Cao Gang 30 and Cao Gang 31 RAmparts 3500 Tugs arrive at Caofeidian Port in Northern China

July 28, 2023

Robert Allan Ltd. is pleased to announce that Cao Gang 30 and Cao Gang 31 were successfully delivered to the owner Caofeidian Port, in the northern part of China in July 2023. The newly completed RAmparts 3500 tugs were built by Zhenjiang Shipyard (Group) Co., Ltd. The new vessels were designed by Robert Allan Ltd. for operation in Bohai Bay for towing, vessel assistance, and fire-fighting purposes.

The vessels were designed based on a well-proven RAmparts hull form. With the required 34.8 metre vessel length, bollard pull of 80 tonnes, and a gross tonnage not greater than 500, which was up to the limit, the design was quite challenging. Substantial but well-worthwhile efforts were spent in the development of hull form and arrangement to provide sufficient displacement; single cabins for 10 crew members as per Chinese Statutory requirement; machinery arrangement for the large equipment of the propulsion system, as well as a fire-fighting system of Fi-Fi 1 Class notation.

The owner was highly impressed and very satisfied with the performance, including speed, bollard pull, and the manoeuvrability demonstrated by the tugs during sea trials.

Key particulars of the Cao Gang 30 and Cao Gang 31 are:

  • Length, overall (excluding fenders): 34.7 m
  • Beam, moulded: 11.1 m
  • Depth, least moulded: 5.19 m
  • Maximum draft (navigational): 4.94 m
  • Gross Tonnage: < 500

Main tank capacities are:

  • Fuel oil: 85 m3
  • Potable water: 30 m3
  • Ballast: 110 m3
  • Fire-fighting foam: 10 m3

The tugs were designed and constructed to the following CCS Class Notation:


★ CSM, AUT-0

Propulsion machinery consists of two Yanmar main engines of 8EY26W 2390 kW at 750 rpm and a pair of Schottel Z-drive SRP 460FP, Ø2700, FP.

Each of the multi-purpose tugs is equipped with deck machinery, including a hawser winch two individual windlasses at the bow; a towing winch on the aft deck. Deck machinery equipment is provided by Karmøy Winch AS, Norway.

Fenders for ship-handling at the bow consist of an upper row of cylindrical fenders and a lower course of W-fender. Sheer line fendering consists of “D” rubbers and a W-fendering at the stern.

The accommodations have been outfitted for a crew of ten including two cabins with a living room for the master and chief engineer, mess, and a galley arranged in the deckhouse, eight other crew cabins located on the lower accommodation deck. The wheelhouse is designed with a split-type control station which provides maximum all-round visibility with exceptional visibility to the bow and side fendering, as well as operation on the aft deck.

Trial results were as follows:

  • Bollard pull, ahead: 81.5 tonnes
  • Free running speed, ahead: 13.1 knots

For more information on ASD or RAmparts tugs, or any other high-performance vessel designs developed by Robert Allan Ltd., please contact