Single Prop with Optional Tandem/Paired Diesel using Wing Engine

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

  1. Bahama
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    Bahama Junior Member

    Thanks for all of the details; I've never seen a diesel setup (obviously from my writing). I just read about them for the first time last night and what was described as the problem was air and water giving what the organism need to start growing, so I just figured skimming would work. I read what you wrote and it seems very practical. I'd be very interested to see how the water gets removed and also this centrifugal force strainer... My first mental picture of it would be a cylinder strainer spins (possibly with some small fins to create a current, like a blender) and the good fuel get sucked out of the center where it would be cleanest; but I'll try to find a picture.

    As I read all that I can about boating in pursuit of my dream, my head gets filled with thoughts about the design; especially since I tend to read late at night.

    Last night I imagined an automatic stabilizer with ballast tanks at each end of the boat fore and aft, and a long pipe connecting them; the water was only allowed to transfer downhill when the peak angle was reached and it started moving the other way; and then it was locked when the water stopped flowing in the downward direction.

    I also pictured a series of water turbines being used in the pipe to collect the energy from the flow back and forth.

    I'm not sure if it would work or not, but it popped into my head.
  2. Bahama
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    Bahama Junior Member

    I calculated 84 HP as ideal and 126 HP as my targeted high end rating.

    I want to get a larger engine and depower it. Would it be reasonable to look at engines that are around 140 to 168 (2x84) HP and depower it to my target 126 HP?

    Continuous Duty NEW engines that I found in this HP range are:

    6D16-NA (129HP)
    6D24-NA (169HP)
    6D16-T 165HP)

    BF6L913 (131HP)
    TD914L6M (131HP)
    BF6L914 (151HP)
    BF4M1013MC (156HP)
    BF6L913C (156HP)
    TCD914L6M (156HP)
    BF6M1013M (163HP)
    BF6L914C (166HP)

    D5A-T (119HP)
    D7A-TA (174HP)

    6068TFM75 (158HP)

    L1066T (135HP)
    L1066A (185HP)

    4-S108-S (128HP)
    6-S108 (128HP)
    4-S108-SR (148HP)

    I'll keep reading about them. I'm not familiar with Lugger and
    Baudouin, but certainly know the others.
  3. apex1

    apex1 Guest

    The Luggers are based on Deere, the Baudouin´s and Volvo´s I would not install, the rest is ok.
    As I said, 6cyl. 6 liter displ. and about 120 horses @ 1800 rpm, thats my recommendation for such boat.
    Leave the old DD animals where they Freds boat.

    I refuse to comment on your trim tank idea.........


    what has your tank system to do with a fuel polishing system?
    Right, nothing.

    When you next time bunker half and half* in Mexico or Spain you will understand me immediately.

    * half water, half fuel.
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    FAST FRED Senior Member

    "I want to get a larger engine and depower it."

    Poor idea , the higher loaded engine (diesel) will live longer with better fuel efficiency than a de rated lightly loaded diesel. Great idea for a car gas engine tho.

    At 24/7 cruising "full" speed 80% of an industrial engines rated power at 90% rated load seems best.

    Try for a prop that will load the engine at Least 60% at Long range cruise rpm..

    The fuel consumption at full speed will be at least double the LRC fuel consumption , but you may be 1 1 1/2K faster.

    Dual engines on one shaft will change the "ideal"prop dimensions.

    "what has your tank system to do with a fuel polishing system?
    Right, nothing."

    The question to me is how do we keep ALL the water + crud out of a tank , and feed clean diesel to the engine.

    Crud growing in a tank with some water in it can be cleaned with piles of big of big bucks of filters , polishing and transfer pumps and pails of chemical$.

    Sure it works

    , but for a cruiser the gear necessary , the power required and of course the pipeing and valving ,spares , pumps , filters that must be changed and discarded (properly?) and a book of valve settings and procedures just are silly ,

    when a better tank design , that costs maybe $100 more to build (one time) solves ALL the problem , CLEAN FUEL,with only some expense of labor .

    Everyone chooses to cruse in the way they feel most comfortable with , a small ,on board refinery just doesn't thrill me.

    Removing a deck plate , pulling a custom fill pipe setup and dumping any water found is less effort and has no power or spares requirements.

  5. Easy Rider
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    Easy Rider Senior Member

    Try for a prop that will load the engine at Least 60% at Long range cruise rpm.

