Cruising RPM's?

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magicalbill

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I'm always curious what RPM range y'all run your outboards, Yam, Suzuki's whatever.

I run my Yam 350's between 3600-4200 depending on how fast I want to reach my destination.

I recall Skunk winds his Zukes up around 5K due to his power-to-weight ratio. On the other end, Wahoo never pushed his 300 Yamaha past 4K on his Great Loop Trip.

What RPM is your max limit before you worry about premature engine wear & tear? Again, I'm not talking about brief bursts of full throttle; I am referring to normal extended cruising speeds, whether it's an offshore fishing trip or a coastal pleasure cruise.

I realize sea conditions often dictate speed; My question is directed to the times it's flat enough to run as fast as you choose.
 
I cruise at 5000-5200 if it’s flat out. I don’t see this as increasing wear. I’ve done this with evinrude, Suzuki, tohatsu, and Yamaha. If you can go fast and burn the gas, why not. Also the engine typically run cooler when going faster. When I’m inside LA harbor and going from end to end, I’m almost wot for 10-15 minutes. The evinrude loved it, my passengers didn’t. By the way I have twin 4 cylinder 150s now so my engines are smaller than most here. I have downsized because I now keep the boat on a trailer. 150s burn less gas the twin 300!
 
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My mechanic recommends running WOT for 10 minutes or so when you can to blow out carbon buildup. Also recommends ring-free additive with every tank. I never shut my engines off and do a lot of idling so getting the carbon out is important.

As far as cruise the "sweet spot" for me is 4,200 to 4,800. 25 to 28 knots. Especially with my new props engines run fine - no bogging down - responsive.
 
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280 marlin ox66 250 yamaha 2 stroke best trim seems to be 3800 rpm getting around 22 gal per hour burn and 30 mph cruise. trimming properly makes huge difference is fuel burn.
 
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330 with 225's sees me at 4700-4800 as normal cruise. I'd run harder, but the fuel gauge seems to spin faster and faster...
 
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I have an I/O Volvo Penta 4.3GL on an overnighter. Typically get up on plane about 3200rpm and cruise at about 3400. WOT goes up to about 4000. PO told me he kept it below 3400 to baby the engine a little and save fuel cost.
 
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I don’t like running over 4500 rpm’s. I have a pair of 250 Yamaha’s 2007 vintage. A previous boat I had the same and seldom ran over 4200 because the speed was adequate at around 28-30 kts between 4000 and 4200 R’s. I put over 2,000 trouble free hours on those and according to the new owner they are still humming.

The new to me Marlin is a heavier boat so the 250’s have to work harder. It may be quite some time before I could justify strapping on a pair of 300’s to get a couple more knots and a little better fuel economy. I’ll keep her at 4500 or less to extend the life of the current 250’s. And at 400 hours currently we should have many years to go. 24- 26 kts works for me. BTW I love the boat. It checks all the boxes for what we do. We have owned a few twin diesel inboards and even though they were great sea boats I don’t miss all the expense and maintenance.
 
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My normal cruise is at 4700-4900 rpm. That seems to be the sweet spot for both speed and performance. These engines don't like to run under 4000. My previous 265 with f225's cruise rpms were roughly the same( these engines surpassed 2K hrs). According to my Yamaha mechanic engines run at sub 4000 rpm and a lot at idle will get carbon build up and will lead to the newer 4.2 yamahas making oil. He has told me numerous times that these engines are designed to run at 5K rpms.
 
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2006 330 Express with F250's & 4 blades 16" pitch. 2,200 hours and counting.

I cruise at 4,300 RPM's doing 22-24 knots. Maybe 4,400-4,500 if I'm heavy with full fuel.
I do not like running at WOT (5,700 RPM) and do so once in a while just to be sure it can do it.
The GPH at WOT scares me!
 
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Thanks for all the replies. As I suspected, there are several schools of thought on this subject.

