Correct Prop for Suzuki DF50?

[Mark Karagianis]

Help!

I bought my new Suzuki DF50 separately from MDR dealer Mike Inmon and ended up with a 10.5 x 13 prop. My new 26M won't break 9 knots under power - I can sail faster! I don't have a tach but it doesn't sound like the engine is revving high either. Mike says they muffed the engine's first service and it needs to go back for diagnosis. The engine dealer says nonsense, that he always put on a low "torque prop" and he wants to go to a 10 pitch. Surely many members have the DF50 and are capable of going fast!

The impatient sailor

MK

[Frank C]

Go w/ the engine dealer & that 10" prop. The 13" is way too much pitch for any Mac w/ less than 100 hp.

[Norm]

Your "engine dealer" is correct. An 11.5" or so 10 pitch will fix you right up.

[Bobby T.-26X #4767]

prior to my 90 tldi, i had an '02 Suzi 50.
it came w/ the standard 13 pitch prop and would not go beyond 5200rpms.
max rpms should be in the 6100-6500 range.
i chose to go with a 12" (if you can get one that large or 11.75 diameter at the very least).
you need "surface area" to push the Mac.
then, regarding pitch, i went with 11 pitch and usually got to 6100 rpms without ballast.
several others that i spoke to on the water went with 10 pitch and got up to 6500rpms with slightly less top end speed.
regardless of the pitch (10 or 11) make sure that the prop is more of a "pontoon boat" prop with big "dog ears".
mine was a "michigan match" brand.

[bwytodd]

The 10 pitch is right for most people, if your boat is REALLY light, and doesn't have bottom paint you can sometimes pull an 11, but not very often

[Robert]

I had the Suzuki DF50 with the Mac26X, the default 11.5" diameter 13 pitch Suzuki prop would go a lot faster than 9 knots, I don't remember the speed, and don't have time now to look it up, i've posted that number here years ago. Is the M harder to push with an outboard than the X?
..
Suzuki 10 pitch is 11.5" diameter and will get up to 6500+ without ballast on a Mac26X, but with ballast it only gets up to 6250 or so. Suzuki makes a 9 pitch that might be usefull if the M is harder to push than the X.
..
Other props that come in 9 pitch, have larger blades and larger diameter or more blades and larger diameter, so they come to about the same WOT RPM as the Suzuki 10 Pitch. The DF50's torque seems to fall away at 6800 RPM, many of the props I tested stopped at 6800 RPM with empty ballast even though they had different WOT RPM with ballast full. The overrevlimiter is at 7250 RPM, and the DF50 with four valves per cylinder that don't have to move very far likes the high revs. So, pick a prop that gets near the 6500 RPM with ballast full, and the it will safely stop at 6800 RPM unballasted. Hp is proportional to RPM. The larger blade area lower pitch prop makes a lot of difference docking and in rough seas.

[Mark Karagianis]

I am ordering a Pirahana 129C 3 x 12.25 x 9. I'll let you know how it TURNS out.

Mark