The exhaust emissions from ships are not only discussed in terms of GHG (greenhouse gas) reductions. The operators of offshore supply vessels (OSV) are concerned about their technical employees who work primarily on deck and are exposed to the exhaust. In addition to these health matters, yacht and cruise ship operators want to avoid that passengers be disrupted by the smell of exhaust gases.
You just got some 2D sketches and need a 3D model? You got a 3D geometry with holes and need a watertight one?