African Cat - Another Hybrid....

Discussion in 'Boat Design' started by Mat-C, Oct 7, 2010.

  1. Mat-C
    Joined: May 2007
    Posts: 255
    Likes: 12, Points: 0, Legacy Rep: 141
    Location: Australia

    Mat-C Senior Member

    Came across this cat being built by African Cats..
    Quite a lot of unusual features - for me at least. The most obvious being the apparent use of the Axe-Bow hull shape....
    Then there's the laminates...
    Basalt is a rock where I come from....:confused:

    And then, of course, the must have hybrid propulsion system...

    Is my maths off, or can you really run 2 x 18kW motors with one 23 kW generator?
     

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  2. steff
    Joined: Apr 2010
    Posts: 7
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    Location: Tunisia

    steff Junior Member

    Basalt fibres

    Hi Mat-C,

    they are more knowledgeable design people on the forum to answer you question on the hull shape, then me, just wanted to say the designer Lavranos is not a newcomer and so there might be some good reasons behind it.
    On the basalt fibres - you are right is a stone, if I recall correctly the Russians ran a development program for it, but it never took off commercially, however it is a real substitute to E-Glass - here a quote:

    Basalt roving 2400 tex

    As a basic material, basalt is a black, alkaline extrusive rock.

    Properties:
    With only 5 % higher density than the conventional E glass fibre, basalt fibre offers in comparison with it a 15 % higher tensile strength, higher compressive strength and rigidity (modulus of elasticity). The thermal stability is extremely high, the fibres themselves only begin to melt at 1450 °C. The chemical endurance, especially against strong acids, lyes and solvents, is very good.

    Application:
    Applications, which, with regard to rigidity and strength, fall between E glass and HT carbon fibre, e.g. spars, force transfer points, wound components, profiles etc. in automotive engineering, the construction of sports equipment, model making, aviation industry and production of receptacles. Suitable for epoxy, vinyl ester and polyester resins.

    Technical data:

    Basalt fibre
    Density: 2.75 g/cm³
    Tensile strength: 4840 MPa
    Compressive strength: 3792 MPa
    Modulus of elasticity: 89000 MPa
    Elongation at break: 3.15 %

    E-glass fibre
    Density: 2.6 g/cm³
    Tensile strength: 3450 MPa
    Compressive strength: 3033 MPa
    Modulus of elasticity: 77000 MPa
    Elongation at break: 4.7o %

    Now to your question on hybrid propulsion - no your maths is right - this set up works only for recharge or medium usage of the e-motors, however there will be a battery buffer bank in between, to cover the peaks. It may very well be that the cat performs well under motors with only half the rated kw is used and it also depends which system, in terms of voltage is used, to achieve a high overall efficiency.
    Hope this clarified your findings a little...

    Regards, Steff
     
  3. apex1

    apex1 Guest

    One at a time, of course (or better: off course as the whole hype).:D

    Basalt fibre is common stock since ages.

    Regards
    Richard
     

  4. TeddyDiver
    Joined: Dec 2007
    Posts: 2,570
    Likes: 119, Points: 73, Legacy Rep: 1650
    Location: Finland/Norway

    TeddyDiver Gollywobbler

    Some info from another source

    Tensile Strength E- Modulus
    Basalt 2418 MPA 85 GPA
    E-glass 1800 MPA 72 GPA
    S-glass 2556 MPA 89 GPA
     
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