Design for a Cardboard Boat Race

Discussion in 'Boat Design' started by Lt. Holden, Jul 30, 2008.

  1. Lt. Holden
    Joined: Sep 2007
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    Lt. Holden Senior Member

    Hi All!
    The local rock radio station is sponsoring an upcoming "Cardboard Boat Race". This is the link to the rules.
    http://www.rock102.com/extra15.shtml I would be interested to hear any ideas on this.
    My initial thoughts are:

    A sit-on kayak or surfboard style design made up of multiple laminations of cardboard with the center portion cut out of the upper layers to make a seating area for use with a kayak paddle. The edges of the laminated cardboard could be sealed using white glue (exterior if possible) covered by a wide strip of suitable tape (what kind would be best?).

    Also based on my interpretation of the rules, I think internal bubble wrap would be out?

    I weigh 150 lbs. Any suggestions for hull shape, length, beam and thickness?

    As creativity and style may also help determine the winner, any crazy (yet doable) ideas out there? Maybe a recumbent mermaid?

    Come on guys and gals let's get creative!

    Thanks John
     
    Last edited: Jul 30, 2008
  2. gschuld
    Joined: Nov 2007
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    Location: Toms River, NJ

    gschuld Junior Member

    Cardboard boat racing, fun stuff. I have competed before, well sort of. I have volunteered to be the designated boat designer/builder for a friend of mine's kids for the last few years. We had more strict rules though...

    -Only one roll of 3M high adhesive duct tape allowed.
    -Only basic single or double corregated cardboard sheets or boxes allowed. (no hard "cardboard" tubes, etc)
    -Only latex paint can be used and only if used 2" above the waterline at rest in the water.
    -No other material what-so-ever, including paddles (unless they are made of cardboard)
    -No surfboard designs allowed.

    4'x8' sheets of double corregated cardboard are typically available at cardboard supply houses. For kid sized craft, this makes great virgin material. I was able to build a kayak for a (skinny)10yr old girl using two sheets of 4x8 with material to spare. It was roughly 20" at max beam, 7' 10" long with a full deck fore and aft. It was folded to come to a point at max beam(about 60% aft) and tapered straight to a pointy stem and stern from there to minimize joints (as ONLY duck tape could be used to "bond" the boat together) I made a 5ft kayak "paddle" out of a triangle section folded with 6" sides and made duck tape handles so she could hold it without needing to cut into the structure of the triangle section. Overall, it worked very well. The race was to a mooring float and back, about 100 yards in all. She killed the competition... LOL. It wasn't even close. The boat was still floating high and dry after the race was over. The other kids finally swamped it after the race playing around.

    I know 4'x12' sheets of heavier construction double corregated are available, but must be ordered ahead of time, atleast around where I live. I think that you could make a real nice 12' kayak with that material if you want to get that involved. I would be interested in knowing how long the course is going to be and if there is likely to be any wave action. One thing that I learned very quickly is that it is essential that you keep water out of the inside of the boat for as long as possible. Once inside, the water quickly dissolves the boat from the inside. If the water is smooth, a well designed/built boat could go a surprising distance before it breaks down assuming that it is kept dry inside, even without being able to paint the boat.

    As far a tape, duck tape works fairly well, but ONLY the high adhesive variety. Typical hardware store stuff is terrible! I imagine quality fiber reinforced clear 2" commerciel grade packaging tape would be a good choice as well. The allowable glue that can be used would seem to be a typical area for bending the rules. There is all kinds of ways to cheat in this type of deal, but I'm not going to get into it as that is not my kind of thing. I suggest using stiff paper of the same shape as your cardboard sheets to cut and fold to get the idea of how it should go. I tried to make as few exposed joints as possible. I had quite a few kayak oragami models made before I started cutting cardboard sheets. Hope this helps...



    George
     
  3. g.maclaren
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    g.maclaren Retired Expert

  4. PsiPhi
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    PsiPhi Newbie

  5. Guest625101138

    Guest625101138 Previous Member

    If you want to go fast the best boat will be long and slender.

