The same and/or better efficiency like old soviet hydrofoils ("Raketa")?

Discussion in 'Powerboats' started by S V, Nov 15, 2020.

  1. S V
    Joined: Jan 2019
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    Location: Lithuania

    S V Junior Member

    Hi there,

    Greetings from Lithuania!
    I want to get theoretical-practical discusion about old soviet hydrofoils: there is a ferry route during the summer in our country, where old "Raketa" type hydrofoil is making trips. The route is:
    -250km, mostly river, with the last stretch of ~30km of not so deep lagoon (it has marked waterway)
    -sea state is 0 in the river and no more that 2 in the lagoon, so fully foilbourne at all times
    -1200L of diesel fuel is used for round trip of 500km, most likelly it is not refueled at the half way.
    -The average speed is ~60-63km/h, one way trip is 4 hours.
    -60-65 passengers depending of the layout, in fairly good comfort and legroom.
    -most likelly the ship has the same old ridiculously complex soviet Zvezda M401 V12 1000Hp engine, it is not changed, but not sure about this as there is not much black/blue smoke going from it when it runs.
    -I have no idea what the exact displacement is but according to most of the data online it should be 18 metric tons with fuel and oil, without passengers

    My question is: are there comparable efficiency similar size passenger ferries, which can make the same river trip at 60-65km/h speed while using similar ammounts of fuel? What type of ship we are talking then? Another hydrofoil? SES? Hydrofoil assisted cat? Hovercraft? Are we deeply into composites teritory or still aluminum hull?

    Please, enlighten me... As I dont believe that in year 2020 we are using the 1960s fast ferries. Literally...

    Thanks!
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    2.4 litres per kilometre is not bad for 60-65 passengers, at 60-63 km/hr. I doubt you would significantly improve it in another type of vessel. The hydrofoil assisted cat is an interesting one, you should be able to garner enough info off the internet to get an idea of the fuel use/speed/load ability, but what will ruin it, in my opinion. the need for two engines, and you could say the same about anything using twin engines, there is a penalty in fuel use when using two engines in place of one, where you can use one. Not really practical in any catamaran.
     
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  3. bajansailor
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    bajansailor Marine Surveyor

    That is impressive efficiency for sure - 2.4 litres / km is approx 1 mile / gallon.

    I thought the Teknicraft cats with foils between the hulls were pretty efficient, but the Soviet hydrofoil does seem to be better, relatively.
    I will attach a couple of PDF's re the Teknicraft cat Aialik Voyager, built by All American Marine, saved from the Teknicraft site some years ago.
    These have a passenger capacity of 149, so a bit more than twice the capacity of the Soviet hydrofoil, but the fuel consumption is 4 times as much, and this is at 'only' 29 knots (as opposed to 60 km / 36 knots for the Soviet hydrofoil).
     

    Attached Files:

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  4. S V
    Joined: Jan 2019
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    S V Junior Member

    It is nice, that you have fuel numbers! Thank you!
    I have converted to metric, and it seems 7.19 L/km for Aialik vs 2.4 L/km for Raketa, 150 passengers vs 58 (actual number of seats for that exact ship), it is:
    4.79L/100km per passenger for Aialik at 25kts, 4.13L/100km per passenger for Raketa at ~33-35kts. That is not that much different if not considering the speed.

    Technicraft looks like sturdy seagoing vessel, with brick-like aerodynamics, Raketa is river boat strictly, slender and thin.

    Can anybody have a wild guess, what percentage of weight Teknicraft rides on foil? It looks like it is less than 50%. Raketa is 100% for sure.
    Also - what is the displacement of Aialik? (EDIT: weight of ship!!! Sory, I do not know all the terms exactly)
     
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  5. S V
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    S V Junior Member

    Yep. Too good to be true. I searched the web, and the data about that hydrofoil varies a lot, fuel consumption from 120 to 190L/hour. Engine had 2 modifications, but it is actually the same engine with minor variations. So 150L/h seems possible, but cruising speed is ~30-33knots, 35 is a bit optimistic. That exact ship maybe had some weight reduction during reconstruction, so again - 35kts is possible. From the TV interview of the one of the owner of such boats, he states that ~460km round trip uses no more than 1200L fuel, depending on load can be anywhere from 1000 to 1200L, and the average speed is indeed ~62km/h or even more.

    There are some videos about these ships, and they seem to generate enough wake, not that silent skimming. The propulsion is from fully submerged prop with shaft at ~30 degrees angle, which looks like not optimal comparing to surface piercing props of hydrofoil assisted cats.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

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  7. Mr Efficiency
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    Mr Efficiency Senior Member

    A type of boat that was said to be relatively easily powered, but I doubt would meet the cruise speed requirements, was a tri-hulled boat called a Hydrofield, I am thinking the wetted surface area would be too great for the 30+ knot cruise, but the family of boats was well known to plane and carry loads with less power, and little wake. And a single engine if wanted. Hydrofield.jpg I can't find anything on-line about performance specifics of the one pictured.
     
