Suzuki DF25A prop

[matt167]

Had my Holiday 14 OB out today in a light chop, not bad. 1st time with the brand new DF25A and it's standard prop ( 10 1/4"x11 ). I got right at 25mph without touching the trim, which made me happy. My RD-28 Johnson 40hp did about that, just with a better hole shot.. However I noticed that I was topped at about 5,300 RPM and the motor is rated to 6,000 so the prop is close but I need a new one.. I used the online calculators which suggested that 10 1/4x 13 or 14 would be right, however wouldn't I want less pitch? I can get a Michigan Wheel Vortex 10.5x10 pitch which seems close to what I think I need, but I only think, I don't know

 

[matt167]

Forgot to mention, that my speed at idle seems to be 2.9 Mph ( GPS ). If I get the prop that allows for a little more slip, would that get me down to 1.9 MPH for trolling? Or should I just plan on trolling bags?

There isn't much available with less than 11 pitch. Solas has an 11"x9" Amita available on Iboats but I'm really not sure what to get. I see 2 pitches is equal to 400 rpm, so I should be at about 5,700 with that prop and that would be theoretically 800" further if the science went that far ( 2 less " per RPM, but 400 more rpm ). The boat is a little bigger than what Suzuki figures the motor would get mounted to, but it's within the boats design and getting almost the same speed as a 40hp suggests it's in the green

 

[matt167]

I ordered the 11x9 Solas Amita while it was on sale. Pretty sure it's as close as I'm going to get without having a custom prop built or something.. This should slow my idle/ troll speed down as well. With the standard prop, I get 2.9 MPH. I'm hoping to get that around 1.8-1.9

I thought about getting a 9 3/4"x 12 prop, which would normally be for a 20hp but I'm not sure as that would do what I want. I'll probably need to have 2-3 props for this boat/ motor. I may need a specific one for trolling, and I'll probably need one for water sports, although the most I'd do is pull a tube.. I may be buying a small cube Suzuki for my other boat I'm building, and they are all 10 spline so I might be able to try the smaller diamater props on the bigger motor, as they wouldn't go to waste so to speak

 

[Sea Rider]

Why is it that everybody is installing non OEM props when going for a prop maximization when OEM Suzuki ones performs top, these guys knows well their prop business. If the motor is currently revving at 5300 wot revs, is revving at 700 rpm less from its max 6 K range, an alum 3 blade 9 pitch should put the motor revving around or close to 6 K. Will better the current hole shot along top end speed, only a wot water trial as loaded on flat calm water cond will tell.

Don't know if with a 9 pitch prop from 11 factory delivered one will achieve less trolling speed than 2.9, likely it's he opposite. ? Will be bored fast if plan changing multipurpose spare props for different water activities on constat basis. Saty with the nine and get a trolling bag if needed...​

Happy Boating

 

[matt167]

Suzuki does not make a 9" pitch in anything bigger than a 9 1/2" diamater, which I deemed too small. I didn't think a 10 1/4"x10 was going to make enough difference and that is the smallest prop that Suzuki lists for the 25hp, and that Suzuki prop was $175 vs the $70 that I spent... If it's wrong, it's a whole lot cheaper.. I think it's because a 14' runabout is a bit different than what Suzuki intended the DF25A to get mounted to.

Trolling bags were my initial thought, but I wish Suzuki put troll mode into motors below 40hp

 

[Faztbullet]

Why is it that everybody is installing non OEM props when going for a prop maximization

Because factory props are inconsistent in manufacturing. You can take 4 new OEM props on same boat and get 3 different results. When I went for training at OMC in Waukegan this question was asked. Due to the wax casting process if prop line is delayed or there is a break/lunch the wax casting will start to sag changing the "rake" of prop. The aftermarkets props do run better than a all purpose OEM due to higher QC and volume of production. If you need to troll slower you can add a trolling plate. I have installed few for my customers that troll for walleye and Lake trout at Dale Hollow. You would need the Trol-a-Matic..

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[matt167]

After spending almost $5k on a motor, I really don't want to drill it for a trolling plate. I do have one though

 

[Sea Rider]

What does an OEM Suzuki prop to do with an OEM OMC one, different brand motors and props. Suzuki does states manufacturung 7 to 11 pitch props for said motor being the 10 the standard factory delivered one. But if being too darn costly compared to a non OEM one way to go saving some cash and expending it in other needs. . Post wot rpm gained with the new prop.

Happy Boating​

 

[matt167]

Not really too costly. Just Zuki doesn't make a 9" pitch in anything bigger than 9.5' diameter. Waste if I bought a non returnable item I knew wouldn't work

 

[Sea Rider]

Not really too costly. Just Zuki doesn't make a 9" pitch in anything bigger than 9.5' diameter. Waste if I bought a non returnable item I knew wouldn't work

The issue with props is that the diameter it's whatever the prop manufacturer wants to play with, pitch is what makes the motor to rev higher or lower, diam is secondary. As the pitch size increases/decreases so does the diameter.

