A friend is sailing 2 up in a Marauder 27 from the mainland to Hobart and his fiance just called me and said that he had been in contact with her and they are off Flinders Island and she is wondering with the current forcast roughly how many days sailing he would have before he would be in Hobart
At a rough estimate i reckon he has around 300nm to go and i have looked at the forcast for the east coast and i would estimate roughly 4 to 6 days if they dont make any stops
I did single handed Stanley to Devonport 10 hours , Devonport to Foster inlet 10 hours Foster inlet to wineglass in 18 hours, and wineglass to Hobart in 12 hours. Nearly didn't make it into Hobart after hitting a storm in STORM BAY! So about 4 or 5 days it took me averaging 5 to 6 knots.
I think you are pretty close to the mark, presuming that they have winds aft of the beam.
27 footer setup for cruising with 2 people, fuel, food and water - I'm guessing 3.5 - 4knots ave speed over the ground is a good average to work to. Add in some time for the occasional calm etc.
I would work on 4-5 days and provision for 6-7 worst case. Presumes they are sailing through the night and not heaving to etc.