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Cabo 47/48 C18 vs Man 800 V8

Discussion in 'Cabo Yacht' started by Cabo47, Mar 5, 2020.

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  1. olderboater

    olderboater Senior Member

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    Extrapolating gives surprisingly close numbers. We've checked the extrapolated numbers against the load factors on electronic engines and found a reasonable correlation. So simply we use fuel burn at actual speed divided by fuel burn at wot as an estimation.

    ICF and EPA even use a different and interesting calculation that I find doesn't come as close, especially at low loads. They use (Actual speed divided by maximum speed) cubed.

    There is actually a formula that combines factors and uses pressures and is more scientific and more along the lines of what ECM's use, but without an ECM or other equipment you don't have the needed information. I'll try to find that formula or have someone find it for me in the next couple of days. However, we have found that using fuel flow divided by maximum fuel flow is extremely close and good enough for the vast majority of purposes.

    I also reference Marmot's post #4 in 2008 in this linked thread.

    https://www.yachtforums.com/threads/calculating-engine-load-factor.8661/

    We have performance charts we've built over time on our boats of fuel burn at different RPM and speeds and find that calculating load from those charts as described is very close.

    As to feedback on what the governor is doing, he's busy right now with coronavirus issues. Oh you mean the engine governor. Sorry. What the governor is doing is normally going to be reflected in fuel burn.

    It comes down to just using the best information one has and accepting it may be off a slight amount but not a significant amount.
  2. Capt J

    Capt J Senior Member

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    Then what are the D2876 LE423s, from the photos they're inline 6 cylinders? They're listed at 800 HP and in a 2007, 43' cabo that is for sale. I believe this is the boat I did all of the tests with for MAN N. America as it has a tuna tower and the test boat was a gulf of mexico dealer (Fox yacht sales) and that's where the boat was headed when finished (tower/electronics/etc.) and in AL now. Odly enough there is a 2006 43' listed with man V8 900HP Common rails. There are only 2 48's listed and they both have 1100 HP MAN CR's.

    So it looks like Cabo used 6 cylinder MAN's for 800 HP and the V8's if you wanted 900HP and V10's If you wanted 1100 hp MAN's, I got heavily involved with being around a lot of Cabo's in 2004 and on......Cabo and their dealers went through a phase where most boats had mans, then around 2005-2007 most had cat's, then when the CR mans came out around 2007 it was a mixed bag and also depended on model.
    2007- 43' MAN I6-800's
    https://www.yachtworld.com/boats/2007/cabo-43-flybridge-3593521/

    2006-43' Man v8-900's
    https://www.yachtworld.com/boats/2006/cabo-sportfish-3253080/
  3. PacBlue

    PacBlue Senior Member

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    You have to look at the. MAN nomenclature.

    D2876 > 28 for 128mm bore, 7 must be some kind of series number, odd probably for inline, and 6 for the amount of cylinders. It’s a pain in the ass to have to account for all 4 numbers plus the extensions beginning with L to identify the all the older models.

    The Cabo 43 had a mix of MAN 6 and 8 cylinder engines at the 800 hp rating, here’s one that you have to go to the picture to get the confirmation that it is a V8:

    https://www.yachtworld.com/boats/2003/cabo-convertible-3651358/

    To make it even more confusing the new I6 - 800 has a slightly smaller bore, 126 mm and is really a D2676 model at a displacement of 12,4 liters while the older D2876 in-line 6 rated at 800hp had a displacement of 12.8 liters.

    The MAN D2848 V8 rated at 800hp had a displacement of 14.6 liters.

    For the Cabo 43 FB I prefer the V8, for the Cabo 40 FB the In-line 6 is a perfect match.

    But the OP is talking about the Cabo 47/48 FB and that includes MAN D2848 V8 at 900hp plus the D2840 V10 at up to 1100hp at a displacement of 18.3 liters.
  4. bayoubud

    bayoubud Senior Member

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    Good point on the cost of Cats since the 6 year aftercooler replacement plus the 2 year service. When factored in Cat maintenance might cost more than Man. Experienced this when looking for boats with Cat's. Cat does has an advantage for service and parts availability.
  5. Capt J

    Capt J Senior Member

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    And ease of maintenance as all of the CAT filters are spin on (secondaries, oil filters), and almost all CAT boats have the filters right in the aisle, whereas every MAN boat I've managed has the filters on one motor on the outbound side of the motor, and they're cartridge filters which take 3 arms to change and more time because you have to drain them first (oil) or fill them after installing (fuel through a fill hole). You almost need a second person to change MAN oil filters. Normally I can change all filters on a pair of CATS in less than an hour, whereas MAN takes 2-3 hours.
  6. bayoubud

    bayoubud Senior Member

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    Had two boats with Man's, no excuse for the Neanderthal filter system. Cat spin on filters on the aisle side are a real convenience. Like my Cats.
  7. PacBlue

    PacBlue Senior Member

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    What is the service interval on CAT after coolers? Does MAN have a remote Oil Filter option?
  8. olderboater

    olderboater Senior Member

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    Clean and test every 15,000 gallons or 1000 hours.

