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NEED HELP - ADVICE 2574 GCW WOT 5300 rpm

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Mike Hill

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I am looking for advice from you guys as I am a new Bennington owner as well as a newbie as a boat owner

Boat - 2574 GCW - Express Tube Package

Motor - 150hp Yamaha 4 Stroke

Prop - 3 blade yamaha - purchased with the boat - pitch unknown to me.

Performance - 2 person, 5300 rpm, 35mph - no wind, still water.

From what I understand the pitch angle is too high causing the motor WOT not to reach 6000rpm.

I understand a 1" reduction in pitch angle will result in an increase of appx 150rpm. That said it seems a 2" reduction in pitch is what would allow my motor to reach WOT more closer to the 5800 - 6000rpm.

My question is just because the rpm increases, if I am reducing pitch It seems I wont neccesarily increase speed?

I have read on the internet and am curious about a 4 blade prop vs. 3 blade. It seems to me I by going to a 4 blade prop would result in less strain on the motor and also increase RPM without decreasing pitch.

So with all that ramble, the question is. 4 blade or 3 blade recommendations and how much reduction in pitch do I need?

Thank you in advance for your expertise and advice

Mike Hill

The
 
Mike: While I will defer to more knowledgeable owners, I'm not sure your speed numbers are that far off. The 2574 GCW is a big heavy boat. My 22 RLi with a 115 hits 28 in similar conditions.

You might be expecting too much from a 150. Yes, the rpms are a little low, but not significantly; you may be propped correctly.

See if your dealer has any props for you to try. DO NOT, I repeat, DO NOT start throwing money at props, especially 4 blade props.

Props require a lot of trial and error. Even the same boats perform differently with the same prop. Tread cautiously.

Randy

Mike Hill said:
I am looking for advice from you guys as I am a new Bennington owner as well as a newbie as a boat owner

Boat - 2574 GCW - Express Tube Package

Motor - 150hp Yamaha 4 Stroke

Prop - 3 blade yamaha - purchased with the boat - pitch unknown to me.

Performance - 2 person, 5300 rpm, 35mph - no wind, still water.

From what I understand the pitch angle is too high causing the motor WOT not to reach 6000rpm.

I understand a 1" reduction in pitch angle will result in an increase of appx 150rpm. That said it seems a 2" reduction in pitch is what would allow my motor to reach WOT more closer to the 5800 - 6000rpm.

My question is just because the rpm increases, if I am reducing pitch It seems I wont neccesarily increase speed?

I have read on the internet and am curious about a 4 blade prop vs. 3 blade. It seems to me I by going to a 4 blade prop would result in less strain on the motor and also increase RPM without decreasing pitch.

So with all that ramble, the question is. 4 blade or 3 blade recommendations and how much reduction in pitch do I need?

Thank you in advance for your expertise and advice

Mike Hill

The
Click to expand...
 
Mike, I have an '05 2550 RL, triples w/strakes. 15 1/4 X 15 stainless. Trimmed out will hit 6000 and run 40 on GPS.

I think you have some on the table. Maybe 5 mph and at least 500rpm. My prop was damaged and repaired before I bought this boat and the prop seems to be missing the slight "cupping" at the edge of the blades, as compared to a Yamaha Reliance prop. I thought this might be hurting mine but maybe not. Steve
 
First thing you should do is find out what kind of prop you have now. It'll be stamped on the prop itself. Location varies, but generally you can find it with the prop still mounted.
 
Here is the recommended prop from Bennington:

150 15 3/4 X 13 Black Steel 6G5-45932-00-98

I also think that you are around RPM and performance that you are going to get with a 25Ft boat and a 150HP.
 
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Mike Hill said:
Performance - 2 person, 5300 rpm, 35mph - no wind, still water
Click to expand...
Also, just want to be sure this speed reading is via GPS and not the dashboard speedometer. That's very important.
 
The specs I posted are measureed with GPS speed at 35mph

Sounds like 35mph is what I can expect, but it seems a change to get WOT up to 5800 rpm would insure the motor wasnt lugging?

I will get the prop specs once I get back to the boat, out of town on business presently.

