Yanmar R27 Cruise Numbers

[CaspersCruiser]

I just completed a 190 SM Florida cruise from Tarpon Springs to 10 miles above Ft. Myers on the Caloosahatchee. I’m on the hunt for what other Yanmar-powered R27 owners use for cruise RPMs and what speeds they attain. I’ve searched the archives until my eyeballs have about fallen out looking for this information, but didn’t find just what I was looking for.

Much of the time I cruised at 2900 RPM and achieved 10mph +/- .5. At times, I used 2500 RPM and got 8mph +/- .5. In the “Slow- Minimum Wake” zones, I used 1500 RPM @5mph. On the last day, I pushed it up to 3250 RPM for about an hour and got 14mph. At that speed, the wake seemed to be less than at 2900 RPM and the boat really handled well. According to the chart plotter, the mpg was BETTER at 3250 vs. 2900.

If you have a Yanmar R27, how do you set cruise?

 

[Crewdog]

http://www.tugnuts.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=52991&g2_GALLERYSID=ff7eb478a3d4576efc7a67ba49c89ebe

I created a word document a while back, where I went out on the lake one day with calm wind and no current, and charted speed and NMPG for a few minutes under each RPM. Speeds over 8 kts had a little trim tab added, and test was done with only myself aboard, full water, half fuel, no supplies, lake elevation about 840 msl.

The link above will download the document.

I printed out a copy and keep a laminated version near the helm so I can readily reference what any RPM combo will yield. Fully loaded with trip supplies and other passenger will lessen results slightly, but not enough to re-do chart.

I guess proper speed depends on wind/waves, weather, time available and whether fuel is readily available; so it's a personal choice for everyone.

forgive the formatting below, but columns on downloadable doc do show.

RPM SPEED NMPG
800 3.6 8.4
900 3.7 8.3
1000 4.3 8.2
1100 4.6 7.6
1200 4.9 7.8
1300 5.1 6.9
1400 5.3 6.1
1500 5.5 5.8
1600 5.9 5.3
1700 6.0 5.0
1800 6.4 4.6
1900 6.6 4.4
2000 6.8 4.0
2100 7.1 3.7
2200 7.3 3.0
2300 7.5 2.9
2400 7.7 2.9
2500 7.9 2.5
2600 8.2 2.4
2700 8.5 2.2
2800 8.8 2.2
2900 9.2 2.1
3000 9.6 2.0
3100 10.3 2.0
3200 11.1 2.0
3300 11.8 2.0
3400 12.4 1.9
3500 13.2 1.9
3600 13.6 1.8
3700 13.9 1.8
3800 14.3 1.7
3950 15.2 1.6

 

[knotflying]

Those numbers jive somewhat with mine. I do a bot better at the higher RPM, around 2.0 NMG. Of course wind and current play a large factor. I usually cruise at an RPM that will give me 3 nautical mikes per gallon that can range from about 6.5 to 8.5 nautical miles per hour depending on current. I have found that once I want to go fast I may as well go at 80% and it is usually a burn of 2 nautical miles per gallon and a speed of around 12 to 14 KTS. Wide open is around 16 KTS and 1.8 nautical miles per gallon.

 

[YukonRon]

Which Yanmar engine are you guys comparing these numbers for in your R27s? We have the 4BY2-180 in our R25sc, and I know that was a common engine for the R27s for a time. Is that what you are running? I'm curious, as those numbers might be fairly similar to what I might expect in my boat; our hull is 2 feet shorter, but also pushing less weight. We haven't had our boat long enough yet to get a feel for the numbers.

 

[CaspersCruiser]

Thanks for the replies.

My speed numbers are in statute miles per hour. I use statute because the mileage numbers on the river, ICW, and Great Lakes charts are depicted in statute. Makes the math easier.

I was really surprised that the noise level at 3250 RPM wasn’t too bad and the wake and handling seemed better. So the question is, is there an engine longevity downside to cruising at 3250? The only reference to max RPM I can find in Yanmar documentation for the 4BY2 is 3600 RPM is the max continuous.

 

[knotflying]

I was told you can go all day at 80% power. I am not real sure what 80% power means. Is that 80% of the full throttle? That would mean 3200 RPM or is that 80% load on the turbo? Coincidentally that seems to jive with the RPM's. I also heard about the 3,600 RPM. So, I am not sure what the answer is. I usually run much lower than those max numbers so have not been too concerned, but would be interested in getting a definitive answer.

 

[knotflying]

Which Yanmar engine are you guys comparing these numbers for in your R27s? We have the 4BY2-180 in our R25sc, and I know that was a common engine for the R27s for a time. Is that what you are running? I'm curious, as those numbers might be fairly similar to what I might expect in my boat; our hull is 2 feet shorter, but also pushing less weight. We haven't had our boat long enough yet to get a feel for the numbers.

