Concrete Canoes

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Glen Smith
Posts: 3719
Joined: Sat May 08, 2004 9:08 am
Location: Baie-St-Paul, Quebec, Canada

Concrete Canoes

Post by Glen Smith »

Dear Sirs,

My name is Neil Johnston and I am currently attending Ryerson University.

For the past two years we have competed in an undergraduate project called "The Concrete Canoe". This is a North American Competition, Canada being one of the Regions. In our brief two year history we have already become a competitor, last year we earned second place.

I recently came across your web page while doing some research and admired your different makes and designs of canoes. I am asking for your help in the design process of this years canoe. Ryerson is one of 4 schools in Canada that offer a Geomatics option for Civil Engineering. With the knowledge base in geomatics we could visually laser scan an existing canoe, and import the data into various computer generated models.

Another reason for my excitement with your company, is that I am from Peterborough as well.

Thank you again for your time,

Neil Johnston

Capatin of Ryerson Concrete Canoe Team
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Glen Smith
Posts: 3719
Joined: Sat May 08, 2004 9:08 am
Location: Baie-St-Paul, Quebec, Canada

Post by Glen Smith »

Neil,
Bear Mountain forwarded your e-mail to me - I am the designer of the Bear Mountain boats. I have been happy to help out with advice to other Concrete Canoe teams in the past, some Canadian and some for the US, with whatever knowledge I have.

I think to learn about various canoe shapes, we can give you several things - you don't need to go to the trouble of scanning a canoe. I would be happy to give you an example 3D computer file of one of our designs and we can send you our catalogue of study plans in the mail. The study plans has the hull lines drawings in small format of 26 small craft which you could scan, trace and model in 3D.

I have taken the liberty of attaching the hull lines for the Freedom 17, which is typical of a performance oriented boat. Your boat would undoubtedly be longer and probably narrower, and considerably heavier! but the shape may help. The units of the IGES file is inches. The hull was originally drawn in FastShip software although I now do most of my work in Rhino3d (www.Rhino3d.com) .

If asked to rank the importance of the various factors in concrete canoe design I would say:
1. weight - your construction team is very important - light weight means better performance and is the number one factor.
2. paddling ability - good paddlers will let you beat a superior design. Practice, practice, practice.
3. hull shape - important for sure to get the hydrodynamics correct.
4. hull fairness and surface finish - a good finish reduces drag.

If you would like to send me the shape of your existing canoe I might be able to make some comments that would be of value.

Regards,
Steve Killing
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Glen Smith
Posts: 3719
Joined: Sat May 08, 2004 9:08 am
Location: Baie-St-Paul, Quebec, Canada

Post by Glen Smith »

Neil,
My experience with AutoCAD is that it is very difficult to create fair surfaces - so you might make your life easier by getting yourself Rhino 3D and spend some time making various shapes before you tackle the canoe. I think you will enjoy the program.

I have put the catalogue of designs in the mail today - you should be able to use the hull lines to re-create in 3D any of the canoes. When you are doing comparisons of wetted surface and prismatic make sure the boats are all floating at the same displacement (weight). Wetted surface especially is sensitive to having the canoes floating at the same weight. The Redbird, although still a good shape will have more wetted surface when it is floated at the same displacement as the Freedom.

You will note that the Redbird is a symmetrical design (bow is the same as the stern), while the Freedom 17 is asymmetrical (stern is fuller than the bow). We have found that the asymmetrical designs have a slightly higher top speed for their length.

The prismatic coefficient is a measure of how fine the ends of the canoe are - low prismatic means fine ends. A boat with a low prismatic will be easy to paddle a low speeds, a high prismatic is good for high speeds. In general I would keep the prismatic between .52 and .62. Because of the weight of your boat compared to a 45 lb Kevlar canoe, I would assume your top speeds would be less and therefore you would want a slightly lower prismatic. You might paddle your last-year's canoe and see what speeds you attain before picking a prismatic. The Redbird prismatic may be a bit low for your use.

We don't have any canoes for you to practice in, and I think you would get a better representation of the shapes by starting with the drawings in the catalogue rather than scanning a less-than-perfect artifact of a canoe.

It sounds like you have the rest of the process well under control and your FLUENT analysis is a good direction to go.

Best of luck with the project and let me know if there is anything else that I can do for you.

Regards,
Steve Killing
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