For the most part I think my next move would be to reduce pitch by 2" on the prop but stay with 3 blade prop.

I was wondering if any pontoon owners out there recommend 4 blade props vs. 3 blade and what are the benefits or disadvantages?

Thanks for the time everyone took to respond!!

Mike
 
3-blade props are normally considered to be best for top end and 4-blade props are for hole shot or big horsepower, relative to boat.

Pontoon boats, as compared to traditional monohulls tend to like larger diameters and lower pitch; but YMMV.

Solas has a 4 blade prop for pontoons that is supposed to give you the best of both world do to the cup in the blades. I think they did computer modelling, but I'm not certain of that.

I don't know where you live because I forgot to look before hitting the reply button, and I'm too lazy to go back and look; but if you're like most of us you have a winter break in which to do all the research in the world.

Keep one thing in mind though...

Pontoon boats are most common in relatively shallow water lakes, and we tend to do thing like take them into even shallower waters. As a result, many people think its wise to stick with relatively inexpensive aluminum props. There are other schools of thought of course, but I thought you should know.
 
Update on the specs -

Boat - 2574 GCW - Express Tube Package

Motor - 150hp Yamaha 4 Stroke

Prop - 3 blade yamaha reliance SS prop, 14.5" diam x 15p

Performance - 2 person, 5300 rpm, 35mph - no wind, still water.

I noticed Scott posted: Here is the recommended prop from Bennington:

150 15 3/4 X 13 Black Steel 6G5-45932-00-98

I am concerned if reducing pitch 2" will reduce top speed of 35mph, while allowing me to get to 6000WOT may reduce Top Speed of 35mph?

Is there anyway to calculate the top speed if I go from a 14.5 x 15p that = 5300 rpm to a 15.75 x 13" that = 5800 rpm?

Mike Hill said:
I am looking for advice from you guys as I am a new Bennington owner as well as a newbie as a boat owner

Boat - 2574 GCW - Express Tube Package

Motor - 150hp Yamaha 4 Stroke

Prop - 3 blade yamaha - purchased with the boat - pitch unknown to me.

Performance - 2 person, 5300 rpm, 35mph - no wind, still water.

From what I understand the pitch angle is too high causing the motor WOT not to reach 6000rpm.

I understand a 1" reduction in pitch angle will result in an increase of appx 150rpm. That said it seems a 2" reduction in pitch is what would allow my motor to reach WOT more closer to the 5800 - 6000rpm.

My question is just because the rpm increases, if I am reducing pitch It seems I wont neccesarily increase speed?

I have read on the internet and am curious about a 4 blade prop vs. 3 blade. It seems to me I by going to a 4 blade prop would result in less strain on the motor and also increase RPM without decreasing pitch.

So with all that ramble, the question is. 4 blade or 3 blade recommendations and how much reduction in pitch do I need?

Thank you in advance for your expertise and advice

Mike Hill

The
Click to expand...
 
lakebum said:
Mike, I have an '05 2550 RL, triples w/strakes. 15 1/4 X 15 stainless. Trimmed out will hit 6000 and run 40 on GPS.

I think you have some on the table. Maybe 5 mph and at least 500rpm. My prop was damaged and repaired before I bought this boat and the prop seems to be missing the slight "cupping" at the edge of the blades, as compared to a Yamaha Reliance prop. I thought this might be hurting mine but maybe not. Steve
Click to expand...
are you running a 150hp yamaha?
 
To be totally honest I think you should stick with the prop you have. If you are running 35 mph with a 150 pushing a 25 foot boat you are in good shape even if the rpms are a bit lower. I just bought the same prop you currently have for my 150 on my rig in my sig below. I want to keep same mph which light load is around 38 mph but wanted to gain a couple hundred rpms but I think I am more capable of it on my 22 foot baot thean you will be on a 25 footer.

I currently have the black stainless yamaha 15 1/4 X 15 prop and am running at 5400 rpms trimmed high loaded and 5500 light load trimmed high.

In Yamaha/Bennington performance bulletins I see the same boat as mine with yamaha 150 running the 14 1/2 x 15 RELIANCE PROP runing 5800 rpms.
 
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