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Author Topic:   Prop Data for Yamaha F70 on 1988 Montauk

DVollrath posted 09-24-2012 02:15 PM ET (US)
I moved my 2011 vintage Yamaha F70 from my 15' CC to my 1988 Montauk in the early summer. On the 15' boat, I was running a 13.25 x 15" Stiletto Advantage I per Tom Clark's recommendation, and it worked very well. When the motor was transfered to the Montauk, it seemed pretty sluggish, presumably due to the increased weight and beam of the new boat. I then re-propped with a 13.25 x 13" Stiletto Advantage I, again obtained through Tom. I took some performance measurements using each prop for comparison. The RPM, speed, and fuel economy numbers were obtained using my Lowrance HDS-7 with a NMEA 2000 link from the motor. Runs were done both east and west in Harney channel in the San Juan Islands of Washington state. Presented are the averages of those runs, and are in statue miles per hour and gallon. The load was little old me at 225# and 22gal of fuel.

15" 13"
RPM MPH MPG | MPH MPG
-----------------------------
2600 10.7 6.6 | 9.0 6.2
3000 14.9 7.3 | 11.5 6.3
3500 21.0 8.0 | 17.0 7.6
4000 25.8 7.9 | 21.4 7.8
4500 29.1 6.9 | 25.5 7.3
5000 33.1 6.6 | 28.6 6.7
5400 35.0 6.0 | WOT for 15"
5500 | 31.2 5.9
6000 | 34.0 5.5
6375 | 35.8 5.6 WOT for 13", rev limited
The data for the 15" prop was collected on 7/21, while the 13" data was collected 9/23. The boat has been kept in the water continuously since then, and I can see some marine growth has occurred on the sides, so perhaps this has affected the latest readings.
Tom mentioned that a 14" might be ideal but that the Stiletto was not offered in that pitch. It seems like that might be the case, given the rev-limiting at WOT.
All in all, I am very pleased with this choice. It has lots of pop to get on plane or powering over wakes/waves, and the fuel economy is still quite nice.
Dennis

DVollrath posted 09-24-2012 02:17 PM ET (US)
I should also have mentioned that the motor is mounted all the way up, and that a constant trim was used for all runs.
Dennis
DVollrath posted 09-24-2012 02:22 PM ET (US)
I should also have remembered that UBB collapses white space, so my carefully constructed table looks pretty awful now. Oh well, I can send the raw data in spreadsheet for to anyone interested. Just move the "|" for the 5500RPM and below rows to align vertically with the 5400 row.
Sorry about that.
Dennis
Tom W Clark posted 09-24-2012 05:21 PM ET (US)
You can use hyphens to kinda, sorta preserve spacing and alignment:
15" ---------------- 13"
RPM - MPH - MPG | MPH - MPG
-----------------------------
2600 - 10.7 - 6.6 | 9.0 -- 6.2
3000 - 14.9 - 7.3 | 11.5 - 6.3
3500 - 21.0 - 8.0 | 17.0 - 7.6
4000 - 25.8 - 7.9 | 21.4 - 7.8
4500 - 29.1 - 6.9 | 25. -5 7.3
5000 - 33.1 - 6.6 | 28.6 - 6.7
5400 - 35.0 - 6.0 | --------- [ WOT for 15" ]
5500 ---------- | 31.2 - 5.9
6000 ---------- | 34.0 - 5.5
6375 ---------- | 35.8 - 5.6 [ WOT for 13", rev limited ]
jimh posted 09-25-2012 08:02 AM ET (US)
ASIDE: It is HTML that removes spaces. It is hard to present tabular data if spaces are used to layout the table. I'll see if I can help with some added formatting.
jimh posted 09-25-2012 08:06 AM ET (US)
Is the fuel flow rate data taken from the Yamaha F70 and its NMEA-2000 data? Or from an in-line fuel flow sensor?
DVollrath posted 09-25-2012 09:31 AM ET (US)
Jim--the fuel flow rates are taken directly from the F70 via the [NMEA-2000] link.--Dennis
elaelap posted 09-25-2012 06:54 PM ET (US)
I'm somewhat surprised at your top end speed at 6300 turns. My 1982 Montauk with a new Suzuki DF70(A) easily hits 37+ mph (GPS, salt water) at 5800 rpm WOT with its stock Suzuki aluminum 17-inch pitch prop.
Tony
DVollrath posted 09-25-2012 06:59 PM ET (US)
Tony,
It is likely a little underpropped with the 13". I have extra throttle left when the motor self-limits the RPMs.
Dennis
elaelap posted 09-25-2012 07:00 PM ET (US)
Why did you maintain a "constant trim," Dennis? That might explain the relatively disappointing top end numbers.
