DF 40 prop suggestions?

[djgtom]

hi guys,

a mate has a edgtracker alloy boat 3.9 m fitted with a df 40 4 stroke side console.
this setup should go like a cut snake i would guess.

the prop is 10.5 x 10 inch dia.
the boat launches like a rocket and then revs it's ar$e off at 6600 rpm doing 42 km/h.
the prop is way under and was wondering which prop should we fit??
Have been suggested 10.5 x 11 inch dia.

any suggestions please????

dean

 

[steelespike]

Re: DF 40 prop suggestions?

Rule of thumb "about" 200rpm for each inch of pitch change.Assuming the DF40 is rated at 6,000 a 13" pitch would get you there.

 

[Silvertip]

Re: DF 40 prop suggestions?

I think you need much more pitch. I run a DF40 on an 18 foot pontoon and it revs exactly at its rated WOT rpm of 5800. So you need to pull 800 RPM off the 6600 so that would suggest an 11 x 14 or 11 x 15P. That engine has 2.26:1 gears so it should spin either of those props just fine and it would likely pick up a little speed. The increase in diameter will have little impact on the performance.

 

[djgtom]

Re: DF 40 prop suggestions?

Thanks so much for your help.

The info makes it so much easier.
I'll go 11 dia with 13- 14 pitch if i can get one up here in regional vic.

thanks again
dean