    Yes and that means you'll be burning 60% of MAX fuel burn.

    Easy Rider
  6. apex1

    apex1 Guest

    I understand what you have in mind when you are talking tank setup.
    Unfortunately life is not so.
    You just don´t manage to bunker clean fuel in every port on a passage. And there is no way to get the water, biogrowth, rustflakes and mud out of your tanks by just running a additional filter. (I am referring to the **** you got in by the bunker station)

    Sufficient separator / filter size and surface are mandatory. That must not be a centrifugal sep. of course (and I did not say it must), but it must be much more than the average filter installation.

  7. david@boatsmith
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    david@boatsmith Senior Member

    Just for grins, I have worked in the past on landing crafts that had 4 671s mated up to 2 transmisions. For what it's worth my work involved putting in new stern tubes and foundations for 2 new single diesels.
  8. BTPost
    Joined: Dec 2009
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    BTPost Junior Member

    There seems to be some confusion over how 4 Stroke Diesel Fueled Engines react to differing Loads. Once the Engine comes up to Operating Temp, it really doesn't matter to the engine, how much higher loading, is applied, up until Max Rated Load is achieved. Operating Temp should be maintained by a correctly designed Thermostat & Cooling System, that will allow the engine to operate from some minimal load (5-10%) clear up to 100% of Rated Load, without having any effects on the engines operation. If the engine operates below Operating Temp, then yes there are consequences, but once Operating Temp is obtained, then it is the Cooling Systems job to maintain that Operating Temp no matter what load is placed on the engine, right up to Max Rated Load. Many boat designers do not really look at this area when deciding on a Engine Package for a specific vessel installation, and this, clearly,a Design Function that needs to be accounted for.
    1 person likes this.
  9. apex1

    apex1 Guest

    Unfortunately that is not the entire truth.

    Loading a Diesel to at least 60% is a must for a service life according (or exceeding) designed hrs. BTO. A CPP does provide that.

    Fuel in oil, carbon build up (yes, even on common rail and fully electronic controlled trains), not free burned valves, set bearings! (who did assume that?), and so on and on.

    The theories are looking so nice........

    Live a year out at sea on a fishing trawler in the northern Hemisphere.

    Reality is so darn ruthless........

    ... and when you would whish to have the salesman right besides you, most probably he will enjoy a nice day while you fear for your life.

    Designed engine displacement X 2, designed hp X 1.5, designed rpm X 0.6 and you may get close to a reliable passagemaker propulsion.

    A real engine for circumnavigating starts at 25 liter displacement (better 60), is always a straight six, and can run on one single cyl. for years without probs.

    Unfortunately that is not a setup our friend could accommodate, so leave it as it is. His choices have been right.


    ahh, when you are back from next circumnav, let us know your renovated opinions.....
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    FAST FRED Senior Member

    Unfortuniatly a diesel engine requires sufficient combustion pressure while operating to survive.

    Simply getting the engine to normal operating temperature does ZERO to get the fuel performance or service life the engine is capible of.

    The firing gas pressure goes behind the compression ring causing a good seal. Lower the compression pressure (load) looses this seal, causing the cylinders to be burnished , loosing the hone scratches that hold the lube oil for the piston.

    Blowby , oil dilution requiring more oil changes

    slobbering , oil burning , and high fuel use for little power.

    Nigel Calder had a series of articles in PBB that showed with lower loads gensets ( constant speed diesels) used 200% to 300% More fuel per hp produced at light loads.

    Not much fun for a cruising boat,attempting LRC.

    National Fisherman had a great series on Underloading a few years back.A very expensive hassle for the fish guys
    600hp trawling, 55hp running hyd stuff retrieving , costs a bunch of engine life.

    Ditto for gen sets , they MUST use a day and a far smaller night loads unit.

  11. Bahama
    Joined: Jun 2010
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    Bahama Junior Member

    I was reading more about the CPP and it seems like it works quite nicely with making any system efficient. I did find an interesting article that also touted it's efficiency with an diesel-electric setup that you may find interesting... the author obviously favors the Diesel-Electric with the CPP over a direct-drive Diesel-CPP system.

