船对船加注软管系统一般采用软管进行燃料输送，因软管挠性可有效应对船间距离不断变化的情况，具有巨大优势。为防止受洋流等因素影响，船间距离增加导致软管损坏甚至破裂，需设置船舶距离监测器监测船间距离并在危险情况下报警。通过分析船舶自身运动、船间漂移等因素对船对船加注系统安全性的影响，提出了船舶加注包络面计算方法，并基于某14000m3加注船实例，计算得到船舶距离监测器ESD1、ESD2报警信号对应的绝缘钢绳缆长度分别为9.5m和17m，与国外系统对应参数9.3m和16.8m的偏差分别为2.1%和1.2%，充分证明了本计算方法可用于船对船加注系统中的船舶距离监测器ESD报警信号的设置，从而提升船舶加注过程的安全性。

The ship-to-ship transfer system using hoses has great advantages because it can effectively deal with the changing distance between vessels. Affected by ocean currents or other factors， the distance between the vessels may increase， which leads to flexible hose being damaged or even broken. To prevent this， the vessel separation detection should be set to monitor the distance between vessels and trigger an alarm when accidents happen. By analyzing the influence of the vessel's movement such as drift between vessels， a calculation method for the safety envelope surface of the ship-to-ship transfer system was proposed. Based on the parameters of a 14000m3 LNG bunkering vessel， the ESD1 and ESD2 alarm distance were calculated as 9.5m and 17m， respectively. The RELATIVE deviations from the corresponding parameters of 9.3m and 16.8m in foreign systems are 2.1% and 1.2%， respectively. It fully proves that this calculation method can provide guideline for the parameter ESD1 alarm setting of vessel separation detection， so as to improve the safety of ship bunkering process.