Archimedes’ death ray might have worked, teen science project suggests | CNN

"I'm standing right in it and I'm not dead."

That is discussed in the article:

The Discovery Channel series “MythBusters” featured episodes in 2004, 2006 and 2010 testing out scenarios for the purported death ray but ultimately declared the legend to be a myth when each test failed to light a wooden boat on fire. In 2005, a class of students at the Massachusetts Institute of Technology, inspired by the show’s first episode, was able to ignite a wooden boat once with a similar technique to Sener’s on a larger scale, but failed on a second attempt.

Sener said he believes that combining MIT’s findings with his own, the data could suggest the death ray was plausible, and Archimedes likely could have used the sun’s rays with large mirrors to cause combustion. But the technology may not work in cold temperatures or cloudy weather, and the sea’s impact on the ships’ motion affects the practicality of this device, he added in his paper.