The size of your prop. Suzuki 50hp, 4stroke

[lajarp]

Hello , I have a new Suzuki 4 stroke 50hp engine on my MacGregor 26x 2000. But i`m not satiesfied with the top cruise level. The boat only does 9 knots at max. 4500rpm with the original 3 blade steel propeller. Type 11 3/8x 14 inches. After that i bought a variable Propulse prop. adjustable from 11 to 17 inches. This one has 4 plastic blades. Now at 12 inches the boat runs 12 knots, 5900 rpm , with 2 persons onboard and the ballast tank empty.A little bit better but not good enough. I think this boat would do about 17-19 knots at max. rpm.At the manual you can read, max rpm = 5900-6500 rpm. My question is , what is the size of your 3 blade steel prop. which does at least 16 knots?
I hope a lot of answers will be sent to my mail, Lars Järpestam

[Catigale]

Lars - you should use the prop that lets your engine reach the specified Wide open throttle rpm (5900-6500) as you typically load the boat. Once you have that prop, whatever speed you get is correct.

You cant get more speed by changing props without risking damage to your motor, in short.

[lajarp]

Hello
yeas i know that the correct max rpm is the best for the engine (5900-6500 rpm). But i think the plastic Propulse are not as good as a steel prop. I would like to know the max. speed of yours macGregors 26x and the type of the steel prop.?

Thanks and looking forward for mails, Lars

[Catigale]

From me

Merc 50 HP Bigfoot 2003

Running the 14x11 Prop from Mercury

5000 RPM WOT with load
Ill guess 14 kts WOT is the most recent recollection

[1st Sail]

My original prop is 13 x 13.75, 16mph with ballast 5400rpm (lugs the engine ETec 50 and will overheat). I have a 14x11 which runs 17.5mph with ballast 18.5x19mph no ballast, 5900rpm (rated 6000rpm, no over heat issues with ballast in). 2 crew, 2 batteries, 12 gal fuel, 2 anchors, no heavy cargo.

[mallardjusted]

I have a 2001 Suzuki 50 EFI 4-stroke. My boat stays moderately to heavily loaded and I get a top of 15 knots no ballast. Top is at about 6200 rpm (manual says correct top range is 5900 to 6500 rpm). With ballast it's 2 or so knots slower. My prop:

standard 3 blade
11-½" x 13"

[lajarp]

Hello
Suzuki 50, 4stroke and the difference between props. are only 1 inch. Yours 13 and mine 14 inches. I dont understand why it is so big difference. My boat WOT 12knots and 4500rpm (no ballast), and yours 15 knots with 6000rpm.
I´ll hope some one can explain this case.
Im looking forward to hear from other owners with Suzuki 50 4 stroke.

Lars Järpestam

[Theo]

Lars,

I have the same boat and motor combo you have, 2000X with a Suzuki DF50. I recently spun my old three blade prop and needed a new one. Based on a search I did at this website, I chose an aluminum Solas Amita 4 blade 11.8 in by 9 in pitch prop. I got it for a whopping US $90 on iboats.com.

The thing works great. With no ballast but a fully loaded boat, two psycho fishing buddies, one over 250#s, and all our gear I was able to do better than 16mph at about 6200 rpm. Mind you this was not wide open throttle. It was a dark moonless night and we were zipping to the fishing grounds but that was as fast as I dared go. I think I had about another 500 or so rpms to go. If anything this prop is a touch under geared. This was at sealevel in the ocean. With ballast I easily hit 11+ mph and was constrained by conditions. She had more.

I found that the motor was revving much more than I was accustomed to but willingly hit the high rpms. From what I have heard the Suzi's like to rev and are comfortable there. If you are not hitting the recommended rpms , you are also not getting the full 50 horsepower the engine is rated at. I am guessing that at 6500 rpms you might be getting a little more than 50 HP.

Good Luck,

Theo

[lajarp]

Hello Theo

Thank you very much , about your prop information. It help`s me a lot when I`m looking for the ultimate prop. for my boat/engine.
I`ll think you have the best performance at 6200rpm (5900-6500). Because the top are at the middle.

Bye Lars

[Catigale]

Lars - what is the final drive ration on your motor - it might be the motors or lower end ratios of the performances you are comparing are different in the EU and US>

[lajarp]

Hello Catigale
I can read at manual/ broschure it is 2.27:1 , Suzuki DF50.

Lars

[mallardjusted]

Lars,

My 2001 Suzie 50 is also 2.27:1 gearing, so It looks like the basic engines are the same.

You could try either the standard prop that I use (3 x 11-½ x 13, top 6200rpm) or Theo's (4 x 11.8 x 9, top @ 6500-6700) and be in the ballpark. Speed outcomes look similar.

It does sound strange there should be that much difference in the prop you're using, though. If you can try one of the above, you could narrow it down to whether the prop is the issue or something else?

[Theo]

Lars, Mallard,

The brand of prop you are using is terribly important to how it will perform. A 11X13 prop from Michigan Wheel is not necessarily the same, or even close, to 11X13 Pirahna prop. According to my prop guy, all manufacturers employ different prop shapes and cuppings so identical diameters and rakes will produce very different amounts of thrust. I know this complicates things immensely. That is why this forum can be so helpful. I found the info for my prop doing a search right here.

Good Luck

Theo

[Carioca]

I have a Yammy 50 hp with a 12 x 3 x 9 pitch prop.
Gets me 17 - 18 mph. at wot.