Turbines and electrical propulsion for a schooner

Discussion in 'OnBoard Electronics & Controls' started by james.smith, Mar 19, 2016.

  1. Rumars
    Joined: Mar 2013
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    Location: Germany

    Rumars Senior Member

    Rastapop it seems to me you do not understand efficiency. There is the pure physics theory "real efficiency". From this point of view DE/hybrid is always going to lose because it is introducing additional conversions of energy between the primary energy carrier (diesel) and the propeller. Then there is the "operational efficiency". This one is tied to the operational parameters (how the vessel is going to be used). Using a navy study to demonstrate fuel savings is only going to be relevant for someone with the same operational parameters as the navy, and that is usually another navy. You could find a study that says exactly the opposite for a different set of parameters, say fixed speed cargo carrier. That is why you never see DE on big cargo ships, see it often on harbor tugs and so on. And that is why your statement that DE can be more efficient for some vessels is true.
    Then there is "financial efficiency". This one depends on fuel price and availability, maintenance costs, etc. It has nothing to do with "real efficiency" and can dramatically change "operational efficiency". That is why coal or LNG fired steam turbines are still used in some new build ships. There are even newly build, wood fired, steam locomotives with classic compound piston engines because of this.
    In the end there is "technical efficiency" where installation requirements may make a Diesel (or something else) - Electric more desirable than a gearbox.
    Gonzo's posts demonstrate that he understands this aspects yours do not. He is not spreading any misunderstandings. For the OP's vessel a DE/Hybrid installation only ads complexity and initial costs without saving any money in normal operation or bringing any other benefits. To somehow benefit from DE the OP's vessel would have to go for azimuth thrusters or Voith Schneider propellers witch are both costly and unnecessary for the normal operation of the vessel.

    I think this project depends on ultimate financial sustainability during operation. That is why I think that Cecelie should probably have no engine. Let me explain:
    Hauling of general cargo for money in traditional tramp operation is not going to cover the costs. That means there is a need for an alternative business model.

    One is the route taken by fairtransport. You find some low bulk/high price commodity, transport it by "sail only" and sell it with with a big markup. For example 1L of Tres Hombres Organic La Palma rum is 64,14 Euros as opposed to Aldea Cana Pura for 44,21 Euro (german retail prices including VAT). It is the same rum, but only one is matured for 7 months at sea under sails alone and produced in a limited run of only 811 bottles. But even so the earnings will probably not cover the costs, so you need to sell adventure to people and take "trainees". All this is possible only because the vessel has no engine whatsoever. The moment you put an engine on her nobody is going to believe the "working sail only" part anymore and you can not make money because you loose your competitive edge. The fact that you have to hire a harbor tug for entering ports or going trough a Traffic Separation Zone, the RIB's with big engines to push and manoeuver the boat that you have on board, or the fact that you run the generator 5 hours every day do not detract from the fact that it is a "pure working sailboat without engine". If you get a eco-hardliner on board that points out this facts to you, you blame the modern rules and regulations and assure him/her that the electricity for his own gadgets is 100% green and point to the 2 solar panels on board.

    Another avenue is that taken by Torben Hass with the schooner Undine: you find a route where transport is expensive and undercut the freight rates by using sail and saving diesel money. He also takes up to 8 passengers for a fee. In this case the owner is a licensed commercial captain with sail experience (former officer on the Gorch Fock) and the route is from Hamburg to Sylt. Passage fee for a truck to the island of Sylt (both ways) is 428 Euro (10,01-15m length) or 570 Euro (15,01-21,80m lenght) so the shipping of bulk cargo and passengers from Hamburg to Sylt can be marginally profitable. Even so the enterprise nearly failed twice. First when he was required to hire additional crew for watchkeeping (he got an exemption) and second when he hit a submerged drifting buoy (in the end he was saved by some sort of crowdfunding). I understand that this year the boat has or will go to a flag of convenience for the first time in her life in order to save costs.
    Website for this enterprise is http://windjammer-shipping.de
    Schooner Undine, https://de.wikipedia.org/wiki/Undine_(Schiff,_1931) is somewhat similar to Cecelie but has her original 1937 vintage 120HP diesel engine besides the 420sqm of sail.

    There are also other avenues like rehabilitation, training and other programs. People are still the most valuable cargo if you can convince them to come on board.

    So at the moment the OP has to decide what to do. If we talk only about a one way trip from Germany to the UK then the yard is right. Put a diesel into her and take her over to be refitted in your back yard. If the boat should have a motor in the future then get the yard to put in the appropriate HP diesel from the start, if not any motor that does the job and can be sold afterwards is OK, and wait for a good weather window.
    That is why I advised you to make contact with fairtransport (you could also contact Cptn. Hass since he has a similar vessel). In order to decide what to do and how to do it you need specific information. Should you have a motor after all? What kind of rig? If she is going transatlantic (or further on the trades route) and selling adventure to people you need "square rig romance" so a brig or brigantine is better then a schooner. If you stay coastal a schooner is better. How much accommodation and on what level of comfort do you need? Do you need the added complication of a teak deck (square rig romance requires it, coastal schooner it is probably a nuisance). Are the passengers only that or are they "trainees" and working the vessel. All this needs to be decided before you begin. Starting with a blank canvas like a rusting hulk is only going to work if and only if you have a pretty good idea of how it is going to be used afterwards.
     
