Should I really be turning 6000 RPMS?????

[CCparker]

Another member posted a question in the all parker boats page about 23SE performance.

I have the 23SE with F-200 and factory black stainless prop. I have a T-top and it is bottom painted.

Best RPMs I have ever gotten is 5200 if I trip it way up. Typically I only get 5000.

At 5200 I am doing 34 knots (39MPH) and burning around 15GPG.

I am happy with my boats performance. I don't really need or want to go any faster than what I get, but should I really be able to turn 6000? Any reason why I should be concerned about anything? Thanks

 

[Foggylink]

CC,

The attached phone photo is with my 14.5 x 17 aluminum. I just changed to a 4 blade Quicksilver. I get to 6000 with both. I still need to get some numbers for the new prop.


Foggy

 

[TheOtherLine]

I don't really need or want to go any faster than what I get, but should I really be able to turn 6000? Any reason why I should be concerned about anything? Thanks

You might be unknowingly lugging the engine. Don't think that's good for em'.

I'll defer to the motorheads who will surely chime in...

 

[DaleH]

I don't really need or want to go any faster than what I get, but should I really be able to turn 6000? Any reason why I should be concerned about anything? Thanks

You might be unknowingly lugging the engine. Don't think that's good for em'.

I'll defer to the motorheads who will surely chime in...

If it is truly a 6K maximum RPM motor, I'd want it to be at least 5700 with 2 guys, std gear and a bit more than 1/2-fuel. Otherwise, yes, you are lugging the motor when loaded and that is absolutely the worst thing one can do to an OB, less not having oil.

IMHO, over-propping motors is what leads to more powerhead deaths than any other reason ...

 

[CCparker]

Foggylink- Can you let me know the size of the quicksilver prop you put on, and are you happy with its performance. Thanks

I'm pretty curious as to why I am only getting that performance with the factory spec'd motor and wheel. I had the same exact situation on my 21SE - could only get to 5200. Sounds like I need to do some experimenting.

Thanks for the input guys.

 

[Foggylink]

I went with a 4 blade aluminum for more mid range control. Not to mention the ledges that move around in my area. A stainless would most likely be better if obstructions are not an issue. I had contacted Parker about props other than that listed in the Yamaha performance bulletin, I got an initial response asking for a hull number, but no responses since then.

Ken at prop gods was right on with his recommendation, 15" x 16p. I'll get some good numbers this weekend ...

http://www.propgods.com/content/quicksi ... llers.aspx

 

[JWL]

the engine should turn 5,000 - 6,000 at WOT. If all you can turn is 5,200 you are runnning on the low side and could be lugging the engine. I would reduce the pitch by 2 inches which would increase RPM's by approximately 400 rpm's. Remember, the heat of the summer will reduce rpm's as well as a heavy load in the boat.

I am a believer one should prop so the engine will turn the max rated rpm's when full of fuel, people, tackle, etc. You can always reduce throttle in order to not over rev when lightly loaded but, there is no way to increase rpm's when fully loaded except to either lighten load or reduce pitch of the prop.

 

[PDP]

As others have said, it really is desireable on that motore (and the F225 and the F150) to turn close to 6000 at WOT, trimmed up with a "customary" (not crazy heavy) load.

I posted on the other thread you mention, and I can spin 5600-5800 (5800 veeeery light and trimmed waaaay up). At that range, I don't believe I am lugging the motor, but I want to spin closer to 6000. I believe low range prefomance will improve, and I believe the engine probably will be happier too.

5200 is definitely on the very low side of the acceptable range (it is in fact the lowest I have heard of on our set-ups). If I were you, I certainly would be thinking about dropping down in pitch - probably more than couple of inches. I suspect almost everything about your boat's handling will improve once you do. Ken at Prop Gods, mentioned above, is a great resource.

None of us with these boats are speed freaks (and there is a huge fuel penalty to running at or near WOT, so I don't do it) - but your engine (and my F225) does not even produce the full stated HP until it spins to 5500 rpm. I'd want to prop the boat to hit at least that mark - I have to think it is better for the engie, but I am certainly no expert.

Paul

 

[Seamaster]

Hi Guys

Could someone please explain what you mean by lugging the engine?

I run my motor where my fuel flow meter (connected to my GPS) tells me Im getting the best mileage, which is usually about 4400 RPM's and I get somewhere between 2.6 and 3.1 MPG. Is there something wrong with operating the boat this way?

 

[JWL]

Hi Guys

Could someone please explain what you mean by lugging the engine?

I run my motor where my fuel flow meter (connected to my GPS) tells me Im getting the best mileage, which is usually about 4400 RPM's and I get somewhere between 2.6 and 3.1 MPG. Is there something wrong with operating the boat this way?

The short answer is, no. Lugging your engine can best be described by making an analogy to car engines. Think about driving a manual shift car or truck and running in 4th gear at 20 mph. You would be lugging the engine. The same thing with a boat. If the engine should be turning 6,000 rpm at WOT and you can only turn up to 5,000 you will be lugging the engine throughout the entire rpm range.

 

[Jawbreaker]

Hi Guys

Could someone please explain what you mean by lugging the engine?

I run my motor where my fuel flow meter (connected to my GPS) tells me Im getting the best mileage, which is usually about 4400 RPM's and I get somewhere between 2.6 and 3.1 MPG. Is there something wrong with operating the boat this way?

Depends. If the 4400 rpm is at WOT (wide open throttle), and that's as high as your engine will rev., that's very bad.

If the 4400 rpm is at an intermediate throttle setting, and you can hit 6000 rpm, or thereabouts, at WOT, you're fine.

NOTE: The above analysis applies to the current crop of four stroke Yamaha motors that are meant to rev. up to about 6000 rpm. For any engine, if it won't reach the WOT rpm range recommended by the manufacturer, this is not good.

 

[Megabyte]

Before you decide to re-prop, have you had a mechanic check the motor to make sure there isn't another underlying reason for the lower than normal RPM's at WOT?

The prop might not be the culprit.

 

[DaleH]

I run my motor where my fuel flow meter (connected to my GPS) tells me Im getting the best mileage, which is usually about 4400 RPM's and I get somewhere between 2.6 and 3.1 MPG. Is there something wrong with operating the boat this way?

As JWL said, as long as your rig is properly propped so you are turning no more than 300 RPMs off the maximum RPMs, then even when you cruise @ 4K RPMs, that is not lugging the motor.

It is the opinion of many esteemed OB gurus (Seahorse & Dunk are but two) thatlugging an OB is the fastest way to kill it ... less not adding any oil.