REBEL surveyors who tarnish the image of the trade should be ''penalised'' by respective flag states, says Norwegian-based Det Norske Veritas (DNV) president and executive officer Sven Ullring. Mr Ullring said it was unethical for a surveyor to issue a safety certificate to a vessel which did not meet sufficient requirements. ''Work is going on in the International Maritime Organisation (IMO) towards having a unified requirement for flag states that will address this problem,'' said Mr Ullring, who was in Hongkong to meet the national committee of DNV, comprising members fromthe shipping industry. He also agreed that some flag states were not taking their services seriously and hoped that the IMO's initiatives would resolve this problem and, in turn, curb activities of surveyors who damaged the reputation of the trade. This was part of a new form of international co-operation that was needed in the industry for the promotion of safety today, Mr Ullring said. ''It is not sufficient that each single set of rules is good in itself if the user can fall through, or deliberately exploit, the gaps in the system,'' he said. He emphasised that quality and safety must pay off for ship owners - for their investment in quality ships, quality maintenance, quality crews and quality operations. ''I think it is important to realise that safety and quality means profitability as quality will lead to good results in the long term,'' Mr Ullring said. He added that higher differentiation of insurance premiums related to quality should be introduced. ''Differentiated premiums would also induce charterers to prefer quality vessels over sub-standard ones,'' he said. But he admitted that although such calls had been raised and many organisations realised that something should be done about it, not much had been achieved. Mr Ullring said he noted that Hongkong shipowners who had accepted safety management much earlier than their counterparts elsewhere, had 130 vessels classed by DNV. DNV's regional manager Eivind Grostad said DNV had classed a total of 220 vessels owned and managed by Hongkong companies. Mr Ullring said that despite the new ship deliveries, ageing vessels would be of concern for many years. ''In the period 1993-95, half of the world's tankers will be due for their 20 year survey and very many of them will not be able to pass it,'' he said. Commenting on ship accidents, Mr Ullring cautiously stated that the increase of accidents in 1991 had been been steady in proportion to the growing world fleet and 1992 had been better. But he admitted that in the beginning of this year there had been a number of accidents in the Atlantic due to terrible weather. He declined to comment on the trend until these accidents were analysed at the end of the year. Mr Ullring said DNV, which had a 14 per cent share of the classification market, had taken several measures to meet the challenge of older tonnage. The organisation had its staff undergo extensive training, put its surveyors through re-qualification programmes and increased scope of inspection of vessels as they got older.