There are basically three bilge areas in the midsection of a Mac26X. Port and Starboard bilges outside of the water ballast transfer tubes that run fore and aft on each side. Then there is the Center bilge between. These all interconnect via spillover so the limiting height (or depth) of water in any one bilge before it communicates to the next bilge is the water transfer tubes. The aft berth is just about resting on top of the water transfer tubes. The typical battery location of the Mac26X is the little port side bench box aft of the galley. The bottom of the battery typically rests on top of the water transfer tube and the battery clamps to the center facing wall of the bench.
No doubt there is a significant amount of water that can collect in the center bilge and over flow into the side bilges (or Vice-versa) but the water would have to leak out of the four access covers of the aft berth floor and into the interior of the cabin before gaining more height.
(Note 1: There is also the floor cover to the bilges under the dinette where water would flow out of … There is also the standard cutout of the galley for the black insert cubby.)
(Note 2: There are also two smaller bilge areas in the aft stern corners that would also fill/overflow to the other bilges at the height of the water transfer tubes.)
All these openings are 4 to 6 inches below the battery terminal height.
Now if the boat is heeled over to either side the relative water height will of course increase but at the same time will still leak over the hatches and other openings.
But getting the water level high enough to potentially “short” the battery terminals would already have water collecting in the cabin floor.
The aspect of the hole in the cabin floor is a good thing to get water into the bilge as well as acting as a tell-tale that water is in the bilges.
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Seems like benefits are pretty high compared to detriments.
Just kind of glad that our Mac26X has the hole as do many other sailboats. It seems like not having one would be a manufacturing mistake and not adding one a liability….
Also glad that we pre-emptively added our three bilge pumps and bilge water alarm as personally We’d rather have the pumps available do the work and the alarm sound well before water is sloshing in the cabin and gaining altitude
The peace of mind that some time could be bought should an incident occur is nice to have for us (especially given the awkward accessibility of actually getting to the bilge areas manually).
For us the addition of bilge pumps and alarm we hope to never need is a great investment.
( As for cleaning up a spilled soda pop getting into the bilge on the Mac26X one can get to the center bilge area via the aft dinette bench to clean up
. Although I’d probably look on it as a justifiable excuse to deliberately do a controlled flood of the bilge with a garden hose to test the bilge pump and alarm 
)Your boat, your rules….
Best Regards,
Over Easy
there is a solid floor at the dinette and no holes there either, so with the battery box being centered and lower than the 
, the bilge could fill dangerously close to flooding/shorting those batteries before overflowing into the companionway floor.
