While the design and production team was working on the high speed motor sailer at BST Engineering (Antalya, TR) a huge hull resistance optimization problem showed up. At the integration process of semi displacement motor yacht hull and sailing yacht hull was impossible with our software and naval architecture knowledge. 

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So our team was decided to design and product a Towing Tank, that we can imitate the phenomena of the displacement and semi displacement regimes for high speed motor sailer hulls and optimize the resistance and seakeeping performances. 

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Main dimension of this tank was:

L = 50.00 m

B = 6.00 m

D = 6.00 m

T = 5.50 m

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which was enough for 1/10 model tests for 17.50 m motorsailers. 

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We made the model tests of 1 built and 4 designed, different, but with same lenght, hull types.

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Firstly we compared the results from model tank, Maxsurf Hullspeed module and full scale results of built hull. Than we compared the results from model tank and Maxsurf Hullspeed module for the other 4 designed hull. 

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With these datas, we derived the transfer function between results of model tests and Maxsurf Hullspeed. Also we could derive the results for full scale experiment and Maxsurf Hullspeed. So we had the exact transfer fuction between model test experiments and full scale experiments. 

So, we optimized the high speed motorsailer hull which can reach the same Froude Number with sailing and motor propulsion both.