A catamaran trading vessel?

Discussion in 'Boatbuilding' started by SET Project, Dec 31, 2021.

  1. SET Project
    Joined: Dec 2021
    Posts: 15
    Likes: 4, Points: 3
    Location: USA

    SET Project Junior Member


    I was curious to know if a performant trading catamaran would be a possibility ?

    Now, on one hand I think a monohull will have more effectiveness in performance when it comes to an additional load on board because it doesn't affect the ship as much. On the other, I've researched that a catamaran is a much more stable (providing less heeling degree) and performant vessel when it excludes add on weight, such as bulk goods...

    Let us say that the vessel length is 50 meters and will carry a load of 350 tonnes. Would a catamaran be an effective transport vessel ?

    Thank you,
    SET Project
    Flotation likes this.
  2. TANSL
    Joined: Sep 2011
    Posts: 7,465
    Likes: 736, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    It is impossible to give a reasonable answer to your question if you do not indicate the SOR of the boat, that is, a description as complete as possible of what the boat should do, in what sea conditions, propulsion, speed, autonomy, type of load and position of the same, materials of the hull and the rest of the elements, etc .....
    The differences in the type of hull and its shapes, depending on the SOR, can be enormous.
    Edited: @fallguy my "verbage" has been checked ("it is" instead of "it is not"). Thanks
    Last edited: Dec 31, 2021
    fallguy and bajansailor like this.
  3. bajansailor
    Joined: Oct 2007
    Posts: 3,650
    Likes: 1,594, Points: 113, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    Re a 50 m catamaran, carrying 350 tonnes.
    If we make some very rough assumptions (note, these are very rough!) lets try to calculate how much the cat might sink when loaded with 350 tonnes.
    If say the hulls are 5 m. wide, and have 40 m. of parallel midbody for simplicity (disregarding the effect of the pointy bow), then the immersion would be approx 1.15 m. with 350 tonnes on board.
    And that is quite a lot really.
    Is this going to be a motor cat, or sailing?
  4. fallguy
    Joined: Dec 2016
    Posts: 7,759
    Likes: 1,721, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    @TANSL check your verbage

    not impossible is opposite of not possible

    The issue of a cargo hauling cat is that available displacement is what allows lots of cargo. And catamarans are generally designed to offer needed displacement; not excess. Consider the space between the hulls. There is no displacement beneath them.

    And back at @TANSL. He is correct. For a catamaran cargo vessel might, for example, be designed for fast deliveries. Like the passenger ferries..so the total sor must be known, otherwise threads like this are open ended and prone to polemics and potshots over things like verbage.

    Wait, did I just take a shot at myself?
    Will Gilmore likes this.
  5. Ad Hoc
    Joined: Oct 2008
    Posts: 7,828
    Likes: 1,709, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    Maybe you've started your new year celebrations early?? :D:D:D

    Some hydro's for a cat we did several months ago that is pretty much fits this "impossible" sor...:rolleyes:


    Will Gilmore likes this.
  6. bajansailor
    Joined: Oct 2007
    Posts: 3,650
    Likes: 1,594, Points: 113, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    No, I am still in 2021 and on the coffee rather than anything stronger. :)
    I saw the Sydney harbour fireworks earlier though online, and they were very impressive! My sister lives in Sydney, and she had a grandstand view of the harbour fireworks (albeit at a distance) from her home.

    My calculation was very rough, with assumptions - but your hydrostatics do look much more promising.
    @SET Project you should engage Ad Hoc in some more dialogue here .
  7. fallguy
    Joined: Dec 2016
    Posts: 7,759
    Likes: 1,721, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Is possible = Not impossible
    Not possible = impossible

    I have my own problems. I have a 10mm impossible cup in my wooden tabletop. It may be possible to fix it. But it will be impossible to do it in one day. Possibly more like a week. My left hip is failing and that creates even more impossibilities.

    More seriously, what is the draft of a big vessel like the one that got sideways in the Suez and created that impassable canal?

