Prop Help Please!

[Ringo]

My Campion 542 came with a Suzuki DF140 which has a 3-blade 14x19 stock prop. With 2 guys, gear and a full tank of fuel, I cruise around 20-22 Kph, @3400-3800 RPM on a calm day. Max speed at WOT with trim tabs is 28 Kph at 5000 RPM. The motor is rated for max 6000-6500 RPM so it seems pretty sluggish at the rate that I’m going.

I spoke to my Suzuki guy and his recommendation was to drop to a 17” pitch, 3-blad prop. The prop shop in Langley recommended a 4-blade with the same pitch.

What do you guys think would be my best option here?

 

[sasqman]

The 17p is probably a good idea. The 4 blade will get the butt end up quicker so i have learned from all the smarter people than me on here this forum.

 

[MikePA]

Interesting, I think you should be able to get alot more out of that engine with a different prop. With a 14 x 19 on my 150, I get 32 mph cruise at 4000 rpm and 50 mph WOT at 5300 rpm.

 

[Explorer682]

I would listen to the Suzuki guy. A 4 blade on a smaller engine is likely not recommended if you go to the Suzuki site they won’t go to 4 blades until you get into larger motors . A 4 blade will give you better hole shot but typically lower top end.Google prop selectors , turning point has a pretty good one but there are many . I went down this worm hole and learned lots in the process , ask the Suzuki guy if he has a couple of demo props you can try before pulling the trigger on a new one. I was able to demo 5 different props before I found the one that suited my needs.Stainless vs Alum can also make a difference

 

[ship happens]

Not enough power for a 4 blade. Try pitching down and get a prop more suited for your application. Stainless for sure. Try a prop with a larger blade and a 17 pitch. Not necessarily a larger diameter but a larger blade surface area.

Honestly Solas make excellent props in a huge selection also.

My 2 c

 

[Foxsea]

You need to drop to a 17 or even 15 pitch to get WOT up into the correct rpm range. Where you are is hard on the engine. I had the same issue a few years ago. Dropped from 19 to 15 pitch. Just wow! It runs like a different boat. The overall performance improvement was amazing! 3 blade is best.

 

[ship happens]

Foxsea is right. 15 pitch sounds about right. That engine according to the book should be proped to run 5600 - 6200 at WOT.

 

[Barman]

Foxsea is right. 15 pitch sounds about right. That engine according to the book should be proped to run 5600 - 6200 at WOT.

I agree as well. It's generally accepted that dropping a degree in pitch adds 200 RPM, so go down 4 degrees should put you in that 5800 range.
This presumes the motor is running correctly. Going to a four blade is like adding a degree or maybe a bit more of pitch, not what you want to do.

 

[Ringo]

Great. Thanks guys for your replies. Just curious, would a SS prop help with the RPM issue as well? Should I aim for a 15” SS prop?

 

[Rain City]

Great. Thanks guys for your replies. Just curious, would a SS prop help with the RPM issue as well? Should I aim for a 15” SS prop?

Unless you plan on constantly being in shallow water and risk hitting rocks there's no point in not going stainless. Other than the cost I guess but it's a drop in the bucket really.

 

[Ringo]

No shallow water for me but then there’s the submerged Fraser crap that we all hit in our area every once in a while. I was just curious if stainless will improve the rpm issue. And I totally agree about the drop in the bucket comment. Boats are no fun if we don’t constantly feed them with $$$.

 

[ship happens]

Unless you plan on constantly being in shallow water and risk hitting rocks there's no point in not going stainless. Other than the cost I guess but it's a drop in the bucket really.

Got this all backwards

Stainless props out perform aluminum no comparision

Banging into the ground or hard material will most likely result in a twisted or bent prop shaft. Not recommended even with rubix style hub props

Stainless will bite better and have less cavitation

 

[Rain City]

Got this all backwards

Stainless props out perform aluminum no comparision

Banging into the ground or hard material will most likely result in a twisted or bent prop shaft. Not recommended even with rubix style hub props

Stainless will bite better and have less cavitation

I think my double negative fooled you lol.

 

[ship happens]

I think my double negative fooled you lol.

Lol whoopsy

 

[Fins -n- Skins]

I have the same motor Suzuki 140 and almost same boat but little heavier.. Wot is 5800-6000 with stock prop. I would have the motor checked first but i,m sure trying a different pitch will help.

 

[paulo]

That does sound pretty sluggish for a 140. I have a 18'podded North River with a 115 and I can cruise two guys at about 4200rpm doing approx. 27-30 mph. By myself at 4200rpm I'll be doing 30mph. I've never gone WOT. So you're doing 12.4 - 13.6 mph. Something doesn't sound right. Are you sure you're speed measurement is in kmh and not mph? I realize there is a weight difference in the boats alone but that just seems way too slow. I run the same prop and have a spare that is 17. I've tried them both and there seems to be little difference between them for me.

 

[Ringo]

The speed measurement is in knots. Sorry for confusion there. so, cruising at 3800-4000 rpm around 25 mph.

Did the compression test few months ago, motor’s running fine. Previous owner told me about Suzuki’s recommendation to change the prop but then he barely used the boat and kept the OEM prop.
My Suzuki guy has the 15 pitch Solas aluminum prop. Any recommendation for a local prop shop on the mainland??

 

[paulo]

Maybe that was my bad. That makes way more sense.

 

[brutus]

The speed measurement is in knots. Sorry for confusion there. so, cruising at 3800-4000 rpm around 25 mph.

Did the compression test few months ago, motor’s running fine. Previous owner told me about Suzuki’s recommendation to change the prop but then he barely used the boat and kept the OEM prop.
My Suzuki guy has the 15 pitch Solas aluminum prop. Any recommendation for a local prop shop on the mainland??

Precision prop

 

[ericl]

I seem to recall that you will gain about 500 rpm with every inch of pitch drop; suggestion sounds pretty right-on. Many benefits to a 4 blade prop expect top speed due ti the drag of the extra blade. I think if the 4 blade is stainless that prop would work as well. They can put a more aggressive cup on a stainless prop.