The first four of this new series are based upon the earlier Peng Chau class. Modifications have been made to the design to make the vessels slightly longer, meet higher standards of soundproofing and improve the layout of crew accommodation.

All four tugs are classed +100A1+ LMC unrestricted service, allowing them to undertake seagoing operations in addition to their normal ship-handling duties.

These compact 4000hp vessels have an overall length of 29m, a moulded beam of 9.50m and a maximum draft of 3.81m. The propulsion system comprises:

two Yanmar 6N260-EN diesels producing a total of 4000bhp at 750rev/min to drive a pair of Kawasaki Rexpeller KST-180ZF/A fully azimuthing propulsion units. On trials the first vessel achieved a maximum bollard pull of 53.5 tonnes at 100% MCR and a free running speed of 13.34 knots.

Compared with the two original Peng Chau class vessels, now operating in the Adsteam fleet in the UK, tugs of this new series embody a number of options planned for but not fitted to those earlier vessels. A Kitagawa Kogyo electro-hydraulic towing winch is installed aft to enable the tugs to tow over the stern when at sea. The two-speed winch has a single drum, with a brake holding load of 90 tonnes, accommodating 750m of 45mm diameter steel wire rope. A similar winch carrying a 110m, 96mm diameter, 'Supermix' towline is mounted on the forecastle for shiphandling. The new tugs are also equipped for fire fighting with a single Isuzu powered fire pump supplying a pair of high level water/foam monitors. Another significant improvement is the inclusion of an internal staircase giving access to the wheelhouse from within the accommodation, a facility not afforded to earlier vessels.

The remaining tugs of this six vessel order will be two improved versions of the 26m Lam Tong class. The smallest of the HKST stern drive tugs, the original vessels of the class are powered by Niigata main engines of 3200 bhp (total) coupled to 'Z-Peller' azimuthing units, to give them a bollard pull of 43 tonnes.

An expansion into new markets in recent years is the reason given for this new building programme.

Harbour and ocean-going tugs from the HKST fleet are now working in Mexico, the West Indies, Arabian Gulf, Australia and Indonesia in addition to their traditional operational areas of Hong Kong and the South China Sea.

The new tugs will initially work in Hong Kong, where the harbour fleet is under strength, to permit the release of tugs chartered in by HKST as a temporary measure. As additional new tugs arrive they will be made available to the wider market. At the same time Tap Mun, the oldest tug in the HKST fleet, has been sold to interests in the Middle East.