04-06 390/40 sundancer. DIESEL Question

Discussion in 'General Discussion' started by see ray, Feb 14, 2018.

  1. rondds

    rondds Well-Known Member SILVER Sponsor

    Oct 3, 2006
    Jersey Shore
    2001 380DA
    Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
    Pictured below is a typical day in the life of my boat. This is on the bay, tanks are just about full (I hold 280g). I can tell you that these consumption numbers (from smartcraft) are generous. When I do the old fashioned calculation (top off, run a bunch of hours and miles, top off again and do the math) I am burning MORE than what you see on the display. (so I don't do that math anymore!)

    But like someone said above, it makes me happy to see numbers like these. I'd say I'm closer to 0.70mpg in reality, and this boat is much lighter than any 400 or 410.

    My previous boat was a 1989 340DB with Gen IV 7.4s. That boat had floscans and they were DEAD ON BALLS ACCURATE when matched up to the calculations done the old fashioned way

    BTW, every car I've ever owned with a computer on the dash spit numbers that were better than what the actual math revealed. It's a conspiracy by the engine manufacturers, I say!! ;-)

    you can click on the image to make it bigger. And no those are not my toes. I'd never wear that color.
    [​IMG]
     
  2. Bop

    Bop Active Member

    255
    Sep 3, 2013
    Georgian Bay/Lake Huron
    2001 410 Express, Highfield DL350 w/40hp Yamaha
    Cat 3126
    I just had a SidePower thruster installed last month. They installed 2 group 27 agm's and a separate charger. Can't wait to test it out!
     
  3. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    Yes. I used East Coast Bow Thrusters. They installed a Vetus 9524 with two AGM batteries and a dedicated charger for those two batteries.
    They did a fantastic job.
    The Thruster is in a floor compartment at the foot of the master berth. They mounted the AGM batteries in Series (Need to be in series to get 24 volts for the Thruster) in trays off to the side in the compartment immediately aft of where the Thruster is installed. About 2 feet from the Thruster. The Battery Charger is mounted in that same space.
     
    Last edited: Feb 20, 2018
  4. RollerCoastr

    RollerCoastr Well-Known Member

    Nov 15, 2007
    Cedar Point, OH / Miami, FL / MacRay Harbor, MI
    1997 400DA
    340HP 7.4 Mercruiser Bluewaters
    Garmin 741, 742, 8212, 24HD, Intellian I2
    1999 280BR
    Twin 250HP Merc 350 Alpha Ones
    I didn't say the data was false, in which case you'd have a legit beef with my stance here. I said it was ridiculous, and it most certainly is. I don't mean this to be personal. After all, YOU aren't the one abusing his boat. I'm trying to steer us away from dock talk and silly assumptions and focus on DATA and realistic expectations.

    By those numbers, your neighbor runs his boat at 3500 RPM, 23.5 sMPH returning .5 sMPG. That means he's burning 47 GPH. As I mentioned before, there is no such thing as "rated MPG" in a boat. However, standard burn rates for properly-loaded big blocks are published. He's over that amount by at least 15 GPH, and probably more. HOW??? WHY???

    Many boaters use a little float as a keychain. Have you ever seen his? Is it by chance a spark plug that should be in his engine??? Has he ever tuned his engines?? Does his exhaust expel a pretty rainbow sheen?

    I'm begging you: please try to convince your neighbor that something is amiss with his boat.
     
    Last edited: Feb 21, 2018
  5. Strecker25

    Strecker25 Well-Known Member

    Nov 20, 2014
    Rochester, NY
    1998 290 Sundancer
    Twin 5.7EFI/Alphas, Kohler 4kw
    LOL. That was a good one
     
    RollerCoastr likes this.
  6. RollerCoastr

    RollerCoastr Well-Known Member

    Nov 15, 2007
    Cedar Point, OH / Miami, FL / MacRay Harbor, MI
    1997 400DA
    340HP 7.4 Mercruiser Bluewaters
    Garmin 741, 742, 8212, 24HD, Intellian I2
    1999 280BR
    Twin 250HP Merc 350 Alpha Ones
    Boat Test's figures on a gasser 380 like yours are 33.2 GPH at 3,500 RPM cruising at 26.6 MPH, so an even .8 sMPG.

    It's a bummer that Smartcraft is so inaccurate. Is there any way to calibrate? I was thinking that it would be nice to have the additional info from the ECM by using a gateway, but it sounds like the "pulse count" method of determining fuel consumption isn't reliable...?

