Operating Cost of 70' Steel Fishing Vessel?

Discussion in 'Powerboats' started by CatBuilder, Sep 15, 2010.

  1. apex1

    apex1 Guest


    Where do you moor? In the windy corner of the bay?

  2. WestVanHan
    Joined: Aug 2009
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    Location: Vancouver

    WestVanHan Not a Senior Member


    I'm sure you realize the varying efficiencies of an engine drive holding plate unit vs an AC refridge. unit.
    You can also have DC run holding plates....

    Starting out burning diesel:
    Engine drive:engine turns pump,pump/cools fridge.

    DC:engine drives alternator,charges battery,runs pump/cools fridge

    AC: engine drives alternator,charges battery,goes through inverter,runs pump/cools fridge.

    Some very good mounts,double pulleys,and electric clutches.

    Throw on a scuba compressor if you want....
  3. srimes
    Joined: Sep 2008
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    Location: Oregon

    srimes Senior Member

    True, if there's no wind you won't get any power from it. Being in a windy place is the first requirement.

    I'm no expert, but here are a few of my notions on the subject:

    1) Were you have wind and sun, wind energy is cheaper, and it should be cheaper than running a generator.

    2) Most small turbines on the market are basically toys. Some never produce their rated power, and if they do it's at very high wind speeds.

    3) Wind energy is a function of (area) x (wind speed)^3. That cube is why being in a windy place is so important. Area is a function if blade diameter^2, so bigger turbines can produce a _lot_ more power than smaller ones. And since power goes up with the cube of wind speed, it's much more important that the turbine is sized for and efficient at the more common, lower wind speeds.

    4) If you want wind power on a sailboat, use the sails which are much bigger than any turbine you can mount, and generate electricity from the flowing water.

    Here's my favorite site on wind power:

    If you want another project you can build one for not too much money, assuming you don't charge yourself for your time ;)

    3 basic questions to consider:
    1) how windy is your location?
    2) how big of a turbine can you fit/tolerate?
    3) how (if at all) would a turbine affect your business?
  4. CatBuilder

    CatBuilder Previous Member

    Another "check" (as in chess):

    Cost to move the boat from our summer base of operations to the winter base of operations? $9500. One way. So, we'd be spending $20K a year in fuel to move the boat. This puts the business model in jeopardy.
  5. Tad
    Joined: Mar 2002
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    Location: Flattop Islands

    Tad Boat Designer

    If you want to reduce fuel consumption you slow down.......

    A 70' hull (even a heavy one) will move very easily at low speed in calm conditions, at 5-6 knots (1200-1400 RPM) you will burn less than half the fuel you use at cruising speed.....and it's a nice restful (quiet) cruise......

    All I'm saying is that fuel consumption is not fixed (though your schedule may be) and you do not have to thunder around with the throttle in the "company notch".
  6. apex1

    apex1 Guest

    ONE WAY CHARTER....................
  7. CatBuilder

    CatBuilder Previous Member

    This is a very crucial component to the decision and the ultimate success or failure of the business.

    Most of the boats I have been looking at give cruising speed of 9 knots. I had been looking up maximum GPH at about 10 Gal/H. Speaking in more universal terms, this is $30 per hour at current fuel costs to go 9 knots and this was for the small, light, 60 Great Lakes fishing vessel that is now off the list (thank you!).

    This is precisely where I'm having trouble to figuring out precise operating costs.

    Is there some data somewhere that anyone knows of that will predict running costs for the following engines at various speeds?

    CAT 343
    CAT 3412TA
    CAT 3408
    CUMMINS 855

    For example, what's the GPH (or LPH) to run a 70' x 20' steel displacement hull at 9 knots, or at 5 knots using a GM-8V71 vs a Cummins 855 vs a CAT 343?

    Where can I find this information?


    BTW: The annual trip is not a race, by any means, but it is a little over 1500 nautical miles. How can I come up with a cost for this trip for a 70ft x 20ft steel fishing vessel for these various engines? I am operating in the East Coast, USA, between Maine and FL. I do not have the luxury of protected water, I don't think, though. The ICW is pretty skinny these days and these boats all draw about 6-7 feet.
  8. CatBuilder

    CatBuilder Previous Member

    No, it can't work that way.

