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Wave-Piercer Cats

Discussion in 'Technical Discussion' started by catmando, Apr 7, 2005.

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  1. catmando

    catmando Senior Member

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    Saw the last 30 minutes of this show on Discovery channel tonight on the Bay of Fundy wave piercer cat. I'll try to stay up for the next showing, but if not I hope they'll show it again this week.

    Didn't see the specs, but it had twin jet drives in each sponson, so four engines and at least 300' in length maybe? Anybody familiar with this craft? Also comes in military trim. I think I saw one in Washington, DC last October during a family reunion.

    There is also one that runs Miami-Key West, right Carl? I know at least two cat ferries make the Ft. Myers/KW run because I tried to get a job on them but they didn't hire me. :(
  2. catmando

    catmando Senior Member

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    The Cat is 91m LOA, 26m beam, 300T weight. InCat of Tasmania is the builder/designer. Four diesel motors and four Lipps waterjets. For 3 meter seas and above there is a huge stabilizing hydrofoil that drops down between the hulls.

    Its cruise speed is 90kph.
    Last edited: Apr 7, 2005
  3. catmando

    catmando Senior Member

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    I think this design would adapt very well to personal yachts. Shorter and not so much beam so it can use pleasure boat docks, and the tab/hydrofoil system in place, a pleasure boat of this type will be extremely fast and efficient.

    Somebody will build it for sure.
  4. YachtForums

    YachtForums Administrator

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    Agreed Catman. Good topic...

    The foil-assisted, catamaran hybrid has merit and I'm certain it will be adopted by more manufacturers in the future. The benefits are many... reduced resistance, which results in reduced fuel consumption. This would ultimately increase range.

    Although a straddling foil would lend itself to greater efficiency at planing speeds, they add a small amount of drag at displacement speeds. However, this would be negligable at best. There is one drawback that comes to mind. Foils have a tendency to catch debris and this can effect performance.

    Cat hulls typically produce a smoother ride and a foil equipped hull should enhance this, as well as its ability to carry a greater load. Actually, sponson shapes could be optimized to further enhance ride quality. For example...

    A combination of symmetrical and A-symmetrical hull form shapes could be blended to achieve this. Symmetrical bow-sections aid in directional stability, especially in short swell and following sea conditions, but A-symmetrical aft sections offer a smoother ride and reduced wetted surface (at planing speeds). The combo should increase the ride quality and directional stability.

    As the sponsons taper toward the rear, from symmetrical to A-symmetrical, the vertical inside shape of the aft-sponsons would reduce the planing area, thereby reducing the vertical acceleration forces. As with any cat, water is broken up into spray while being deflected from the hull. This mixes with air passing through the tunnel (between the sponsons) and creates a high-density medium, which results in a dampening effect. Ofcourse, with sufficent speed this becomes more of an air dampening effect as tunnel pressures increase.

    I had done some theoretical work on this concept a number of years ago, but nothing that we pursued at the time. Still... it's interesting and I'm sure it's worthy of further development.
  5. YachtForums

    YachtForums Administrator

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    For reference purposes, I've included an image on this topic. Although the cross members of the trailer blend with the foil, if you look closely... you will see a forward-swept foil with mid-beam support strut.

    Attached Files:

  6. catmando

    catmando Senior Member

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    Carl great post explaining the concept. :) Maybe you could get Lars to work something up, or post your drawings? Also do you have more pics of that hydrofoil cat on the trailer?
  7. CTdave

    CTdave Senior Member

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    Ummm, yeah! Carl took the words right out of my mouth :rolleyes:
  8. YachtForums

    YachtForums Administrator

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    ... I need to get a life. ;)
  9. brian eiland

    brian eiland Senior Member

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  10. catmando

    catmando Senior Member

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    Thanks for those links Brian, very interesting reading. I wonder how the foils would work on our big offshore cats-Skater, Nor-Tech, Ocean Express etc.? My boat of choice would be the 64' Prout Panther with the new 1500hp MTUs. With that power it should run 55 knots at least.
  11. YachtForums

    YachtForums Administrator

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    I was researching power-cats and came across atleast one yacht builder who has adpapted the Husycat system. These are pics of the 61' Prout Panther...

    The exterior fore-aft shots are for reference, but the other two shots show the mid-ship foil and the stern foils, located on the inside of the sponsons. Cruising speed is 32 knots, fairly impressive for a 61' yacht. But most of this speed can be attributed to A-symmetrical sponsons... and 1150 horsepower. ;)

    I saw the Panther close-up at Bahia Mar one day, but never went onboard. The quality of workmanship looked good from the outside. Mabe one of our members can further expand on this boat for us.

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  12. catmando

    catmando Senior Member

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  13. TRY

    TRY Senior Member

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    Foils to the cat!

    The man behind the fixed foils for fast catamaran vessels is Prof Hoppe from the Stellenbosch University in South Africa.
    Commercially you need to contact Gary Vos of Hydrospeed on gvos@iafrica.com.

    The beauty of a cat hulled vessel (apart from many others) is the flexibility towards speed.
    Due to the extreme slimness of the hulls (1/20 in many good designs) allows for variable speed options related to installed power, which is not possible with monohull hulls where you have to make a choice from the outset (displacement or planing).
    Referring to the TRY 100 by Lars Modin for our large cat project, speeds of 15 kts cruising will be obtained with quite modest power units.
    Increasing the power would allow to increase speed to say 25 kts; at these speeds the foils become an interesting option.

    Relative to the Kingcat: I made the contact between the Kingcat owners and Gary Vos which led to the installation of foils with great success.
  14. YachtForums

    YachtForums Administrator

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    Here's a company going into production on a foil-based cat...

    The “AEROYACHT CHALLENGER “, built by Blubay is a 45’ power catamaran that is proposed to travel at over 40 knots through rough water. With twin 440HP engines, it is expected to exceed 55 knots and a range of over 1500 nautical miles.

    Nice renderings... :)

    Attached Files:

  15. TRY

    TRY Senior Member

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  16. TRY

    TRY Senior Member

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  17. YachtForums

    YachtForums Administrator

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    I looked at BluBay many months ago. They had some intriguing new designs and it's great they are moving forward with production. If their website is any reflection of their quality and attention to detail... the boats should be outstanding. Looking forward to their development...

    Thanks for the links Luc! Enjoy your summer. :)
  18. catmando

    catmando Senior Member

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    The TC45 is stunningly beautiful! Outstanding use of interior volume. How many cats have a stateroom full across the bows?! :eek: Too bad they didn't show the helm.

    The foils bring it up on plane quickly too, which saves fuel and wear on the engines. I think with Yanmar 480s and Arneson ASD8s it will run 60 knots.
  19. YachtForums

    YachtForums Administrator

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    An example of how much lift these foils can develop... this is the Stealth Cat using the Hysucat system, running at top speed. Not much hull in the water!

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