推算船位之前的英文

• ahead of reckoning

• 推算:    calculate; reckon; reckoning ...
• 船位:    accommodation
• 之前:    before; prior to; ago
• 推算船位:    dead reckoning position; eestimated position; position by dead reckoning; reckoning (or dead recking)
• 推算船位积算船位:    dead reckoning position