Last tank left is the 100 gallon center fuel tank. The space allows for a taller tank, but, in the future, such a tank could never get through the companionway, so the size of the tank was limited to one that would fit. As a result that has left some empty space underneath.
Now, never wanting to let empty space go to waste, we came up with an idea for usage: grey water storage. What?
Well, my wife, working in the marine construction/repair biz, is always hearing rumours of overboard discharge regulations becoming more restrictive. Boaters are well aware of the existing laws prohibiting black water discharge on inland waters (boats must have holding tanks and pump out at pump out stations throughout the area). But, there are some areas that prohibit discharge of ANYTHING. Including stuff from sink drains. There are a few such areas up in Canada (Desolation Sound) and I think Lake Washington is a no discharge zone. The Dept of Ecology continues the "threat" that discharge regulations may get more restrictive.
So, given this potential restriction, and this empty space we are presented with in the boat, we decided to install a grey water tank. Turns out Ronco Plastics makes an 18 gallon tank that will fit this space just nicely. It will have to be installed from the engine room by "sliding" it through the bulkhead, underneath the center fuel tank. It will have a 1 1/2" inlet and outlet, 1/2" vent, and 6" inspection port all accessible from the engine room. In may not ever get plumbed/used till after launch whenever the laws appear imminent.