Single Prop with Optional Tandem/Paired Diesel using Wing Engine

Discussion in 'Diesel Engines' started by Bahama, Jul 9, 2010.

  1. Bahama
    Joined: Jun 2010
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    Location: Minneapolis

    Bahama Junior Member

    I want to take the time here to thank everyone for all the smart information that I do find and for the very knowledgeable suggestions that I've received.

    I want the ability to eventually circumnavigate and so I want to design for maximum distance with the propulsion; and so that means keeping the diesel engine size down to a moderate size. I'm fine with that unless, for emergency reasons I want to go fast.

    What are good design choices that allow me to have a moderate main engine, and optionally join my wing engine that I use for generating electricity use as a get-home engine as an emergency backup, and to offer go-fast reserve power for emergencies?

    For example, I'm going to build a cutter cruiser that has a LOA 48’; Beam: 14’ 2-5/8” LWL 41’; Draft 6’2”; Displacement 21 Tons. I ordered the Orca plans from Ted Brewer and plan to stretch her 3 feet and add 4 inches to her beam (http://www.tedbrewer.com/sail_steel/orca.htm).

    I'd like to get your opinions as to sizing the main and wing engines; I want a modest sized diesel motor that will work well for me and yet give me maximum range, and enough electricity to run the AC if I want and all the toys; I do plan to have a decent sized array of batteries. So any suggestions regarding the size for the wing engine and how to tie best tie them together is greatly appreciated. Thanks.

    One suggestion that I read somewhere else was to use both motors to generate electricity and then power the single prop using an electric motor.

    I also read that 3 to 4 Braking Horse Power per Ton is adequite, 5 is ample, and 6 is a bit too much. Given that, what if I had a 3 B.H.P./Ton size and a 5 B.H.P./Ton? The 3x size would be used for blue water and the 5x for all else. Either could be used to generate the batteries, although the 3x would be the best for that. For emergencies this provides near 8x to get moving if you really needed to.

    Thanks for any recommendations.
     
  2. apex1

    apex1 Guest

    Why for goodness sake are you trying to complicate EVERY single aspect on your project?

    You are (as too many others here) on a perfect way to end up with no boat at all. Or worst with a never ending catastrophe.

    What you have in mind is just not sensible, it is a "Oviparouswoolmilkpig".

    Do NOT go for a small Diesel and run another one (or two) systems for emergency or El. requirements.

    Install a beefy, proven, derated Diesel in the upper ballpark of your maximum demand and run a CPP.

    Have a 150 or even 250 amps alternator coupled, and a proper sized batterybank / inverter- charger- power management.
    That will take you round the world as long as you live and at the lowest (lifetime) cost possible.

    Look here and download the whitepaper: "achieving the impossible"
    http://www.victronenergy.com/support-and-downloads/white-papers/

    If in doubt, book a flight to Tahiti and have a look at the real circumnavigators setups! No wing engines, no wind generators (there is no wind where you anchor at night), no additional gimmicks. And usually ONE PV panel to keep the starter battery up on level.

    The fear of being out at sea with a broken engine is unreal. (as is the idea of the unsinkable boat)
    Choose the right one and be fine.

    Richard
     
  3. Easy Rider
    Joined: Oct 2009
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    Location: NW Washington State USA

    Easy Rider Senior Member

    Consider diesel-electric. Two engines but either one can drive both props independently or both engines for full power. This is an over the counter thing using bus components but I don't know if anything is available for smaller units.
    With an efficient hull like you plan one can actually go at very slow speeds and there are many other advantages.

    Easy Rider
     
  4. mark775

    mark775 Guest

    Please listen to Richard's advice. He comes off gruff (probably a tad impatient because this comes up often) but he knows what he is talking about.
    IMO, diesel-electric doesn't work here. "With an efficient hull like you plan one can actually go at very slow speeds and there are many other advantages" Keep it simple. You don't need too much power to attain hull speed.
     
  5. Bahama
    Joined: Jun 2010
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    Bahama Junior Member

    What I'm curious about is how to decide on the proper power. As I've been reading I see many different formulas; and I need power for the generation of electricity, because I will have AC on this, and if I choose to turn it on at night, I want the option.

    Also, what the best CPP power inverter setup (as Richard suggests).

