Home > Watercraft > Quadramaran


A multi-hulled boat, my first marine vessel. Features simple propulsion system with two independent motors. Β 


Completion date: 24/05/2011
Power: electric (Power Functions)
Dimensions: length 61 studs / width 28 studs / height 30 studs (from the propellers’ lowest blades to the top of IR receiver)
Weight: 0.871 kg
Suspension: none
Propulsion: 2 x PF Medium motor
Motors: 2 x PF Medium

The idea for this construction first came in 2010, and it started with a catamaran, that is a boat with two hulls. As the displacement of the Lego catamaran hulls turned out rather small (roughly 230 grams per hull), the project turned into a trimaran (three hulls) and then a quadramaran (four hulls) as more hulls were added. I suppose that the next step is something like a pentagramaran, with ability to float on liquid sulphur and fire black cats, but I was happy with four hulls giving a total displacement of 920 grams.

The hulls are composed of two parts, lower and upper one. Their disadvantage is that if a hull is submerged too Β deep, or tilted, water can come in through the connection between the parts and the hull drowns in an instant. As I decided not to modify the hulls in any way (I have considered gluing them solid or sealing them with a wrapping film), it was my assumption that the weight of the vessel should be kept as low as possible to reduce the risk of sinking. Taking the risk of sinking into account, I have used the cheapest motors I had, as well as a regular battery box with regular batteries. The construction is therefore very simple – there are two independent PF Medium motors geared up 1:2.7, driving two 4-bladed propellers made of two 9-studs long Lego propellers each. I assumed it will be more efficient to use a small gear acceleration and 4-bladed propellers than to use large gear acceleration and 2-bladed propellers, as high gear acceleration is always inefficient. I have also given up any ideas for a rudder system, as such a system would be more complex, less robust, and would require the power of at least one motor to be used only for steering. With two independent propulsion motors, the vessel can be steered like a tank and both motors can be used to propel it.

Initial tests have shown the vessel to be relatively fast and very responsive to steering. The steering was so accurate that I was able to make a 360 degree turn perfectly in place with it. The vessel was tested on a small lake and performed above expectations, despite the presence of small waves and some algae that kept tangling into propellers when the vessel was too close to the bank. As it was easy to loose the IR link outdoors, I have used the PF speed dial remote to control it, because it makes the IR receiver maintain the last command if the link is lost. Thanks to that, it was possible to make the vessel take wide turns, going away from the bank and then back close to it. Eventually, as the vessel showed no tendency to sink, I mounted a camera on it. The result was fairly good, and I only regret that there was no space to put the camera back far enough to get the vessel’s twin bows in view.

There was one advantage of the vessel not being built earlier – I was able to film it with my recently bought telephoto lens. Looking how the video turned out, I should have used a polarizing filter though.


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  1. nicolas
    August 1st, 2012 at 08:41 | #1

    thank you very much, sorry I had not read the whole description

  2. Sariel
    July 31st, 2012 at 21:19 | #2

    It’s in the description, but for you I will past it here again: http://www.bricklink.com/catalogItem.asp?P=2952

  3. nicolas
    July 31st, 2012 at 20:53 | #3

    where did you find the propeller and what is the reference

  4. Sariel
    November 7th, 2011 at 08:25 | #4


  5. Kshomiv
    November 7th, 2011 at 00:39 | #5

    Could the propulsion and steering systems be build around a turntable, with a motor rotating the turntable for steering?

  6. Sariel
    October 21st, 2011 at 08:41 | #6

    That’s why I put link in the description, but for you I’ll put it here again: http://www.bricklink.com/catalogItem.asp?P=50821c01

  7. tyler
    October 21st, 2011 at 02:42 | #7

    hey sariel where did u get those floating pieces cuz i cant find those ones one lego.com any more

  8. shawn
    July 21st, 2011 at 22:14 | #8

    I like this one better then your trimaran.

  9. Sariel
    June 16th, 2011 at 12:25 | #9

    I did, and they were terribly inefficient.

  10. June 16th, 2011 at 11:38 | #10

    Cool boat !
    About propellers, have vou tried with the small 3 bladed ones ? Their angle of attack is much higher than the large ones you used, which I find quite ineffective (probably because of the oval-shaped cross section of the blades) . Plus, the small ones can be ducted, which will help increase their efficiency.

  11. technikfreak
    June 2nd, 2011 at 15:59 | #11

    i have to say REALLY GOOD WORK πŸ˜‰

  12. Kathryn Brown
    May 31st, 2011 at 03:56 | #12

    Hi, this is so cool I just know youre going to build a bigger one I’ll keep watching of course.

  13. Mike
    May 31st, 2011 at 00:41 | #13

    Bricklinklink? Link? of Bricklink? πŸ˜€
    as I see it’s (the hull) not particularly expensive, a few Euros for one… so basically one can buy a lot of them and build more complex vessels.
    Question: have you thought about making a boat that isn’t powered by propellers under water? I mean, these propellers used as air propellers, geared up pretty good, maybe with a rudder behind ’em moved by a micromotor. Like those swamp boats.
    Maybe it would be faster. Maybe not.. these propellers could be small for that. HAH… ther’s alot of space for experimenting! πŸ™‚

  14. Sariel
    May 31st, 2011 at 00:10 | #14

    Catamaran set. Check the Bricklink link.

  15. Mike
    May 30th, 2011 at 22:35 | #15

    I bet πŸ˜€ they have a speedboat shape to them. I guess they were from some speedboat set originally…

  16. Sariel
    May 30th, 2011 at 20:49 | #16

    I have some bigger hulls already. But I like how these from Quadramaran are shaped.

  17. kshomiv
    May 30th, 2011 at 20:35 | #17

    Now all you have to do is design a truck and trailer to haul it! Very good job! A great build! πŸ˜€

  18. Mike
    May 30th, 2011 at 20:21 | #18

    the hull is the critical point… if it wasn’t, sure a half meter long steamer with side propulsion would be nice πŸ˜€
    I have the old set for the police motor boat, with the black hull with white insides. If I had three more of that and the pf stuff, an interesting quadramaran could be built.. πŸ™‚
    Are you planning to carry the boat theme as far as to buy some hulls, bigger ones from boat sets?

  19. Bullet for my Valentine
    May 30th, 2011 at 14:23 | #19

    Very cool boat. I tried to built a rc lego boat, but its decreased (Rip all Rc parts πŸ™ ). At next can you make a rc lego titanic ? πŸ˜€
    Sry, if google translator is bad πŸ˜‰

  20. Sariel
    May 30th, 2011 at 13:32 | #20

    You know, I provided link to Bricklink for this hull in the description.

  21. Mike
    May 30th, 2011 at 13:02 | #21

    Very simple, very good. Nice job! Let’s see some more boats later on πŸ˜€

  22. panos
    May 30th, 2011 at 12:57 | #22

    The hull…is it made by regular bricks or it is on solid piece?

  23. May 30th, 2011 at 12:44 | #23

    Hey Paul – very good filming skills ! You know have to add value to your models with that. Very good movie.

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