the 19 might put you over wot rpms when by yourself but as you load the boat down then your rpms will be in the specified range.
Depends on what you want.
"any thoughts?"
if jimmbo is right, you were only 400 rpm below the max.
Increasing the diameter, # of blades, and pitch, decreases rpm's.
The same diameter, blade count, and pitch can still give different results with different manufacturers.
The only #'s that matter are what's current. If your concentration is on 60 mph, then the motor isn't making it for whatever reason. It's not the prop. Props are for fine tuning.
You want 4200-4500 @WOT....speed is irrelevant.....
"Any thoughts?"
I prop for proper manufacturer's recommended RPM @WOT. So 3700 rpm@wot would be lugging my motor. The resulting speed is irrelevant. Prop diameter also affects rpm results.
oil is oil....got it. But when you have a new motor that cost $12,000 you're taking a huge gamble under warranty by not following the owner's manual, especially when it comes to oil specs.
And I do believe there is some truth to manufacturers engine designers specific oil spec requirements for...
I've owned my used pontoon since 2017. I've researched all aspects and items including getting new pontoons. I've never seen any type of reference to replacing motor pods.
Are you sure about your motor height mounting position being correct?
I've looked at pics of monarchs and the transom angle...
fwiw. The 2 years in the brackish upper chesapeake with my new in 2021 Merc 115 has not hurt it. Just changed the impeller and checked the thermostat. No signs of corrosion. It does get a fresh water 2day lake run every summer, guess that helps.
I bought a new Merc 115hp CT in 2021. 10w-30 Merc/quicksilver synthetic is recommended. I'd not deviate from that especially under warranty. I don't have my manual in front of me, but 20w-50 I think is acceptable.
by book #'s : Dropping pitch by 2 inches raises WOT rpm's by 300-400 rpm's. Then adding a blade can reduce rpm's by 100-150..200 rpm's. So the net is about a 200 +/- rpm increase at WOT...that's by the book, actual results can only be determined by running results.
You have to decide what...
