National Ship Design Competition. Need Help

[HaveANiceDay]

Hello everybody!

I'm a student in Norwegian College and myself and my group are participating in the national boat design competition. The three main things which are going to be evaluated are speed, stability and design. So I'm really confused what type of ship would be best in my situation, as I'm quite inexperienced when it comes to ships technology. I'm going to shortly explain the rules of competition:

• The model should be made in scale 1:100 of 90m long ship(total length), so it shouldn't be longer than 90cm.

• The boat should be made out of polystyrene.

• Model should be designed with a hull.

• It should transport a load of a total 3 kg water, spread into 6 juice boxes. The boxes should be placed on the deck and simulate containers on the real ship. The deck should be above the waterline.

• It should be equipped with 3 kg ballast, in form of a metal plate on the hull bottom.

• Powered by an electric battery, engine and propeller.

Testing of the designed boat:

• Speed test : Sailing distance is 2 x 50 meters. Up to 50 and back.

• Stability test: The models will be tested for the amount of roll that occurs at a given load displacement. The offset will be defined by the load center is 5 cm on the starboard or port side.

• Design: Design and creativity of the boat.

I was thinking about some kind of catamaran ferry design. It would probably be stable and fast enough. But I really need your advice guys. What kind of ship would be stable and at the same time fast enough + has a nice design? Is 1:6 L/B ratio best in my situation? I would appreciate a LOT any kind of help, any ideas, any pictures, any tips. If anyone has any FreeShip drawings, that would be great too.
I want to apologize for my bad grammar, and Thank you a lot in advance. If you have any further questions, just ask.
Have a nice day!

[rwatson]

I would start out with a 90cm steel hull (to just below the waterline, with polystyrene topsides), that weighed 3 kg

[HaveANiceDay]

Thank you for your reply. Any ideas what type of ship would be fast enough and stable in my situation?

[Submarine Tom]

Your grammar is fine, don't worry.

How long do you have before the competition date?

What is the budget ($$$).

How large is your design/build team (number of people)?

-Tom

[HaveANiceDay]

Hey Tom!
1) Competition starts on 10th of March, so i think we have plenty of time. But I need to decide which type of ship we are going for pretty soon.
2) Ehmm, what are you thinking about when it comes to budget? Because motor and propeller we are getting from school, same as the rest of the materials. But if there is something in particular you are thinking about, I think it shouldn't be a problem to get it, if its okey with the rules.
3) Number of people is 3 (including myself).

[Submarine Tom]

Okay, thanks.

First, use the "Search" option in the header (above) on this forum to look for previous threads (posts) as this comes up every so often and there is already lots of information there.

Post the rules for us to see. Are there any other "Rules" we should know that have been spoken of in your class room. Is it supposed to look like a freighter?

1:6 is not so ideal for this model. I'm not sure but I believe 1:12 or even 1:16 may be better.

It sounds like it's going to come down to motor, propeller, and battery selection. A li-ion hand drill may be the way to go and just tear it down for parts. But you said you get these from the school so are they standardized or can you source your own?

What you want to do is get something in the water very, very soon and then test and develop your design.

How much time and energy are you inclined to put into this event?

You will find many, many ideas and suggestions here.

-Tom

[Stumble]

I would probably start with one of the high speed ferries like http://en.wikipedia.org/wiki/HSC_Tarifa_Jet

[KJL38]

Does the third rule you listed rule out a catamaran?

"Model should be designed with a hull."

Does this define the number of hulls as one?

[rwatson]

Originally Posted by Stumble

I would probably start with one of the high speed ferries like http://en.wikipedia.org/wiki/HSC_Tarifa_Jet

Heeeeey - that Catamaran was built just up the road from me - in Tasmania :-)

I would tend to go for a single hull - since you 'have' to have all that ballast. Make it the maximum length for speed. Having to build multiple hulls is a pain - and for the speeds you will be going, and the cargo - a long single hull might be just as fast. 3kg of ballast in a catamaran that size will ruin that configuration.

I cant believe you have to have so much ballast for such a small boat.

Its also a shame that the batteries cant be part of the ballast. maybe you assemble a steel/copper circuit soldered to the top of the steel ballast to increase the electrical output.

[Poida]

The rules say it has to be a scaled down model of a ship and obviously a container ship. Therefore a catamaran seems out of the question.

You could purchase a model ship and scale it to suit your needs.

You would need the electric motor as low as possible to act as ballast and sit it between the two pieces of metal that form the ballast.

Poida

[HaveANiceDay]

To Tom:
The things I listed are pretty much all the 'rules'. It doesn't matter at all how the ship looks like, but yeh its main function would be to transfer containers in reality. But that is minor thing, all I want is it to be stable, fast enough and if possible some nice design.
Can you explain me what role does the width play in my situation? Would it be more stable if it not so wide, f.e as u said 1:12 ratio?
The motor is standard for every model in country. Otherwise it would be unfair if everyone had different.
Thanks for the advice, I'm going to search this forum a lot and will try to find something. I'm willing to put as much energy as it takes to win

To KJL38:
No you can have as many hulls as you like, but I should probably stick to one.

To rwatson:
Thank you for your reply. I will think about what you said. That part with increasing the electrical output, could you explain it little bit more detailed?

To Poida:
The rule doesn't say that you can't go for catamaran. As I said, it can be whatever shape we want. But I guess there is a reason why there are none catamaran-freighter. And thank you for your reply!
Have a nice day!

[Tad]

The ideal hull form is derived from your operating speed.

You have a maximum length, add up your weights (cargo, propulsion, hull, ballast) to establish displacement. Calculate speed (Froude number) from power and weight.

Then get into Freeship and start modeling for minimum drag at your operating speed. Create a series of models of varying beam/depth, pick the best compromise between speed and stability.

[Submarine Tom]

Hi,

I'm trying to help this kid out.

Is this a reasonable hull design for 1-2 m/s?

He's judged according to the OP, although, it turns out he left maneuverabilty off, which is also judged.

Centre section shown.

Loa 90 cm, Draft is 20 cm, Beam 12.5 cm (7.0 cm at water line), freeboard 5.5 cm.

Displacement 7.2 kg.

-Tom

[Submarine Tom]

The kid needs to start building.

Is the design above going to win him points?

Criteria:

• The model should be made in scale 1:100 of 90m long ship(total length), so it shouldn't be longer than 90cm.

• The boat should be made out of polystyrene.

• Model should be designed with a hull.

• It should transport a load of a total 3 kg water, spread into 6 juice boxes. The boxes should be placed above the waterline.

• It should be equipped with 3 kg ballast, in form of a metal plate on the hull bottom.

• Powered by an electric battery, engine and propeller.

Testing of the designed boat:

• Speed test : Sailing distance is 2 x 50 meters. Up to 50 and back.

• Stability test: The models will be tested for the amount of roll that occurs at a given load displacement. The offset will be defined by the load center is 5 cm on the starboard or port side.

• Design: Design and creativity of the boat.
  
  And Maneuverability test.
  
  The kid needs to start building.
  
  Is the design above going to win him points?
  
  -Tom

[Mr Efficiency]

I'm not sure I know what I'm looking at.