    I would look at a central cylinder about 8ft long and 1ft in diameter with cones of similar length to form the bow and stern. The seam for each would be along the topside to minimise leakage. There would be a circular seam where each cone joins to the cyclinder. This seam would be reinforced inside with cardboard, staples and glue. Outside would be taped over to seal it. You would need to staple in some round and longitudinal bulkheads for stiffening inside.

    There would also be two long slender hulls made for outriggers. These would not be intended to do much other than keep the central hull upright. You simply straddle the main hull using rope stirrups to keep feet from dragging.

    The overall underwater form would not be a lot different to a rowing scull and it should go reasonably well. It is also an inherently strong form that should not take much effort to seal completely. I would use a kayak paddle with aim of keeping it well balanced.

    Rick W.
     
  6. Lt. Holden
    Joined: Sep 2007
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    Lt. Holden Senior Member

    Thanks to all for your well-informed replies. I guess my original idea was bad in that it would have several long edges of the cardboard (although taped) below the waterline. I thought of using the kayak paddle as it on hand and I thought it would be simpler than trying to fabricate oarlocks that would be sturdy enough to last.

    Rick, I like your idea of the central cylinder with (2) (conical?) ends, how long? So I would sit atop the central tube facing forward with my feet held above the water in rope stirrups?

    How would you fashion the conical ends to keep them watertight and how would I gain access to the inside of the main tube to fasten the ends to it?

    I like the idea of the outriggers for stability but how far apart would they need to be to allow clearance for the paddle? Also would you use laminated solid or hollow triangular beams to support them? One of my main concerns would be how to fasten it together; staples wouldn't be much good unless I had access to the back side to clench them. Is Tite-Bond III water-based so as to be legal?
     
  7. g.maclaren
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    g.maclaren Retired Expert

    Kiss

    Not to beat a dead horse, but my solution many years ago exposed no
    cardboard (actually "paperboard" to those in the trade -- cardboard is
    another material altogether, really) to the water.
    (Once that corrugated gets wet, it fails. You sink.)
    I used no glue, no tape, no paint.
    The paddles were also made of corrugated and failed
    to keep their crisp shape, but added plenty
    of needed area/drag to my hands.
    The folded-in sides and ends held the boat firmly together.
    My boat floated much longer (10 x longer) than any other
    boat in the contest.
    Before the competition, I wrapped my prototypes in
    plastic sheet to get the right sizes -- and practiced
    racing. Not one other boat had been tested in the water
    prior to the competition. All the pretty ones sank!
    Have fun, KISS and win!

    : -)

    www.grantmaclaren.com/cardboard
     

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  8. g.maclaren
    Joined: Jul 2008
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    g.maclaren Retired Expert

    John,
    Had another thought.
    Why not make a bunch to my design, take them
    to the race and sell them to people who want
    to race?

    Print "ROCK 102" on them, and maybe the station
    would buy a bunch of 'em.

    : -)

    -=Grant=-
     
  9. BHOFM
    Joined: Jun 2008
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    BHOFM Senior Member

    The one I saw that worked well was made ffrom four
    18x18 Uhaul boxes with pointed bow and stern added.

    They where tapped in a row with the center partly removed
    for the passenger! The end two were closed for floation!

    They also used a kayak style paddle. I think it was just
    four or so layers of cardboard wrapped with tape!

    I thought something like a cardboard oven mitt might
    do well?
     

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  10. Guest625101138

    Guest625101138 Previous Member

    My take on the rules is that you can only tape joins so your idea of taping the whole underwater section would not be permitted.

    The cones come to a point so would just be taped at the tip.

    The proposed boat is 3 X 8ft ; ends up 24 feet long. With a 24ft boat you can place outriggers well away from any area to paddle. That said it would make sense to form a tubular cross beam of say 6" X 12" that would double as a seat. The outriggers are just end-to-end cones formed up similarly to the main hull but only 6" in diameter and each 2 X 4ft long cones. These are tied and taped to the cross beam. They should just sit on the top of the water. The cross beam is say 7ft long with the outriggers on the ends. This will give plenty of space for paddling.

