Loss of Speed / RPM from New Engine

[never monday]

Charlie and Spindrift, what are your serial numbers? do you have the same transmissions and gear ratios?

I doubt fuel is the problem. You can reach 3000 RPM in reverse.

A MaxProp is geared internally IIRC. a pitch change large enough to drop RPM that far is doubtful.

I'd focus on the transmission

[fstbttms]

Originally Posted by Charlie

As a seperate question but relevant to the thread does anyone know if the settings on a Max Prop can change once the prop has been installed?

If you have the "Classic" model, the prop must be disassembled for pitch setting to change. Virtually impossible otherwise. I suppose a "Variable Pitch" model's settings could change inadvertantly, but it seems highly unlikely.

[Charlie]

Sorry to be a thread stealer here. I have the classic Max Prop. I noticed the difference when I changed the pitch. I had replaced my Yanmar 4JH3E with a 4JH4E and thought I should change the pitch. When the engine was installled we didn't pull the boat out of the water so I didn't change the pitch to match the recommendations of Max Prop. The original setting worked better so this time when I pull the boat I will return to the original settings on the boat.

[fstbttms]

Originally Posted by Charlie

When the engine was installled we didn't pull the boat out of the water so I didn't change the pitch to match the recommendations of Max Prop. The original setting worked better so this time when I pull the boat I will return to the original settings on the boat.

Any Max Prop can be adjusted while the boat is in the water. PM me if you want more info.

[Charlie]

Thanks FB. I'm pulling the boat in a month or so anyway.

[Jim Cate]

Originally Posted by delmarrey

Mathematics say more pitch more speed. One just needs the HP to push it over hull speed. A 4JH4E only has about 55 HP, which is not a lot for a Warwick 46 displacing 14 tons.

G'Day Del,

I believe that the OP reported that he still got the same boat speed at 2400 rpm as before the problem started, just took a greater throttle setting to acheive the rpm's. Thus, to me it does not sound like a change in pitch.

Cheers,
Jim