Scott Lithgow's Kingston shpyard at Port Glasgow which, in 1982, was building 3 semi-submersible barged to facilitate the assembly of the deck module onto the jacket of the semi-submersible drilling platform Sea Explorer (corrected identity),building at Cartsburn.
Correction and additional information courtesy of Tom Carreyette -
"The barges SLB1, 2 & 3 were for the load out of deck module for semi-submersible drilling rig SEA EXPLORER. The pontoons & columns launched from Cartsburn (seen in the next picture) were ballasted down at The Hole (deep part of Tail o' the Bank) and the deck floated over on these 3 barges for 'mating'. OCEAN ALLIANCE was a different semi-sub built and launched in one piece from the Glen Yard, under the Goliath crane."