Described is a multi-use offshore structure having a first configuration and a second configuration. The first configuration includes a pontoon base disposed at a lower end of the multi-use offshore structure. A deck is disposed at an upper end of the multi-use offshore structure, and hull column structures extend between the pontoon base and the deck. The second configuration includes the pontoon base, the deck, and the hull column structures of the first configuration. A set of sponsons is formed to be installed on the hull column structures, and a deck expansion unit is connectable with the deck.

Described is a multi-use offshore structure having a first configuration and a second configuration. The first configuration includes a pontoon base disposed at a lower end of the multi-use offshore structure. A deck is disposed at an upper end of the multi-use offshore structure, and hull column structures extend between the pontoon base and the deck. The second configuration includes the pontoon base, the deck, and the hull column structures of the first configuration. A set of sponsons is formed to be installed on the hull column structures, and a deck expansion unit is connectable with the deck.

A method of manufacturing a submersible vessel, the method comprising: forming a foam mold of a predetermined shape and size from at least a first piece of foam having a first density and at least a second piece of foam having a second density; cutting at least one channel into the foam running in a longitudinal direction or a lateral direction within the foam; and coating the foam with at least one layer of reinforcing fiber and resin.