No_11_November_1969 — Page 34

rapid hardening cements which cure underwater.

Perhaps the most distinctive fea- tures of ferro cement for the ship-

Vessel's frames at start of construction

Vessel just prior to application of cement mortar

owner are its virtual elimination of maintenance costs and the fact that the material increases in strength with age. Of its disadvantages the two most

prominent are its weight and puncture strength. The weight problem has largely been solved by improved tech- niques and greater strengths in the material, enabling thinner sections to be used, and this is no longer a major consideration other than in the small- est of boats.

Recent extensive research on the distribution, size and weight of the reinforcement used in ferro cement, has resulted in greatly improved punc- ture strengths of the material as com- pared with earlier specimens.

The Pak Tak

Hong Kong's first ferro cement boat, the Pak Tak, is of 62 tons and of 54ft. 6in. overall. It was built by Ferro Cement Marine Construction Ltd., at Taikoo Dockyard, for local fisherman, Mr. Yip Kam-hung, through the auspices of the Agriculture and Fish- eries Department of the Hong Kong Government and the Aberdeen Mec- hanised Trawler Fishermen's Credit Co-operative Society, with a loan provided by the Fish Marketing Or- ganisation (FMO).

A loan of some HK$95,000 was made to Mr. Yip by the FMO towards the cost of the boat. This sum repre- sented slightly more than 80 per cent. of the total cost of the Pak Tak, including fishing gear, insurance and initial operating expenses.

Mr. N. Rodokal, the ship building manager of the builders' New Zealand associates, Ferro Cement Ltd. of Auckland, spent five months in Hong Kong to supervise the building of this prototype boat and to train local craftsmen in this type of construction.

The boat has an average hull thick- ness of 11⁄2 inches and is said to be comparable in weight with wooden boats of its size. In fire-resistance experiments, test panels of the material used with stood temperatures of up to 1700 degrees centigrade without effect.

At the recent launching, the managing director and founder of Ferro Cement Marine Construction Ltd., Mr. Philip A. Leonard, said that at present the size of ferro cement vessels is limited to about 100 ft. This limit was not imposed by the material itself but by the application of the cement to the steel matrix.

Research was continuing and it was hoped that much larger vessels could be built within a short time. Mr. Philip said that his company was already capable of building pre-stressed barges comparable in size to the largest steel barges in the world.

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Far East BUILDER, November 1969