    I don't know if I'd say "much"... Dry weight of 18k+ vs. 22k+ If you cruise heavy while I cruise light, it's not much of a gap.
     
  7. rondds

    rondds Well-Known Member SILVER Sponsor

    Oct 3, 2006
    Jersey Shore
    2001 380DA
    Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
    Interesting what Boattest came up with. Sounds like fantasy. I'm getting the proper WOT, always have a clean bottom (brackish water we get little to no growth), but 26mph at 3500 RPM? HA!

    Calibration is not possible. This is data pulled right from the ECM.

    The way I look at weight difference is like this. If I put an Acura MDX in my cockpit, it would weigh as much as the 400DB. That is substantial...22% less.

    Maybe the guy getting 0.5mpg is just really bad at math?
     
  8. RollerCoastr

    RollerCoastr Well-Known Member

    Nov 15, 2007
    Cedar Point, OH / Miami, FL / MacRay Harbor, MI
    1997 400DA
    340HP 7.4 Mercruiser Bluewaters
    Garmin 741, 742, 8212, 24HD, Intellian I2
    1999 280BR
    Twin 250HP Merc 350 Alpha Ones
    WOT is a better measure of being over-propped than under-propped, and applies more to diesel than gas anyway. I'm not sure what's stamped on your 8.1's, but WOT on my old 7.4's is a range, not an absolute. It sounds like you're slightly under-propped, but when your meters show .78 and your guess is .7, I don't think prop tuning is warranted.

    DON'T LOOK AT IT LIKE THAT! :D

    I don't know. How bad can his math be? They start at the same dock, cruise the same speed to the same fuel dock... My current guess is that one or both engines isn't firing one or more cylinders. I can't imagine being THAT out of touch about how your boat runs, but we know it happens.
     
  9. rondds

    rondds Well-Known Member SILVER Sponsor

    Oct 3, 2006
    Jersey Shore
    2001 380DA
    Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
    WOT on 8.1s is 4200-4600 - or something pretty close to that. I forget exactly.

    When I had my '89 340DA with carb'd 7.4s, I used to travel a lot with a friend who had a '99 330DA, with 7.4s. His boat was a jack-rabbit, weighing in at 12500lbs dry. He cruised comfortably at 3300rpm and 26mph. My DB (16500lbs dry) would chug along at 18.5mph at the same RPM, and that was with light fuel and minimal headwind. My friend would complain about how slow I'd go, and I told him to put his MDX (the car he had at the time) or 4 Walter Hudsons (in his prime) in his cockpit, throttle up to 3300RPM and see how fast he could go (that's where I get the analogy).

    For those of you who don't know who Walter Hudson was, google it. But here's a pic...

    [​IMG]
     
  10. midexp

    midexp Active Member

    133
    Oct 5, 2016
    Harrison Township, Michigan Lake St.Clair
    1999 40' Sundancer
    454 merc
    My buddy had a 420 DA and and had the valve seat problem. About 10 grand. Cummins did help, but was still about 6K for him. That's the biggest reason I strayed away from diesel when I bought my 400 gas last year. And another friend last year bought a 40 Tiara with I believe the same Cummins. Valve dropped, about 10 grand also. Like my buddy with the 46 DA says, my heart stops every time I go to start the engines.
     
  11. see ray

    see ray Member

    249
    Sep 28, 2008
    Cleveland OH / LakeSide yacht club
    06 40DA HARD TOP. 8.1L HO 420 hp L
    I LOVE MY BOAT.
    Previous boat 05 340 DA 8.1L 370 hp
    8.1L HO 420 hp
    V Drives
    Can you tell me what they charged you I’m getting ready to close on this deal on the boat then I want to call them to have them come out next
     
  12. Bop

    Bop Active Member

    255
    Sep 3, 2013
    Georgian Bay/Lake Huron
    2001 410 Express, Highfield DL350 w/40hp Yamaha
    Cat 3126
    If he doesn't respond you're safe at $8-10k.
     
  13. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 Express
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin GSD 22 Sounder
    Garm
    454 Crusaders
    My 390EC gets almost identical numbers as RollerCoaster. I also have Garmin GFS10s. 3100 rpm gets about 21 mph and .7 mpg on ValvTec 89 octane.
     
  14. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    Sent you a PM
     

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