3 kts down, where's it gone?

[Max...]

Tach worked great but too choppy for real testing. Bouncing around so much hard to be exact but I think max revs at WOT was 5300 or so. Not exactly ideal conditions though and as per 'losing air' topic not the best day for other reasons.

[lightning]

My Tohatsu 9.8 managed about 5500rpm on calm waters.

This equated to a max speed of just under 20mph. So it sounds like you have got it about right.