    We must move the boat when the hurricane season comes and move it again when winter comes. It isn't possible to rely on a charter booking to move the boat from Maine to FL and back.

    You could get lucky and get one, but it is not guaranteed at all to have someone who wants to go on a 1500 nautical mile trip one way
  9. wardd
    Joined: Apr 2009
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    Location: usa

    wardd Senior Member

    is there enough charter business in this economy?
  10. CatBuilder

    CatBuilder Previous Member

    Don't start down a road to knocking at the foundation of my business model. I won't even answer off topic questions like this. Forums are filled with people who want to give you advice on your life. I'm done with that kind of advice. Many years of listening to ****** and naysayers on forums hasn't been a good experience. I'm looking for real, relevant information on operating costs of 70ft fishing vessels with the above engines.

    I don't mean to be a jerk and I'm certainly not calling you, in particular a *****, but I have listened to people who try to put doubt into your mind for years. No longer.

    Also, no longer will I try to defend my choices from naysayers.

    Post about running costs of 70 fishing vessels (at various speeds) or be gone from the thread.
  11. apex1

    apex1 Guest

    NO, there is no such data.

    But you don´t need it anyway. Find a REAL boat and we can calculate that.

    The Malahide Trawler I have on offer at present, consumes about 4ltr, mile/hr at 8kn in calm waters. But 5,2ltr at 9kn and just 3ltr at 7kn.

    It is a 21 x 6,8 meter boat of 130 tonnes. Much like the boat you have in mind (except for the price).http://www.boatdesign.net/forums/marketplace/68ft-malahide-trawler-true-passagemaker-sale-34333.html

  12. CatBuilder

    CatBuilder Previous Member

    This is a very good starting point. I need a close approximation, not decimal point precision, so this is perfect.

    This boat (the Malahide) is nearly identical in size, but the hull shapes are slightly different. Maybe this makes a big difference because I am finding wild variations on the internet for consumption by looking up the engines alone. Some say 10 gallons (37 liters) per hour, some say 36 gallons (136 liters) per hour! Either way, nothing sounds the same as 1.37 gallons (5.2 liters) Malahide uses at 9 knots.

    Do you know how many kW or HP the Kelvin 8 cylinder in the Malahide puts out or what the exact model of the engine is? It will help a lot to at least have a starting point.

    Here are some pictures representing the hull shape. I have many of these types of boats to choose from. The boats are about 70' (21.5 Meters) x 20' (6 Meters). The draft is approximately 2 meters.

  13. WestVanHan
    Joined: Aug 2009
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    Location: Vancouver

    WestVanHan Not a Senior Member


    The drag of water goes up by the cube of the difference in speed.

    You can work out the differences in speed,find hp needed at that different speed....then look at the exact engine charts for rpm vs hp vs fuel consumption and get kind of a rough idea.

    The prop will have differences,and form drag will affect things a bit (?)

    In semi or planing boats it's useless.

    Take Richard's trawler:
    3ltr at 7kn.
    5,2ltr at 9kn

    7 to 9 knots is +1.28,cube that and u get 2.1 times the drag.
    So on the surface it seems 2.1 times the hp and 2.1 times the fuel use but the engine at 9 knots is at it's torque and most efficient rpm and load.

    If you want to slow it down,do the inverse cube.

    Thats why it's hard to say exactly what a boat will get by slowing down.
    Hopefully any boat you look at will have Flowscans or the owner can give you an idea.
  14. apex1

    apex1 Guest

    I don´t remember the engine model, the max output is about 440hp.

  15. CatBuilder

    CatBuilder Previous Member


    That's good information, but bad news. I can't rely on the owner of a boat to tell me the fuel consumption because he'll likely make up the lowest number he can.

    Somehow, I need to know the fuel consumption, at least to the gallon. If I could find out the maximum consumption, at lest I could make a good guess at how much I can save by slowing down. I can't even find max consumption.

    I'm nearly certain the hulls (commercial shrimping boats) won't have Flowscans because they are old, steel boats built before computers were used.

    This is proving to be fairly difficult...
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