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

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

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    I am sort of assuming that the waterway might also be conducive to waterjet drive, if a hydrofoil is able to operate without getting tangled up with river debris.
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    I guess there is still some call for "sea-kindliness". if you are encountering substantial wakes of large vessels. But you know the conditions.
     
  3. S V
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    S V Junior Member

    East europe rivers are mostly free of debris, it is not an issue. The bigger issue is of river depth as climate change made it more shallow in the last 20 years. It is not a problem for Danube or Rhein, but for smaller rivers it is, where guaranteed depth of the waterways kept by authorities is in the range of 1.2-1.5meters.

    Most likelly that theoretical boat will be the biggest wake maker. It is not an issue also.
     
  4. S V
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    S V Junior Member

    Now I finally got the point. Thank you!
     
  5. Rumars
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    Rumars Senior Member

    Is this to be a tourist route or a commuter route?
    The reason you don't see much development in fast river craft is because you can't compete with buses. By now most areas where you can sell such a boat have roads, the market is slim. They are only viable if the local conditions don't allow terrestrial transport (river deltas) or as tourist attractions.

    As for the soviet engines don't pound on them to much. They were designed in the 50's, their TBO was absolutley OK at the time. Western engines didn't last longer back then. Todays problems are mostly because of low quality spare parts.
    When you select an engine pay attention to the duty rating, you need "continuous", "heavy", "patrool boat long", etc. I don't know of any marine 1000HP engine with this rating that is lighter then 2000kg.

    The boat might benefit from a material mix, Al for the lower hull and passenger deck, carbon sandwich superstructure.
     
  6. S V
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    S V Junior Member

    This will be mixed: part commuter, part tourist. Emphasis on commuter, for example city center - another city center, city center - some cool resort in island or peninsula and so on. For the boat beeing fast, comfortable and having paint job with lightnings and go-fast stripes certainly will help to sell tickets. The competition is more with the other boats and the mixed transport: bus in the car ferry, bus-passenger ferry-another bus, taxi-suburban train-foot, bus-slow ferry and so on. If the area is developed, like Western Europe, North America the roads are usually over-congested, East Europe on the other hand has many really wide big rivers, with the bridges only every few hundred km, big lakes, lagoons.

    Well... I lived in soviet times a little, so, their technology back then was ok if it was intended for military and some of those which were copied from western tech and/or built with lots of metal (read: heavy). In this case that engine is/was used in military applications, that helps, but being lightweight, soviet and reliable usually does not go in one sentence. The "Raketas" use full power only until take off on wings, that is couple of minutes max, then there is cruise at, wild guess, ~50% or less engine power, as 160L/h fuel at 1000Hp full power is not possible. In such case even "patrol boat short" and other even shorter regime engines may work.

    Mr Efficiency made emphasis on single engine construction, maybe with waterjet, you - on it being built from mixed material.

    Now the question is what type of boat it will be? Hydrofoil assisted cat with big share of weight riding on foils was my first thought, but if we are talking single engine... hmm... that somehow leaves me scratching head.

    Hickmans sea sled? Hickmans sea sled, but in trimaran form??? Air lubricated? Air supported? Super-mega-hyper slender hull catamaran or trimaran?
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    I just feel a hydrofoil cat is better suited to more open waters, and wave encounter, you have the luxury of smooth, or at worst semi-smooth waters, so you can get away with something that is not needing to be sea-kindly, like a beamy low-to-moderate, constant deadrise planing monohull. But, you would need it not to get too heavy, to be a fast boat. Waterjet does start to become as efficient as a prop once the speed gets over 30 knots, and you are drawing minimal water depth. How that would stack up against the hydrofoil is doubtful, the performance figures you gave are quite impressive for a 65 passenger boat. Wetted surface area is what kills speed, and the old hydrofoil keeps that down low. The low deadrise monohull would be the most common solution, which the boat pictured would be, but your speed requirement is a little bit exacting in a scaled-up version. I think those boats have at least two waterjet drives, but the more engines and drives, the less thrust per unit of weight of machinery.
    Jet2.jpg
     
  8. S V
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    S V Junior Member

    Do you have any example of similar sized (50-65passengers) planning low deadrise monohull? The boat in attached picture is 1650Hp, tripple engines...
     
    Last edited: Nov 19, 2020
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    I have a vision of a wide flat runner plank with moderate deadrise either side, something to get some good rise in the water to reduce the wetted area. That plank might be two feet wide or more. The boat would need to be light to work properly. 65 passengers is a challenge, though. You have a long way to travel between refueling, which adds another problem for weight control. That old hydrofoil is hard to go past. You might find a jet mono in your size range on the internet, i have not probed that deeply, but a lesser passenger capacity would be a lot easier.
     
  10. S V
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    S V Junior Member

    Twin City Liner - Wikipedia https://en.wikipedia.org/wiki/Twin_City_Liner

    Twin City Liner 3

    Length : 39.9 meters
    Width : 11 meters
    Height : 5.9 meters
    Draft : 0.8 meters
    Dead weight : 70 tons
    Seats : 250
    Captain's Lounge: 35
    Top speed : 81 km / h
    Cruise speed : 60 km / h
    Power : 4400 hp

    Slender non planing catamaran, draft is very small, speed is comparable to hydrofoil, installed power is ~17.6Hp per passenger, "Raketa" is 1000Hp/58passengers = 17.2Hp

    This kind of ship would benefit from foil assistance?

    The most interresting thing is price: 7 million EUR...
     
  11. S V
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    S V Junior Member

    Wide flat runner plank - is it kinda running pad or part of the multi chine bottom which is very low deadrise?

    As trip distances are pretty big, this type of boat cannot be too small, the other things of commercial operations scale bad if on the smaller side: captain and crew, ticket sales, marketing, waste management, docking/storage fees and so on. Also, there may be things, like debris,"rogue" wake waves which are better in a bit bigger ship. Most importatntly 1 trip with 70-80 seats boat may be more profitable than 2 trips on 40-50.
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    What are the seating arrangements ?
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

  14. S V
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    S V Junior Member

    Nothing specific. 1 deck 3-3 preferable, but it depends. Raketa seating which is 3-3 is ok, maybe a bit more space in the middle, also a bit higher ceiling, maybe 2-2.2m to make passengers confortable to walk around. More legroom than economy airlines is a must.

    Really nice boat. Side walking is no doubt very cool feature, but to make such boat as a cargo platform you have to haul smth very expensive. Also, 1150Hp and only 30kts with 15tons is not very good.
     

  15. Mr Efficiency
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    Mr Efficiency Senior Member

    Just an illustration of a type of large monohull jet boat, I think the first thing you have to decide is how many engines you want, you would think two would be more or less the norm, for redundancy, to avoid the need to be towed home, but the hydrofoil uses one, so really whatever comparison you make, between that hydrofoil and other boats, can only fairly made with a boat that can run on one engine, catamarans of any kind will mandate two. There is no doubt that two engines that give the same speed as (a larger) single engine will get less km/litre.
     
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