Crusing Rpms

[krisnowicki]

How high is to high for a cruising rpm... Just curios what is to high to be healthy for the motor.

 

[Zackman]

Re: Crusing Rpms

Not really the answer to your question, but normally the best crusing rpm is at the best efficiency point. Most gasoline marine engines' bep, with a planing hull, is between 3000 and 3500 rpm.​

 

[woosterken]

Re: Crusing Rpms

I would think nailing the red line (wot) and keeping it there for an extended time would NOT be good.the best would be the sweet spot for your set up.
the point where it will stay on plain the engine is not under strain

woosterken

 

[bowman316]

Re: Crusing Rpms

Get on plane, then back off slowly, until you feel the boat wanting to not be on plane any longer, then give a little more gas to stay on plane. This is the most efficent point.

The lowest speed to stay on plane.

 

[Fu-Inator]

Re: Crusing Rpms

It is interesting that you asked this question because I was wondering the same thing a few months ago. I looked in my engine manual and all that is listed are idle RPM and WOT RPM ranges. The first time out I?ll check those two and figure everything in between should be ?good enough?? lol.

 

[n2ostroker]

Re: Crusing Rpms

Once you get on plane you kind of feel things ease up. You won't have to hit the throttle anymore and the rpms will kinda settle in maybe even pick up some speed. You may try playing with the trim a bit too. That is where my efficient point is. Seems to be around 34-3500rpms

 

[mthieme]

Re: Crusing Rpms

For me, an economical cruising speed is around 3000 +/- 200.
The lower the rpms, the longer your motor will last.

 

[krisnowicki]

Re: Crusing Rpms

I thought the same around 3000-3200 it just seems rough on an engine to run it at 3200+ for a long time. Like it shorten the engine life.

 

[abj87]

Re: Crusing Rpms

Generally you don't want to go past 80% of full rpm. Figuring 4800 for full rpm your cruise is 3840rpm.

 

[stonyloam]

Re: Crusing Rpms

That 3000-3500 range sounds about right to me. One other thing to do is adjust the trim and watch the rpm to find your most efficient trim angle at a given throttle setting. On my 19' 4WINNS a small trim change can result significant rpm change. If you are running flat, at a given throttle setting the rpm should start to increase as you raise the bow angle and then begin to drop off when the bow gets too high. The maximum rpm should be your most efficient planing speed. That trim angle will change of course depending on how the weight is distributed in the boat (when cousin bill decides to sit in the bow you should re-trim), water conditions and safety must also be taken into consideration. Just make changes in small increments, and give it a little time for the rpm change to show up. Trim is very important for efficient cursing. Most of you already know that, but there are a lot of new boaters here.

 

[Tuna Van]

Re: Crusing Rpms

Just floor it until it blows up, and then next time keep it 100 RPMs under that.

 

[FreeBeeTony]

Re: Crusing Rpms

I think my most efficient RPM is probably ~3400...............but I like 3600-3800 better...........

 

[QC]

Re: Crusing Rpms

How high is to high for a cruising rpm... Just curios what is to high to be healthy for the motor.

If that's your question, then I don't think you've been given a relevant answer except by abj87 . . . If it's economy, then the other answers are pretty good.

I often cruise @ 4000 RPM but my 6.2 WOT range is 4800 - 5200 RPM. I lose 3/10 off of mpg as compared to best and I get where I am going faster and that's important if you have a long way to go. Merc says you can run at WOT all day long. Will it live as long? No, but are you hurting it? No. If you think of life as delivering some grand sum of horsepower over time then life is probably not shortened either . . .

 

[mylesm260]

Re: Crusing Rpms

I'm propped a little higher than most.

I can generally stay on plane @ 30 MPH @ around 2700 or so

 

[fat fanny]

Re: Crusing Rpms

Good water conditions (smooth) 2800 rpm's trim @ 1/3 up from dead end down nice and smooth very relaxing with the wife on the bow. MAN! I can't wait to get it on the water counting the days.

 

[krisnowicki]

Re: Crusing Rpms

I think my most efficient RPM is probably ~3400...............but I like 3600-3800 better...........

My boat will maintain plane at around 2600.... but... my questions is would you feel comfortable running a 305 chevy at 3600 for long periods of time... IT just seems like abuse to me.

 

[lowkee]

Re: Crusing Rpms

Just floor it until it blows up, and then next time keep it 100 RPMs under that.

Hehe. Says the guy with the corvette avatar

 

[bigbob_FTW]

Re: Crusing Rpms

My boat will maintain plane at around 2600.... but... my questions is would you feel comfortable running a 305 chevy at 3600 for long periods of time... IT just seems like abuse to me.

They're made for it.

 

[cbavier]

Re: Crusing Rpms

I would think it would depend on the boat, weight and size of engine and wind and waves. My 4.3 V-6 properly trimmed planes out at about 31-34 MPH at about 3100 -3300 RPM

 

[Johnshan1]

Re: Crusing Rpms

I run my 2000 GM 350 2800-3200 at cruise. You can feel the sweet spot after you run it for awhile.