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  8. Rumars
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    Rumars Senior Member

    It's hard to improve on the Raketa's. You could do an engine swap to a modern diesel and that would reduce fuel consumption vs. the old soviet engine (something between 150-200l for the 500km). Interestingly, a new 1000hp, 24l MAN diesel weighs the same 2200kg as the soviet 67l engine. The big saving would be maintenance, the MAN has a TBO of 18000h vs. 4000h for the Zvezda.
    Making the boat completley out of carbon/foam would lighten it vs the Al, but you need to engineer it for the same lifespan and operating conditions so the weight reduction will not be very high and I doubt carbon would be more profitable over the entire lifespan.
    As for the system itself, we have better foils and controls now, but operating conditions again, a simple foil system that can take the occasional debris is preferable.
    The most profitable thing you can do is to cram more people in the boat, economy class style, no luggage, ultralight seats, no legroom.
     
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  9. baeckmo
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    baeckmo Hydrodynamics

    That's still true, and there are few (if any) competitors even today with comparable shoal water capacity. In the 1980-ies Vosper Hovermarine built the HM 216, 218 and 221 sidewall ACV:s for similar passenger numbers, but they needed over one meter depth on cushion (something closer to 1.8 m off cushion), and were slower with the same power. I think the "Luch" sidewall ACV and the "Zariya" skimmers were close in regard to pax numbers and shoal operation. I travelled on the "Luch" with its waterjet operating in the Danube down in Bulgaria many years ago; it was practically floating on the dew. I think the Alexeyev Design Bureau is now updating some of the rivergoing vessels right now, but apart from that there is not much of new activity in terms of high speed passenger transit vessel development going on anywhere today, as far as I am informed.

    One common misunderstanding about foilers and ACV:s, is that they would not create wave wash. That is not true, they represent a travelling pressure disturbance on the water surface, which transforms to waves on that surface. This causes a substantial resistance "hump" during acceleration just before getting foil-borne for the "Raketa". This is where the engine needs plenty of power with a propeller, and this is where you will see the traditional (=old type fuel injection) diesel having problems with smoke emission. At cruising speed, I think the Raketas Zvezda engine is running at about 65 to 70 % power. If smoking then, it certainly needs an overhaul.

    For a long period of time, there were few engines with the weight/power ratio of the Zvezda's as Rumars noted. And to be correct, the shaft angle of the Raketa is about 13 degrees, not 30 as stated by SV. The propeller is placed very carefully in relation to the vorticity of the rear foils in order to work efficiently in the wash region. The design is old, yes, but Mr Alexeyev knew his hydrodynamics better than most......
     
  10. S V
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    S V Junior Member

    Yep. You are right about the engine. Reality is even worse - you have to literally stockpile spare engines if you want to make any meaningfull use of that ship. I think there is comparable Scania V8 engines, which are a bit lighter with the same Hp or even I6 900Hp.

    Raketas, Voskhods and other hydrofoils were made for long trips, I am not so sure if to cramp passengers will make it much more profitable - the "luxury" part will be missing.

    There seem to be "Nordblitz" and "Rheinjet" hydrofoil assisted cats which were similar in terms of power/performance. Does anyone know their specs and the price they were built?
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    What is your minimum acceptable cruise speed ?
     
  12. S V
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    S V Junior Member

    Straight to the point question!
    It has to be at least 1kmh better than "Raketa", because from the marketing point of view the launch of the slower ship makes little sense. Overall usability and most important long term TCO has to be better or very very similar.
    50-65 passenger ship, daytime rivergoing, capable of 500km range unrefueled, adequate maintenence, for 3-5hour trips one way, comfort level comparable to the Economy+ class of air travel. Max draft 1.0 meter of the most submerged part during run, the less the better. I understand that the comparison of new ship vs the old 40y old russian hydrofoil is a little bit apples to potatoes...

    In the year 2018 I could make a business plan and search for government grants for new routes, but now all the world is locked at home for at least 2 more years, so, this is just theoretical...
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    Well that does restrict your options, 30+ knots is quick for a boat that has 65 passengers. Waterjet drive works well at that speed, and mightily helps meet the draft requirement. You don't need a sea-kindly boat, because it won't encounter rough water. These things might channel your thinking.
     
  14. S V
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    S V Junior Member

    Waterjets and low TCO? What is maintenance and build price comparing to other propulsion types?
     

  15. Mr Efficiency
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    Mr Efficiency Senior Member

    I am thinking along that single engine line of thought, would that be passed for a boat plying for profit ? Certainly makes for a reduction in cost.
     
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