The boat is a 6.75m Hooker centre console It has 400L tank and is very fast with 225 suzy on the back. I only plan on going if conditions are perfict and was thinking of camping at roonies. Fuel should be no probs the Hooker gets about well at 26 knots only using 14L an hour.
Do you have to cross the bar?
I also have access to a mothership if need but at a price
You don't have to cross the bar if you go right to the top. There are several shifting channels which can be navigated before the end - best to utilize local information for this.
We use roughly 90 litres of fuel in a 260hp Yanmar diesel just getting to Roonies. You'll obviously conserve a lot of fuel if you just cruise but the temptation to gun it is often irresistable. You need to remember that you will be travelling at least 80km just going back and forth each day from the end of the spit. We took 600 litres of fuel and still struggled to safely fit in 3 fishing days - general statement to take in as we did a lot of moving around.
Either way - plan wisely! If the weather blows up it would be wise to turn back or half your projected mileage for the trip.