One of the principle factors involved in our decision to buy Odyssey was that the storage bays were tall enough for us to contemplate putting a pair of small motorcycles in them. Furthermore, one whole bay on Odyssey, just as she came to us, was empty all the way across, with a full door on each side. (Well, OK, it had a golf cart in it, but we dispensed with that in short order.) So the starting point for our bay design was that this bay would have to remain vacant for this purpose.
Since we ended up ripping out all the systems that had been located in (and almost completely filled) the rest of the bays, we once again had a clean sheet to start with. On most buses, starting with a set of empty bays makes the systems layout a walk in the park. However, Odyssey, being a Neoplan Spaceliner, has a very unusual bay layout. To begin with, while the two forward-most bays look identical from the outside, only the front one is actually a rectangular prism (a box-shaped volume) and close to the size it appears to be from the outside. The next bay back has a large obstruction in it, specifically, structural framing above the A-frame (the main thrust-transferring member connecting the drive axle to the rest of the frame), as well as the housing for the A-frame swingarm pivot itself.
Since the more easily used, empty forward bay was inviolable as the only viable place for the motorcycles, we had to somehow come up with a layout for the oddly shaped second bay that would accommodate all our tanks, as well as water heater, pumps, and an auxiliary air compressor. To make matters worse, the massive 17KW generator was already located in this bay, on a pair of hefty slides. We also had the two shallow (about 11" tall) bays above the two rear axles to work with, but we very quickly determined that the only systems that would fit there would be water tanks, and storing water that far back would wreak havoc with our weight-and-balance equation.
I immediately set to work with an accurate scale drawing of the framing in bay #2 that would have to be worked around, and a copy of the Ardemco poly tank catalog.
Everything else would be driven by determining a workable combination of tanks to go in this bay. With the generator already in the bay, it was going to be a very tight squeeze indeed. In fact, the only way to make it work, and also keep the left-right balance of the coach fairly constant independent of tank fill, was to turn the generator 90 degrees from its existing orientation, which would necessitate even larger slides to access it for maintenance, and a magic feat to get an exhaust system in place that could tolerate the entire system sliding 4-5' for this purpose.
As I was in the umpteenth design iteration, Infinity, having finished stripping out old house batteries, inverter, and a giant battery charger (the kind normally used for forklifts), as well as bunch of A/C condensers for the old driver air system, started investigating the possibility of relocating the generator to the pair of compartments at the right-rear corner of the coach where these items had been located. It would mean cutting out a minor piece of framing, and reinforcing to compensate, but it would give us a good location for the generator that had direct maintenance access, meaning we could dispense with the heavy slides, and use a fixed exhaust system. Another benefit to this location is that it puts the generator in an area that is already designed as an engine room, with all the implications thereof. The only downside was moving that much weight to the very rear of the coach -- a factor we compensated for by moving the house batteries from their originally planned location (over the drive axle) to the area over the front wheels.
With the generator thus relocated,
bay #2 became available in its entirety for tanks and associated equipment, and we began to call this the "wet bay." The A-frame tower was still a design factor, and I spent many more hours with the Ardemco catalog until I came up with a combination of tanks that would fit. Here is a drawing of the layout. The red lines represent the fixed structure of the bay and A-frame tower. Note also that we have both a "fresh" water tank and a "drinking" water tank -- a design goal that we included in the spec based on our traveling experience: sometimes, drinkable water is unavailable, but you still need to fill your tank to have water for washing and sanitation. We will carry a portable pump with us, so that the fresh water tank can even be filled from a stream or lake if necessary, while the 45-gallon drinking water tank, being used for no other purpose, should let us go quite a ways between potable water sources.
Here is a "floor plan" of the entire lower level of the coach, including the bays.
Turning our attention back to the motorcycle bay, we needed a way to get the bikes in and out. Moreover, the pantograph-type bay doors did not rise far enough to completely clear the opening into the bay, a problem that would limit even further the size of any motorcycles we tried to fit. Infinity was able to reinforce the bottom of the door openings to accept a hinge, and, after a good deal of searching, I was able to find spring-loaded cable retractors to balance the weight of the doors as they swing open, making the doors themselves into loading ramps and simultaneously getting them clear of the opening.
As I mentioned above, the additional weight of the generator in the rear meant the house batteries would have to go as far forward as possible. Fortunately, we were already contemplating using AGM batteries, which are relatively safe to locate in personnel areas, and the 8D size is a perfect fit above the front wheel wells. More detail on the battery layout is in the electrical section.
Rounding out the "lower level" we have the cockpit forward of the steer axle,
and a small tunnel between the front wheels leading from the cockpit to the motorcycle bay, which will be closed off by a sliding fire door while underway. The shallow bays above the rear axles are mostly empty and available for storage, although a small section at the rear of the right side for intake air ducting for the generator (the intake air is brought in from between the tags, above the transmission, for noise reduction) and part of one bay one the left side is allocated to the cats' litter boxes (conveniently accessible from outside the coach for cleaning)