What's the purpose of the vermiculite? Maybe now that you have cleaned it all out, could you put stringers and limber holes in and make one common bilge? I like the removeable floorboard idea in that area for future access and maintenance.
We have hull # 497 and there are 3 hoses, encased and running through the verm dam. Manual bilge, drain for aft end of hull and icebox drain. The manual bilge had cracked (I fed a smaller diameter hose through the original) and water had saturated the area and raised a lump in the floorboards. The other two drains work, but at some point I'd like to clean the whole area up underneath.