Tony
elaelap posted 09-25-2012 07:05 PM ET (US)
Okay, gotcha. Yeah, the last thing you needed was trimming out more. I think you need more pitch. BTW, I had an F60 on my Sport 15 and absolutely loved that motor!
Tony
Tom W Clark posted 09-25-2012 07:12 PM ET (US)
Tony -- Your DF70A has a 2.59:1 gear ratio and a 6000 RPM redline. Dennis's F70 has a 2.33: gear ratio and a 6200 RPM redline. Big difference.
I believe Dennis's boat is under propped. The problem is that there is a 13" and a 15" but no 14" in Stiletto or Turbo. I have just ordered him a Yamaha branded 13-1/4" x 14" Performance Series 3-Blade (same design as the Stiletto Advantage and Turbo 1 bit offered in even pitches not odd).
I had though that the 14" Yamaha was the same actual pitch as the 13" Stiletto/Turbo, but now I am not so sure. We'll find out when it arrives next week.
I was checking my notes earlier today and found that Paul Mucciolo reported that his Montauk with a new Yamaha F70 and 13-1/4" x 14" Yamaha Performance Series 3-Blade hits 38 MPH at 6200 RPM.
jimh posted 09-25-2012 08:29 PM ET (US)
Dennis--it is quite cool that the Yamaha F70 now has a NMEA-2000 interface, and you can get the usual dynamic engine data from it via the network. Having a NMEA-2000 interface is a big plus for an outboard engine these days, as most multi-function display devices can show engine parameters. That is a nice feature of the Yamaha.
DVollrath posted 09-26-2012 09:35 AM ET (US)
Jim,
I do really like the information available from this engine via NMEA 2000 as well. I find myself adjusting my cruise speed to maximize fuel economy to a large extent.
The one thing I have not yet found the trick to is integrating the instantaneous fuel consumption over time to get a fuel used value. I'm sure the Lowrance HDS-7 does this, but my limited attempts have not been successful thus far.
I just reach down and lift the fuel tank for an indication of how heavy it remains.
Dennis
jimh posted 09-28-2012 08:42 AM ET (US)
ASIDE to Dennis--with an HDS series multi-function display, the FUEL MANAGER function needs an EP-85r Data Storage Device on the network to be able to accumulate fuel flow data into fuel used data. See my article
http://continuouswave.com/whaler/reference/NMEA2000.html
and read the section under the sub-heading "Instrument-added Functions" for more details.

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Author	Topic: Prop Data for Yamaha F70 on 1988 Montauk
DVollrath	posted 09-24-2012 02:15 PM ET (US) I moved my 2011 vintage Yamaha F70 from my 15' CC to my 1988 Montauk in the early summer. On the 15' boat, I was running a 13.25 x 15" Stiletto Advantage I per Tom Clark's recommendation, and it worked very well. When the motor was transfered to the Montauk, it seemed pretty sluggish, presumably due to the increased weight and beam of the new boat. I then re-propped with a 13.25 x 13" Stiletto Advantage I, again obtained through Tom. I took some performance measurements using each prop for comparison. The RPM, speed, and fuel economy numbers were obtained using my Lowrance HDS-7 with a NMEA 2000 link from the motor. Runs were done both east and west in Harney channel in the San Juan Islands of Washington state. Presented are the averages of those runs, and are in statue miles per hour and gallon. The load was little old me at 225# and 22gal of fuel. 15" 13" RPM MPH MPG \| MPH MPG ----------------------------- 2600 10.7 6.6 \| 9.0 6.2 3000 14.9 7.3 \| 11.5 6.3 3500 21.0 8.0 \| 17.0 7.6 4000 25.8 7.9 \| 21.4 7.8 4500 29.1 6.9 \| 25.5 7.3 5000 33.1 6.6 \| 28.6 6.7 5400 35.0 6.0 \| WOT for 15" 5500 \| 31.2 5.9 6000 \| 34.0 5.5 6375 \| 35.8 5.6 WOT for 13", rev limited The data for the 15" prop was collected on 7/21, while the 13" data was collected 9/23. The boat has been kept in the water continuously since then, and I can see some marine growth has occurred on the sides, so perhaps this has affected the latest readings. Tom mentioned that a 14" might be ideal but that the Stiletto was not offered in that pitch. It seems like that might be the case, given the rev-limiting at WOT. All in all, I am very pleased with this choice. It has lots of pop to get on plane or powering over wakes/waves, and the fuel economy is still quite nice. Dennis
DVollrath	posted 09-24-2012 02:17 PM ET (US) I should also have mentioned that the motor is mounted all the way up, and that a constant trim was used for all runs. Dennis
DVollrath	posted 09-24-2012 02:22 PM ET (US) I should also have remembered that UBB collapses white space, so my carefully constructed table looks pretty awful now. Oh well, I can send the raw data in spreadsheet for to anyone interested. Just move the "\|" for the 5500RPM and below rows to align vertically with the 5400 row. Sorry about that. Dennis
Tom W Clark	posted 09-24-2012 05:21 PM ET (US) You can use hyphens to kinda, sorta preserve spacing and alignment: 15" ---------------- 13" RPM - MPH - MPG \| MPH - MPG ----------------------------- 2600 - 10.7 - 6.6 \| 9.0 -- 6.2 3000 - 14.9 - 7.3 \| 11.5 - 6.3 3500 - 21.0 - 8.0 \| 17.0 - 7.6 4000 - 25.8 - 7.9 \| 21.4 - 7.8 4500 - 29.1 - 6.9 \| 25. -5 7.3 5000 - 33.1 - 6.6 \| 28.6 - 6.7 5400 - 35.0 - 6.0 \| --------- [ WOT for 15" ] 5500 ---------- \| 31.2 - 5.9 6000 ---------- \| 34.0 - 5.5 6375 ---------- \| 35.8 - 5.6 [ WOT for 13", rev limited ]
jimh	posted 09-25-2012 08:02 AM ET (US) ASIDE: It is HTML that removes spaces. It is hard to present tabular data if spaces are used to layout the table. I'll see if I can help with some added formatting.
