50 Hz at 1,500 rpm.

The tugs have a full Fi-Fi 1 rating in accordance with Class notation requirements.  The fire pumps are driven from the front-end of the main engines through a Kumera gearbox, which also drives the main hydraulic pumps, powering the winch.

The configuration of the new AZT 2400 Class tugs are shown on the accompanying General Arrangement drawing and photographs.

For further information on this or other high-performance tug designs, please contact us.