Looking for range under power

Discussion in 'Motorsailers' started by Andrei Taranu, Dec 1, 2020.

  1. Andrei Taranu
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    Andrei Taranu Junior Member

    Hey there. I'm looking for tech specs of 25 to 45 meter long sailing yachts that include:

    * displacement
    * loa
    * beam
    * sail area
    * engine model
    * maximum range under power (and the speed at which that range is achieved)

    Haven't been able to find this last data point. I've looked on a few boat manufacturer sites like Perini Navi, Nautor Swan and others. Any help would be valued.
     
  2. TANSL
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    TANSL Senior Member

    Welcome to the forum.
    Maybe playing with this spreadsheet you can get something of what you are looking for.
     

    Attached Files:

  3. Andrei Taranu
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    Andrei Taranu Junior Member

    Thanks @TANSL, that seems useful. Can't seem to get the dropdown to work at "select boat type", which is probably why I can't use any of the "calculate" buttons.
    I see in the tab MonoH Database that there are a bunch of boats, but the names of the columns are kind of cryptic. Do you know if all the specific data points that I listed above are represented in that form? I'm particularly interested in maximum range under power.
     
  4. TANSL
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    TANSL Senior Member

    You may have to "Enable editing"
    Yes, the column titles on the "MonoH Database" sheet are in Spanish. I'm sorry.
    What do you mean with "maximum range under power"?.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Realistically, the range of a sailboat under engine power will largely be a function of the fuel capacity, so if that is adjustable upward, the range will go up largely in proportion, as in a boat that size and type, extra weight in fuel won't make that much difference to MPG.
     
  6. Andrei Taranu
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    Andrei Taranu Junior Member

    @TANSL I mean the distance it is able to cover on engine alone (without raising the sails), and the speed at which that distance is achieved.

    Some estimations/approximations within a reasonable margin of error would also be useful. I'm really new to the whole field so I'm interested to find out what is the expected minimum distance that a sailing yacht should be able to go on fuel alone. I know the need for that arises when going in and out of port and also on the high seas when the wind stops blowing. Interested to find out the capability of sailboats in that regard. And I don't know if it makes a difference or not, but I'm interested in boats that are around 20-30 meters long.
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    To repeat, it gets down to fuel tankage, even a large fuel load would not slow down the boat that much, being the type and size of boat concerned.
     
  8. Andrei Taranu
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    Andrei Taranu Junior Member

    I'm looking for a number of miles. I'm not sure how I can convert the size of the tank into that. I think it has to do with accounting for the hull efficiency, the transmission loss (shaft efficiency) and a bunch of other things. But I was hoping someone could tell me what is a good range for that type of boat.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    How many miles do you want ?
     
  10. bajansailor
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    bajansailor Marine Surveyor

    Maybe this could be one way of looking at it - your sailing yachts in the range 25 m. - 45 m. are effectively displacement vessels.
    There is a LOT of information out there on trawler yachts re their typical speeds and fuel efficiencies.
    You can look up what the typical specific fuel consumption is for a diesel engine. And look up the installed power in the large yachts that you are using for reference.
    If a sailing yacht has (for example) a Cummins 300 hp diesel, and a trawler has a similar engine, and you get data from the trawler re it's range and fuel consumption at different speeds (eg from www.boattest.com) then you should be able to get at least a rough idea as to what sort of fuel consumption / range the sailing yacht might have?
     
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  11. Andrei Taranu
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    Andrei Taranu Junior Member

    @Mr Efficiency: I don't "want" a specific number of miles. I want to know how many miles that type of boat generally gets on fuel.
    Here's another way of asking the question: if you were in the market for a 25-40 meter sailboat, what would be the minimum range you would want/need it to have on fuel? Not in an idealistic type of way, but based on capabilities of existing vessels.
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    Its like this, you can fit long range tanks, even very long range tanks, which would be retrofitting in most cases, as people with sailing boats typically want to sail, and the fuel capacity is limited accordingly. Naturally there is a limit to how far it would be able to motor, but it would be a very considerable distance, if it was prioritized, as the increase in displacement that it would take to slow the boat down appreciably, under engine power, would equate to an awful lot of fuel, and miles. So it really does get down to what you want in terms of miles under power, if you opt to use it. But of course, it has to be weighed against what you lose, by carrying big fuel tanks full of fuel. If you want to know what the actual miles covered would be, in existing boats, just use the specs for the engine HP and fuel tank capacity, and be a little conservative with your speed estimate for the boat, propelled by that engine.
     
  13. Andrei Taranu
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    Andrei Taranu Junior Member

    Seriously? I can't ask the question any simpler than that. What is a good range for a sailboat to go on fuel? A number of miles. What would you personally want or need? Not interested in any theory, just a NUMBER OF MILES.
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    It is not what I or anyone else wants, it is what you want, and there is a great deal of flexibility in the calculation, IF YOU WANT EXTENDED RANGE. Which causes me to ask, what range do you require ? Select a boat, and make your own calculations, based on the fuel capacity and engine HP listed by the maker. Can you come up with some examples ? If you don't like the figure, then you can improve it with greater tankage.
     
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  15. TANSL
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    TANSL Senior Member

    There is no NUMBER OF MILES. The rank depends on what the boat is going to do, how it is going to be used and what navigation it is going to do. It depends to a great extent on the power of the engine and the capacity of the tank that you want to place and, of course, on the way of operating the boat. There are no two ships with the same parameters, therefore, THERE IS NO NUMBER OF MILES.
    And please be a little more patient with those who only want to help you.
     
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