    What motors should I consider? I was looking at a Detroit Diesel 4-71, which seems very hardy and would last forever for me. From what I read it had the benefits of the legendary 6-71, but toned down for less power while still maintaining the hardy construction. I also looked at the Volvo’s, but they are certainly more pricey than the DD’s. I hear that the Detroit Diesels will cost less to maintain and more mechanics know the DD than a Volvo. I want a beefy block that will last forever and I want to run her at far less than what she’s capable of, again, so that she’s not strained and will last a long, long time. Perhaps toning down the 6-71? I just need some help determineing the right engine.
     
  6. Easy Rider
    Joined: Oct 2009
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    Location: NW Washington State USA

    Easy Rider Senior Member

    Mark,
    Most boats at slow speed need to go in and out of gear constantly to go 1 or 2 knots as most boats go several knots at idle. No problem w DE. Go as slow as you like.

    Easy
     
  7. mark775

    mark775 Guest

    I was just thinking of efficiency losses and expense, Easy. I get yelled at in the harbor until the Harbor Master gets sick of yelling - I could slip to whatever RPM I want but I don't tell him! (I just throw a perceived wake at three knots!)
    Bahama, there are certainly better people than I to say what horsepower. This I do know - there is always talk of glazing cylinder walls and carboning up and such from running too cool/ not enuf load. It is my experience that as long as you are not at idle, and under some load, that is not a factor - so go with a bit more HP. In the US and probably EU, there is no such thing as carbon (to speak of) any more. As much as I respect the old diesels, parts are going to be harder to find and the new stuff is wonderful! I know that the good Detroit mechanics are going to be dying as time goes on and there will be fewer that can make a Jimmy run well. Richard's knowledgable about CPP and can get you pointed to a good dealer. It is a trade-off in cost in the short-term. No reduction/reverse gear but add the cost of CP.
     
  8. apex1

    apex1 Guest

    No Easy, sorry.

    DE is not the way to go (except you don´t mind cost and expenses).

    The house load is much too low on a yacht to make that sensible. (cruiseships are a bit different)

    In a yacht of the mentioned size and use, I would go for the smaller 6cyl. engines in the 6 liter ballpark. Deere or Deutz for example. They come in M1 ratings around 120 hp @1800 rpm (or can be derated to that figure).
    Coupled with a Hundested, Westmekan, or Helseth CPP you have a fuel sipping setup which does not bother you under sail and under motor.
    Though some 40hp are sure enough to get up to hull speed in dead calm water (it should need less), you are in need of another 40hp pretty often. The last 40 you should wish to never being in need, but it is more likely than not that there comes a day when they get you out of the way of a weather front. (when you are really on passages)

    The El. requirement should be handled by a large alternator (or two) of high quality (Zena), a good quality battery bank (Surette, Trojan), and a highest quality inverter / charger / batt. manager. (Victronenergy)

    One does not need a AC generator on a boat of that size, as long as there is no air cond. running. But if air cond. is a must, install a DC genny instead (you will have the extra money for a DC genset, when you are able and willing to install aircond.!). The controller unit you have already on board, the Victron!

    Go through the whitepapers as I recommended, and have a look at the CPP thread here (although the latter was much spoilt by some stubborn *********, it is worth reading).
    http://www.boatdesign.net/forums/props/controllable-pitch-propeller-summary-30695.html

    Regards
    Richard
     
  9. Bahama
    Joined: Jun 2010
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    Location: Minneapolis

    Bahama Junior Member

    >>The fear of being out at sea with a broken engine is unreal. (as is the idea of the unsinkable boat)<<

    I wanted to comment on this from a previous post; I'm just trying to examine all angles of a problem and come up with what is a good idea. Although I ask out of the box questions, it's typically to examine all avenues to see if there is any merit to the idea. I don't just go with complex for fun, it's merely that I'm willing to look at simple and complex to see what is best. Simple is alway preferred if possible (less things to go wrong), but it's good to look at a wide view of things... and to learn. I don't have a fear of a broken boat (although it's always a remote possibility), I was really trying to come up with an economy engine that would sip fuel, yet also have some extra ponies on reserve to haul butt away from a storm if needed-a wing engine seemed like a nice possiblity.

