Thoughts on this hull design - what seas and speeds etc.?

Discussion in 'Boat Design' started by RSD, May 5, 2024.

  1. RSD
    Joined: Nov 2022
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    Location: Red Sea, Egypt

    RSD Junior Member

    My quest for a fast stable boat to take recreational divers out has been on hold for a while due to life getting in the way, but I came across this vessel and would appreciate everyone's thoughts on what height seas etc it would be able to do various speeds at. From what I have gathered it is 15 metres / 50 feet long, I don't know the beam yet unfortunately, but it has diesel inboards powering propellers and does 25 knots at full speed. What are people's thoughts about how it would handle say 1 metre waves at what speed, 1.5 metres waves at ? speed, 2 metre waves etc? The waves in the Red Sea tend to fairly short interval - around 4s.
    [​IMG]
    upload_2024-5-5_16-13-0.png

    Any and all thoughts would be appreciated.
     
  2. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    It is not easy to know how a boat sails just by looking at photographs. What I can tell you is that a boat for divers needs a platform that is as wide as possible, and close to the flotation, to transport the diving equipment and for the divers to attach the equipment and jump into the water, or get out of it. The ship's freeboard should be as small as possible, within the permitted limits. That doesn't seem to be a feature of this boat.
     
  3. RSD
    Joined: Nov 2022
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    Location: Red Sea, Egypt

    RSD Junior Member

    Sorry I should have added that if the design is suitable then will be adding a largish platform on the stern that raises up and down on rails - this boat is for technical diving which means the divers are carrying closed circuit rebreathers, several extra cylinders of breathing gases etc - they need the platform to get them out of the water.
     
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  4. mc_rash
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    Location: Netherlands

    mc_rash Senior Member

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  5. RSD
    Joined: Nov 2022
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    Location: Red Sea, Egypt

    RSD Junior Member

  6. mc_rash
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    Location: Netherlands

    mc_rash Senior Member

    I do not know more than stated on their website, sorry!
     
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  7. RSD
    Joined: Nov 2022
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    Location: Red Sea, Egypt

    RSD Junior Member

    Cheers! Will have to contact them!
    Looks like the props and rudders are fairly well tucked up out of the way which is always a damn good thing in the Red Sea!
    upload_2024-5-5_19-42-34.png
     
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  8. BMcF
    Joined: Mar 2007
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    BMcF Senior Member

    Only basing this on years of experience testing fast catamarans and not any direct knowledge of this particular vessel, but....I wouldn't expect that hull would manage even 1-meter HS waves without difficulty. It appears to be suitable for calm-water taxi service.
     
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  9. RSD
    Joined: Nov 2022
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    Location: Red Sea, Egypt

    RSD Junior Member

    Ah OK - we might skip that one then! If that's the case they might be having some really ugly times with it - I've just found out that it is in service as an inter-island ferry and sightseeing vessel in the Comoro Islands several hundred miles off the east coast of Africa - so pretty open ocean!
     
  10. kapnD
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    kapnD Senior Member

    That was might thought as well, based on the information provided.
    First impression - top-heavy.
     
  11. Ad Hoc
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    Ad Hoc Naval Architect

    Agreed.
    Also its LD ratio is low, so would squat lots as she approaches hump speed, and in a heavy chop, would not be pleasant at all.
     
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  12. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Apologies for the thread drift, but I found it 'interesting' how the Grandsea folk appear to have acquired this fishing cat design from MacDuff Shipyard in Scotland -
    12.40m Aquaculture Catamaran - Lonabrak - Macduff Ship Design https://www.macduffshipdesign.com/ship-design/lonabrak/

    Or maybe they have copied it - here is the Grandsea version :
    18.5m Aluminum Catamaran Work And Utility Boat for Sale - Buy cat https://www.grandseaboat.com/products/work_boats/18_5m_aluminum_catamaran_work_and_utility_boat_for_sale.html

    The Grandsea vessel is apparently 6 metres longer, but they post a photo of the 12.4 metre MacDuff vessel......
     
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  13. RSD
    Joined: Nov 2022
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    Location: Red Sea, Egypt

    RSD Junior Member

    ...and the cabin somehow fits a lot more seats into it!

    I learnt recently that when you see CE in advertisements for Chinese things it doesn't mean that it has European approvals - cleverly they have decided that CE also stands for "China Export"
     
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  14. RSD
    Joined: Nov 2022
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    Location: Red Sea, Egypt

    RSD Junior Member

    The problem with any vessel that is ever advertised is that they only ever show photos and videos of it on glassy smooth seas - never how it rides in anything else.
     

  15. C. Dog
    Joined: May 2022
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    Location: Coffs Harbour NSW Australia

    C. Dog Senior Member

    So it appears Grandsea isn't so grand at sea after all?
     
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