That helical wheel was the idea of Captain Phil Elsey, who had the reputation of being unable to let well enough alone. The primary idea was to reduce vibration. That worked fine. The buckets were expected to push better, but that was a very iffy result. When backing the boat tended to "wander" and pilots seldom knew which side she'd take. Those three monkey rudders were really needed when handling. The idea worked well enough that both this boat and the Weber W. Sebald had helical wheels until they were retired.