    I'll look at the papers (links) that you mention, thanks for the recommend.
     
  10. Marco1
    Joined: Oct 2009
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    Location: Sydney

    Marco1 Senior Member

    Agreed 100%.
    My choice of engine
    If money for new engine: John Deere
    If you are after a second hand: A factory rebuilt Gardner all polished and chromed.

    If you want to exercise your inventive juices, I would use them into developing a good filtering and polishing fuel system.
    For example. Two holing tanks with a centrifuge between them to eliminate water and rubbish you are bound to pick up when refueling. Plus. A day tank hooked up to a polishing system to keep a small amount for the day (or the week) perfectly clean and with no sediments at all.
     
  11. apex1

    apex1 Guest

    Do not get me wrong,

    I am not hammering on your (a bit stubborn) attempt, to reinvent the wheel, I just want to tell you, that is ALL already handled here on the Forum, and we came always to the same conclusion:

    Proven systems, simple systems, all the beef you can find in any item, and the ability to say: "I do not really need that", makes happy years on a passage.
    Any MUST is probably as deadly as a fixed schedule on the open ocean.

    Go ahead, and do not mind when we kick your *** sometimes, I do never mean it insulting, just to get your feet back on the ground.
    You only have one life, why wasting it in inventing new methods, systems, rules or scantlings?
    We know how we bring our industry further, we are aware of all the possibilities to take advantage over a competitor. Unfortunately they are as well aware.
    Read:
    If you do not find it at least in some noticeable figures, you can be sure it has no merits. (do not make the mistake to count the other way round! 80% of the boats in any marina worldwide are crap)

    So, go ahead with your ideas, and be prepared to find no assistance, no applause, no advice on them. It is not meant to belittle you, but might save you some time, much money, and maybe, one day.... your ***.

    Regards
    richard
     
  12. Bahama
    Joined: Jun 2010
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    Location: Minneapolis

    Bahama Junior Member

    Fuel Tank stuff

    I laughed when I saw your note because I was logging on to ask this very question! I just got done reading about all the bio bugs in fuel and how they are caused from water that may be in the fuel as it's pumped in and from condensation in the tanks as the lay around mostly empty.

    When I read that it made sense to me that you'd want some kind of a small filling tank to act like a huge glass bulb and then provide a filtration system on the output; then this would feed into the main tanks.

    Then to keep the water out of the tanks, just have an fuel intake placed at the end of a floatation device and skim the top layer of fuel into a filter and water separator device; the pump is turned on automatically for awhile every morning when the sun first rises and then 12-hours later (this is an easy clock device to make). So twice a day it runs for a few minutes to clean the fuel and remove any water, simply from skimming.

    I read these micro organisms need air at first to get started... why not flood the tank with Nitrogen? That's what is done to preserve wine in a wine bottle after it's been corked. The Nitrogen is heavy and lays on the surface of the wine (or fuel in this case).

    Also, related to fuel, I was wondering if anyone has ever channeled a water pipe into the fuel to heat it up when the water becomes cold. I would have the input and output of the pipe run from the top of the tank and then just run the pipe around the inside a bit to provide good heat exchange. Then I would pump clean water through this pipe and a heat exchanger that was hooked up to the output water cooler from my engine. The heat from the engine would heat up the fuel, but not heat it up too much. A temperature sensor could determine the temperature of the fuel and determine if the pump should start to flow, if so, then it would simply pump when the engine is running until the fuel temperature rose above the minimum temperature threshold. This type of system would use less electricity to heat up the fuel; pumping hot water is certainly less energy than what it would take to heat up the fuel using some form of electric coil.

    And lastly on this subject, I've searched around and not found anything so far where magnetic fields are used to determine fuel level. It's not hard to create your own device that measures fuel level safely 100% outside the tank--no holes to drill, no electricity in the fuel (very nice for gas because it's spark free). It can work through any material, even steel. You're just measuring the change in magnetic field between the top and bottom of the tank--the presence of fuel changes the magnetic field because it has different magnetic efficiencies than the dead air space.

    Ok, the last last thing... reserve fuel tank... any great ideas for this? The best I can think of is make sure that it's continually fed fresh clean fuel; and so I imagine it being a small separate tank where the cleaned filtered fuel is fed into (from my auto filter comment) and the top part of the tank feeds into the other tanks-so it acts like a reserve that is constantly fed and can only be drained dry by opening a separate fuel line into it.
     
