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Do I need to go down in pitch?

Old 10-28-2019, 04:16 PM
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Default Do I need to go down in pitch?

Can someone please tell me if this prop is good based on max rpm?

I have a 2019 Pathfinder 2400 with 9 hrs. We ran with 3 people, 1/2 tank of fuel, 4 batteries, coolers empty, essentially a medium load. The max rpm I could get is 5400. Should I go down from 22 to 21 pitch? I would normally have a little more weight on the boat.

Prop: Yamaha HS4 15x22
Engine: Yamaha 300









Last edited by Smoak352; 10-28-2019 at 04:23 PM.
Old 10-28-2019, 04:18 PM
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I would go down
Old 10-28-2019, 04:18 PM
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what engine?
Old 10-28-2019, 04:22 PM
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Originally Posted by smooth move View Post
what engine?
Yamaha 300
Old 10-28-2019, 04:31 PM
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What's the max RPM for your engine?
Old 10-28-2019, 04:36 PM
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Yes. Go down in pitch. I would start with a 20" pitch.

Using the same brand and model of propeller. Only problem is that Yamaha does not offer the HS4 High Seas in anything less than a 21" pitch. Who chose that particular propeller for your motor?

Objective is to have the motor be able to reach at or near 6000 RPM when the throttle is wide open, boat is loaded, and the motor trimmed up only to the point of best efficiency.

You are a long way from 6000 RPM. The boat is apparently not loaded.
Old 10-28-2019, 05:01 PM
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The published acceptable range is 5000-6000rpm, so you are likely in spec with any load you can put on that boat. That said, you are giving up some performance with it that way. The F300 gets the best performance at 5700rpm heavy.

Is there something you were trying to correct with the 4 blade?

I'd check the engine height first. Assuming the prop is in good condition, you are getting 14% slip, which is a little high. Changing to a 21 is only going to get you 100-150rpm more. A 3 blade 21 will probably get you to 5700. A three blade 19 will get you close to 6000.
Old 10-28-2019, 05:15 PM
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Combo of what everyone is saying
as long as motor is mounted at proper height
dropping a pitch would help a little
otherwise 3 blade sws11
or if you want stern lift and better low-mid
performance go power tech ofs4
email ken at propgods
Old 10-28-2019, 05:25 PM
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The PB on that boat, with that engine and that prop, mounting hole #1, as tested with 2 people, 50 gals of fuel and 1 battery says you should be hitting 5800 rpm @ 59 mph. You have 3 extra batteries and 1 more person on board. I see you're trimmed up pretty high, so that does not appear to be the problem.
Old 10-28-2019, 07:01 PM
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Originally Posted by scooperfl View Post
The published acceptable range is 5000-6000rpm, so you are likely in spec with any load you can put on that boat. That said, you are giving up some performance with it that way. The F300 gets the best performance at 5700rpm heavy.

Is there something you were trying to correct with the 4 blade?

I'd check the engine height first. Assuming the prop is in good condition, you are getting 14% slip, which is a little high. Changing to a 21 is only going to get you 100-150rpm more. A 3 blade 21 will probably get you to 5700. A three blade 19 will get you close to 6000.
There is more to it that just being within a range.

The Owner's Manual goes on to say:




Old 10-28-2019, 07:05 PM
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It’s surprising that optimum cruise for this boat is at only 2500 RPM. Your numbers are not far off from the Yamaha performance bulletin until you get to the upper RPM range. Propellers were the same. At 5,000 RPM, Fuel consumption is significantly lower (worse...-23%) on your boat than the test boat, while speed is only 1+ MPH slower. Your boat only has 9 hours. I would give it a bit more time until you start making changes to your propeller.

Pathfinder-2400-TRS-F300XCA.pdf



Last edited by jfbetz; 10-28-2019 at 07:17 PM.
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Old 10-28-2019, 07:10 PM
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Originally Posted by scooperfl View Post
The published acceptable range is 5000-6000rpm, so you are likely in spec with any load you can put on that boat. That said, you are giving up some performance with it that way. The F300 gets the best performance at 5700rpm heavy.

Is there something you were trying to correct with the 4 blade?

