In an exciting fight Tia ran out the 15-13 winner and she booked a final place against the number one seed and up to that point undefeated Alexanne Verret.
There was scant time for Simms-Lymn to rest up as the final was scheduled for three hours after the semi.
The final proved to be very tactical with both fencers not wanting to risk too much, but the city student prevailed in a narrow but impressive 11-9 victory.
The Olympic hopeful’s coach Andy Hill who is director of pentathlon and fencing at Plymouth College, said: “Tia is beginning to fulfil her potential and with hard work and dedication from both of us, she has a possible chance of qualifying for the Rio Olympics.”
Simms-Lymn’s success at the Pan American Championships reflects her progress over the past 12 months in which she has won the GB under-16 epée and foil titles before qualifying for the Youth Olympics in Nanjing, where she reached the last-eight.