Happy Boating​

 

[matt167]

The issue with props is that the diameter it's whatever the prop manufacturer wants to play with, pitch is what makes the motor to rev higher or lower, diam is secondary. As the pitch size increases/decreases so does the diameter.

Happy Boating​

I understand that, but Suzuki does not list the 9.5" props for the 25hp. I know they will fit, but they are 9.9-20hp props. By prop calculations I need a 9" pitch, which Suzuki does not list for a 25hp. The Solas happens to be about exactly what I need and within the parameters that Suzuki would make a prop in

 

[Faztbullet]

What does an OEM Suzuki prop to do with an OEM OMC one, different brand motors and props.

It doesnt but the manufacturing process is the same on all OEM brands, and they can have the same problems.

 

[Sea Rider]

It doesnt but the manufacturing process is the same on all OEM brands, and they can have the same problems.

So for my particular boating needs you'll recommend me to buy 3 alike 8.2 x 8.5/ 3 blade alum props and pick the one that revs best and throw money into the deep blue for the rest 2 ? Surely will turn into an extremely out of this world expensive recommendation.

In real boating world no one gives a crap if a prop revs slight less or more due to the manufacturing process, besides in small to medium range motors no one wants to buy an induction tach to check that out which have been recommending for years now, if a boater goes that route will go straight for a cheap induction tach and save some cash by not buying the more expensive ones that works best to buy cold beers, who understands them ?

Prop calculators are not that spot on, it's a great calculator to pick a prop in the event that your boat/motor combo doesn't count with a prop, that's why are called starter props. Have used them and for my boating purposes dialed 10 pitch props when my combo runs top to 6K revs with an 8.5 pitch prop as currently fixed loaded. Only a wot trial on flat calm water condition as loaded will tell if a chosen prop will satisfy your needs to rev towards middle or max wot rpm range factory stated. Won't be possible to dial both scenarios with a single pitch prop number, will need to pick one or the other...

Happy Boating

​

 

[matt167]

FWIW, I have an OEM 4" Suzuki tach with monitor in the dash. I think if I get it to 5,700 on a calm lake, it would be ok

 

[Sea Rider]

FWIW, I have an OEM 4" Suzuki tach with monitor in the dash. I think if I get it to 5,700 on a calm lake, it would be ok

Propping right any motor will depend entirely ir boating with a fixed or variable load and if wanting the motor to run at least middle wot revs which achieves slight more top end speed and slight hole shot decrease or towards max wot pm range which achieves slight better hole shot with slight less top end speed decrease. Thumbs UP for the Suzy Tach, way to go.

Will you be boating with fixed or variable number of passengers and load ? which of both mentioned water scenarios would you like to count with ?

Happy Boating​

 

[matt167]

Variable, but the calculations I can do from the original 1966 Johnson 40hp, to the new DF25A, and then testing the new prop will be with an identical load, same 2 people in the boat. I doubt I'm ever going to have 4 grown adults. Kids, yes

 

[matt167]

Made it out today. 22 mph flat calm at about 6k. Planes in an instant trimmed all the way in. Trimming out brings it to about 26 mph but 6100 rpm.. a 10 pitch prop may work better. I only need 100rpm less for safety

 

[Sea Rider]

If motor sits at the sweet transom height with deck load well distributed don't need to trim the motor all the way in, test same with trim set to neutral (90 deg) just full throttle from a dead stop and that combo will jump on plane instantly with 2 up and surely with some kids, a matter to test.

Not an issue if the motor revs slight over its max wot rpm range, a + 5% it's torerable and if counting with a rev limiter much better. Stay with that current prop, no way that can fine tune less 100 wot revs with any prop. A +,- one pitch will dial 300 to 500 wot revs depending on the application.

For recreational purposes no one runs their motors at their max speed for long time periods, unless racing against someone. More speed = More fuel consumption. 3/4 throttle it's more than enough to have fun with at reduced fuel consumption.

Happy Boating​

 

[matt167]

It cruises about 3/4 throttle, holding on plane at about 15 MPH which is a nice speed for the boat. Even trimmed all the way in it jumps on plane. The 30hp version of the motor which is mechanically identical is rated to 6,300 so I know that the engine can take it mechanically, and the ECU did not light up the over rev warning so I know it was 'ok' with it... IF I decide to 30hp convert this motor, I know it would cruise at 20-25mph and do about 30 MPH. The only reason I didn't do a 30hp is because Suzuki does not build a 15" shaft DF30A

Also, it put my speed at idle to 2.2 MPH give or take, which is just fast for trolling. A bucket in the water should bring it down