1) Forward head toilet discharge
2) Forward head sink discharge/toilet intake
3) Galley sink discharge
4) Refrigeration intake
5) Refrigeration discharge
6) Bilge pump discharge
7) Cockpit drain
8) Raw water intake
9) Speed Log
10) Depth transducer
11) Aft head toilet discharge
12) Aft head sink discharge/toilet intake
From the above list, I'm confident that several of these could be combined using "Y" valves, and at least two could be eliminated completely.
The speed log is just about useless. The only speed that really counts is your speed over ground, which is the information derived from your GPS. Glass that one over.
The depth transducer is another that you may be able to eliminate. This, of course, depends upon whether your boat's bottom is cored or solid glass. If the bottom is solid glass, which is the case with most boats, you can shoot the depth directly through the hull from the inside using a puck type transducer. If the bottom is cored, then you'll have to stick with the thru-hull transducer.