    I talked to the NA about engine size and he recommend going down lower to save on weight; he felt that going beyond 90 HP is not going to do much of anything beyond costing fuel, which I think we were all in agreement with--I don't think I agree with his assessment that it won't go "any faster"... I think more accurately you'd say that the costs in fuel per extra knot goes up astronomically beyond 90. I could double my HP and maybe only get 1 or 2 more knots (or whatever the calculations end up being). So, where this is heading based on the info from him I think is that going beyond 90 offers very little extra for me, so I have to decide is my target HP engine going to be: 90, or a range between 90-100, or 90 to 110 or 120? Anything beyond 90 seems to be a decision of how much "emergency" room do I want to escape a storm at 9 or 10 knots rather than 8 knots.

    Litterally hundreds of tiny little decisions in boat building... fun and mind boggling at the same time.
  12. Bahama
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    Bahama Junior Member

    Smoothing out the ride in rough seas

    You're a good man Richard, you crack me up with your threads sometimes. I did get this idea to noticably work while testing it out in a canoe, but I don't think that the water would scale well because I'd rather have the space for something else useful--this was only pondered while thinking of how to smooth out rough seas, not for everyday travel.

    I did consider the idea of temporary bags mounted on deck for the same purpose, which would work, but it's above the waterline and that's not desirable in rough seas.

    So that led me to the idea of sea anchors on each end with heavy ballast placed at the bottom of each one to keep them pointed down in rough seas. The sea anchors would be designed to open up like a parachute on the upswing, but glide effortlessly on the down swing. Lead ballast weight in the bottom of the sea anchors would keep it pointed downward. The lines of a 50' boat would probably need to be 25' (tangle free) to maybe 30 to 35' (low risk of tangle). Now that's a lot more simple and safer... but I got there to that idea while thinking of water bags on a deck... just part of the creative process.

    So, take a swing or two at that idea. I think what is key is keeping the sea anchor pointed down, and so that would mean FAR more weight than a traditional sea anchor that is normally horizontal, not vertical.

    What this idea has going for it is simplicity and leverage. Because it's placed on each end of the boat you have huge leverage on your side and that reduces the diameter required for the anchor.

    A design like this would need some kind of a safety release hitch mechanism that would release the entire anchor from pulling hard on a line that leads to it, that way, if it's causing problems during a real crazy storm (I don't think that it would), then the captain can just release it from the Pilot House or helm with the hard pull on the hitch release line.

    I like this idea as well because it's not heavy, it's just using drag friction to our advantage when we want it.

    Even having one of these devices would smooth things out a bit--I think the bow would have the most impact if you installed just one.
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    FAST FRED Senior Member

    If you really want efficiency you need to set the boat up for Long Range Cruise LRC.

    Take the square rt of the LWL and multiply it be between .9 and 1.15 . the higher number if the boat is at the slimmer lighter end of "normal", the slower if its a fat heavy boat.

    That will give your LRC cruise speed , there you should only need about 2 hp for each ton (2240lbs) of boat in the water.

    IF whatever that HP required number is is over 60% of the engines realistic rated output , GREAT.

    Hopefully its at a nice low RPM to load the engine better and reduce on board noise.

    Next question is prop efficiency , almost always its impossible to go too large a prop diameter , as a large 2 blade is even better , nore efficient than a 3 blade at putting HP (now called thrust) into the water.

    Dave Gerr Prop book will give all the rules to get started.

  14. Bahama
    Joined: Jun 2010
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    Bahama Junior Member

    Thanks Fred--

    The LWL will be 41' 10-3/4" (41.89583333')
    Square Root of that is: 6.472699076
    x0.9 = 5.825429169
    x1.15 =7.443603938

    42000 Lbs. / 2240 x 2 = 37.4 HP

    37.4 / 0.6 = 62.5 HP

    So if I'm understanding what you wrote correctly; the most fuel efficient HP would be 37.4 HP; however, we have wind and currents to fight at times, and so giving myself the 40% extra for that will give me an optimal engine for fuel economy at 62.5 HP.


    So going beyond 62.5 HP is costing me extra fuel because I'm no longer at optimum.

    If I were to compare apples to apples from the many rules of thumb that I'm reading, I'd break them down to this:

    1 HP / 1120 Lbs. is optimal fuel efficiency in calm weather

    1 HP / 672 Lbs. is 60% of optimal, giving the diesel motor some extra power for harder weather conditions

    1 HP / 550 Lbs. seems to be the minimum power needed for what is deemed to be a "seaworthy" vessel capable of getting you off a lee shore in a gale.

