Ibaizabal Diez & Ibaizabal Once – Two new high-performance escort tugs from Robert Allan Ltd.

November 21, 2012


The Spanish tug company, Remolcadores Ibaizabal has taken delivery of two new AVT 36/70E Escort tugs from the drawing board of Robert Allan Ltd. The tugs were constructed by Astilleros Armon in Navia, Spain.


Particulars of the AVT 36/70E Class, Voith propelled tugs are as follows:


Length Overall:
Beam, Moulded:
Depth, Moulded:
Maximum Draft (overall):
Bollard Pull:
– 36.65 metres
– 13.60 metres
– 4.80 metres
– 4.0 metres
– 5,280 kW
– 70 tonnes


Tank capacities are as follows:


Fuel Oil:
Reserve Fuel Oil:
Potable Water:
Engine Lube Oil:
VSP Oil:
Fi-Fi Foam:
Recovered Oil:
– 218 m³
– 130 m³
– 67 m³
– 10 m³
– 10 m³
– 15 m³
– 2 m³
– 130 m³


The design features a full raised forecastle running nearly half the length of the tug to provide a high standard of accommodation and the best possible sea-keeping capability for operation in exposed conditions. The general layout of the lead tug is illustrated in the general arrangement drawing here:



The vessel will be outfitted to the highest standards for a crew of up to 14 people. Main deck accommodations include three two-person cabins, four one-person cabins, a galley, mess, galley stores, workshop, oil lab, locker room/lobby, and deck store. The deckhouse at forecastle deck level includes four one-person officer cabins. The wheelhouse is designed for maximum visibility with a single control station providing maximum visibility to both fore and aft deck working areas, with the emphasis on the aft deck. The lower deck includes engineer’s stores, and laundry facilities. All cabins are of a generous size, and boast en-suite lavatory facilities. The noise level throughout the crew accommodation is predicted to be in the range of 60 dBA, based on utilizing advanced methods of isolating main propulsion machinery, as well as high grade insulations and floating floor techniques.

Main Propulsion for the AVT 36/70E comprises a pair of MaK 8M25 diesel engines, each rated 2,640 kW at 750 rpm, and each driving a Voith model 32R5-265-2 cycloidal propeller in tractor configuration. This combination is predicted to deliver a Bollard Pull of 70 tonnes, and provide a free running speed of not less than 13.5 knots. The indirect escort steering force is estimated at 110 tonnes at 10 knots.



The operating range at economical cruising speed is estimated at 3,500 nautical miles.

The electrical plant is comprised of three identical diesel gen-sets, each with a 380 volt/50 Hz power output of 125 kW.

Fire-fighting will be to a Fi-Fi 1 Class.

The main towing winch is a waterfall-style, double drum type, in which the upper drum contains 1,000 metres of 56 mm steel wire rope. The lower drum is a split configuration with a 250 metre synthetic hawser for escorting, and a 150-metre synthetic line for harbour towing. The anchor windlass, in a horizontal axis configuration is fitted with two chain wildcats and two warping heads, which are clutched separately.

Towing flexibility is enhanced by the inclusion of a 70-tonne, radial arm tow hook, while salvage and general stores/deck operations are aided by inclusion of a 25-tonne-metre knuckle boom crane. Ship-handling fenders at the stern (skeg end) comprise a 900 x 450 cylindrical fender above a row of 450 mm “W” block fenders. A 300 x 300 hollow “D” fender provides protection at the main and foc’sle deck sheer lines, and “W” block type fendering is used again at the bow.

For more information on the AVT 36/70E Class tugs, or other high-performance terminal or escort tug designs, please contact us at design@ral.ca.