  2. keysdisease
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    keysdisease Senior Member

    I exhibited at the Electric and Hybrid Propulsion Show in Ft Lauderdale in January of this year. Sat in on a few seminars, listened to a few case studies, talked to a lot of my neighbors. The keynote speaker was the head of the US Navies Electric Boat Division.

    One case study in particular was very enlightening as the vessel in question was a harbor tug that worked a very regular routine on a daily basis. The examples were Diesel, Diesel-Electric and Battery-Electric.

    In my opinion almost every player in Electric/Hybrid Marine Propulsion was in attendance and just about every available or soon to be available system was discussed.

    The Euro Version opens June 23rd in Amsterdam. Maybe a good place to go for some thoughts.

    http://www.electricandhybridmarineworldexpo.com/

    In my opinion, this technology is not quite ready for prime time except in a vary narrow range of circumstances for very specific vessels. I am familiar with Turbine/Jet powered vessels and Turbine Generators for ground power and I doubt Turbine Electric would be suitable for your Schooner

    :cool:
     
  3. SamSam
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    SamSam Senior Member

  4. Jamie Kennedy
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    Jamie Kennedy Senior Member

    The Canadian Kingston Class Coastal Patrol Boats uses such a system. Four diesel-generator sets driving two electric motors driving Z-drive azimuth thrusters. I understand they have some issues, but they probably just made it more complicated and less efficient than they needed to.

    From wikipedia...
    https://en.wikipedia.org/wiki/Kingston-class_coastal_defence_vessel#Propulsion
    The ship is equipped with four main Wärtsilä UD 23V12 diesel engines which are coupled to four alternators (600 V AC). Two Jeumont electric motors (±740 V DC) provide power to the two LIPS Z-drive azimuth thrusters which are fitted with fixed-pitch reversing propellers. The propulsion system provides 15 knots (28 km/h) maximum continuous speed. The range at the economical cruising speed of 9 knots (17 km/h) using two engines is 5,000 nautical miles (9,000 km) with a 20% margin in tank capacity. Mechanical minesweeping is carried out at 8 knots (15 km/h). The crash stop length is five ship lengths from a speed of 15 knots (28 km/h). Sometimes if you are going down a wave they reach the speed of 16.42 knots (30 km/h).
     
  5. Rastapop
    Joined: Mar 2014
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    Rastapop Naval Architect

    No, Rumars. There is only efficiency. Your term "real efficiency" simply refers to "operational efficiency" with assumptions in place (i.e. that the diesel will be at peak efficiency rpm all as much as the hybrid will).


    My links in this thread were not for the OP. There were just quick links found for Gonzo that showed entities with much more knowledge than he, Wartsila and the UK Navy, had calculated they would achieve fuel savings with hybrid propulsion.

    You appear to be effectively repeating me back to myself - I don't know why.

    As for "never", never say it. Some links I've posted for Gonzo in other threads:

    Hybrid tankers: http://www.nassco.com/products-and-services/comm-dc/bp-tankers.html
    Hybrid cargo: http://www.centralindustrygroup.com/maritime/shipbuilding/delivered-projects/jaguar-cig-6000-gc-e/
    A DNV study for a hybrid box carrier: https://www.dnvgl.com/Images/Gas Tech Würsig_2015-10_web_tcm8-45310.pdf

    Yes, there are many factors that go into making a propulsion choice (calling them all efficiency appears to be unique to yourself though). Gonzo didn't mention them when he made his incorrect statement about losses, and I haven't mentioned them either. They're beside my point.

    Unfortunately he demonstrates poor and/or incomplete understanding. He compares part of the losses that diesel has and hybrid doesn't (3% gearbox losses), to the losses a hybrid has that a diesel doesn't (energy conversion).

    He ignores the remaining losses that a diesel (for some vessels) has that a hybrid effectively doesn't: extra engine losses due to using it at worse than peak efficiency.
     
  6. Rumars
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    Rumars Senior Member

    To me it seems that gonzo replied to the OP that his proposed DE system of one motor/generator is not going to be viable because of conversion losses.
    If you wanted to correct him you shoud have said that it can be done but in order to preserve the diesels sweet spot you have to use multiple motor/generators and a smart management system. You could have even explained to the OP what it takes to design a hybrid system (big enough battery to supplement power on demand and constant use until the generator can be loaded enough).
    In my opinion neither of you demonstrates poor and/or incomplete understanding. Gonzo was replying to the OP and was right and you ignored the OP and the meaning of gonzos post.
     
  7. gonzo
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    gonzo Senior Member

    The OP indicated that the auxiliary motor was of very modest power. Therefore, it would be almost always operating at close to its rated HP. My response was for this installation and I never mentioned the UK Navy.
     