  13. apex1

    apex1 Guest

    Bahama,

    you have a really impressive addiction to make even the simplest systems overly complicated.


    Your day tank is the reserve tank. The fuel in there is the cleanest you can get because much of it ran through the engine already.

    A proper fuel polishing system is mandatory on every passagemaking vessel which relies on Diesel propulsion.
    When you can afford it, have a centrifugal separator prior to the filters (plural) polishing the fuel before it enters the day tank. If these 5000 to 10000$ are too much, have at least two static separator filters installed.

    The optimal setup would look like:

    Main tanks- separator- filters- day tank- fine filters- engine intake- return pipe- day tank.

    With such a setup you don´t have bio growth or water in your fuel.

    It is not only the water and oxygen you could see with your eyes what you have to address, there is as much or more in solution in the fuel. That you have to get rid of.
    On larger motoryachts we run dry one of the tanks (usually there are 5 or more), then use that one as a reservoir to polish the fuel from one tank into the other. Quite often you can hear the separator running even in port for exactly that reason.

    Regards
    Richard
     
  14. apex1

    apex1 Guest

    Bahama,

    you have a really impressive addiction to make even the simplest systems overly complicated.


    Your day tank is the reserve tank. The fuel in there is the cleanest you can get because much of it ran through the engine already.

    A proper fuel polishing system is mandatory on every passagemaking vessel which relies on Diesel propulsion.
    When you can afford it, have a centrifugal separator prior to the filters (plural) polishing the fuel before it enters the day tank. If these 5000 to 10000$ are too much, have at least two static separator filters installed.

    The optimal setup would look like:

    Main tanks- separator- filters- day tank- fine filters- engine intake- return pipe- day tank.

    With such a setup you don´t have bio growth or water in your fuel.

    It is not only the water and oxygen you could see with your eyes what you have to address, there is as much or more in solution in the fuel. That you have to get rid of.
    On larger motoryachts we run dry one of the tanks (usually there are 5 or more), then use that one as a reservoir to polish the fuel from one tank into the other. Quite often you can hear the separator running even in port for exactly that reason.

    Regards
    Richard
     

  15. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    I would build such a vessel (desire for two propulsion engines and a need for an efficient generator) very differently.

    2 ways,

    The prime engine would be your favorite engine that can produce 50 -60 hp at 1500 , or the lowest rpm the mfg will allow. The prop would be a oversize cruising prop that was efficient at 1500 and would allow 1800 with out overload,.The main engine would have a hyd pump, probably a hyd start too.

    The genset would be a hyd package .

    The house loads for electric would be a hyd power pack ($1800 6KW) that could run off either main or genset power.

    The shaft would have a chained Hyd motor to use sometime either when the main fails or if you get really hungry for range and prefer to go slower and simply run on the genset.Both together should allow the main to reach 2100 on the oversized prop if FLANK speed is needed to escape Krackatoa, or the Tax Man.

    Advantage is that the vessel will either be at anchor (95%) or in a slip 5%.

    The genset at high speed would make enough power for a hyd windlass or a bow thruster , while the ideling main would get your slow motion under control.

    Depending on the size of the freezer eutetic plates , and weather a huge $$$ Universal AC converter is aboard would decide if the fridge/ freezer ran on Hyd or AC voltages. Ditto for air cond.

    Second way is an LST tranny , two engines on a BIG common shaft , either or both can be run together.

    A 2-71 for genset and or long range efficiency and the trusty old 6-71 for throwing 7 ft wakes (or the 4-71 for 5 ft wakes).

    All use SAE #1 sized bell housings so whatever you decide is bolt on.

    "A proper fuel polishing system is mandatory on every passage making vessel which relies on Diesel propulsion.
    When you can afford it, have a centrifugal separator prior to the filters (plural) polishing the fuel before it enters the day tank. If these 5000 to 10000$ are too much, have at least two static separator filters installed."

    Quite true for most stock boat tanks , but a proper (bailing sump) tank has little need for anything but the std twin primaries and one engine secondary.

    Even if you get 10% water in the "fuel", its free and simple to cure , just some time and effort.


    FF
     
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