'Unusual' Brand New Shannon Class lifeboat design. .

Discussion in 'Boat Design' started by rustybarge, Apr 1, 2014.

  1. rustybarge
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    rustybarge Cheetah 25' Powercat.

    ####Home build ? Seems very ambitious ! Perhaps a little downsizing to meet your finances ? I would imagine the fuel bill is daunting, the boat is likely built like a brick outhouse, and with jets probably not the most economical alternative. I think the people inside are supposed to break before the boat does.######


    The original twin engine design has 2'6" draught.
    I was thinking that a weight saving with just one engine would save 1 ton.
    Hamilton jet drives are horrendously expensive, so i was thinking of shaft drive in a propeller tunnel, so should be able to get in at about the same draught or slightly more, and this would mean a more efficient drive at displ. speeds where jets don't operate very well.

    Obviously the propeller will hang down below the tunnel, but the weight saving will probably compensate for this.

    Dutch sailing barges use steel 'planks' to create compound curves; maybe this would be possible in the bow section?
     
  2. rustybarge
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    rustybarge Cheetah 25' Powercat.


    Now that's what I call prop tunnels!!!
    On the east coast of England nearly all the boats have bilge keels for that very reason, when the tide goes out they stay upright on the drying ground.
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    No bilge keels here:

    https://www.youtube.com/watch?v=eCoYeAgui6E

    Presumably a vessel of the same genre, but much broader in the shoulders. Maybe the self-righting would be less likely to be needed, than the other boat.
     
  4. rustybarge
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    rustybarge Cheetah 25' Powercat.

    Nearly identical hull form, without the keels.....I'm getting a bit confused.:confused:
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Not really that similar, the 'watercat' is much fuller in the bows, would probably give the crew a bit of a hiding in the rough, though.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    These are pretty beamy boats, and probably not that suitable for running at "transition" speeds, economy-wise.
     
  7. rustybarge
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    rustybarge Cheetah 25' Powercat.

    Just as an example of a steel boat, very obviously not a similar design,this design is being built on the MBM forum, stretched to 50' with twin 600hp cummins at less than 20 tons. http://www.ybw.com/forums/showthread.php?374141-Fifty-Feet-of-Grey-(steel)

    The 45' version with single engine should come in at about 17 tons.[guess]

    57,000 euro's for complete hull and superstructure....http://www.bonitoboats.eu/en/product/Bonito-46-FO-2.html

    So steel might just get in at the correct displ.
    Fantastic value.:)
     
  8. rustybarge
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    rustybarge Cheetah 25' Powercat.

  9. AdvEndureDesign
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    AdvEndureDesign Junior Member

    This exactly. Not an afterthought, I'm sure.

    Again, easy to see why the Safehaven design was rejected.

    The Watercat 1500 Patrol III was designed as a new boat for the Finnish Lifeboat Institution. Different conditions call for a different boat. Base design was the Watercat 1500 Patrol shown in the video.
     
  10. rustybarge
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    rustybarge Cheetah 25' Powercat.

    I'm sure your'e right, the Baltic is a much more protected sea but can get pretty rough too.

    I think the Shannon should be called a semi~planing hull, half semi~displ at the bow and with the bilge keels, and half classic planing vee at the aft and mid sections.

    It will revolutionise hull design.

    Re the cost of the RNLI build:.
    Jet space
    £206,000
    Engine room
    £389,000
    Tank space
    £118,000
    Survivors space
    £263,000
    Fore store
    £100,000
    Forepeak
    £74,000

    Page 26: http://www.berthon.co.uk/publications/BerthonVII_LifestyleMagazine.pdf

    Told you those Hamilton jets were expensive.....where did I leave my lottery ticket?
     
  11. jonr
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    jonr Senior Member

    The Shannon looks great. The catamaran in the first video looks scary when it sticks the bow into a wave.
     
  12. The Loftsman
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    The Loftsman The Loftsman

    Another good reason why everyone with the least bit of interest in ships, boats or the sea should contribute what they can to an organisation which has been saving lives at sea for many, many years and all voluntary as well when that flare goes up the guys drop whatever they are doing and head for the boat no matter what the weather or the time of day or night.
    Big thank you to the R.N.L.I.

    Cheers
     
  13. rustybarge
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    rustybarge Cheetah 25' Powercat.

    ...but they are the vessel of choice for commercial operators on offshore wind farms, summer and winter 365 days a year; and actual practical experience on the sea must be worth something in the end rather than a concept on a NA's drafting board.
     
  14. rustybarge
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    rustybarge Cheetah 25' Powercat.

    ...and they don't even get paid for it.
     

  15. Mr Efficiency
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    Mr Efficiency Senior Member

    These rescue boats don't seem to me to be a good template for a pleasure craft, especially if you intend to potter around at 8 knots most of the time. At that speed they are much less efficient than a boat purpose-designed to run at that speed. You will pay through the nose for the ability to 'dash' home at 17 or 18 knots when the weather turns. The aim of these boats is extra speed to get to the trouble more quickly than the traditional lifeboats, and to do so without bashing the occupants senseless. They are designed for conditions where prudent pleasure boaters are not on the water. I'd be looking elsewhere for inspiration, possibly at small pilot boat designs, where a turn of pace and good sea keeping are both required.
     
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