  8. Rastapop
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    Rastapop Naval Architect

    You: "The link to that article says that the Navy started the study in 2008 when a barrel of oil was $174. It is less than $42 nowadays. That will nullify any savings. Also, the Navy..."

    Whether it was the UK or US Navy you were referring to is of no interest.

    My point was, is, and will always be that you were wrong to compare only gearbox losses of diesel propulsion to conversion losses for hybrid compulsion. You also need to include engine losses, which results in hybrid systems being more efficient than diesel for some vessels, and less efficient than diesel for other vessels.
     
  9. gonzo
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    gonzo Senior Member

    The real point is that you cut off a sentence that gives context to my statement. Lies come in many varieties, including those of omission.
     
  10. SamSam
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    SamSam Senior Member

  11. Aireli
    Joined: May 2016
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    Aireli New Member

    Ah, first post on boatdesign.net!

    Have you considered using compressed air for a large part of your energy storage? No degradation like batteries have. For a monohull can become part of the ballast, even part of the structure.

    Biggest problem is our friend, the 2d Law of Thermodynamics - the compressed air needs to be turned into electricity and there will be some loss.

    A couple of other problems, but it is something I am looking into. The plan would be to run the air compressor at the dock, then recharge the batteries at sea using the pressure vessels.
     
  12. gonzo
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    gonzo Senior Member

    The losses would be huge comparing to simply charging the batteries at the dock.
     
  13. Aireli
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    Aireli New Member

    Gonzo - true, but the idea is to be able to charge away from the dock. The energy loss at the dock between using a compressor rather than a battery charger is largely irrelevant. Really not that much in actual dollars either where the power comes from a meter - and for many transient slips, there is a flat fee to hook up overnight.

    The benefit of using compressed air is unlike batteries, pressure vessels do not degrade in their ability to hold a "charge". They are so heavily built that, even left unserviced, the tanks will likely outlive the hull. So say that you have put half of your stored energy into the pressure vessels, you can cut your financial outlay for battery replacement in half. Example; $20k versus $40K. Do that every ten years or so. Your grandkids will thank you.

    Additionally, my plans for a large schooner include her use for scuba charter. You can charge the scuba tanks directly from the ship's tanks. For many power tools, the same thing. Since compressed air cools rapidly when released, I also am wondering about its use for refrigeration and even air-conditioning.

    It has also been suggested to me that I could use the air to directly power the prop through a pneumatic motor - but do I really want to go "putt, putt, putt" as I come into harbor?
     
  14. powerabout
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    powerabout Senior Member


  15. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi James,
    I have different idea’s than a lot of other people and am willing to get some flak from the experts.
    1) If there is wind, one does not need an engine and you just raise the sails.
    2) If there is a storm, one raise a storm jib and maybe a small powered means to keep the bow into the waves. Whatever the “small powered” could be.
    3) If the sea is smooth, what the hell do you need a 400 hp engine for, except if you are busy to make the boat into a flying dolphin.
    4) What I have seen from the pictures, it is still going to take you some years before you are able to start sailing.
    5) I have highly respect for the mechanical methods the Germans are building something and most likely a 40 hp, 30 KWh electric brushless engine could do the job. It will run probably at half the power in anyway.
    6) That brings us to the batteries needed. Today there are already expensive Lithium batteries which could provide you with: a) For 100 Euro you can get a 1.7 Kg 22.8 Volt 16 Ah lithium battery. (i.e. 0.36 Kwh , 200 of them in serial and parallel would give you 72 KWh, or good enough for 4 hours at a reasonable speed) This would only be 350 Kg, less than the weight of a 400 Hp engine + fuel.
    7) However there are new technologies on the horiszon, I expect to be on the market in 2 - 3 years time with o.a. Zinc- Manganese batteries, good for 4000 – 5000 re-charging and an energy density of 285 mAh per gram, or for 1000kg= 1.44Volt x 0.285 Ah/gram = 410KWh energy. Good for 22 hours.
    8) This bring us to the charging of the batteries. I would have multiple chargers of 3 KW per example, which would the batteries in 2 days. The problem is that harbours cannot easy provide you with a max. 25 Ampere outlet and at maybe 380 V AC, Thus you need multiple sockets to spread over the harbour outlets.
    9) Also I hope that very soon we will have solar panels which provide us with energy in the dark. A combination of Solar panels (or maybe solar sails) for dark + sunlight solar panels could even bring you further , also in time it takes to recharge your batteries.
    10) Thus the big question is, would you be willing to gamble and go for electrics and gamble that the new technologies will help you. Or do you go the smelly way and use a diesel. That only you can decide.
    Bert

    P.S. The sailing ship Tres Hombres
    Schoonerbrig 'Tres Hombres' Conversie van een Kriegsfischkutter (Duits marine vaartuig WOII) naar een zeilend vrachtschip Conversion of a KFK (WWII German navy )
     
    Last edited: May 11, 2016
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