We have an F33 and it sounds similar in set up with a box section runing between the 2 engines which the engine mounts go on to. The Engine room bilge pumps are located in this box section and we have an access hatch at the front and rear. I believe this set up is there to prevent you pumping bilge water from directly under the engines and has the drain holes and bilge pump float set in a way that minimises the risk of you pumping oil etc overboard.
We had a lot of oil in ours following an engine issue and it has take a long time to get it properly cleaned out, we found that after manually cleaning it, sticking an oil absorbent roll got rid of the rest. Leaving some water in there will help it swill around a little.
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