jimh	posted 09-25-2012 08:06 AM ET (US) Is the fuel flow rate data taken from the Yamaha F70 and its NMEA-2000 data? Or from an in-line fuel flow sensor?
DVollrath	posted 09-25-2012 09:31 AM ET (US) Jim--the fuel flow rates are taken directly from the F70 via the [NMEA-2000] link.--Dennis
elaelap	posted 09-25-2012 06:54 PM ET (US) I'm somewhat surprised at your top end speed at 6300 turns. My 1982 Montauk with a new Suzuki DF70(A) easily hits 37+ mph (GPS, salt water) at 5800 rpm WOT with its stock Suzuki aluminum 17-inch pitch prop. Tony
DVollrath	posted 09-25-2012 06:59 PM ET (US) Tony, It is likely a little underpropped with the 13". I have extra throttle left when the motor self-limits the RPMs. Dennis
elaelap	posted 09-25-2012 07:00 PM ET (US) Why did you maintain a "constant trim," Dennis? That might explain the relatively disappointing top end numbers. Tony
elaelap	posted 09-25-2012 07:05 PM ET (US) Okay, gotcha. Yeah, the last thing you needed was trimming out more. I think you need more pitch. BTW, I had an F60 on my Sport 15 and absolutely loved that motor! Tony
Tom W Clark	posted 09-25-2012 07:12 PM ET (US) Tony -- Your DF70A has a 2.59:1 gear ratio and a 6000 RPM redline. Dennis's F70 has a 2.33: gear ratio and a 6200 RPM redline. Big difference. I believe Dennis's boat is under propped. The problem is that there is a 13" and a 15" but no 14" in Stiletto or Turbo. I have just ordered him a Yamaha branded 13-1/4" x 14" Performance Series 3-Blade (same design as the Stiletto Advantage and Turbo 1 bit offered in even pitches not odd). I had though that the 14" Yamaha was the same actual pitch as the 13" Stiletto/Turbo, but now I am not so sure. We'll find out when it arrives next week. I was checking my notes earlier today and found that Paul Mucciolo reported that his Montauk with a new Yamaha F70 and 13-1/4" x 14" Yamaha Performance Series 3-Blade hits 38 MPH at 6200 RPM.
jimh	posted 09-25-2012 08:29 PM ET (US) Dennis--it is quite cool that the Yamaha F70 now has a NMEA-2000 interface, and you can get the usual dynamic engine data from it via the network. Having a NMEA-2000 interface is a big plus for an outboard engine these days, as most multi-function display devices can show engine parameters. That is a nice feature of the Yamaha.
DVollrath	posted 09-26-2012 09:35 AM ET (US) Jim, I do really like the information available from this engine via NMEA 2000 as well. I find myself adjusting my cruise speed to maximize fuel economy to a large extent. The one thing I have not yet found the trick to is integrating the instantaneous fuel consumption over time to get a fuel used value. I'm sure the Lowrance HDS-7 does this, but my limited attempts have not been successful thus far. I just reach down and lift the fuel tank for an indication of how heavy it remains. Dennis
jimh	posted 09-28-2012 08:42 AM ET (US) ASIDE to Dennis--with an HDS series multi-function display, the FUEL MANAGER function needs an EP-85r Data Storage Device on the network to be able to accumulate fuel flow data into fuel used data. See my article http://continuouswave.com/whaler/reference/NMEA2000.html and read the section under the sub-heading "Instrument-added Functions" for more details.