A replacement of 1-2 diesels of a power boat with a small gas turbine

Discussion in 'Boat Design' started by Stoyan Ivanov, May 10, 2018.

  1. Stoyan Ivanov
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    Stoyan Ivanov Junior Member

    Yes , we understand the issues arising from water pressure . We'll not use a viewing pod for the time being although very tempting 'cause the hull is a kind of double not mon . We'll have acrylic windows .
    Agree with you about the deep V , ours will be a kind of a flattened deep V , now designing the bottom . Besides , our shape is similar to Cigarette but different enough , with bigger beam and height .
     
  2. Stoyan Ivanov
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    Stoyan Ivanov Junior Member

    Yes , I understand , no problem . But theirs are semi submersibles not real ones .
     
  3. Stoyan Ivanov
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    Stoyan Ivanov Junior Member

    I understand your pessimism about considerable weight . I share it a bit as well and that is why we calculating the weights more precisely now and will be using ( if we have to) lighter materials .
     
  4. Magnus W
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    Magnus W Senior Member

    I think you need to consider a different approach/approaches. A 40 foot vessel capable of cruising at 30ish knots and then being able to dive to sightseeing depths (about 10-15 meters?) with crew and 5 passengers paying top dollar and wanting a comfortable ride will be hard to achieve. Simply consider the heat of the engines when you go below – extra cooling of the diesels in a diesel electric sub takes time and if you don't do it the sub will be very hot. Imagine how hot your vessel will be with two hot diesels virtually inside the cabin (a turbine with it's relatively low mass is better but on the other hand harder to cool).

    Is it not possible to to leave the go-fast machinery on the surface, with one crew, and detach the sub from it? A mother vessel of sorts.

    You haven't stated how long you need to travel at the surface. If not too far it may well be more beneficial to design a faster sub and go at 15 knots submerged to the sightseeing location. The longer travel time will be somewhat offset by the fact that you're already below, prepping a sub for dive takes some time.
     
  5. fredrosse
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    fredrosse USACE Steam

    With respect to passenger comfort and high temperatures within the submarine, it would be a relatively simple task to insulate the crew and passengers from engine room heat when running in the submerged mode. They do not need to be in the compartment with the machinery.
     
  6. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    I've been part way down this road before.
    Here is my suggestion:
    Have a mothership built for cruising speed, diesel or turbine but have a second vessel, the sub and simply tow it for underwater use.
    Less weight over-all, lower cost, increased safety factor, and simpler.
    Carry it on the mother ship for transiting or tow it at depth, less drag than towing it on the surface.
    It may prove challenging to flood the sub to the extent of reaching neutral buoyancy.
    One could maintain communications through the tow line / umbilical.
    Just an idea...
     
  7. gonzo
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    gonzo Senior Member

    If you tow the sub, there is not need for it to be powered.
     
  8. Stoyan Ivanov
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    Stoyan Ivanov Junior Member

    Yes you right , passenger and pilot are not in the engine compartment , of course .
     
  9. Stoyan Ivanov
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    Stoyan Ivanov Junior Member

    The concept is - a power boat that can dive not a sub that can be a powerboat . The diesels will work only above the surface , without any snorkel diving .
    Before diving there is of course the slow electric movement on the surface and the same mode under ( 10-40m) with diesels switched off . In this situation I don't see two hot diesels . If I am wrong , pls tell me , maybe cooling needs a certain period of time .
    Most of the time we travel at the surface , 10-20% under .
     
  10. Stoyan Ivanov
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    Stoyan Ivanov Junior Member

    Thanks for the idea , but with regard to better design I would not split it into 2 vessels . Besides , preliminary design is almost ready .
     
  11. Stoyan Ivanov
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    Stoyan Ivanov Junior Member

    Hi Gonzo ,
    My main question was about horse power and displacement and we instead , a bit more focused on the sub movement . In this case I have one question - how do you think :
    Is it possible to use water jets under water ? I would like to use 2 water jets for both diesels on the surface and under the surface , is it possible to use water jets under the surface and if yes how efficient is it ?
     
  12. Stoyan Ivanov
    Joined: Sep 2017
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    Location: Opatija

    Stoyan Ivanov Junior Member

    Hi Magnus ,
    My main question was about horse power and displacement and we instead , a bit more focused on the sub movement . In this case and with regard to your experience I have one question - how do you think :
    Is it possible to use water jets under water ? I would like to use 2 water jets for both diesels on the surface and under the surface , is it possible to use water jets under the surface and if yes how efficient is it ?
     
  13. Stoyan Ivanov
    Joined: Sep 2017
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    Location: Opatija

    Stoyan Ivanov Junior Member

    Hi Yellowjacket ,
    Thanks a lot for your comments , I really highly appreciate them !
    My main question was about horse power , displacement and turbines but we with the other participants a bit moved the subject to the sub movement . In this case I have one question - how do you think :
    Is it possible to use water jets under water as well ? I would like to use 2 water jets ( one for each diesel) on the surface and under the surface for each electric motor as well ( diesel - electric motor - water jet on one axle) . And if it is possible to use water jets under the surface , how efficient is it ?
     
  14. Magnus W
    Joined: Nov 2017
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    Magnus W Senior Member

    I have little to none experience from jets but from what I've heard and read the lose a lot when submerged. Will it work as in move you forward – yes. But a jet is best at high speed so low and below seems like a bad deal.
     

  15. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    "My main question was about horse power , displacement and turbines"

    Probably not, would be my answer.
    You may achieve 20 - 30 knots but there are so many unknown variables.
    The design spiral is very complex, convoluted and has no guess work involved.
    It usually boils down to weight and money.
    Towing the sub would remove the weight of it.
     
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