I'd check the engine height first. Assuming the prop is in good condition, you are getting 14% slip, which is a little high. Changing to a 21 is only going to get you 100-150rpm more. A 3 blade 21 will probably get you to 5700. A three blade 19 will get you close to 6000.
A 3 blade 21 what? A 3 blade 19 what? There’s a bit more to it than blades and pitch. Different propeller models of similar pitch and blades can behave very differently.
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Old 10-28-2019, 07:16 PM
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Originally Posted by scooperfl View Post
The published acceptable range is 5000-6000rpm, so you are likely in spec with any load you can put on that boat. That said, you are giving up some performance with it that way. The F300 gets the best performance at 5700rpm heavy.

Is there something you were trying to correct with the 4 blade?

I'd check the engine height first. Assuming the prop is in good condition, you are getting 14% slip, which is a little high. Changing to a 21 is only going to get you 100-150rpm more. A 3 blade 21 will probably get you to 5700. A three blade 19 will get you close to 6000.
It is the prop used in the Yamaha Performance bulletin and they went 59mph at 5800 rpm so I thought it would be a good choice.
Old 10-28-2019, 07:18 PM
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Originally Posted by jfbetz View Post
It’s surprising that optimum cruise for this boat is at only 2500 RPM. Your numbers are not far off from the Yamaha performance bulletin until you get to the upper RPM range. Propellers were the same. At 5,000 RPM, Fuel consumption is significantly lower (-23%) on your boat than the test boat, while speed is only 1+ MPH slower. Your boat only has 9 hours. I would give it a bit more time until you start making changes to your propeller.

Attachment 1106376

Ok, i was wondering if the low hours would affect that. What should I wait for the 20 hour service?
Old 10-28-2019, 07:24 PM
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OP - Performance tests are done with 3 gallons of fuel, and two starving Ethiopian testers on board - you are over propped, have a too deeply mounted engine or some combination of both. Continuing to run it in an overpropped state may lead to oil making and increased fuel useage but will not fix it.
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Old 10-28-2019, 07:24 PM
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Originally Posted by Smoak352 View Post
It is the prop used in the Yamaha Performance bulletin and they went 59mph at 5800 rpm so I thought it would be a good choice.
In general, virtually any boat used for a Yamaha Performance Bulletin will be over propped by ~ 2 inches when the boat is put into service.

PB boats are new and as light as they will ever be. Nil equipment on board. Low fuel. Few people.

Your boat seems to be following the modus operandi.

One other point, most Yamaha motors are mounted lower than the optimum performance mounting height. Check the engine mounting height before making any further moves. Adjust if needed. Then retest with the boat fully loaded to see how far off you are and what adjustment(s) need to be made. The PB shows the motor being mounted even further lower than is normally the situation.
Old 10-28-2019, 07:49 PM
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See if you can get a picture of the AV plate while on plane in the upper RPM range, or a picture of the boat/engine showing the relation of the AV plate to the keel. This will determine if height adjustment is necessary. It would not be surprising if your current mounting height is a bit low. If your RPM numbers do not improve at the 20 hour dealer service interval, record the numbers at that time and put them in front of the dealer. Ask if you can test a few other recommended propellers to better dial in RPM’s. Throwing money at propellers at this point will get expensive quick. They could adjust mounting height as well.
Old 10-28-2019, 08:00 PM
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Originally Posted by jfbetz View Post
See if you can get a picture of the AV plate while on plane in the upper RPM range, or a picture of the boat/engine showing the relation of the AV plate to the keel. This will determine if height adjustment is necessary. It would not be surprising if your current mounting height is a bit low. If your RPM numbers do not improve at the 20 hour dealer service interval, record the numbers at that time and put them in front of the dealer. Ask if you can test a few other recommended propellers to better dial in RPM’s. Throwing money at propellers at this point will get expensive quick. They could adjust mounting height as well.
Is this necessary if I have a jack plate?
Old 10-28-2019, 08:10 PM
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Originally Posted by Smoak352 View Post
Is this necessary if I have a jack plate?
Manual or hydraulic? If you have a hydraulic jack plate, you can adjust on the fly and determine optimum mounting height for all your operating conditions. If it’s a manual plate, ratchet the engine up an inch or so and record your data.
Old 10-28-2019, 08:19 PM
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Hydraulic.

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