I'm doing a refit this winter.I have C-30 #10, built in 1975.It still has two of the original glassed in pipes with gate valves for the sink drain and the engine raw water intake.The head discharge and intake through hulls are under the port side settee.Where are the through hulls on the newer boats?I'm going to change the glassed in pipes and gate valves for proper through hulls and seacocks (not pipe fittings and ball valves). I'm also going to change the head intake to a flush fitting rather than the mushroom type that is there now. The head intake and discharge need to be moved so I can finally install a holding tank.The head intake can go under the sink in the head. I suspect the discharge should go somewhere aft of the macerator?The sink in the head shares the galley sink drain (long hose), do the new boats also use this system?I'm assuming the holding tank should go under the port settee (where my through hulls are now)? How big is the tank?I'd like to know where the through hulls are on the newer boats so I can end up with a system that works correctly.Thanks in advance!