Best trolling prop size for fuel economy
Cheers from the other side of the pond. I have a zodiac hurricane 540 rib with a 90hp 2 stroke in which i am a safety boat for a "long" kayak race on a river.
It's 340 miles or approx 550 km. I will be doing a large majority (99%) of it just boating at the speed of a paddling kayak, approx 7 knots with river current. (There is a strong current on the river)
Fuel stops are spread out, so i'd like to maximize my range.
I am familiar with prop sizing for ideal RPM at WOT and cruising speeds on plane, however since i'll be going for such a long distance not on plane, rather just floating at little above 2k rpms, would going UP in prop diameter yield better fuel economy?
For example going from a 19p to a 21pitch, allows me to lower the rpms slightly to achieve same speed?
I know this seems trivial, but curiosity has me wondering. Thank you