Combo should be propped to run to its full max 6K wot revs with 8 passengers if that's the max it will take with a 115 HP. Boating lightly loaded or with just 4 adult up, expect OB to over rev or rev limiter kicking in prematurely. Will need to watch tach while boating full hammer down with less passengers. Once at max wot rpm range for 8 passengers can throttle less to your likeness of 5800 revs with exellent performance with tad less throttle & OB stress..
Dialing best prop performance for a boat which has more hull drag being a toon and used with more or less boaters is a real PITA as the rpm equation changes in accordance with load. That's why have limited my boat passenger/OB capacity to just 2 to run at max wot rpm which I like exeedingly with a underpowered OB,
Happy Boating
