I have a 4 h p evinrude motor with a 2 blade plastic prop. can i change to a 3 blade to get better perfomance?

Question

i fish lake erie with sixteen foot fiberglass 75 horse mercury engine and in rougher water the 4 horse doesn't push it very well for trolling unless it is wide open.

Answer 1

It is according to what year of motor you have.

Check this site:

http://www.maxrules.com/fixomcprop1.html

Answer 2

Whether 2 or three blades is not as important as the pitch and the design specifications for the model outboard engine you have.  For a trolling motor on a bigger boat, you will need a lower pitch propeller than the standard 7" pitch. Go to

http://shop2.evinrude.com/ext/index.aspx...

find your exact outboard model and see which propellers are available.

I have a 4 hp Evinrude for my sailboat which came with a 7" pitch prop. This did not push it well at all, so I bought the 6" pitch propeller, which works great.

Pitch is the theoretical distance forward the propeller will travel during exactly one complete turn. It is something akin to gears in a car transmission. Your 4 hp engine needs to operate in low gear on such a large boat.