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Max RPM for 70hp merc 1989 3 cylinder

kiwikraut

New member
"Hi can you help? I would like

"Hi can you help? I would like to know the max rpm of my motor to match the prop to my boat,it pulls just over 5000rpm with two people. I understand this should be done with as little weight as possible in the boat.
Thank you
Tony"
 
"If you are trying to match a

"If you are trying to match a prop you should load your boat as it is "normally operated" and then shoot for a pitch will allow you to come within 200-250 rpms of max (so in this case 5550-5600 rpms).

That should give you the best all round prop for your rig with a little wiggle room when you are running heavier or lighter than normal and allow for some seasonal variations as well.

Although, if you prop your rig in the winter your motor could be underperforming by as much as 15% in the middle of summer (due to the hot/humid air).

Because of that, if you only plan on running 1 prop, it's best to fit it in late spring..."
 
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