    As to remote oil filter option, I'm not sure if it's actually a MAN kit or just ones they suggest can be used. We never pursued as we didn't consider the problem worth doing so and had space shortages on any boats we had MAN's on. I'd have to ask to find out.
  9. Capt Ralph

    Capt Ralph Senior Member

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    Even on SeaRays, the V8-900 CRM had remote oil filters on the stb engine. Around to the port side of the bell housing. Still room to service the raw water pump.
  10. bayoubud

    bayoubud Senior Member

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    My Cat manual for 3406E and C15 dated 4/15/2015 states to replace aftercooler every six years. Clean and test every 15,000 gal, 1000 hrs, or "2 years". Which ever occurs first. Likely it will be the two year interval that's the rub, most boats won't have more than a few hundred hours. Most Cat maintenance items vary stating gallons of fuel used, hours used, or a time period which gets over looked. Most always refer to the hours used which can go way beyond the time period. For example the oil change is 250 hrs. or 1yr, even with 40hrs run time.
  11. PacBlue

    PacBlue Senior Member

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    So I view the MAN Oil Filter location as a builder choice. If you got access outboard leave them factory, if not, remote mount them in a more accessible place, take care of your customer, just the basics.
  12. Capt Ralph

    Capt Ralph Senior Member

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    I remember the ultimate serviceable boat.

    Detroit oil filters.
    Detroit - LubeFiner by-pass oil filters.
    Twin Disk oil filters.
    Hynautic power steering fluid filter.
    All spin on-off.
    And; Naiad (old styled) oil reservoir.

    All on the back bulkhead with bucket room under every one of them.
    I'm sure this was after factory but done well. Never found this anywhere again.
  13. Capt J

    Capt J Senior Member

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    They do, it's about $4500 per motor so I've been told. It still utilizes the upside down metal filter cartridge housings that you have to take the bolt out of and drain, and they're always just above the floor height so getting something to fit under them is a pain if you even can, and then the 2 filters still make a mess. I've run a ton of MAN boats, I've only seen the remote filter option installed on 1 boat out of close to a 500-1000 boats. Might've been a 58' Searay. Even the 2 oil filters that are in the aisle are a pain in the rear because they're upside down metal housings with a bolt through the middle top and when you remove them, the filter cartridge wants to fall out of it on the floor.

    CAT specifies changing the aftercoolers every 6 years. Between parts and labor it's a pretty pricey proposition. I'm not sure why they're seeing so many failures, the only thing I can guess is they seem to love to mount them above the engine or high on the side of the engine and they drain when the motor is not running and exposed to air.

    Capt. Ralph- I had a boat like that. A 2007 55' Neptunus express with C15's. I could sit on a bucket and change all of the oil and fuel filters on both motors in the middle of the aisle, and they were all high enough to get a bucket underneath. If I was working real fast and had all tools ready and a fuel can, I could change all filters in 30 mins flat.
  14. Capt Ralph

    Capt Ralph Senior Member

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    Oh, the dual Racors were forward easy to get to also on this tub. Still room for a bucket under all.
    F M, nobody thinks of this when cramming all into an E R.
  15. mapism

    mapism Senior Member

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    That's also true of MANs, though.
    My guess is that it has more to see with being designed to require anodes (as opposed to MANs that don't).
    And many folks aren't as religious as they should be, with anodes replacement.
  16. Capt J

    Capt J Senior Member

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    But I don't see any failures on the MAN aftercoolers or Cummins or others. I manage a 2007 yacht with MAN 1100 common rails right now, never been changed, only cleaned. I had a SF that was 2-3 years old with 1600 HP C32's and an aftercooler leaked and dealer had to rebuild the engine (had extended warranties). I had an aftercooler fail on 2 year old 2006 DD/MTU series 60's once too (in 2008) I deal with a couple of Cummins boats, 2003 6BTA's, a 2006 with QSM-11's and they both have original aftercoolers. Cat never had issues with the 3412 aftercoolers either. So I don't understand it.
  17. mapism

    mapism Senior Member

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    I get that, and I'm aware that the durability of Cat aftercoolers is nowadays much worse than it used to be.
    I was just saying that if it were a matter of placement, also MAN should be equally affected - hence my guess that anodes might have more to see with that.
    In MAN engines, it's impossible to neglect the anodes replacement, since there's none!:)
    Another reason might be the use of alu vs. bronze for several important parts, to make the engines lighter and cheaper to build...
    I don't think the placement has a lot to see with the problem, anyway.