The Research And Application On The Intact Stability Of Keel Sailboat

The stability of sailboat is the ability to restore the heeling when the external force results in the trim or heel of the ship,which is the basic security of sailing and main contents of sailboat test.It is also one of the most concern problems to the person who is designing and using.Usually ship's stability is only considered in calm water.In actual voyage,the impact of waves and sailing to ship safety and capsize,both cannot be ignored.For keel sailboat,hanging sailing is a complex process.The motion attitude is different from conventional ship,such as sailing with a certain angle.At the sometime,with a big sail wind area and a high wind pressure center,the security risk of capsize is larger than general ship.At present,the literatures about stability of keel sailboat are rare.This paper is carried out to study the variable rules in calm water stability,following sea stability and dynamic stability when sailing of keel sailboat.This paper,taking a keel sailboat by domestic enterprise,for example,studies as follows.1)Establishing the three-dimensional hull model of keel sailboat,using the method of variable weight position change to stability and based on the software MAXSURF to calculate calm water stability.Focus on the research the influence rules of crew layout as load position change to the stability of keel sailboat,getting the maximum influence on stability respectively located in cabin room,aft deck and upper deck.According the specification,getting the range of wind speed is 3.8m/s to 8.8m/s at the security sail wind speed under the full sails.In other words,the crews in different load position can meet the specification to achieve the maximum operating sail wind speed is nearly 57%.2)Based on the surface integral method to study the following sea stability of keel sailboat,analyzing the influence rule of different wave factors to stability,such as wave amplitude and height,the relative position of wave and ship.The results show that wave factors have a larger influence on the initial stability.When the ship in following sea in uphill section position,the initial stability will reduce nearly 37% than the calm water.For the larger angle stability,when the ship in following sea in crest and in downhill section,it will decrease and occurred in the heeling angle greater than 60 degrees.The trend of following sea large angle stability and calm water stability is opposite in following sea in troughs and uphill section by a heeling angle 65 degrees.3)Based on the theory of mechanics and VPP,using MAXSURF VPP to analyze the motion attitude of keel sailboat,getting the range of speed and sailing angle.According to the actual sailing,to establish numerical towing tank and using CDF to simulate dynamic stability under different speed and heeling angle,comparing the different righting moment under different speed and heeling Angle while sailing on the calm water and following sea.Conclusions are drawn that Sailing in the design speed the righting moment will decline 8.0% and 6.4%,respectively with the increase of speed,when keel sailboat sailing in calm water with heeling angle 10 degrees and 20 degrees.The righting moment in following sea around the calm water righting moment fluctuates up and down,and the maximum righting moment compared to calm water righting moment can reach 22.40% to 53.61%.4)According to the intact stability criteria for keel sailboat in “Guidelines for Survey of Sailing Craft-2012”-CCS.The paper carries on the re-development to Rhinoceros by C# program and realizes to the development of keel sailboat intact stability computation system,which has the advantage of high computing precision and efficiency.