I've always been apprehensive about pushing any of my engines hard. My previous Gulfstream with F200 V6's ran in the neighborhood of 3600-4200 and were in great shape after 1200 hrs. (Except for the exhaust corrosion that they got. Everyone knows that soap opera.)

The consensus seems to be that whether you run them hard or baby them, with maintenance they seem to run easily past 1000 hrs.
 
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magicalbill said:
Thanks for all the replies. As I suspected, there are several schools of thought on this subject.

I've always been apprehensive about pushing any of my engines hard. My previous Gulfstream with F200 V6's ran in the neighborhood of 3600-4200 and were in great shape after 1200 hrs. (Except for the exhaust corrosion that they got. Everyone knows that soap opera.)

The consensus seems to be that whether you run them hard or baby them, with maintenance they seem to run easily past 1000 hrs.
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Agreed .... 1,000 hrs and well beyond. Friend of mine has a pair of the 250’s on a 31 Cape Horn with over 3500hrs and running strong
 
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I try to keep it just under 10gph on the way out which is around 28-30mph and just below 4k RPMs. On the way back in from fishing I usually run it harder and will hit WOT in the river for short duration. I run my small boat the same way.
 
And here's a short story speaking of operating at W.O.T. RPM's

When I was evaluating my boat to be purchased (319 hours 10.5 years ago), I hired a Surveyor to check on the Engines (twin F250's on a 2006 330 Express).

After checking all the basic stuff (oil, electrical charge, etc.), he took it out in the ocean and ran it for 10 full minutes at W.O.T.
He said, if something were to go wrong, it will surely happen in those ten full minutes.

Sure enough, one of the fuel pumps had a few hick ups. The Seller gladly paid to have it replaced.
 
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Great thread magicalbill started,

I suppose I do not have to push my engine like the rest of you sea bearing sailors, but I like to cruise at 4000-4200RPM. I am frugal when it comes to fuel burn.

Thanks for you that said you will push the envelope to get rid of carbon.

A final thought on this, you mostly have Yammies, and I have a Honda. The Coast Guard use Honda's and pretty comfortable saying they push them hard at time and get 5000-6000 hours from the engines, so I think the new generation of engines have hiccups here and there, but they in general can take a beating for a long time.
 
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I run my Freedom 275 with a single F350 at 4300 RPM. This keeps me going at a fast plane without burning too much gas (the F350s really consume fuel above 4500 RPM) and just out of the F350's flywheel degradation range. I will occasionally run at WOT for a few minutes to let the engine stretch its legs.

I think 5000+ RPM consistently would result in increased wear. However, marine engines are engineered for running at high RPMs. I read once that GM engineered the 8.1L big block engine (offered in three-quarter ton and larger trucks as well as the marine market) for durability against the "Marine Dock" test where an engine is run at virtually wide-open throttle for 300 hours straight (60-minute cycle—55 minutes wide-open-throttle/5 minutes idle). This testing is more severe than standard durability testing used for truck applications. So I think that is a good sign that marine engines like outboards are meant to run consistently at 4500-5500 RPM.
 
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It all depends for me the mood I am in at the time. lol. On the lake I will run it around 4,200 to 4,500 most of the time. I will run it WOT for 20 or 30 minutes mainly to help with the carbon stuff. Outboards are built to be run at high rpms for extended times.

When I am on the ocean I run what she gives me which is often 3,900 to 4,000 range because I don't like getting beat up. There are days though when the seas are calm I will run 30 or 35 if I can to get fishing sooner, that's between 4,000 and 4,500 RPM.
 
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SmokyMtnGrady said:
It all depends for me the mood I am in at the time. lol. On the lake I will run it around 4,200 to 4,500 most of the time. I will run it WOT for 20 or 30 minutes mainly to help with the carbon stuff. Outboards are built to be run at high rpms for extended times.
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Absolutely! You will find more issues from lack of use and boats that idle for long periods of time. Motors that didn't do proper break in and now "make oil". I will say I was a bit nervous on my first oil change on the new motor. lol
 
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