Prop change?

[trita306]

I have a Polar Kraft Sportsman 1860 SE with a 2004 Yamaha 50hp 2-stroke, approximate Wet Weight: 1667. I will have to check the current prop specs but lets assume it is stock. Currently, with just myself it will pop on plane alright and do 30mph. I dont have a tach so I cant report RPM.

If I add another person it struggles greatly to get on plane. My question is, what diameter/pitch can I try on this motor to ensure it planes easily with more than one person? I am not concerned with top speed in the least. Also, would it be advantageous for me to switch to 4 blade to help with this?

I am thinking something like this:
Solas Amita 4 Blade Aluminum 10.5" dia. X 13" pitch SR

 

[flyingscott]

You need a tach to prop it properly. When you prop a boat you want the motor at the upper end of the rpm range. For Yamaha I believe you want to be at 5500 rpm for a light load. That way when you load up the boat the motor will still be running in the recommended rpm range at WOT. Get a cheap tach and go from there

 

[steelespike]

Is the 30 mph by gps? Only accurate way.
Your prop size should appear under the prop nut.There really isn't a "stock" prop.Prop would depend on the activities and typical load.
if you get us the prop size and lightly loaded wot gps speed we can approximate the rpm until you get a tach.
Also should tell if the setup works.
Your underpowered so careful prop selection will be important.

 

[trita306]

That mph would be with gps. I will grab the current specs on the mounted prop and report back. Thanks guys.