Mobilisation of a diving support vessel

N-SEA Offshore intended to hire a DSV (diving support vessel), but due to unexpected circumstances they were forced to hire the OSV Larissa, an offshore supply vessel.

This meant that the OSV Larissa had to be adapted to function as a DSV, which involved placing a lot of equipment on the large aft deck of the ship. Not only containers with specific diving equipment, but also stores, tools, a command office, a decompression room, racks with oxygen and Nitrox gas bottles (quads) an HPU, LARS, generators, a chute, etc. etc.

NSEA needed sea-fastening engineering for this project urgently and Vuicon was asked to make the sea-fastening calculations to Seastate 5, the deck layout and the detailed drawings as soon as possible. All equipment had to be placed in a logical order, taking into account the relation and the distance between the various pieces of equipment. Moreover, we had to create logical walkways and doors that would open without obstructions. After a few changes the most optimal configuration was chosen. One of our naval engineers arranged frames with breech plates and dovetail twist locks for 10 and 20ft containers and an HPU. Some containers and racks were placed direct on deck or in between beams with lashing D-rings.

On the wooden deck surface of the Larissa are steel T-bars which could be used to secure the loads by welding-on brackets and lashing D-rings.  In this way, sea-fastening frames, beams and lashing points were connected to these T-Bars. All sea fastening items were calculated and reported by one of our structural engineers. Shop drawings of the frames and beams were made. Also a lashing plan was issued to indicate where to weld lashing points and connect ratchet straps and chains with chain tensioners.

The ship was mobilized in the port of Den Helder and started the project in time. Vuicon thanks N-SEA Offshore to trust Vuicon Engineering to design (sea) FAST! (-ening).