The CS27 has a pretty standard set of plumbing components. There are through hulls and associated valves and hoses. These work with the head (toilet), two sinks, engine water intake, cockpit drains, and bilge pump system. In addition, most CS27s appear to have been purchased with a pressure water system which feeds the two sinks.
A common problem with boats built in the 1970s was the use of gate valves. They are not compliant with modern standards of boat building, and at nearly 30 years of age, most of it spent in water, they are dangerous. They had to go. With a 30 year old boat, you often have 30 year old rubber hoses attached to those gate valves. Guess what? Rubber doesn't last 30 years without some form of structural compromise. The hoses have to go as well.
The bilge pumping system in this boat is very much 30 years old. It has a few issues I want to address. There are multiple bilges in the boat which mean having to deal with pumping multiple areas. I think a few strategically placed limber holes would help. In addition, the only pump is a manual one with 1.5" hoses. It's not even able to remove water unless the depth is 2+ inches. With this redesign I intend to relegate the manual system to something which is rigged up in an emergency, but not in the way for normal use. The primary pumps will be electronic, and will cover all necessary bilges, as well as having a degree of redundancy.
Galley Stove Update
My boat came with a two burner gimballed propane stove in the galley. The propane tank which fed it was mounted in an ugly rack off the stern pulpit. It jarred the graceful lines of my boat and I wanted it moved somewhere I didn't have to see it. After much deliberation, I decided that the boat's original design was best, and that used an alcohol stove. A modern non-pressurized alcohol stove is much safer than the older designs, and does away with the complex and expensive ABYC propane codes. What really sold me on this strategy was getting rid of the stern propane tank.
The existing holding tank has three problems. The access hatch is sealed closed and has broken tabs. There is one 1/2" vent, and there should be two 3/4" vents by modern conventions. And last, the lower fitting (pump-out) leaks. Not cool. Newer tank designs use a pick-up tube for the pump out which keeps all fittings high and avoids the leaks, even when changing hoses. Can't have poop leaking under the v-berth.