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Gas Turbines Updated

Discussion in 'Technical Discussion' started by hamall9, Feb 23, 2015.

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  1. hamall9

    hamall9 New Member

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    Hi there,
    I would like to revisit the subject of gas turbines since it appears that several years have passed by since the last post and technology has moved forward enormously in the past few years.
    My history is with yachts and I feel that I have one last design/build/sail project in me before I finally resign myself to charter.
    I was considering a catamaran for the Caribbean and it slowly dawned on me that I should get rid of the rig and settle for a power cat but employing the very best of the exciting new technology.
    My thoughts turned to gas turbines which is a subject I know little about and so I am hoping some Learned Souls here may be kind enough to bring me up to speed and keep me in check as to the the realities of GTs

    If this subject is of appeal, I can add a few more thoughts as to the direction I am leaning towards. However, to begin with, accommodation for 8 is required plus toys, and I happen to enjoy speed.

    Basically, I want to assemble a good feasible brief before I start knocking on Designer's doors.
    regards
    John
  2. rcrapps

    rcrapps Senior Member

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    Your thinking about GTs as primary power? How large of a cat are you thinking for 8?

    I remember delivering some Mares (45'??) up/down the US south/east coast many years ago. Always wondering how fast could they go. The factory rep told me then that HP was the factor and they hoped to find larger HP orders. Not even sure the company is still in business. It was a fun boat to drive at speed.

    I could not imagine then, GTs in one of those cats, but it's fun to think about now. The air box (tunnel) would have to have some way to dump over pressure, maybe some vents under the hulls like the fast CCs do now to break drag. Some parts of the boat have to stay wet a little.

    There are a few great design kids here, look forward to hear from them. I would like learn some more myself.

    ,rc
  3. Capt J

    Capt J Senior Member

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    They usually don't work well as the primary propulsion in a yacht, because they are grossly in-efficient at slower speeds, where yachts travel at a lot. They do well as a pusher motor to achieve a higher top speed when mated to a jet. Another option is small propulsion engines for slow speeds and maneuvering and the turbines for cruise speed in the ocean. Air intakes also have to be well thought out. As well as heat they create.
  4. hamall9

    hamall9 New Member

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    The cat I have in mind will resemble a sailing cat without the rig more than a traditional power cat platform...the profile and indeed the whole boat will be as 'cutting edge' as I can make it... both in function and form
    The boat is 'live aboard' and I don't envisage making great use of marinas. Size will be around 86' by 45' , with the forward 20' being lightly used ( paddle boards etc)
    Weight (or lack of it) and hull form are the keys to efficiency rather than simply increasing horsepower as we all know.
    I don't know what the displacement will be, but it will be light for it's size, which is why I have an interest in GTs.
    I know that GT units of at least 200kw (maybe more) are available with coupling gearboxes, so two units per hull would yield in excess of 500 Hp or around 1100HP for the boat. I read about a Kiwi Company that is building carbon fibre surface drives.
    Whether this is sufficient to lift the hulls with the assistance of foils is what I need to establish.
    By coupling and uncoupling GT units I am trying to solve the problem of low speed inefficiency .... it may be possible to rotate individual units as gensets .. I don't know.
    Otherwise smaller mini GTs are available.
    Solar power plus the new batteries coming to market will reduce the reliance on fuel, but once again it is a weight trade-off. Solar power will have the effect of smoothing our energy demand over the sunshine hours rather than over specing a genset to accomplish a day's needs within an hour or two.
    I am appreciative of all input, because I would really like to undertake this project as it is not my first design/ build project with boats ... and in answer to the unspoken question, yes there is a significant cost premium attached to this concept.
  5. Capt J

    Capt J Senior Member

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    What about diesel electric units for slow speed, as well as peak power use, and possibly a smaller generator for light use. However, the light electrical use part rarely seems to come into play in actuality. Then 2 turbines with jets maybe. But again, you're trying to make lighter weight but then adding it with solar and toys.....I'd say just make a reasonable power cat along the lines of the 44' Lagoon, which is very efficient at 10 knots 3 mpg, and burns 1.5 gpm at it's 16.5 knot cruise......The more gadgets and machinery, I've found the more problems.
  6. hamall9

    hamall9 New Member

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    I agree with your thoughts Capt J ... however it is not in my nature to do as you suggest, and as this project will turn out to be my 70th birthday present, I fear that I am not about to change ... I tried retirement once and it almost killed me
  7. PacBlue

    PacBlue Senior Member

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  8. hamall9

    hamall9 New Member

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    Yes exactly, this is where I am coming from.
    I have not seen it used as primaries but a few of the more adventurous SY Owners are trying this as a genset option.
    USN is also deep into this school of thought.
    If we are going to assemble a Power Cat of the future it cannot have yesterday's power systems.
  9. rcrapps

    rcrapps Senior Member

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    Oh, this is cool. I understand some of it. Homework tonight.
  10. captholli

    captholli Senior Member

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    The easiest way to deal with a G.A's power band or continuous output for ALL maneuvering be it slow ahead or astern for docking or full speed is through variable pitch propeller systems. Well proven for decades for vessels using these systems and there are V.P systems for small boats also that are compact and wont break the bank.
  11. Capt J

    Capt J Senior Member

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    Well, if you're looking for 1100hp total. What about 2 five seven outboards? Broad powerband and simple, bolt them on the stern and go?
  12. Perlmudder

    Perlmudder Member

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    Turbine marine put turbines in "pleasure" boats all the time. They do not require variable pitch props to adjust speed.
  13. captholli

    captholli Senior Member

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    Tell us more, coupled to what?
  14. captholli

    captholli Senior Member

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    I went on Turbine marines web site, Interesting stuff for race boats. I figured the gear reduction would be some type of torque converter and their literature mentions a dry sump gearbox with a vague reference to a torque converter system. cool thing is that you can start a turbine with a T.C. I don't know how robust this would be for Op's use nor do I think V.P would be the Utopia solution.
    The Capstone Micro Turbines used as generators driving electric motors would more than likely be the most efficient way but the only problem there is the amount of space for the electronic switch gear and panels.
    It'll be interesting to get a few hundred micro turbines in the field the next few years (hopefully) and see how viable these installations will be to replacing diesel generators aboard.
  15. Perlmudder

    Perlmudder Member

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    I am no expert by any means, but I know they can throttle the n2 and they use a trailer break set up to stop the driveline to switch gears.
  16. hamall9

    hamall9 New Member

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    Many thanks for your inputs.
    I still remain a fan for installing two GTs per hull as primaries and rotating them as gensets.
    The weight saving is impressive ... the fuel burn has yet to be calculated.
    I imagine that as a general rule we will either be dawdling along under 10 knots (uncoupled GTs) or moving along at 30+ (coupled)

    If there is anyone out there with CAD who would enjoy translating my ideas of the profile ...please drop me a line [e-mail deleted, use PM]
  17. Glyn willmoth

    Glyn willmoth New Member

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    Interesting concept, with the development of Siemens electric motors over the few years I'm sure they could put out a600hp though what size mico turbo gen you would need to drive it is anyone's guess as the weight of a 6oohp electric motor plus the gen weight may be the same as motors with shafts. have you gone any further with your concept as it has been 2 years since last post.
  18. Lepke

    Lepke Member

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    Apparently fuel use is no issue... Even the USN in high speed patrol boats used diesels for slow speed. I have used diesel electric in ships and tugs. My favorite, but not as fuel efficient as direct diesel. Something I would think about. The world isn't making more crude oil, only discovering oil in new spots. Fuel will get more expensive and what is affordable now may not be in 10 years.
  19. 1000 islands

    1000 islands Member

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