I'll go with the others who suggested that you should get 4-5knots. In practice, under good conditions, maybe a little more. Do use a GPS
and a trial run to get a much more accurate idea of power setting, fuel consumption
and expected speed.
What I would suggest is to get a copy of the "Beacon to Beacon" book. It shows the recommended routes through Morton Bay - helps in keeping away from big ships and off the sandbars. It also gives distances between waypoints.
Bitter experience has taught me that you need to have a plan on how to stay well away from all commercial
traffic. While there are some real gentlemen who understand the difficulties of managing a small boat there are others on the other end of the bell shaped curve.
When we came through Morton Bay I put the Beacon to Beacon tracks into our plotter and set the autopilot
to follow the tracks. Worked out pretty well.
If you can get hold of a copy of Lucas' Guide it has some pretty good tips for most places. We followed them all the way up from Sydney
and they worked out pretty well.
I had a look at Google Earth
and have saved a sreenshot - see photo
. My experience has been that it is essential to arrive at any river on a rising tide. Lucas may have some recommendations here.
gave me a distance of 40 nm from the mouth of the Mooloolaba Rive to the entrance of the Cabolture River so I'd plan for 10 hours for that plus an hour or so of mucking about either end. It looks doable in daylight but there's not a huge safety
The other essential is to check your weather
forecasts carefully for at least a few days before you leave. I'd echo those sentiments about not going with any forecast
above 15 knots.
Do check your fuel
carefully (both for quality and quantity) and have a couple of spare filters ready (a new one to start the trip may be a good idea) and know how to bleed your injectors.