R-25SC Fuel Consumption

T

tlkenyon

Well-known member
Joined
Sep 30, 2010
Messages
679
Fluid Motion Model
R-25 SC
Non-Fluid Motion Model
3 kayaks, 1 canoe; R-21 (Nellie May I)
Vessel Name
Nellie May
MMSI Number
338219131
Presented below are four graphs of various fuel consumption data for my 2015 R-25SC, with the D3 Volvo. Multiple runs were taken throughout the RPM range in various conditions, with time allowed on each run for readings to stabilize. Where readings did not fully stabilize, the visually apparent average of the fluctuating values was recorded. All runs were in fresh water with no current. All winds are headwinds - as this represents worst-case conditions. The boat is stored on a trailer, so the bottom is clean and was recently painted, so all boat-bottom conditions are consistent.

If anyone wants to record additional data and send it to me, I will add it to the dataset. Record the RPM (1000-1400 at 50 RPM increments and 1500 to WOT at 1,000 RPM increments), GPH, MPG and GPS Speed for each RPM setting. Utilize autopilot heading hold and cruise control for consistency. Provide on-board fuel and water quantities as well as wind/wave conditions. All winds are headwinds.

TK

 
Interesting charts and ones I someday had planed to do. I made them for all my sailboats. A question has been in my mind recently to ask, that is related to your charts and I've not found in earlier discussions. What is WOT available for the 25SC with the D-3? I have the same year, 2015, with an unpainted bottom (kept on a trailer and bottom waxed). My max WOT is 2820 both in fresh and salt water. The engine now has about 150 hours. Your charts stop at 3000, so I am assuming you get this much--maybe more? Thanks.
 
Are your MPH and MPG figures statute miles or nautical miles?
 
Portlandtug25...statute miles.
MoonshadowV...Good Question. WOT is 3000 RPM. I have never been able to get any more than that...ever.

TK
 
It is interesting to learn the R25SC D3 WOT is 3000. The D3-200 WOT on our R27 is 4000 with just a bit more speed (21mph or so) and of course more fuel consumption! I suspect we also deal with greater noise level. We are much quieter at 3000 RPMs. 4000 is a lot more WOT RPMs for the same basic engine (although different HP settings). Just an interesting data point for folks to consider.
 
I guess maybe the operative question might be, is 3000 really WOT on the D3-150? That is all I can get out of it, but is that correct?

TK
 
Our 2015 R25SC with D-3 150 is programed to turn 3000 RPM at wide open. Our boat is stored on the trailer with a clean bottom and runs in fresh water. With full fuel and water (and full cruising gear, dogs, inflatable Zodiac in cockpit, clothes, food, etc.) it generally will not run at more than 2950 or 2960 RPM, which I believe is close enough to max RPM that it does not make sense to adjust the prop any. Lower the fuel tank to half which sheds about 316 lbs and give it temperatures in the 60s or 70s (less dense air at 90 degrees apparently has a negative effect) and it will turn between 2970 and 3000 RPM at wide open. Give it a wave to run down or a tail wind push and I have seen the tack bump up to 3010 and as high as 3030, but it will not run there for long.

Given the discussion that says these engines can run at 80% of max RPM all day long, and the D-3 200 they put in the R27 is the same block with the same compression etc., but different programming and I presume different boost in the turbo, but its 80% of 4000 RPMs is 3200, do you suppose it really hurts the D-3 150 to run at more than 80% for extended periods of time? ( I do not do it, but have pondered the question in the event I wanted to outrun an approaching storm for 10 or 20 miles.)
 
I'm back at home now with access to my files. I have attached the Ranger Tugs performance charts from 2014 I received from another Tugnutter. The small differences in performance from your own boat are probably due to configuration, load, or water conditions.

The D3 manual says to cruise at least 10% below maximum throttle. That is 3600 on our R27. The Ranger Tugs Captain who did our factory training said we can run at that RPM all the way to Alaska no problem. In fact he said it likes to be run hard more than the lower RPMs. He also said to run it at WOT for 5 - 10 minutes every time out to "burn out the carbon". We regularly cruise at 3500 RPM because it is just a bit bit quieter and an overall more comfortable ride. To beat a storm, I would not hesitate to run at WOT for a bit but I would watch the temp gauge. We run at 181 to 183 degrees at 3500 and 187 to 189 at WOT. If it got above 190 degrees I would slow it down.

 
I have been pondering the question of rated HP and RPM for some time. There do not appear to be any physical differences between the various ratings of D3 engines, all have the same bore, stroke, compression ration, etc. The difference must be in the programming. Volvo says the D3-150 top end is 3000 RPM and that all the other higher HP ratings go to 4000. This suggests that the rotating parts are OK to 4000 RPM so that extended 3000 running would not be an issue.

