Russ Calasant
Active Member
Good stuff
32 GPH Cummins
- Thread starter Russ Calasant
- Start date
- Feb 4, 2007
- 7,251
- Boat Info
- 1996 450DA, TNT, Caribe dink w/15hp OB.
- Engines
- 3126 427HP TD transmissions
moral of the story is Cummins burn a lot of fuel.
Alex F
Well-Known Member
- Nov 14, 2006
- 9,166
- Boat Info
- 2005 420DB with AB 11 DLX Tender, Raymarine Electronics (2x12" MFDs) with Vesper AIS
- Engines
- Cummins 450Cs, 9KW Onan Generator, 40HP Yamaha for tender.
Not true. I love my Cummins. :grin:
Russ Calasant
Active Member
Big surprise coming from a CAT owner, btw is that where the "turtle" came from?
Before this turns into a spitting match, here are some real world figures. We just returned from a trip to Mackinac Island, 721 statute miles (I will do the nautical conversion later but my Tridata reads it that way). Over 10,000 miles on this boat so I am confident of the numbers.
GPH: 27.9 total burn
0.76 mpg or 0.66 Mpg (nautical)
average speed around 23-25 mph, 20-21 knots
sea conditions were very challenging at times but the boat tracks so well that I just set the autopilot and left the motors synched even in beam seas. I do leave the dinghy behind on these longer trips so I don't have that extra 600 lbs on the stern.
So, the boat did well and I am very pleased with those numbers. We were burning 34 GPH in previous years but I had the props reduced by two inches of pitch. Speed suffered a bit, GPH improved substantially and overall mpg improved a bit. The big plus is that instead of cruising 88-90%, we are now in the 82-85% range, now that the WOT is raised to 2710.
The 450DA that we travel with is faster but burns more fuel with his 3126 CATs. He is incorrectly pitched and because he has a lighter boat it should be more efficient than us.
James
GPH: 27.9 total burn
0.76 mpg or 0.66 Mpg (nautical)
average speed around 23-25 mph, 20-21 knots
sea conditions were very challenging at times but the boat tracks so well that I just set the autopilot and left the motors synched even in beam seas. I do leave the dinghy behind on these longer trips so I don't have that extra 600 lbs on the stern.
So, the boat did well and I am very pleased with those numbers. We were burning 34 GPH in previous years but I had the props reduced by two inches of pitch. Speed suffered a bit, GPH improved substantially and overall mpg improved a bit. The big plus is that instead of cruising 88-90%, we are now in the 82-85% range, now that the WOT is raised to 2710.
The 450DA that we travel with is faster but burns more fuel with his 3126 CATs. He is incorrectly pitched and because he has a lighter boat it should be more efficient than us.
James
osd9
New Member
James. If you don't mind, let me poke a few holes ...and I mean no disrespect
First...Are you using your tridata for distance?
Second....tell me you're not using your tridata for speed info too!
I've wiggled and tweaked that tridata,.....on three sepearte vessels that I have personnaly owned, and on a few neighbors boats.......many times. It is notoriously inaccurate. Especially if you run with/against currents, tides, rivers, etc.
If in fact you are using your tridata for your data...again, no disrespect....it's no good...throw it away.
The longer the trip...the more inaccurate the data.
GPS is the only way that you should measure distance and speed for accurate data.
Third....I said it early.... percentage of WOT has nothing to do with how the motors are loaded....it's mearly the percentage of WOT RPM...period. WOT RPMs will vary with how the boat is loaded, how clean the bottom is, the pitch/condition of the props, etc. Load on your motors can only be measured by knowing your instaneous GPH and then dividing that by the 'CALCULATED' GPH that your motor manufacturer publishes. I say 'CALCULATED' because the manufaturer's published numbers of GPH are a 'CALCULATED' value based on a formula that assumes ideal conditions for a NON PLANNING HULL. There is some give and take in those numbers and they will probably come close to what you are actually burning, but the ONLY way to know for sure is to install a instaneous Fuel Flow devise (Flo-Scan for mechanicals) and then compare the two. Some folks here have Flo-scans and or electronic governors with fuel flow readouts at thier helm. I've yet to hear one skipper say that his instaneous fuel flow numbers exactly match the manufacturers published GPH numbers. It just won't happen unless you get lucky.
Otherwise....stick to the magic of average and go boating.
First...Are you using your tridata for distance?
Second....tell me you're not using your tridata for speed info too!
I've wiggled and tweaked that tridata,.....on three sepearte vessels that I have personnaly owned, and on a few neighbors boats.......many times. It is notoriously inaccurate. Especially if you run with/against currents, tides, rivers, etc.
If in fact you are using your tridata for your data...again, no disrespect....it's no good...throw it away.
The longer the trip...the more inaccurate the data.
GPS is the only way that you should measure distance and speed for accurate data.
Third....I said it early.... percentage of WOT has nothing to do with how the motors are loaded....it's mearly the percentage of WOT RPM...period. WOT RPMs will vary with how the boat is loaded, how clean the bottom is, the pitch/condition of the props, etc. Load on your motors can only be measured by knowing your instaneous GPH and then dividing that by the 'CALCULATED' GPH that your motor manufacturer publishes. I say 'CALCULATED' because the manufaturer's published numbers of GPH are a 'CALCULATED' value based on a formula that assumes ideal conditions for a NON PLANNING HULL. There is some give and take in those numbers and they will probably come close to what you are actually burning, but the ONLY way to know for sure is to install a instaneous Fuel Flow devise (Flo-Scan for mechanicals) and then compare the two. Some folks here have Flo-scans and or electronic governors with fuel flow readouts at thier helm. I've yet to hear one skipper say that his instaneous fuel flow numbers exactly match the manufacturers published GPH numbers. It just won't happen unless you get lucky.
Otherwise....stick to the magic of average and go boating.
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No problem Dom,
My Tridata is about 5% optimistic overall. I know that based on paper charts, GPS and correction of course steering, etc. It's just that it is easy to read. I base my speed on GPS display.
Hey, I'm happy with my boat's performance and it now burns less fuel than previously. (We've made this trip eight times now so I know the distance calculation is reasonably accurate)
Thanks for the reply.
James
My Tridata is about 5% optimistic overall. I know that based on paper charts, GPS and correction of course steering, etc. It's just that it is easy to read. I base my speed on GPS display.
Hey, I'm happy with my boat's performance and it now burns less fuel than previously. (We've made this trip eight times now so I know the distance calculation is reasonably accurate)
Thanks for the reply.
James
Russ Calasant
Active Member
No spitting here! Just fun and learning a lot ,thanks gentlemen.
