Sorry I bailed out of this discussion, an unexpected trip away. We've bitten the bullet and ordered the Flonet series for 2x twin engine boats. Not cheap but payback will be under 6 months if we can achieve 5% fuel savings by operational changes. We went with the higher end model as it has a data logging function and the ability to query realtime data via smartphone. If we're going to make changes to operational speeds etc we needed to know the skippers were implementing them properly.