    1 HP / 500 Lbs. is another common rule of thumb used as a minimum HP size to use (I assume giving up some more fuel economy for safety in running from storms)

    1 HP / 450 Lbs. seem to be the final reasonable limit; anything beyond this number (e.g. 449 or lower) will really cause the fuel economy to rapidly decline--until by the time that you reach numbers in the 1HP per 400 to 350 Lbs. area some would say at that point you are just wasting fuel unless your hull will fully plane above the water.

    1 HP / 400 Lbs. seems to be a common limit for many high-end American coastal cruisers

    1 HP / 350 Lbs. is the final limit given by people who are willing to have an upper end of power left to run from a storm--but it will dramatically cost you in fuel.

    From everything that I've read and heard, this seems to be the best recap where I'm comparing apples to apples by converting to 1 HP per various weight ranges.

    Anyone wanting to critique it please do.

    Fred, I really appreciate what you wrote because I do want to get some decent fuel range and that forces me to keep my HP down because I DO want the range and I DON'T want to be the typical American with too much engine.

    I made a list of what I could find so far and sorted it by RPM; I've limited my RPM to 2300 or less; and I'm staying with HP between 84 and 97:
    Manufact/Model Curr/Old HP RPM Duty Rating
    --------------------- -------- -------- -------- ---------------
    Deutz/TD229-6 Old 89HP 1500RPM Continuous Duty
    Deutz/D229-6 Old 83HP 1800RPM Continuous Duty
    Deutz/F6L913 Old 84HP 1800RPM Continuous Duty
    Daytona/DME-4 Old 90HP 1800RPM Heavy Duty
    Volvo/D5A-T Old 97HP 1900RPM Heavy Duty
    CAT/3304B-NA Old 85HP 2000RPM Continuous Duty
    Deutz/D229-6 Old 91HP 2000RPM Continuous Duty
    Deutz/BF4L913 Old 86HP 2150RPM Continuous Duty
    Deutz/F6L913 Old 97HP 2150RPM Continuous Duty
    Sisu/320 DSM Old 83HP 2200RPM Heavy Duty
    Sisu/420-DM Old 84HP 2200RPM Heavy Duty
    Lugger/L439T Old 86HP 2200RPM Continuous Duty
    Lugger/L4239T Old 86HP 2200RPM Continuous Duty
    Deutz/TD229-4 Old 87HP 2300RPM Continuous Duty
    Deutz/BF4L914 Current 93HP 2300RPM Continuous Duty
    Deutz/F6L912 Current 93HP 2300RPM Continuous Duty

    Thank you to everyone for your insight and help.

  15. mark775

    mark775 Guest

    Always, I have advocated for a simple fuel system with good, large vents, a sump from which the fuel is taken and multi-stage filtration. My vision has been biased by a pretty clean, dry supply. When in Mexico, I use these: . They are slow, cumbersome, and one more thing to clean/store but work amazingly well at removing contaminants and water. Knowing how Richard feels about this (You just don´t manage to bunker clean fuel in every port on a passage. And there is no way to get the water, biogrowth, rustflakes and mud out of your tanks by just running a additional filter. (I am referring to the **** you got in by the bunker station)), tho there are some places in BC and Alaska where the fuel is not perfect, my filtration system deals with it nicely but I believe that if I were more of a world-traveler, I wud do it his way. The main thing about these West filters is that they are excruciatingly slow (most people have slow fills/small vents anyway- so it wudn't matter but I am accustomed to 100 gallons, coffee and signing in under five minutes) and do allow a little water thru. One last note - fuel shud always come from the lowest part of your tank - a sump is even better. Do you want to find the dregs/slag/water right after you fill...or just when it gets ruff out?
    As far as wing motors and inventive ideas, if one keeps it simple and robust, it is reliable by its nature. The more stuff you have to deal with, the more thru-hulls, shafts, plumbing, etc., the more there is to fail. Problem is, depending on the failure, the very idea that was supposed to lend redundancy or "get home" ability can cause catastrophy. I don't mean to be a wet blanket but all one needs to do is look at how the commercial fleet does it (bigger, simpler, slower, stronger). Forget the "what-ifs" of things like a broken shaft (You're going to have a safety factor of five or better and cannot break the sucker), dirty fuel (you previously dealt with it, one way or another), or mechanical malfunction (you are running slow and doing maintenance? Dang near anything is good for a lifetime). In short, I feel that you are over-thinking the thing...
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