“There are also the “Plan A” and “Plan B” versions, which seem to have been available through both builders. The original Sen Koh boats (Plan A) had access to the engineroom through a hatch in the galley sole as well as through a small door from the lazarette. The hatch had a vertical ladder and, as one owner noted, more than a few people have fallen through the open hatch, not knowing someone had left the galley hatch open while working in the engineroom.
DeFever designed an alternate layout called Plan B. It included a stairway that went from near the galley into the master stateroom, which had the berth turned athwartships to allow a full-sized door into the engineroom through the after bulkhead.”