Birth of the Bigger Sister
Build on what you know.
From the beginning of Kraken, the idea was to have 3 boats in the range; K50, K58 and K66. The first K66 was built for Dick Beaumont, Chairman of Kraken, and after which we focused on the K50s. During the last 4 years we continuously refined the K50, the results could be seen when we launched Sofia Marie this summer in Istanbul and the next K50 that is coming in the spring 2022 will be even better. At the same time Dick Beaumont covered over 30,000Nm on his K66, sailing from Hong Kong to Turkey, which provided further insights into our design solutions.
Over 4 years of development is no small feat and the K58 design, which was developed originally in 2017 needs to follow suit. This presents us with a great opportunity to take all the accumulated experience and funnel it into the lines of the new and improved K58. And much like the original Birth of a Blue Water series, you, the reader, will have a great opportunity to follow the design process of a Kraken Yacht from start to finish.
For some there is the circle of life, while others will try to balance everything like yin-yang. For a yacht designer there is the design spiral. It illustrates the steps and order of works to design a yacht. In simple terms you start with a set of requirements, then you design the hull, deck and appendages, then the rig, followed by interior and major systems. Structures are next. Finally you check the weights, stability etc.
The last step is evaluation. What always happens is as you move to the next step you will upset something from the steps before. You have designed a beautiful flowing deck but no headroom in a bow shower? Amazing saloon layout, but no space for frames? At the evaluation stage you take all of these notes into account and go again. Now you no longer have a set of requirements but an updated data set for the next iteration. You fix the headroom situation with the bow head but now the rope channels don’t work. “99 problems in the design, fixed one. 100 problems in the design…”
This is why it is called the design spiral, you go around and around until you iron out all the kinks. Roughly it takes 3 passes to have a good design and about 7 passes to have a finished drawing set. Very often passes 6-7 are done during production, despite designers best intentions some issues cannot be spotted until it’s in production.
The first steps.
The very first step is to nail the set of defining factors for the design. This is achieved over quite lengthy meetings within the Kraken team and at the end we have a robust design brief which allows Kevin Dibley to work on the hull, appendages and rig. Everything that makes the boat sail well and be comfortable. After a decent amount of back and forth we have our first drawings; the lines plan and sail plan.
The lines plan.
The lines plan shows the shape of the hull and side profile of the appendages. It is probably the single most important drawing in the set, it dictates all other aspects of the project, so it is extremely important to get this right. All other aspects of the build take second place, so while the designer is going round the design spiral they will very rarely make significant changes to the lines of the hull. Here we look at all the numbers that make up a good canoe body shape. Refer back to my series of articles about hull design where I go more in depth about this topic, October, November and December 2020 Ocean Sailor Magazines.
Apart from making sure the LCB, VCB, Cb, Cp etc are all correct we also need to make sure that the hull has all of the key characteristics of a Kraken yacht. The deep V shape on the bow for improved comfort in rough seas, the keel is optimised for the Zero Keel production method while maintaining a NACA section for best lift characteristics. The rudder, while of course skeg hung also has to have the right NACA section that is shared between the rudder and the skeg. Also, at the same time the designer is making a note of the centre of lateral resistance of the underwater section that is later needed for sail lead. This is something that often is adjusted in the next pass when the optimal mast position is established. Most likely the rudder position would be updated.
The sail plan.
The sail plan follows soon after. Since these are sailing boats first and foremost it makes sense that it sails well. And it will, with a Solent rig and the Code K we design the sails in such a way to have an optimised setup for any point of sail.
Sail sizes are established to give a position of the mast based on desired sail lead. For a well balanced rig we work with around 10.5% under full main and jib.
Then all the rig ratios need to be addressed; SA/Disp ratio, CoEff optimised for righting moments while maintaining a good aspect ratio of the sails for optimal drive. While the sailmaker and the spar maker will have a lot of input into this further down the road, it’s the yacht designer that sets the main parameters and overall design for this.
The next steps.
With the “shell and stick” on paper, the focus then shifts towards the general arrangement and main systems. A slight departure from the norm is that at Kraken we look at the GA and major systems before focusing on the deck. The very basic deck shape is usually drawn at the same stage as the hull but rather than developing that further early on we want to see how the inside pans out and then fit the deck to that as much as possible.
Therefore the GA and systems are the next step and we will focus on that in the next segment of this story.