Lackenby与Raven浅水航速修正方法应用对比

Correcting Shallow Water Effect on Ship Trial Speed——With Lackenby or Raven

对Lackenby浅水航速修正方法和Raven浅水航速修正方法进行介绍,并结合30万吨级超大型油船(Very Large Crude Carrier,VLCC)、40万吨级矿砂船和18万吨级散货船等3种典型船型的实船航速试验数据对这2种方法进行对比。结果表明:当水深临近浅水上限时,Raven方法相比Lackenby方法对航速修正结果不利;当水深接近深水标准时,Raven方法的浅水航速修正结果与Lackenby方法相近。在此基础上,给出典型肥大型低速船在应用ITTC 2017采纳的Raven方法时选择试航水深的建议。

Lackenby’s method and Raven’s method are used to calculate the shallow water effect on sea trial speeds of three ships,a 300000 t VLCC(Very Large Crude Carrier),a 400000 t VLOC(Very Large Ore Carrier)and a 180000 t BC(Bulk Carrier).The two calculated results are compared.It draws a conclusion that the two methods give similar results when the water depth in trial area is close to the deeper end of shallow water definition,but they deviate when the water is really sha-llow,with Lackenby giving more accurate results.Suitable water depth for speed trial are suggested for low froude number and high C B vessels,to which ITTC 2017 has recommended Reven’s method.