Hey guys!
So I finally got the 18 and tested it yesterday.
I gained 1.5 knots (from 20 to 21.5), a bit disappointing.
Same boat, tubes inflated and checked and same weight.
The 9.9hp (15) had a 8.5 prop and the 18 has a 9.
Revs at WOT was 5700 on the 18.
Any ideas?
Check compression...