The deep water offshore platforms (>300 m) is expected to grow from 3% in 2003 to10% in 2020. The semi submersible is generally used for wet tree operation and is not suitable for East Coast in the Bay of Bengal since the 100 year design waves are of 20 m significant height and 14 s period. Hence, a dry transportation with self-erection capability is looked with a semi-submersible concept with telescopic keel tank. The new vessel technology is suitable for dry-tree support production and this reduces the cost of the entire field development in the East Coast of India. The new platform produces acceptable heave, pitch and surge motions and highly stable and reliable to operate with moderate storms. The risers, moorings and umbilical hanging loads are significant in a deepwater and could be supported by the extra buoyancy in the keel tank and thus the deck pay load is not affected by the riser, mooring and umbilical pull down loads. © 2013 Taylor & Francis Group.