#20 G.A.S. 16.6 knots, not impossible as I was on 1943 ships that service speed of 15 knots with a little bit in reserve.
#19 Work never stops on a ship whether in port or at sea. In port there are numerous derricks working cargo, anything twixt 10 and 24 per vessel, average Port Line vessel 16 - 20, these need constant attention shifting luff and position to stevedores requirements, cargo runners to change when stevedores deliberately got them jambed and kinked because they wanted a smoko or finish early and still get paid. Moorings and gangway to constantly monitor, slack or tighten, raise or lower. Dunnage down hatches to collect stack and secure, derrick guys and preventers to monitor slack or tighten, hatches to open/close, cargo tents to rig/unrigg, hatch boards to take on and off or macgregors to open and close, chipping and painting away from where stevedores are working, don't want to give them an excuse to stop working because of noise, lifeboats to turn out, turn in and secure, stages and bosuns chairs to rig, painting overside on floats or stages or on quay, tweendecks and holds to clean, broken mooring ropes to resplice, new splices in back springs, we haven't scratched the surface yet,
Alas as most people think, we do not spend all day in the bunk or sunbathing or sightseeing when in port, only Radio Officers have that privilege!