Cranfield Institute of TechnologyResults incorporated in this report show that SMAW may be successfully applied to underwater repair and maintenance tasks. However, process tolerance is tight in view of limitations on acceptable pre-heat levels usable in confined sub-sea habitats. It is therefore suggested that further investigations with SMAW should be conducted to explore ways in which the process can be more safely applied. It is also recommended that suitable forms of very low hydrogen processes are examined with a view to hyperbaric operations.