Just a follow up on this post, I did not realise it was that long ago. I finally got new pair of F70 Yamahas fitted at the end of last year. I have done 21 hours on them and at this stage I can not complain. They are fitted with 15 inch yamaha aluminium props and the height is set the same as the previous 2 strokes.
The old 2 stokes were fitted with aluminium 17 inch props.
I have no intention of changing props as I am happy with the performance.
With 2 people on board and half fuel it revs to 6300 rpm at 63 km/hr.
Attachment 116679Attachment 116678
I am happy with the fuel economy with each motor doing around 3.1 - 3.2 km/lt @ cruise.