DF50 owners what size prop you running

[chris69]

Hi all im just wondering what size props your running on your boat with the DF50 i run a standard 11 1/2 x13 but would like to try a 11 1/4 x14 has anyone played around with there prop sizes,cheers chris.

[Blackened]

G'day

First things first, how's your engine height and what RPM are you achieving at WOT?

Dave

[chris69]

hi Dave im unsure of revs but i do know im over 6000rpm going by the service print outs and its on the keel as in height i can just see the cav plate, ive got a tiller its very hard with out a tacho.

[Blackened]

G'day


I've just been through this with my new rig. Basically when i took it out, motor was buried and prop was too small to compensate for buried engine.

In all, we lifted it another hole (absolute max for this, had to do some modifications as the original builder stuffed up). The gauge for a correct height engine is not "in line with the keel" per say, it's now it is on the water, trimmed out comfortably, the anti ventilation plate (plate immediately above the prop) should be skimming the surface of the water or just on it. This is where you check your numbers, RPM for eg.

To give you an Idea, my DF70 (RPM 5300-5800) came with a 13.25x15 3 blade alloy,

With this prop 1 up, full fuel (117L) and light load) I was achieving 6000rpm max with a 30.5kt max speed, with 18.4 kts @ 4000.

I then knew I needed to drop RPM, so I went with a taller prop, 13.25x17 to trial some numbers.

With the suggested prop of 13.25 x 17 , 2 up, full fuel plus a bit more gear (heavy esky etc) I'm now getting Max rpm of 5450 at 30kts, 21 kts @ 4000 and 23 kts @ 4400 for 10 lph.

So all things equal, the 17 is a much better prop for me. I'vejust ordered one in stainless.

There's a few options for a tacho..... NMEA network with your electronics package if it allows (that's what I did) ot you could purchase a "tiny tacho" They're accurate and worthwhile as they also show hours.

Dave

[chris69]

Thanks for that Dave looks like yo have found the sweet spot in revs and prop,as for tacho yes ive been all around the net looking , the tiny tachos dont and cant work on the suzukies,or any motor that has the coil on the spark plug,and as for NMEA just trying to source a cable to run the tacho on the raymarine but to get it here in australia very dear compaired to the US and since browns point marine is out of action ive got only a couple of places here to try as i need a K8 EP21 adapter for every thing to work so more bloody cost just to do all of this and to get the cable to get the smart meter tacho same sort of cost,once i can prop it right ill never use it as i just run on my speed and cruise around at 18 to20 knots.

[Blackened]

G'day

Maybe ask around to borrow a cable first? Never know who has what lying around.

Dave