Wouldnt burning oars do?

Ancient Greeks were masters of commitment and preparing for victory. When they landed on the enemies shore, the first thing the commander did was instruct the troops to burn the boats. THAT is how YOU have to think. If you have a Plan B, Plan A is never going to happen.

— Bo Eason (@BoEason) June 15, 2019

When I was little, I had to incorporate an idiom into a sentence.

"eru daati theppa thagalbettinattu"

to burn an oar after crossing the river

I used it in an example as tearing your bus ticket after a trip. I did understand that it didnt totally get to the idiom's saying of makign something useless to self/others after having benefited from it. By tearing a useless ticket, you dont capture the essence of this idiom.

From the motivational point of burning boats, wouldnt just burning oars do? Or you would find poles from the forest and quickly make make-shift oars? or may be your enemies would do that?