Yes the 4BY2-180

 

[BB marine]

I'm not a Yanmar owner,( D3 Volvo) but I'm interested in this topic. I find comparing your numbers for the 4BY2-180 close to the numbers I am getting with 220hp D3 in 26 Cutwater. Mine are slightly higher because of the increased HP. I have been trying to find out the same answer to the question percent of Rpm compared to percent of power output. Most Diesel experts say a diesel runs its best at 80% of its power output. Volvo says the light duty marine diesels D2,D3,D4,D6 can be run continuous at 90 % of rpm range. My question is does 90% rpm range equal 80% power output. I read an article that used fuel consumption as a gauge for power output. The maximum power output is rated by fuel consumption.( I'm simplifying the explanation ) This is how I understood the explanation in the article. If a engine manufacture rates 220hp Volvo at 11.9gallons per hour at 4000rpm and your engine is loaded properly using this amount of fuel.Then you can calculate that 80% of load would be when you are operating the engine at a speed that uses 9.52gph which in my boat is appox 3700rpm. 90% of Rpm would be 3600 Rpm which is slightly lower then 80% of max output. Looking at Crewdogs numbers it looks like he is burning approx 9.5 gallons an hour at 3950 and at 3600rpm he is burning 7.55 gph These are based on his performance chart. 9.5 X 80% = 7.6 gph. So with that calculation 3600rpm would be 80% of output. If I am figuring this out right or understanding this properly the 90% of rpm range is equivalent to 80 present of engine output. I'm interested in this because I too would like to run the engine at higher rpm cruising speeds. The 26 Cutwater runs its best at 15 to 16 MPH. which is 3600 rpm. I have always run at 3250 which is slightly better efficiency approx .2 mpg as 3600 but 3 to 4 mph slower. I actually have 2 cruising speeds 1950rpm 2.0 gph or 3250 7.0 gph. I realize these are light duty Diesels, high rpm, high HP from small engine displacement. That is another question do these High HP small displacement diesels fall into the continuous 80% power range and maintain longevity ?

 

[NorthernFocus]

...I have been trying to find out the same answer to the question percent of Rpm compared to percent of power output..

Didn't you get a copy of the performance curves(dyno test curves) with the owner's packet? If not you can find various versions of same on the web.

... Most Diesel experts say a diesel runs its best at 80% of its power output..

What does that mean? Who are "most diesel experts? Automotive, marine, or industrial experts? Even among marine diesels there are differences between engines intended for pleasure and commercial use.

... Volvo says the light duty marine diesels D2,D3,D4,D6 can be run continuous at 90 % of rpm range. My question is does 90% rpm range equal 80% power output...

Who is "Volvo"? Is that coming from the owner's manual?
Local shop? Mechanic? Regarding whether 90 percent RPM equates to 80 percent power the performance curves are needed to answer that. Keeping in mind that what the curves show and how the engine load vs RPM is related in a given boat is dependent on hull design, how the boat is loaded, prop selection, etc. Because of the many variable involved any performance claims made in literature produced by the manufacturer typically refer to the base performance test curves.

... I read an article that used fuel consumption as a gauge for power output. The maximum power output is rated by fuel consumption.( I'm simplifying the explanation ) This is how I understood the explanation in the article. If a engine manufacture rates 220hp Volvo at 11.9gallons per hour at 4000rpm and your engine is loaded properly using this amount of fuel.Then you can calculate that 80% of load would be when you are operating the engine at a speed that uses 9.52gph which in my boat is appox 3700rpm. 90% of Rpm would be 3600 Rpm which is slightly lower then 80% of max output. Looking at Crewdogs numbers it looks like he is burning approx 9.5 gallons an hour at 3950 and at 3600rpm he is burning 7.55 gph These are based on his performance chart. 9.5 X 80% = 7.6 gph. So with that calculation 3600rpm would be 80% of output. If I am figuring this out right or understanding this properly the 90% of rpm range is equivalent to 80 present of engine output. I'm interested in this because I too would like to run the engine at higher rpm cruising speeds. The 26 Cutwater runs its best at 15 to 16 MPH. which is 3600 rpm. I have always run at 3250 which is slightly better efficiency approx .2 mpg as 3600 but 3 to 4 mph slower. I actually have 2 cruising speeds 1950rpm 2.0 gph or 3250 7.0 gph. I realize these are light duty Diesels, high rpm, high HP from small engine displacement...

It sounds like the article was referring to "specific power" which is the amount of power produced per lb of fuel burned. Specific power is often used for simplicity rather than having to "normalize" conditions for atmospheric pressure, air temperature, and humidity. Which all boils down to say that your logic above is sound. Though on a test bench under controlled conditions I'd be very surprised if 90 percent of max rated RPM only equated to 80 percent of rated power. But if that's what you're getting on your particular boat, i.e. 90 percent rated RPM equates to 80 percent rated fuel consumption (at rated HP), then it is unlikely that the engine is being overloaded.