  8. bajansailor
    Joined: Oct 2007
    Posts: 3,650
    Likes: 1,594, Points: 113, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    I don't think the draft was the main issue for the Ever Given - her reported max draft on Marinetraffic is 11.2 m.
    Ship EVER GIVEN (Container Ship) Registered in Panama - Vessel details, Current position and Voyage information - IMO 9811000, MMSI 353136000, Call Sign H3RC https://www.marinetraffic.com/en/ais/details/ships/shipid:5630138/mmsi:353136000/imo:9811000/vessel:EVER_GIVEN

    Rather, she is simply so long that she got wedged sideways across the canal - I think she is longer than the canal is wide.
  9. Will Gilmore
    Joined: Aug 2017
    Posts: 960
    Likes: 445, Points: 63
    Location: Littleton, nh

    Will Gilmore Senior Member

    How about considering a hybrid cat/monohull/foiler?

    Unloaded, she is a cat with foils between the two keels and, perhaps, short wings on the outside, angled downward slightly. With load, the bridge deck sits in the water to support more cargo weight without gaining too much more draft. The hull could be V'ed on the tunnel side to meet in the middle so additional bouncy goes up as draft is increased. Once underway, the foils would help lift the vessel up to become a catamaran again.
  10. Skyak
    Joined: Jul 2012
    Posts: 1,461
    Likes: 146, Points: 63, Legacy Rep: 152
    Location: United States

    Skyak Senior Member

    When I read this it looks like the question (better stated) is why aren't catamarans commercially viable for shipping?
    -catamarans take too much space in port loading and unloading
    -every dollar spent making bridging structure and the second hull would be better spent adding to length -the return is better for a monohull because the fuel/lb shipped is lower for the longer ship.

    If you use the stability or area of the catamaran to some advantage you might find a reason. Rob is working on micro shipping with a proa -wind power, no major port facilities required....
    I have my own idea for a solar catamaran that delivers giant barges across oceans carbon free.
    Barry, Will Gilmore and Flotation like this.
  11. ExileMoon
    Joined: Oct 2009
    Posts: 68
    Likes: 21, Points: 8, Legacy Rep: 45
    Location: Shanghai

    ExileMoon Junior Member

    The main advantage of a catamaran is that it can have both a slenderness ratio and a high initial stability (the two are contradictory on a monohull) when it has a small displacement, and it has a large deck area.

    But cargo ships are very heavy-displacement ships (because they carry a lot of cargo). Heavy-duty ships do not need high initial stability, because they are already stable enough, and there is no need to add an extra floating body on the side to balance themselves (for example, A proa). The cargo does not need to have a wide view and sunlight like passengers, and there is no need to run around, so there is no need for a large deck area.

    Once the catamaran becomes heavy, its low resistance characteristics will also be lost, and its economic efficiency will become worse. It can only be a light-loaded high-speed ship, not a heavy-loaded low-speed ship.

    Of course, if you want a small-sized high-speed heavy-duty cargo ship, it is not impossible to consider a catamaran (usually A Small Waterplane Area Twin Hull ship). However, the fuel consumption per ton mileage of small-sized cargo ships is very high, and the economy is very poor. Generally only on ships with extremely short voyages and high speed requirements (such as ferries).

    If it is a sailing ship, a small cargo boat can be considered a catamaran, because the sails of a boat require the hull to have greater initial stability. However, a large cargo sailing ship still does not need a catamaran, because the initial stability provided by her hull is enough to meet the needs of the sail.
    bajansailor likes this.

  12. SET Project
    Joined: Dec 2021
    Posts: 15
    Likes: 4, Points: 3
    Location: USA

    SET Project Junior Member

    Hello ExileMoo,

    Thank you for the answer! I had assumed that a catamaran would be efficient in a light loaded high speed ship and not in a heavy load situation.
    However, it is interesting that you point out that a sail catamaran could be considered in as an effective cargo boat... I will do more research!

    Thank you,
    SET Project / Welcome to SET https://www.set-project.com
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.