posted 07-01-2000 07:30 AM ET (US)        

I was using a MERC BLACK MAX 3-blade, 10.125" x 15" prop, but I felt like this was too much pitch. The boat did not have good mid-throttle response; it ran like a car would if you were stuck in 5th gear.

So I moved down to a MERC BLACK MAX 3-blade, 10.375" x 14" prop. As I handed over the credit card at the Merc dealer for this one, I was wondering if changing the pitch by just one inch would make much difference.

But despite such a minor change in the prop, the results are significant. The boat now handles the way I want it. It feels like we're not stuck in overdrive. There is much smoother mid range power. When in a seaway, the boat has much better handling and response.

DIA. PITCH RPM MPH
10.125 15 5200 32+
10.375 14 5400 [n.a.]

Both props are of similar design and have cupped blades. The operating range for the engine is 5000 - 5500 RPM.

It might be good to note that my engine is a 1976, so the rating of 50 HP referred to powerhead horsepower. A current 50 HP outboard would have 50 HP at the prop and could possibly handle the taller pitched prop better. Also, the 24-year old engine might be a little tired, too.