I wonder if there is a way to "turn up the wick" on the 150 to get more HP and therefore, speed if dire circumstances require that speed. There are chips out there that do that, but I am very hesitant to go that route. More HP might also translate to more economy...

TK
 
TK,

See the other topic currently active on max RPM. It seems you should have no problem running WOT indefinitely, especially with the low WOT RPMs of the R25SC.
 
Yup....following that thread with great interest. Thanks.
 
tlkenyon said:
Presented below are four graphs of various fuel consumption data for my 2015 R-25SC, with the D3 Volvo. Multiple runs were taken throughout the RPM range in various conditions, with time allowed on each run for readings to stabilize. Where readings did not fully stabilize, the visually apparent average of the fluctuating values was recorded. All runs were in fresh water with no current. All winds are headwinds - as this represents worst-case conditions. The boat is stored on a trailer, so the bottom is clean and was recently painted, so all boat-bottom conditions are consistent.

If anyone wants to record additional data and send it to me, I will add it to the dataset. Record the RPM (1000-1400 at 50 RPM increments and 1500 to WOT at 1,000 RPM increments), GPH, MPG and GPS Speed for each RPM setting. Utilize autopilot heading hold and cruise control for consistency. Provide on-board fuel and water quantities as well as wind/wave conditions. All winds are headwinds.

TK

Click to expand...
Would you mind sending me these fuel consumption charts via email? Chris.Giblin1@outlook.com. I have a 2017 Ranger 25SC in Santa Barbara.
 
tlkenyon said:
Presented below are four graphs of various fuel consumption data for my 2015 R-25SC, with the D3 Volvo. Multiple runs were taken throughout the RPM range in various conditions, with time allowed on each run for readings to stabilize. Where readings did not fully stabilize, the visually apparent average of the fluctuating values was recorded. All runs were in fresh water with no current. All winds are headwinds - as this represents worst-case conditions. The boat is stored on a trailer, so the bottom is clean and was recently painted, so all boat-bottom conditions are consistent.

If anyone wants to record additional data and send it to me, I will add it to the dataset. Record the RPM (1000-1400 at 50 RPM increments and 1500 to WOT at 1,000 RPM increments), GPH, MPG and GPS Speed for each RPM setting. Utilize autopilot heading hold and cruise control for consistency. Provide on-board fuel and water quantities as well as wind/wave conditions. All winds are headwinds.

TK

Click to expand...
I am really interested in this as we have the same boat, however, this site does not let me see what you attached - this is what I am seeing:
1723066154064.png
Could I possibly beg you to email them to me? And in advance, I thank you for the work. That is another thing I wanted to do this summer but my ToDo list is long and distinguished! My email is pugwerks487@gmail.com. Again, thank you! Doug
 
tlkenyon said:
Presented below are four graphs of various fuel consumption data for my 2015 R-25SC, with the D3 Volvo. Multiple runs were taken throughout the RPM range in various conditions, with time allowed on each run for readings to stabilize. Where readings did not fully stabilize, the visually apparent average of the fluctuating values was recorded. All runs were in fresh water with no current. All winds are headwinds - as this represents worst-case conditions. The boat is stored on a trailer, so the bottom is clean and was recently painted, so all boat-bottom conditions are consistent.

If anyone wants to record additional data and send it to me, I will add it to the dataset. Record the RPM (1000-1400 at 50 RPM increments and 1500 to WOT at 1,000 RPM increments), GPH, MPG and GPS Speed for each RPM setting. Utilize autopilot heading hold and cruise control for consistency. Provide on-board fuel and water quantities as well as wind/wave conditions. All winds are headwinds.

TK

Click to expand...
Remember, you're pushing just over 3 tons through a viscus matter.
If you want better fuel economy you'll have to get into a boat that is not as heavy and semidisplacement.
 
Me too! I tried to open your attachments and they are just boxes with X's thru it. My email is pugwerks487@gmail.com. I would really appreciate it. I have 2017 R25SC in the Hood Canal in WA state. Many thanks in advance
doug
 
wa7pug said:
Me too! I tried to open your attachments and they are just boxes with X's thru it. My email is pugwerks487@gmail.com. I would really appreciate it. I have 2017 R25SC in the Hood Canal in WA state. Many thanks in advance
doug
Click to expand...
Sent it to this address "pugwerks487@gmail.com" and it was returned as "undeliverable to that address." I have been having problems with my email, so it is probably on my end. Maybe Chris can send it to you. Sorry. I am working on my email client.
 
I just got it and replied to your email - thx much!!!! Backup email is pauhanatoo@gmail.com - I use that one exclusively for boat stuff like the Garmin updates and such but anyway, thank you very very much! Doug & Viv
 
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