Originally Posted by tugboatdon
I have seen pictures of this type of sailboat and she likes to heal. So anywhere near midship might cause a problem with egress of water.
I gather you mean ingress of water when the boat is heeling. You could run a vent line out through the transom I guess. That would work ok except possibly with a following breeze, just keep it an adequate amount above the waterline.
Why are you locating the holding tank so far from the head? At least I assume it's farther than necessary.