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Design Philosophy

Why do you commission a custom yacht? Surely because the existing designs do not meet your requirements.
This also gives us the basis for our design philosophy. Firstly, a good designer should design a product that best meets the customer’s requirements. Secondly, there is no point designing yachts that are similar to the current mass produced, on interior volume focused boats.
Our third philosophy is “less is better” especially for cruising yachts. Yachts that have to be sailed by a small crew. We aim to minimise weight and drag which will allow us to use a smaller sail area for the same performance. This results in a safer and easier to handle boat.
To minimise drag at normal sailing speeds the width of the waterline has to be reduced. You can think of it as a peloton in a bike race. It is more efficient for the riders to cycle in a long line than next to each other because most of them are in the slipstream of the rider ahead. The same principle applies to hulls. The aft parts of the hull are in the slipstream of the parts in front and produce less drag.
Narrow boats can also heel more before the hull shape becomes inefficient. This means they are actually keel yachts where the keel produces the majority of the righting moment. At zero heel angle the keel produces zero righting moment. Wide yachts have to be sailed more upright and rely in large parts on the crew weight on the rail to ensure the boat is fast. On cruising yachts this contradicts the small crew requirement. To substitute the crew weigh one would have to start looking at water ballast.
Therefore, we prefer relatively narrow boats which are also more sea friendly and comfortable to sail.
In regards to materials we would recommend carbon fibre. The material costs are higher than most other materials but the labour hours can be less compared to glass fibre. This is because less layers of material are required. We prefer to use a smaller amount of high quality materials.
For a custom yacht project glass fibre makes less sense because the material costs are only a small fraction of the overall project costs. Think of it as getting a custom piece of jewellery designed and then casting it in iron instead of a precious metal. Why would you do that?
Similar thoughts apply to core materials. We would not recommend balsa because it is relatively heavy, brittle and can soak up water. Water will eventually lead to rot and delamination. It is not worth risking this. Instead we recommend ductile foam cores for high impact resistance. These cores have a closed cell structure. Even if water should get into the core it can’t migrate because every single cell wall acts as a barrier.
If you have a project in mind that meets our philosophy, please contact us. We would be excited to learn about your ideas.

Other Projects

We have also worked on large rail projects managing engineering teams as well as taking responsibility for the design and engineering of various metal and composite structures. Most of these project have team members on different continents. We are therefore used to working in an international environment. We also experiment with micro controller based electronics.

More info can be found at www.kj-engineering.com.au