Some boats (Gemini's) don't have or need a bilge
pump. Boat comes with a 250 gph shower sump
pump with a hose that you can, if needed, take to the either side and
pump.
Something about half boats having tons of lead that makes them sink, I watched my slip neighbor get deeper and deeper in the water last year, only the ground and his keel kept him above water by spring.
Having said that, the plan (boats new) is to retro fit an automatic
pump in both sides, dumping into the centerboard slot with single intregrated switch because my 'bilge' is actually only 4 inches or so deep.