1400 RPM loss from 13 to 15 pitch!!!

[QBhoy]

Dare say this is as a result of trim of the engine. Either that or you’ve been mislead by the pitch. Not often that props come in 1” pitch increments. Not for general props anyway.

 

[Miked3]

Never heard of Vesselview before today. Think what you want, but a one inch pitch difference on pretty much any Outboard or I/O is going be a 200 rpm change. A 800 - 900 change is something else, Blow out from Exhaust, Ventilation from Surface Air, or severe Cavitation.

And once again, the MPH proves none of that to be the case, at least with the Solas props.

 

[Miked3]

Dare say this is as a result of trim of the engine. Either that or you’ve been mislead by the pitch. Not often that props come in 1” pitch increments. Not for general props anyway.

Lol yup this must be my first rodeo trimming an engine to get the most out of it

I invite ANYONE on this forum to join me on my boat, prove me wrong, show me anything that is being done wrong or different from anything I have stated in this thread. We can even put some money on it, I could use some extra!

1" pitch changes listed below on the Solas site for my motor. The 13 and 14 are the last two I have been testing on that list. Gear ratio is most likely playing one of the biggest parts in this endeavor.

 

[QBhoy]

And once again, the MPH proves none of that to be the case, at least with the Solas props.

Vessel view will tell you one way or the other, exactly none of the last few things that @jimmbo mentioned to you. I tend to agree with him there. Got to be something else going on there. I’d just double check the prop size again. Make sure it’s for your gearbox size and fitting is correct. It’s absolutely got to be related to one of these things, or trim position/grip on the water.
I’d also add, that having had the vessel view mobile since the very early days, I’d you are referring to the max speed @RPM achieved screen afterwards…this isn’t always an accurate picture of what’s going on. It takes varied moments in time to record that data. So for example, if I run up to 6000 rpm at 45 mph in real time, then back off just as I achieve that top speed…the max speed recorded screen will have a little lag. So it will most times show the recorded data at 45 mph and @5700 or similar. Reason for this is that it’s taken a particular moment in time just as I’ve pulled off the throttle. So recorded the rpms lower as it’s dropped quickly, but the boat is still carrying momentum at 45mph, if you get me. Best to use real time data witnessed with your own eyes.

 

[QBhoy]

Lol yup this must be my first rodeo trimming an engine to get the most out of it

I invite ANYONE on this forum to join me on my boat, prove me wrong, show me anything that is being done wrong or different from anything I have stated in this thread. We can even put some money on it, I could use some extra!

1" pitch changes listed below on the Solas site for my motor. The 13 and 14 are the last two I have been testing on that list. Gear ratio is most likely playing one of the biggest parts in this endeavor.

Wasn’t meaning that you were inadequate with the trim. Have a look at my last list there. See if that makes sense.

 

[Scott06]

Lol yup this must be my first rodeo trimming an engine to get the most out of it

I invite ANYONE on this forum to join me on my boat, prove me wrong, show me anything that is being done wrong or different from anything I have stated in this thread. We can even put some money on it, I could use some extra!

1" pitch changes listed below on the Solas site for my motor. The 13 and 14 are the last two I have been testing on that list. Gear ratio is most likely playing one of the biggest parts in this endeavor.

You were barely tapping your rev limiter on the original prop- that is basically about as good as it gets prop wise for a rig like yours. That is exactly how I prop my boat, just cause it can hit rev limiter doesn't mean you have to leave it pegged there.

One of the issues maybe overlooking with these results and the slip/rpm numbers that don't make sense is you are assuming the props published pitch is what it actually is, on relatively inexpensive aluminum props. Before you drive yourself nuts maybe worth finding a prop shop who can validate if the listed pitch is accurate.

 

[racerone]

Test done by me 40 years ago.----A 16' ski boat.----1970 115HP Evinrude.-----All on same day.----Just me in the boat.------No power trim tilt.-----Thrust pin in same hole.---A 19" pitch SST prop.----Great acceleration top speed 54 MPH at 5800 RPM.-----A 21" pitch SST ----Good acceleration top speed 54 MPH at 5300 RPM.----A 23" pitch SST ---Slow acceleration and top speed of 55 MPH at 4800 / 4900 RPM.

 

[briangcc]

I'm no prop expert but when you went from your original 4 blade prop to the exact same size in a 3 blade design, that the 3 blade didn't have enough "grip / bite" so it was just churning the water after a certain point which is what caused that prop to kiss the rev limiter.

The 14 x15 prop had sufficient "grip / bite" that it never blew out so that's why the rpm's are so low - you're lugging the engine to death.

So there's another variable in play here that you're missing in your comparison.

 

[jimmbo]

Test done by me 40 years ago.----A 16' ski boat.----1970 115HP Evinrude.-----All on same day.----Just me in the boat.------No power trim tilt.-----Thrust pin in same hole.---A 19" pitch SST prop.----Great acceleration top speed 54 MPH at 5800 RPM.-----A 21" pitch SST ----Good acceleration top speed 54 MPH at 5300 RPM.----A 23" pitch SST ---Slow acceleration and top speed of 55 MPH at 4800 / 4900 RPM.

Shatters the old "I put a Speed Prop on, and gained 7 mph" fallacy that we have heard from Frogmouth boaters for Decades.