...That is another question do these High HP small displacement diesels fall into the continuous 80% power range and maintain longevity ?

I suspect that your previously referenced "expert" was talking about light weight engines. But at any rate, what kills engines(or anything else with lubricated wear parts) is heat. The cooling and lubrication system is designed to handle the heat generated at full load. Operating at 80 percent load means only (nominally)80 percent of the fuel and therefore 80 percent of the rated Btus are going through the engine. That's a pretty good cushion for the cooling/lube system. The Mercruiser controls on my boat calculate and display percent load and that is what I use to set my cruise speed. At 80 percent 😀

 

[BB marine]

[/quote]

Didn't you get a copy of the performance curves(dyno test curves) with the owner's packet? If not you can find various versions of same on the web.

Yes I have seen the performance curves but I was not able to answer my question by reading them. They gave a base line of peak torque, rpm range, peak HP in a rpm range , and fuel consumption in a Rpm range.

Keeping in mind that what the curves show and how the engine load vs RPM is related in a given boat is dependent on hull design, how the boat is loaded, prop selection, etc. Because of the many variable involved any performance claims made in literature produced by the manufacturer typically refer to the base performance test curves.

Who are "most diesel experts? Automotive, marine, or industrial experts? Even among marine diesels there are differences between engines intended for pleasure and commercial use.

My interest is in marine Diesel so the "experts" that I would be referring to would be knowlegable in marine diesels. References would be from articles read, Volvo service Rep., Patten Power systems Cat marine service technician, and Volvo service technician I have spoken to them at the marina where I keep my boat. None of these technicians have a lot of experience with small diesels like the D3. They work on larger engines.From my readings and statements made by the technicians, all stated that running a diesel at 80 % output will not hurt the engine and is a good range to cruise at. This leads back to my question is 90% Rpm Range equivalent to 80 % output ?

Who is "Volvo"? Is that coming from the owner's manual?

That is Volvo marine, the information is from the D3 Volvo owners manual stating 90% of RPM is maximum for continuous operation. WOT can be used for short intervals.

It sounds like the article was referring to "specific power" which is the amount of power produced per lb of fuel burned. Specific power is often used for simplicity rather than having to "normalize" conditions for atmospheric pressure, air temperature, and humidity. Which all boils down to say that your logic above is sound. Though on a test bench under controlled conditions I'd be very surprised if 90 percent of max rated RPM only equated to 80 percent of rated power. But if that's what you're getting on your particular boat, i.e. 90 percent rated RPM equates to 80 percent rated fuel consumption (at rated HP), then it is unlikely that the engine is being overloaded.

Yes this is the article I was referring to.

The Mercruiser controls on my boat calculate and display percent load and that is what I use to set my cruise speed. At 80 percent

At your set cruise speed of 80 % load what is the percentage of Rpm to WOT?

Thank you for responding to this. I am somewhat uncomfortable running at 90% of rpm ,but if that equates to 80% load I feel better about it. My intension is not to run at these speeds all the time. I do like to run harder when in open water.

 

[NorthernFocus]

...At your set cruise speed of 80 % load what is the percentage of Rpm to WOT? ...

At 80 percent load I'm typically at about 3250rpm which is 81 percent of design/governed WOT and 85 percent actual WOT(I'm slightly over-propped for my operating conditions).

...Thank you for responding to this. I am somewhat uncomfortable running at 90% of rpm ,but if that equates to 80% load I feel better about it...

If your engine controller doesn't indicate power output then I'd go by fuel consumption for a given RPM compared to what is indicated on the curves at that speed. Unless your boat is under-wheeled for your operating conditions I would be very surprised if 90 percent of max RPM only equated to 80 percent fuel consumption/power.

One cautionary note for that particular engine. Looking on the Volvo site they show the D3 in 110, 150, 170, 200, and 220 HP models. With multiple models built on a common frame like that typically the only thing that is different is the fuel delivery system and possibly the turbo. So with your engine being at the max output for that frame the lube system, cooling system, turbo operating temperature, etc. are pushed to design limits. In other words there is a lot less room for error. So operating conservatively is a good idea.

 

[BB marine]

Thanks, I think we are both on the same page. I agree Max HP with small displacement. I am slightly under propped. Max HP rated at 4000rpm I turn 4130 WOT normal load. Volvo recommends that it be propped to turn no less then 3900RPM. I like having it slightly under propped so that when we are loaded down with extra supplies and traveling we maintain 4000rpm WOT to prevent from over loading the engine. When we took our trip last fall for a month with extra supplies I could still achieve 4050rpm at WOT. So you are correct I am under propped slightly.The engine is governed at 4150 RPM ( this is information I was given by a Volvo service technician 4150 RPM )