    You need to experiment at a smaller scale if you cannot work out how to assemble it. You would make round bulkheads about 16" in diameter and cut 2" radial slots at say 2" intervals around the circumference these will be folded at 90 degrees to the bulkhead, consecutive ones in the opposite direction, to form gluing tabs. You have similarly tabbed longitudinal bulkheads that connect between the round ones and also onto the outer skin of the hull.

    First step is to make up this internal frame of bulkheads. Round bulkheads at 2ft intervals in the central part and only 2 round bulkheads in either end. There is a single vertical bulkhead connecting between each round one. So this series of bulkheads make up a frame that has folded gluing tabs to bond to the skin.

    The central skinning is done first from the bottom up. You can use the tape to hold the tabs in place until the glue sets. Once you have glued the bottom half let the glue set and then do the top half in one go. Overlap the longitudinal seam in the skin and glue. You now do the same process with the ends. The cones should be flush to the cylinder and bonded all the way around to the joining strip. You may need to feather the ends of the joining strip with "V" notches say every 2" so it will take the conical shape as the cone is pulled up into shape.

    If the cardboard wants to crease then place gentle longitudinal creases at about 2" spacing rather than letting it crease uncontrollably. It will be better to form the cylinder in its preferred direction of folding but with the cones you will have to work a little across the corrugations.

    It really is better to make say a 4ft model out of light cardboard to understand the detail.

    This main hull will be good for about 100kg. If the total weight is going to be more than this then make the diameter a little larger.

    THis boat will be fully sealed internally so should not get wet inside until the outside gives up. If it is well painted it will last a long time.

    Just because it is cardboard does not mean it cannot be well made and perform as good as a paddled rowing scull. The only issue will be durability. If it is done right and fully sealed it should be OK for a few years with the occasional recoat.

    Rick W
     
  11. Lt. Holden
    Joined: Sep 2007
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    Lt. Holden Senior Member

    Thanks to all for your input. Rick, could you do a quick sketch to demonstrate the relationship of the parts with the tabs? I think we are on the right track here as far as design goes. But in order to win the overall prize I need to get creative with the above waterline shape and graphics. Tomorrow I will look for cardboard and contact ROCK 102 and the local Miller Distributor for decals or stickers. Any input from the artistically gifted would be a great help.

    Thanks again,

    John
    P.S. Has anyone guessed wher my 'alias' "Lt. Holden" comes from?
     
  12. Guest625101138

    Guest625101138 Previous Member

    The seat will ned to be away from the cross-brace to allow full strokes.

    Rick W
     

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  13. BHOFM
    Joined: Jun 2008
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    BHOFM Senior Member

    get creative with the above waterline shape and graphics

    OK OK,, It's a space ship,, UFO,, unidentified Floating Object!
     

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  14. Guest625101138

    Guest625101138 Previous Member

    The attached shows a cylinder and cone hull made from aluminium. I always thought it would look good with a shark mouth painted around the flared bow and where it meets the front cone.

    A tail and dorsal fin behind the paddler might complete the picture as riding a menacing looking shark. In fact the rudder could have a top and bottom. A rudder steered by the feet using rope would be more effective than trying to steer it with a paddle. Hope it is not a slalom because the long boat will want to go straight.

    Rick W.
     

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  15. gschuld
    Joined: Nov 2007
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    gschuld Junior Member

    Rick,

    I like your design concept. It sounds like a straight line speed demon. The reason why I asked about the length of the course is an important one. For my local cardboard boat race, it became apparent that most of the boats entered were not capable of floating for long. The course was way shorter than I expected it to be the first year, I'm talking 100ft and back. Still most did not finish. If, for example, the race was only 100ft to round a float and back, the ability to turn quicky becomes a very important factor. The longer the race, the more the longer waterline pays off.

    It would be handy to know if there are other people interested in taking the event seriously. If the only people that enter are there for a temporarily floating carnival show, the event may be less than satisfying.
     
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