About 50 years ago, I too did similar trials, and discovered that MPH remained very much the same with Acceleration being the Variant.
On the 1960s OMC V4s with their tiny Props and 23:20 gear ratio, a 1" change in Pitch still yielded a 200 rpm difference

 

[QBhoy]

I'm no prop expert but when you went from your original 4 blade prop to the exact same size in a 3 blade design, that the 3 blade didn't have enough "grip / bite" so it was just churning the water after a certain point which is what caused that prop to kiss the rev limiter.

The 14 x15 prop had sufficient "grip / bite" that it never blew out so that's why the rpm's are so low - you're lugging the engine to death.

So there's another variable in play here that you're missing in your comparison.

Oh really ?? I thought the fella said it was two exact same props, just an inch apart. The 4 blade explains just about everything really.

 

[racerone]

That high revving tiny prop and pointy lower unit were not efficient.-----But it allowed motor to rev up quicker until prop started to bite as speed increased.

 

[jimmbo]

The Props(all 5 of them) were not the best Designs either. The 1966 100hp was a big improvement in gearcase design, but 1969 was the big year for the V4s

 

[Scott06]

Oh really ?? I thought the fella said it was two exact same props, just an inch apart. The 4 blade explains just about everything really.

He had a 4 blade spitfire to start with and 2 hustlers - from post 1

Props- SPITFIRE PONTOON (13.8 X 13") MERCURY RH PROPELLER, 48-8M8026570 - 4 blade - 25mph @5500rpm
Hustler 3 blade 14 x 13- 25mph @6200rpm
Hustler 3 blade 13.75 x 15- 29mph@4800rpm

 

[QBhoy]

He had a 4 blade spitfire to start with and 2 hustlers - from post 1

Props- SPITFIRE PONTOON (13.8 X 13") MERCURY RH PROPELLER, 48-8M8026570 - 4 blade - 25mph @5500rpm
Hustler 3 blade 14 x 13- 25mph @6200rpm
Hustler 3 blade 13.75 x 15- 29mph@4800rpm

Doesn’t make numerical sense to me at all. In terms of physical prop slip possibilities

 

[southkogs]

I've cleaned a few things up in this thread.

Keep it civil or this thread gets locked. Debate is fine, but there's no need to insult or taunt. If you've made your point - let it be.

 

[briangcc]

Going off OP's numbers, a 14 x14 3 blade prop would be around 27mph and 5500rpm. **Just using some simple math to connect some dots in data points...2" pitch difference and 1400rpm difference between the two 3 blade props.

Which kinda lands right back where the original 4 blade is.

Not sure what all this means as you can't get from point A to point B using Merc's prop selector using OP's data points.

Something is off, perhaps engine performance? We are talking about a 2014 outboard so that's 9 years worth of usage. Or a heavier boat. Or some sort of user error - trim? Or vessel view is off?

Was it mentioned how the mph was measured? I'm old, fat, lazy, and don't want to read through 4 pages to find that nugget...

 

[Miked3]

Going off OP's numbers, a 14 x14 3 blade prop would be around 27mph and 5500rpm. **Just using some simple math to connect some dots in data points...2" pitch difference and 1400rpm difference between the two 3 blade props.

Which kinda lands right back where the original 4 blade is.

Not sure what all this means as you can't get from point A to point B using Merc's prop selector using OP's data points.

Something is off, perhaps engine performance? We are talking about a 2014 outboard so that's 9 years worth of usage. Or a heavier boat. Or some sort of user error - trim? Or vessel view is off?

Was it mentioned how the mph was measured? I'm old, fat, lazy, and don't want to read through 4 pages to find that nugget...

MPH and RPM comes straight from live Vesselview. The motor is in excellent shape and only has 120 hours on it now. The kicker is, with this motor, this boat at weight is only about 30mph give or take no matter what. With a non command thrust you can squeeze out a little more. This is based on not only all the calculators but also what others in the Lund groups are getting with this same boat. So I know I am getting top end what I am supposed to be with the 14 and 15 pitched props. The issue is staying in the safe RPM band at WOT. I am working with a local Lund dealer right now and a big custom prop shop I spoke with yesterday. They did not have nice things to say about Turning Point props but like the Solas.

 

[jimmbo]

I don't have anything Nice to say about TP props, except they are cheap. But you get what you pay for, they often had at least one blade that was Bent, as in different Rake, than the other 2.
They also made a Weird Prop, a 4 blade(first strike against it) that had 2 sets of totally different Blades, it excelled at Nothing, and provided Lack-Luster Performance all around

 

[briangcc]

I'd gps the boat to compare vessel view. That's just me.

I have nothing more to add so I'm going to tag out of this discussion.

 

[Miked3]

Oh really ?? I thought the fella said it was two exact same props, just an inch apart. The 4 blade explains just about everything really.

Boat- 2014 Lund Fury 1625 XL
Motor- 2014 Mercury 60hp 4 stroke elpt Command Thrust 15 spline, 2.33 gear

Original Prop- SPITFIRE PONTOON (13.8 X 13") MERCURY RH PROPELLER, 48-8M8026570 - 4 blade - 25mph @5500rpm
Hustler 3 blade 14 x 13- 25mph @6150-6200rpm hitting rev limiter.
Hustler 3 blade 13.75 x 15- 29mph@4800rpm
*Moved motor up 1 hole*
Solas Amita3 13 pitch is 29.5mph @6150-6200rpm.
Solas Amita3 14 pitch is 30.5mph @5350rpm.