Samples of 3 wood species including: Beech (Fagus orientalis), Oak (Quercus castaneafolia) and Hornbeam (Carpinus betulus) were treated with creosote and celcure. The dimension of samples were 200 x 7 x 20 mm. Both treated and untreated samples were placed in sea water (Boshehr in Persian Gulf) according to IRG/WP-4432(l985). After 5, 9, 15, 24, 29 and 38 months, the samples were inspected according to recommendation of ASTM D 248. The control samples (untreated wood) of Beech, Hornbeam after 9 months, the samples of Oak after 14 months, seriously attacked. Treated samples of Beech, Oak and Hornbeam with celcure, after 14 months, were seriously attacked. Creosote, treated samples of Beech, after 29 months, Oak and Hornbeam after 38 months were seriously attacked. It can be concluded that treatment with creosote using full cell process (Bethell) increased resistance of investigated wood species against marine borers.

Four hardwood species including: Alder (Alnus subcordata), Oriental plane (Platanus orientalis), Eucalyptus camaldulensis and Babul (Acacia arabica) were treated with Creosote and Celcure. The dimension of samples was 20 x 7.5 x 2 cm. Both preservative treated and untreated samples were placed in seawater (Boshehr in Persian Gulf) according to IRG/WP-4432 (1985). After 9, 15, 24, 29, 38, 47, 53, 58 and 64 months, the samples were inspected according with recommendation of IRG/WP-4432(1985) and ASTM D- 240. All the control samples (untreated wood) of Alder and Oriental plane over 9 months, Eucalyptus and Babul over 20 months, were seriously attacked. Treated samples with Celcure of Alder and Oriental plane after 38 months were completely damaged and Eucalyptus over 38 months were severely degraded. Creosote treated samples of Eucalyptus over 58 months and Babul over 38 months were seriously attacked. Creosote treated of Alder and Oriental plane samples after 64 months installation were sound. It can be concluded that treatment with Creosote using full cell process (Bethel) increased resistance of investigated wood species against marine borers.

Wooden structure, specially vessels and launch boats were studied along all shores and ports of Persian Gulf, Oman Sea and Caspian Sea during two years in different seasons .Factors causing damage in the vessels and coastal wooden constructions were evaluated. Based on the results, north coasts, as compared to south cost of the country, were affected more intensively by fungi damages were lower at Caspian sea shores than those at shores of Persian Gulf and Oman sea. A major reason of this is lower level of salt in Caspian sea than in Persian Gulf. At the south coast, in addition to wood decay, marine borers are the main cause of damages. At coastal zones of Khozestan province, fewer damages were found, as compared to other points of several rivers flowing to the sea at these shores and sailing of vessels through low salt waters.

Wood samples of teak (Tectona grandis) , keruing (Dipterocarpus alatus), yellow balau (Shorea laevis) and chengal (Balanocarpus heimii) were treated by Creosote, using ruping method. The dimension of samples were 200x75x20 mm and the retention were 188, 186, 331, 40 kg / m9 respectively. Both treated and untreated samples were installed in sea water (Mahshar in Persian gulf and Bandar Torkman and Noshahr in Caspian sea coasts) according to IRG/WP-4432(1985). In Mahshar coast, after 6, 10, 20, 23, 27 months and in Caspian sea coasts every 6 months and after 11 years the samples were inspected according to recommendation of IRG/WP-4432(1985). In Mahshar coasts (Persian Gulf), during this installation period, the control samples (no treated) of chengal and keruing were sound, samples of balau were severely degraded and Teak samples seriously attacked. All the treated samples after 27 months installation in sea water, were sound. In Caspian sea coasts, expect soft rot on the samples surfaces, both treated and untreated samples after 11 years installation were sound. It is concluded that there are no marine borers in Bandar Torkman and Noshar in south coasts of Caspian sea.

7 hard wood species including: Beech (Fagus orientalis), Oak (Quercus castaneafolia), Hornbeam (Carpinus betulus), Alder (Alnus subcordata), Oriental plane (Platanus orientalis), Eucalyptus camaldulensis and Babul (Acacia arabica) were treated with Creosote and Celcure. The dimensions of samples were 20 x 7.5 x 2 cm. Both preservative treated and untreated samples were placed in seawater in Mahshahr (Persian Gulf), Bandar Torkman and Noshahr (Caspian Sea) coasts according to IRGIWP-4432 (1985). In Mahshahr after 8, 17, 23, 28, 35 and 49 months, in Bandar Torkman after 8, 14, 22, 29, and 39 months and in Noshahr after 8, 18, 25, 31 and 40 months, the samples were inspected according with recommendation of IRG/WP-4432 (1985) and ASTM D-2481. All the control samples (untreated wood) of Beech, Oak, Hornbeam and Alder over 22 months, Oriental plane over 25 months and Babul over 20 months, were seriously attacked. Untreated Eucalyptus and all the treated samples with celcure and creosote were sound. All the treated and untreated samples in Caspian Sea were sound. It is concluded that there is no marine borers in south coasts of Caspian Sea.

Wood samples of seven Iranian hardwood species including: Beech (Fagus orientalis), Oak (Quercus castaneaefolia), Hombeam (Carpinus betulus), Alder (Alnus subcordata), Oriental plane (Platanus orientalis), Eucalyptus camaldulensis and Babul (Acacia arabica) were treated with Creosote and Celcure. Then the samples were installed in the sea water of Bandar Abbas coast (Persian Gulf) for a period of 36 months. During 9, 12, 18 and 36 months, the samples were inspected according with recommendation of IRG/WP/4432(l985).The results showed that, untreated samples of all species were not resisted to the marine borers. The samples treated with creosote using full cell process increased durability of all species expect Hombeam and Babul. Treated samples with celcure were not resisted very well and after 15 months were destroyed.

Samples of teak, keruing, balau and chengal were treated (impregnated) by coal tar oil (Creosote) using ruping method. The treated samples were compared with control samples of exotic wood, beech and oak (Iranian wood species) were also installed in sea water according to IRG/WP/4432. During 6, 9, 21, 28, 46 months, the samples were inspected according with recommendation of IRG/Wp/4432. During this installation period, all the control samples (no treated), expect chengal, were seriously attacked by marine borers. All the treated samples, expect balau, after 46 months installation in sea water, were undamaged. Treated samples of Balau after 21 months were attacked by marine Borers.

The importance of maintenance of naval construction and their intensity of destruction have taken our attention to carry out a research project on this connection. The aim of this research shoud be described as follows: 1- Study on natural durability of the exotic wood species (Teak, Keruing, Balau, Chengal) against marine borers. 2- Study on the effect of treatment on increasing of durability of those species. Among those species, some sampling have been choosen using C.R.S. Method. Samples, were treated (impregnated) by coal tar oil (Creosot) in Gazvin impregnation plan. The treated samplings were compared with control samples of exotic wood, also beech and oak (Iranian wood species) which have been installed in sea water according to IRG/WP. During 6, 9, 19,21,27 months, the samplings were inspected according with recommandation of IRG/WP. During this instalation period, all the control samplings (no treated), expect chengal, have been seriously attacked by marine borers. All the treated samplings, after 20 months instalation in sea water, were completely safe.