The Titan, like many of my other models, began with the cockpit. The design came from an interesting idea I had, to use the large windscreen panels from the Aquabase Invasion (7775) at angles I hadn't seen before. So, after two days of building, redesigning, rebuilding and brick math (yes, building using opposing angles can take some extra thought) I finally arrived at a model that was sturdy, functional and visually striking. The cockpit features seats and controls for three, along with extra scuba gear.
From the cockpit I started working my way back, building an airlock tunnel, fins, engines, a cargo area and other features. The door to the airlock opens when not otherwise impeded, though it is cramped enough to be pretty impractical during use. The large scaffolding columns along either side were a feature I wanted from the beginning, and built the rest of the model around. Behind the airlock is a small sliding track, on which the tiny submersible craft from set 7775 can be mounted and released out the back of the vessel. I later added hoses and valves (always a nice feature) and decided they may be used to regulate the airlock. There is also a spare air tank nestled between the hoses and scaffolding columns, just barely visible in the picture. Mounted above the cargo track is a Blunt shooter (That's just what I call it; the real name is 'Technic Missile Launcher'), which has a limited range of motion both vertically and horizontally. The propellers are the only pieces not from an Aqua Raiders set, since I didn't have any others bulky enough to suit my needs.
I used the leftover pieces to build a docking pad of sorts, which also doubles as a nice display stand. It isn't terribly flashy, but has some useful things like air tanks, spears, etc. With more bricks I'd love to make a better one, but it was not opportune at the time.
Along with the Titan, I built a much smaller, personal craft which I dubbed the Vindicator. It's a little smaller than the Deep Sea Treasure Hunter (7770) but has all the bells and whistles, namely jets, fins, control panels, spear guns and translucent cones (who knows what those are ever meant to really be?). For this model I toyed with the idea of the pilot merely hanging on, with no actual seat. As a result, there are no exposed studs on the entire craft, making for a sleek, hydrodynamic look. The main spear guns are also locked in place and not removable, which I needed to do in order to have the connection between the jets and the front of the fuselage. (Yes, there are additional spear guns on the bottom for minifig use). It can also be easily attached to a joint and transparent post for display (seen below).
I enjoyed building both of these models, and I intend to build up a large enough collection of classic underwater sets to use those themes as well. In the meantime, Happy Building!