Need help on Catamaran Design.

[kharon]

Hi Every1;

I am a last year student on mechanical engineering and as a class project have to design a catamaran form scratch. Well the problem being with that is i have no idea where to even begin.

I have looked everywhere for some research material and could only find Larsson's Yacth design. the book is good and all with some neat explanations but it doesn't involve multihulls. So this is my problem. The end result should have a;

Carrying capacity of 4 ppl + 100 kg of weight (this is as a baggage)

speed: 40knots (max)

how we achieve these is in our hands. I just cant let myself do a 2. rate design and i want this to be a good catamaran in the end.

So if any1 can point me in the right direction it would be greatly appreciated.

Thnx

[Sistrunk]

Try this link: How to dimension a sailing catamaran?

Downloads that might be of help:

[Richard Woods]

I assume you need to design a powercat?

otherwise you'll find 40 knots a VERY challenging design criterium!

Richard Woods of Woods Designs

www.sailingcatamarans.com

[kharon]

Originally Posted by Richard Woods

I assume you need to design a powercat?

otherwise you'll find 40 knots a VERY challenging design criterium!

Richard Woods of Woods Designs

www.sailingcatamarans.com

Well i dont think my prof. considered that when he gave the assignment to us but why would it be a very challenging criteria? well in any case i am gonna check powercats now also. thnx

Originally Posted by Sistrunk

Try this link: How to dimension a sailing catamaran?

Downloads that might be of help:

These are awesome ty.

[Ad Hoc]

Get some magazines and search the interenet. Look for cat's doing 40knots of the size you're looking at. Look to see if there are dimensions that are common. Then just sue the most common dimensions as your starting point.

Then draw up your basic GA from the dimensions. So you'll need to know the size of engines/jets/props etc...seats...and then work out what the weight of all this would be. The only part that would be tricky for you would be the structure weight.

If you work out the structure weight in steel, ally, compoiste, then then use the differnces in weight as part of your design of "why".

[messabout]

A 40 knot cat is certainly doable but totally impractical in terms of common sense, fuel consumption, cost, durability and a few other constraints. If you prof. assigned this project he is not a shrewd boat person.

[Sistrunk]

Maybe he is very shrewd and we are simply overlooking his approach?

[outside the box]

Read the post properly folks 40 knots (max)

[Mr Efficiency]

Why is a mechanical engineer being asked to design a boat ? Are budding chefs asked to design dresses ? Seems a bit wacky to me.

[FMS]

Originally Posted by messabout

A 40 knot cat is certainly doable but totally impractical in terms of common sense, fuel consumption, cost, durability and a few other constraints.

I beg to differ. There are economical very practical powerboats that have a wot of 40 knots. For example, http://www.glacierbaycats.com/site/w...665_Yam150.pdf
3 MPG cruise at 20 mph or 2.2 MPG at a 28 mph clip.

[Mr Efficiency]

I can just see a novice designing a boat like that......not !

[FMS]

Yes, with an academic project such as this, the student needs to start by asking himself what criteria will be used to evaluate the final project. Sometimes you have to know the professor or get a look at past work that has gotten top marks. It could be in this "hypothetical testbed" 85% of the final mark will be based on aspects a ME is expected to be in his element working out, such as material properties, structure, basic stability and weight distribution, etc. and 15% on the aspects outside the normal curriculum. Does the school or the professor have a NA connection? How will your final result be evaluated?

[kharon]

Originally Posted by FMS

Yes, with an academic project such as this, the student needs to start by asking himself what criteria will be used to evaluate the final project. Sometimes you have to know the professor or get a look at past work that has gotten top marks. It could be in this "hypothetical testbed" 85% of the final mark will be based on aspects a ME is expected to be in his element working out, such as material properties, structure, basic stability and weight distribution, etc. and 15% on the aspects outside the normal curriculum. Does the school or the professor have a NA connection? How will your final result be evaluated?

well this is a design class so everything is based on the boat. and about the NA connection none that i am aware of. He changes the final project every year this year it was a 3 wheel car and a catamaran. In the draw i go the catamaran. so we dont even have a past project that we can check out.

Originally Posted by Mr Efficiency

Why is a mechanical engineer being asked to design a boat ? Are budding chefs asked to design dresses ? Seems a bit wacky to me.

Well i think he just wants us to feel challenged.