IRG/COIPM INTERNATIONAL MARINE TEST - to determine the effect of timber substrate on the effectiveness of water-borne salt preservatives in sea-water. Progress Report 7: Second report on the samples in Papua New Guinea
S M Cragg, C R Levy
This report presents the findings to date regarding specimens installed in Papua New Guinea, as part of a world-wide marine trial of certain timbers treated with CCA or CCB preservatives. The details of the trial are set out in document number IRG/WP/414. The report discusses the findings in the context of the conditions prevailing at the trial site and of the properties of the trial timbers. The trial is the third to be installed in the waters of Papua New Guinea. In 1967, pine and eucalypt samples treated either with CCA or with creosote, were installed at Rabaul, Lae and Port Moresby. Tamblyn et al (1978) describe the performance of these samples. A second trial, consisting of fifteen Papua New Guinean timbers, vacuum/pressure treated with CCA, was established at Lae and Port Moresby in 1973. This trial is described in the report of Rayner (1974). The necessity for effective treatment against marine borer attack is particularly evident in the waters of Papua New Guinea. Shillingaw and Moore (1974) found that most wharves constructed around the coast of New Guinea during the war became unserviceable within eighteen months. A timber which has a considerable reputation for durability in Australian waters - turpentine (Syncarpia glomulifera) - has proved to be vulnerable to borer attack here; it gives a service life of as little as two years at Wewak, though a somewhat longer life can be expected at Port Moresby. The most destructive borers in these waters are the members of the family Teredinidae. Nearly forty species of teredinids occur here. The isopods, Limnoria and Sphaeroma are also responsible for damage to timber wharf installations in certain areas. The pholad Martesia is also found, but never in sufficient numbers to cause economically significant damage.